NCRP report no 127 operational radiation safety program

This Report reiterates the basic principles for establishing and maintaining an effective operational radiation safety program.. Rel- evant aspects of such a program are discussed includ

OPERATIONAL

PROGRAM

Recommendations of the

NATIONAL COUNCIL ON RADIATION

PROTECTION AND MEASUREMENTS

Issued June 12,1998

National Council on Radiation Protection and Measurement

791 0 Woodmont Avenue / Bethesda, Maryland 2081 4-3095

LEGAL NOTICE

This Report was prepared by the National Council on Radiation Protection and Measurements (NCRP) The Council strives to provide accurate, complete and use- ful information in its documents However, neither the NCRP, the members of NCRP, other persons contributing to or assisting in the preparation of this Report, nor any person acting on the behalf of any of these parties: (a) makes any warranty

or representation, express or implied, with respect to the accuracy, completeness or usefulness of the information contained in this Report, or that the use of any infor- mation, method or process disclosed in this Report may not infringe on privately owned rights; or (b) assumes any liability with respect to thc use of, or for damages resulting from the use of any information, method or process disclosed in this Report, under the Civil Rights Act of 1964, Section 701 et seq a s amended 42 U.S.C

Section 2000e et seq (Title VII) or any other statutory or common law theorygovern-

ing liability

Library of Congress Cataloging-in-Publication Data

National Council on Radiation Protection and Measurements

Operational radiation safety program : recommendations of the National Coun- cil on Radiation Protection and Measurements

p cm (NCRP report ; no 127)

"Issued June 1998."

Includes bibliographical references and index

ISBN 0-929600-59-2

1 Radiation-Safety measures I National Council on Radiation

Protection and Measurements 11 Series

NCRP Report No 59, Operational Radiation Safety Program, was published in 1978 That report provided the philosophy, basic principles and requirements for a radiation safety program In the intervening years, there have been many new developments including: new NCRP recommendations for limiting exposure to ionizing radiation (NCRP Report No 91 in 1987 which was super- seded by NCRP Report No 116 in 1993); new techniques for the measurement and control of exposures and the disposal of radioac- tive waste; and new applications for ionizing radiation and radioactive materials These developments served as the Council's rationale for preparing the current Report which supersedes NCRP Report No 59

This Report reiterates the basic principles for establishing and maintaining an effective operational radiation safety program Rel- evant aspects of such a program are discussed including: facility design criteria, organizationaVmanagement issues, training, inter- nal and external radiation control strategies, radioactive waste disposal, environmental monitoring, radiation safety instrumenta- tion, and emergency response planning

This Report does not attempt to summarize the regulatory or licensing requirements of the various federal, state or local author- ities that may have jurisdiction over matters addressed in this publication

This Report was prepared by NCRP Scientific Committee 46 Serving on the Committee were:

Kenneth R Kase, Chairman (1991-1

Stanford Linear Accelerator Center

Menlo Park, California Members

John W B a u m (1993-) Kenneth L Miller (1995-) Brookhaven National M.S Hershey Medical

Upton, New York Hershey, Pennsylvania

Florida Power Corporation

Crystal River, Florida

J o h n W Poston, Sr (1991-1 Texas A&M University

College Station, Texas Keith Schiager (1991-1997) Salt Lake City, Utah

Ralph H Thomas (1991-1996) Moraga, California

P a u l G Voillequk (1993-)

M J P Risk Assessment, Inc

Idaho Falls, Idaho Robert G wissink*

(1991-1995) 3M Health Physics Services

Eric E Kearsley (1997-), Staff Scientist

Thomas M Koval(1993-1997), Senior Staff Scientist

J a m e s A Spahn, Jr (1991-1993), Senior Staffscientist

Cindy L O'Brien, Editorial Assistant

The Council wishes to express its appreciation to the Committee members for the time and effort devoted to the preparation of this Report The Council also gratefdly acknowledges the support pro- vided by the Health Physics Society in 1998 that permitted the completion of this Report

Charles B Meinhold President

Contents

F'reface 111

1 Introduction 1

1.1 Purpose of this Report 1 1.2 Purpose of the Operational Radiation Safety Program 2

2 Application of ALARA 5

2.1 Applicability of Cost-Benefit Analysis in the

ALARA Process 7 2.2 Concepts of a Cost-Benefit Approach to ALARA 8

2.2.1 Applicability of Collective Effective Dose 8

2.23 Dose Magnitude and Distributions 8

2.2.3 Monetary Value of Avoided Dose 9

2.3 Screening for ALARA Assessment 11

3 Organization and Administration 12

3.1 Management Commitment and Policy 12

3.2 Radiation Safety Organization 13 3.2.1 Radiation Safety Advisory Organization 13

3.2.2 Radiation Safety Officer 14

3.3 Accreditation and Certification 14 3.4 Radiation Safety Program Policies and

Procedures 15

3.4.1 Radiation Safety Manual 15

3.4.2 Radiation Safety Operating Procedures 16

3.5 Responsibility 17

3.6 Quality Assurance 18

3.6.1 Management Goals 19

3.6.2 Surveillance 19

3.6.3 Program Audits 20

3.6.4 Incident and Accident Investigations 21

3.6.5 Deficiency Tracking 22

3.7 Records Management 23

3.8 Occupational Medicine 23

3.9 Recommended Additional Reading 24

4 Facility Design 26

4.1 Site Selection 26

vii

4.3 Equipment and System Design 29

4.4 Shielding 30

4.5 Ventilation 32

4.6 Radioactive Material Waste Management 35

4.7 Instrumentation and Access Control Systems 36

4.8 Nuclear Criticality Safety 36

4.9 Recommended Additional Reading 36

5 Orientation and Training 38

5.1 General Principles 38

5.2 Design of a General Training Program 39

5.3 Specific Training Requirements 41

6 External Radiation Exposure Control 42 6.1 Radiation Dose Controls 43

6.1.1 Limits 43

6.1.2 Administrative Dose Guidelines 43'

6.2 Radiation Dose Control Techniques 43

6.2.1 Time Distance and Shielding 44

6.2.2 Access Control and Alarm Systems 45 6.2.3 Radiation Safety Procedures and Radiation

Work Permits 48 6.2.4 Exposure Planning and Dose Reduction Activities 49

6.3 External Radiation Dosimetry 49

6.3.1 Personal Monitoring 49

6.3.2 Dose Assessment 5 1

6.4 Monitoring and Surveillance Program 5 1

6.4.1 Radiation Surveys 51 6.4.2 Area Monitoring 53

6.5 Protective Clothing 53 6.6 Records 54

6.7 Recommended Additional Reading 55

7 Internal Radiation Exposure Control 56

7.1 Radiation Dose Controls 57

7.1.1 Limits 57 7.1.2 Administrative Exposure Guidelines and Reference Levels 57

7.2 Contamination Control Programs 57

7.2.1 Access Control and Alarm Systems 59 7.2.2 Radiation Safety Procedures and Radiation

Work Permits 60 7.2.3 Exposure Planning and Dose Reduction

Activities 61

CONTENTS / i~

7.3.1 Personal Monitoring 62

7.3.2 Bioassay Measurements 6 3

7.3.3 Dose Assessment 6 5

7.4 Monitoring and Surveillance Program 66

7.4.1 Monitoring for Airborne Radioactivity 66

7.4.2 Contamination Surveys 69

7.5 Protective Equipment and Devices 69

7.5.1 Containment Systems 69

7.5.2 Respiratory Protection 70

7.5.3 Protective Clothing 70

7.6 Records 7 1 8 Control of Low-Level Radioactive Waste 73

8.1 Minimizing t h e Production of Waste 74

8.1.1 Practices for Minimizing Waste 74

8.1.2 Practices for Reducing Mixed Waste 75

8.2 Decontamination and Reuse of Tools and

Equipment 76

8.3 Collecting Sorting and Classifying Waste 76

8.4 Radioactive Waste Volume Reduction 77

8.5 Storage o f w a s t e 78

8.6 Disposal of Waste 78

8.7 Recycling of Waste 79 8.8 Records 79

8.9 Recommended Additional Reading 80

9 Control of Exposure to the Public 81

9.1 Standards a n d Guidance 81

9.2 Control of Off-Site Exposures 82

9.2.1 Determining the Need for Monitoring 8 3

9.2.2 Monitoring Airborne Effluents 84

9.2.3 Monitoring Liquid Effluents 86

9.2.4 Monitoring Solid Waste 86

9.3 Environmental Monitoring 8 7

9.3.1 Preoperational Monitoring 88

9.3.2 Operational Monitoring 8 9

9.4 Measurement Methods 90

9.5 Dose Assessment 9 1

9.6 Quality Assurance 92

9.7 Records 93 10 Radiation Safety Instrumentation 9 4

10.1 Instrument Specification 95

102 Calibration 96

10.3 Instrument Maintenance 98 10.4 Use of Instruments and Acceptable Uncertainty 99

10.5 Selection of Instruments for Various Applications 100

1 Introduction

1.1 Purpose of this Report

In 1978, the National Council on Radiation Protection and Mea- surements (NCRP) published Report No 59, Operational Radia- tion Safety Program (NCRP, 1978a) to provide, in a systematic way, the philosophy and the basic principles and requirements for a n operational radiation safety program Since that time, a number of reports detailing specific aspects of operational radiation safety have been published by the Council These include, NCRP Report

No 71, Operational Radiation Safety-Training (NCRP, 1983a);

NCRP Report No 88, Radiation Alarms and Access Control Sys- tems (NCRP, 1986); NCRP Report No 105, Radiation Protection for Medical and Allied Health Personnel (NCRP, 1989a); NCRP Report

No 107, Implementation of the Principle of As Low as Reasonably Achievable MLARA) for Medical and Dental Personnel (NCRP,

1990); NCRP Report No 111, Developing Radiation Emergency Plans for Academic, Medical or Industrial Facilities (NCRP, 1991a);

NCRP Report No 112, Calibration of Survey Instruments Used i n Radiation Protection for the Assessment of Ionizing Radiation Fields and Radioactive Surface Contamination (NCRP, 1991b);

NCRP Report No 114, Maintaining Radiation Protection Records

(NCRF', 1992); NCRP Report No 118, Radiation Protection i n the Mineral Extraction Industry (NCRP, 1993a); NCRP Report NO 120, Dose Control a t Nuclear Power Plants (NCRP, 1994); and NCRP

Report No 122, Use o f Personal Monitors to Estimate Effective Dose Equivalent and Effective Dose to Workers for External Exposure to Low-LET Radiation (NCRP, 1995a) Reports in progress in the area

of operational radiation safety include those on radiation safety design guidelines for particle accelerator facilities, assessment of occupational exposure from internally deposited radionuclides, radiation safety related to special medical procedures, and shield- ing design for radiotherapy facilities

Since the publication of NCRP Report No 59 (NCRP, 1978a1, new recommendations have been made by the NCRP for limiting exposure to ionizing radiation (NCRP, 1993b) In addition, new applications for radiation and radioactive materials i n research,

medicine and industry have been developed Techniques for the measurement and control of radiation exposure as well as the dis- posal of radioactive waste material have evolved The principle that radiation exposures should be kept as low as reasonably achievable, economic and social factors being taken into account

(the ALARA principle) now guides the development of operational radiation safety programs The above factors provided the motiva- tion to revise NCRP Report No 59 (NCRP, 1978a)

This Report is not intended to be a design manual, e.g., for radiation shielding or ventilation systems Its objective is to describe the elements of a n operational radiation safety program that is based on the implementation of the ALARA principle below the radiation dose limits Basic principles and practices of radiation safety are emphasized Relevant elements of various NCRP reports pertaining to specific types of facilities or specific aspects of radiation safety are incorporated into the specifications provided here for operational radiation safety programs This Report should provide guidance for the development of new radiation safety programs and serve a s a useful tool for assessing mature radiation safety programs

For management personnel, this Report provides information about the basic requirements of a radiation safety program It details specific aspects of operational radiation safety and refer- ences more detailed information in other NCRP reports, publica- tions of the International Commission on Radiological Protection (ICRP), and other consensus bodies such as the American National Standards Institute (ANSI) This Report does not address regula- tory or licensing requirements that may be imposed on a radiation protection program by state, local or federal authorities

1.2 Purpose of the Operational Radiation Safety Program

Every institution and organization that uses nonexempt quan- tities of radioactive material or regulated devices that produce ion- izing radiation should provide a program plan that specifies the policies and practices that are necessary to control radiation expo- sures to its employees and the public within the prescribed limits and to levels that are ALARA The operational radiation safety pro- gram is the mechanism for the implementation of that plan The size and definition of the program should be commensurate with the potential hazards

1.2 PURPOSE OF THE OPERATIONAL RADIATION SAFETY PROGRAM / 3

The objective of a comprehensive radiation safety program is to protect people from the deleterious health effects that may result from exposure to ionizing radiation Large radiation doses can cause such effects within a short time Because such large doses, except for medical radiation therapy, are never intended, but are possible in the event of certain accidents, the radiation safety pro-

gram should function to reduce the likelihood of accidents through careful facility and equipment design, safety procedures, and train- ing (see Sections 3 , 4 and 5) Failures in facility design, failures in equipment, and human error can lead to unnecessary radiation exposure of individuals Plans should be made and individuals should be trained for normal procedures as well as for emergencies (see Section 11) Even with the most careful planning and training,

an accident (or near accident) can occur Consequently, procedures should be established for evaluating failures, whether or not they result in accidents The cause of any failure should be identified and actions should be taken to prevent recurrences

Normally, work with radiation sources does not result in radia- tion doses large enough to cause immediate or observable effects However, the accumulation of radiation dose over a long period of time may result in an increased risk for delayed health effects The NCRP recommends both annual and cumulative dose limits for individuals (see Table 1.1) that limit the risk to workers and the public (NCRP, 1993b) Program and facility design, and worker training are important to ensure that radiation exposures remain within these limits and are ALARA (see Sections 2, 3, 4 and 5) In addition, the program should include adequate control and evalua- tion of radiation exposures and radioactive wastes (see Sections 6,

7 , 8 and 9) Because radiation measurements are necessary for any

radiation safety program, Section 10 provides information about

the instrumentation that can be used for that purpose Certain sec- tions of this Report may not be applicable to a particular program Consequently, there is some intentional redundancy included to remove interdependency between sections This is especially true for Sections 6 and 7

In addition to the list of references supporting specific state- ments in the text of this Report (see page 119), five sections include lists of recommended additional reading These lists are to be found

at the end of Sections 3 , 4 , 6 , 8 and 10 A Glossary is also provided

TABLE 1 .l-Summary of NCRP recommendations specifying limits for radiation exposure [adapted from Table 19.1 of

NCRP Report No 116 (NCRP, 1993bll.a

A Occupational exposuresb

1 Effective dose limits

a Annual

b Cumulative

2 Equivalent dose limits

for tissues and organs (annual)

a Lens of eye

b Skin, hands and feet

B Public exposures (annual)

1 Effective dose limit, continuous or frequent

exposureb

2 Effective dose limit, infrequent exposureb

3 Equivalent dose limits for tissues and

organsb

a Lens of eye

b Skin, hands and feet

4 Remedial action for natural sources

a Effective dose (excluding radon)

b Exposure to radon decay products

C Education and training exposures (annuaUb

1 Effective dose limit

2 Equivalent dose limits for tissues and organs

a Lens of eye

b Skin, hands and feet

D Embrydfetus exposures (monthly)b

1 Equivalent dose limit

E Negligible individual dose per source or prac-

tice ( a n n ~ a l ) ~

50 mSv

10 mSv x age

a Excluding medical exposures

Sum of internal and external exposures but excluding doses from natural sources

2 Application of ALARA

The basic radiation protection assumptions and objectives rec-

ommended by the Council are given in NCRP Report No 116, Lim-

itation of Exposure to Ionizing Radiation (NCRP, 1993b) Specifically:

Based on the hypothesis that genetic effects and some cancers may result from damage to a single cell, the

Council assumes that, for radiation-protection purposes,

the risk of stochastic effects is proportional to dose without threshold, throughout the range of dose and dose rates of importance in routine radiation protection Furthermore, the probability of response (risk) is assumed, for radia- tion-protection purposes, to accumulate linearly with dose At higher doses, received acutely, such a s in acci- dents, more complex (nonlinear) dose-risk relationships may apply

Given the above assumptions, radiation exposure a t any selected dose limit will, by definition, have a n associ- ated level of risk For this reason, NCRP reiterates its previous recommendations concerning:

(1) the need to justify any activity which involves radiation exposure on the basis that the expected benefits to society exceed the overall societal cost (justification),

(2) the need to ensure that the total societal detri- ment from such justifiable activities or practices

is maintained ALARA, economic and social fac- tors being taken into account and

(3) the need to apply individual dose limits to ensure that the procedures of justification and

ALARA do not result in individuals or groups of individuals exceeding levels of acceptable risk (limitation)

Justification is not normally a radiation protection consideration and the dose limits are now considered simply as upper bounds As

a result, the radiation protection program is driven primarily by

ALARA considerations In most applications, ALARA is simply the continuation of good radiation protection programs and practices which have traditionally been effective in keeping the average of individual exposures of monitored workers well below the limits (NCRP, 1989b) Many of the decisions involved in control of radia- tion exposure result, primarily, from professional judgement of those responsible for health protection Operationally, this is achieved by the application of good practices based on staff knowl- edge, training and, very frequently, common sense In general, a graded approach is needed for making decisions based on the unusualness or complexity of the operation For example, if the operation is routine and the potential for radiation exposure is small, only a small and inexpensive effort can be justified to avoid the exposure Whereas, if the operation is new, and the potential for significant radiation dose is high, a much greater effort and expense can be justified Most situations fall between these two extremes

Perhaps the most important approach to achieving ALARA

is creating the proper "mind set" in managers, supervisors and workers so that they always ask if a particular level of exposure is necessary

In a well organized facility, almost all the technical decisions will have been made during planning and design During opera- tions there must be constant awareness and attention given to

avoiding unnecessary exposures Thorough work planning is a vital part of the ALARA process Many times a small amount of shield- ing can be added to reduce the dose that workers might receive Administrative controls on exposure can be used to identlfy work processes and procedures that may be modified to reduce exposures

a t little cost

Three NCRP reports deal with the application of the ALARA

principle in very different operational situations NCRP Report No

107, Implementation of the Principle of As LAW As Reasonably Achievable (ALARA) for Medical and Dental Personnel (NCRP, 1990) described its integration into radiation safety in medical and

dental facilities NCRP Report No 120, Dose Control at Nuclear

Power Plants (NCRP, 1994) discussed the use of the ALARA princi- ple in dose control programs a t nuclear power plants A third,

NCRP Report No 121, Principles and Application of Collective

Dose in Radiation Protection (NCRP, 1995b), is closely related to

the application of the ALARA principle ICRP issued Publication 37

on ALARA, Cost-Benefit Analysis in the Optimization of Radiation

Protection (ICRP, 1983) That publication stresses cost-benefit

2.1 APPLICABILITY O F COST-BENEFIT ANALYSIS / 7

approaches, while ICRP Publication 55, Optimization and

Decision-Making in Radiological Protection (ICRP, 19891, suggests other approaches

2.1 Applicability of Cost-Benefit Analysis

in the ALARA Process

Instituting procedures for applying the ALARA principle will require the judgment of radiation safety professionals When the potential for exposure of people to significant radiation doses exists, quantitative cost-benefit analyses may be justified to arrive

a t the optimum approach for dose control This Section presents the NCRP guidance for using some quantitative approaches that are important in applying the ALARA principle in the context of operational radiation safety

Protective measures that go beyond the basic design require- ments should be considered and evaluated to determine the incre- mental cost related to the value of the collective effective dose avoided Stated another way, the incremental cost of any elective radiation safety action should be justified by the value of the incre- mental collective effective dose avoided.'

The principle of maintaining radiation dose ALARA has been introduced into radiation safety programs because of the prudent assumption that potential deleterious effects might occur a t any level of exposure, while recognizing that as the doses become smaller and smaller, the likelihood of a deleterious effect becomes

vanishingly small The concept of ALARA allows accounting for

"social and economic factors" in determining an acceptable level of societal detriment for a n activity It is a principle by which the col- lective effective dose, and presumed detriment associated with a n activity, may be constrained Although individual doses should be controlled below the dose limits, there is no specific or unique value

of dose for a task or occupational category that can be defined a s

"ALARA," and the principle of ALARA is not a quantitative stan- dard of care for individual workers or individual members of the public

"I'he costs related to an adequate design that complies with all cur- rent building codes and architectural standards are not associated with the application of the ALARA principle

2.2 Concepts of a Cost-Benefit Approach

3 the monetary value of the dose avoided

2.2.1 Applicability of Collective Effective Dose

The collective effective dose is the appropriate radiation quan- tity to be used for most risk assessments; however, there are prac- tical limitations to its application Estimation of collective effective dose requires definition of the sizes of various age and sex groups and of the pathways by which they are exposed (NCRP, 1995b) Col- lective effective dose should be used for risk assessment with cau- tion if both the exposed population and the radiation doses can not

To determine the reasonableness of such assessments, uncer- tainties in both demography and in dosimetry must be identified and carried through the calculations to estimate the overall uncer- tainty in collective effective dose If the relative uncertainty in col- lective effective dose is more than a n order of magnitude, the estimate of collective effective dose is not adequate for making deci- sions (NCRP, 1995b) When the uncertainty for a projected poten- tial collective effective dose is very large, i t may be more appropriate to estimate risks to typical individuals in a critical group of people who might be exposed in the future

2.2.2 Dose Magnitude and Distributions

The concept of a n individual dose that is negligible because it implies a n individual risk that can be ignored in the context of

2.2 CONCEPTS O F A COST-BENEFIT APPROACH TO ALARA 1 9

everyday life has been defined by the NCRP The value of the neg- ligible individual dose is taken to be 0.01 mSv annual effective dose per source or practice (NCRP, 1993b) However, for collective effec- tive dose calculations, all doses should be included, no matter how small because the use of the no-threshold dose response model log- ically implies that all doses contribute to the total risk (NCRP, 1995b)

Examination of the distribution of doses that contribute to the collective effective dose is a n important step in any assessment If the distribution is very broad, separation of the distribution into reasonably sized groups of persons with smaller ranges of doses is advisable The collective effective dose may be dominated by expo- sures to one or more groups, while doses to other groups may be very small It is appropriate to focus attention and resources on dose reduction for groups receiving the largest doses As discussed

in Section 2.2.3, when doses to some groups approach dose limits, the upper end of the distribution of doses should receive more attention in ALARA evaluations Section 2.3 addresses the issue of the level of effort that should be devoted to ALARA evaluations

of small collective doses

The ICRP (1983; 1989) recognized that the potential detriment caused by radiation exposure consists of a t least two components The first component is the "objective health detriment," including all stochastic health effects for which quantitative estimates of the probability of occurrence as a function of radiation dose have been derived from exposed populations These effects are primarily fatal and nonfatal cancers and birth defects For purposes of radiation safety management, the dose-response function for the "objective health detriment" is assumed to be linearly proportional to collec- tive effective dose and without a threshold For this portion of the collective detriment, the value of the detriment per unit dose is a constant (a)

The second component of detriment includes social factors and possible health detriments that reflect such factors as anxiety over individual levels of dose, uneven distribution of doses, the per- ceived risks of the doses, and concern on the part of management when individual doses are significant fractions of authorized limits (ICRP, 1983) For this portion of the collective detriment (P), the value of the detriment may be a function of dose and therefore may

change over the range of doses included in the collective effective dose assessment

ICRP (1989) defined the total detriment resulting from the use

of radiation by a practice, a t a n installation or from a specific radi- ation source as:

j where:

a = the monetary value of the objective health detriment per unit of collective dose

S = the total collective effective dose

Sj = the collective effective dose originating from a per caput dose Hj delivered to the Nj individuals of the jth group

Pj = the value of the collective detriment assigned to a unit of collective effective dose in the jth group

Unless doses approach either legal limits or internally imposed constraints, the second component of detriment may be very small

in comparison with the value of the objective health detriment and can usually be ignored In t h a t case, the ALARA principle would lead to implementation of an action that would reduce the collec- tive effective dose by an increment (AS) a t a cost not exceeding the quantity (M)

When individual doses are near the limit appropriate for the exposed population, considerations other than the objective health detriment may justify additional expenditures for dose reduction Justification for these choices will vary from one organization to

another and may depend upon assessments of parameters t h a t are specific to a particular practice or industry

Although the NCRP does not recommend nor endorse any spe- cific values for a or pj, the examples used by the ICRP (1989) illus- trate the numerical application of these concepts For all dose ranges, the value of a is assumed to be $20,000 (person-~v)-l Val- ues of pj were defined for three individual dose ranges:

1 For groups with individual doses of <5 mSv, PI = $0 (person-~v)-l

2 For groups with individual doses in the range 5 to 15 mSv,

Pa = $40,000 (person-~v)-l

3 For groups with individual doses in the range >15 to 50 mSv, PB = $80,000 (person-~v)-l

2.3 SCREENING FOR hLARA ASSESSMENT / 11

2.3 Screening for ALARA Assessment

When the ALARA principle is applied, the cost of the assess- ment of risk should be included in the optimization The effort expended in assessing the risk should not be disproportionate to the risk itself An obvious threshold for optimization occurs when collective effective dose is so small that the benefit obtained from its complete elimination would not justify the cost of evaluation A simple mechanism should be used to determine whether the poten- tial collective effective dose related to a proposed practice, proce- dure or situation is likely to exceed this conceptual threshold Direct measurements of exposure rates (or of concentrations of radioactivity in air) are appropriate a s screening measurements to determine if an evaluation of the application of ALARA is needed

A screening level for a minimal level of documentation of the application of the ALARA principle for occupational exposures can

be estimated While the value of some dose reduction actions may

be apparent from a simple mental calculation, an avoided collective effective dose of the order of 0.01 person-Sv appears necessary to justify an optimization evaluation that entails formal procedures This estimate assumes that the doses are reasonably distributed among individuals and that none of the occupational doses approaches a limit Additionally, the formal procedures and docu- mentation needed to implement ALARA should also be minimal if the expected collective effective dose lies below 0.01 person-Sv For collective doses of less than 0.01 person-Sv, the total value of the dose that might be partially avoided by a formal A U R A program does not justify the effort required for the preparation of formal procedures and documentation However, less formal efforts to maintain doses below t h a t level may still be justified

For a practice that results in exposure of the general public, sim- ilar considerations apply A determination of whether projected doses to individuals approach appropriate limits or are very unevenly distributed is a first step However, a study of alterna- tives that could reduce dose to the public may well be more complex than a n evaluation of a workplace improvement

Administration

3.1 Management Commitment and Policy

The highest level of management of a n organization is responsi- ble for establishing the goals of the organization and for ensuring that i t has sufficient resources to safely c a n y out the operations needed to meet these goals I t also has the responsibility to ensure that an effective radiation safety policy is established and that the radiation safety program is implemented for the protection of employees and the public

All employees who may be occupationally exposed should be informed of the radiation safety policy and programs It is espe- cially important that all employees be thoroughly instructed in and understand their responsibilities in support of the radiation safety policy and program

The radiation safety policy should define the goals of the radia- tion safety program, including the organization and administrative control required for the use and handling of radioactive sources and radiation-producing equipment It should state a commitment to

the application of the ALARA principle and the adequate and cost-effective control of radiation exposure of workers and the pub- lic This policy should represent a commitment by management to provide suitable budgetary support for the radiation safety program

Effective implementation of the policy requires that good radiation safety practices be followed and that the applicable regu- latory requirements2 be met Activities that involve radiation or

'1n the United States, federal regulatory requirements pertaining to radiation safety have been established by the Nuclear Regulatory Com- mission (NRC), Department of Energy (DOE), Environmental Protection Agency (EPA), Department of Transportation (DOT), Food and Drug Administration (FDA), Occupational Safety and Health Administration (OSHA), and the Federal Emergency Management Agency (FEMA) State agencies have varying degrees of additional regulatory requirements, and,

in some cases, act on behalf of a federal agency

3.2 RADIATION SAFETY ORGANIZATION / 13

radioactive materials should be under periodic surveillance by work area supervisors, the radiation safety staff, and safety audi- tors Operational records should reflect safety-related actions (NCRP, 1992)

Management support of worker training is essential NCRP Report No 105 (NCRP, 1989a), for example, states that an effective training program requires significant involvement by everyone, management and workers, not just the radiation safety staff Guid- ance is given for medical and dental activities in Reports Nos 105 and 107 (NCRP, 1989a; 1990) which can be adapted for other radi- ation programs a s well

3.2 Radiation Safety Organization

The key to a n effective program is the formal delegation of authority to competent staff members The manager of the radiation safety program may be referred to a s a Radiological or Radiation Safety Officer (RSO), Radiological ControI Manager, Radiation Protection Manager, or some other title For this Report, this manager will be referred to as t h e RSO The RSO should be directly responsible to the highest level of management a n d should have ready access to all levels of the organization

3.2.1 Radiation Safety Advisory Organization

Management should appoint a Radiation Safety Advisory Group Certain regulations may specify the establishment, mem- bership and responsibilities of such a group For this Report, the group is referred to as the Radiation Safety Committee (RSC) The responsibi1it;y of the RSC is to formulate institutional radiation safety policies, review and audit the effectiveness of the radiation safety program, and provide guidance to the RSO on the opera- tional uses of radiation and radioactive materials The RSC should include individuals who are knowledgeable about the use of radio- active materials and radiation-producing equipment in the facility

It may also include persons who are knowledgeable about the over- all organization and its legal, financial, procurement and other business functions The RSO should be a n ex offGcw member of the RSC

The RSC should perform reviews of the purpose, safety and com- pliance with t h e radiation safety program and regulatory require- ments of all proposed work with radioactive material or

radiation-producing devices Members of the RSC should be quali- fied in their normal field of endeavor Management is responsible for assuring that members, and especially the chairman, have the necessary experience and qualifications to meet the responsibili- ties of the RSC

3.2.2 Radiation Safety Oficer

The RSO is responsible for advising management concerning radiation safety practices and regulations This individual should

be delegated the authority to supervise the operational radiation safety organization, develop a budget and commit expenditures that are allowed by that budget The RSO should have adequate funding to maintain a stable radiation safety program and should have access to consult the highest level of management on any con- cern regarding the radiation safety program The RSO is responsi- ble for periodic and special surveillance of activities such as acquiring and disposing of radioactive materials, training in radia- tion safety practices for facility employees and users, developing and maintaining radiation control and dosimetry records, and authorizing the use of radiation and radioactive materials within

t h e facility The RSO is also responsible for developing and main- taining a radiation safety manual

The activities of the RSO and the radiation safety staff should

in no way remove or reduce the responsibilities of radiation users

or line supervisors to conduct their work in a safe manner The principal functions of the RSO and staff are training and support through the provision of common radiation safety services, includ- ing radiation safety surveillance

3.3 Accreditation and Certification

The minimum qualification of the RSO will depend on the mag-

nitude of the potential hazards and complexity of the operation The RSO should possess a n appropriate academic background together with practical radiation safety experience germane to the operation Specialized education in health physics a t the college level, combined with practical experience, is preferable The Amer- ican Board of Health Physics and the American Board of Medical Physics certify professional health physicists who meet their requirements An individual who is certified or has equivalent qualification is generally considered qualified to serve a s an

3.4 RADIATION SAFETY PROGRAM POLICIES AND PROCEDURES / 15

RSO for a n organization utilizing complex and varied sources of radiation

The RSO is responsible for developing a qualified staff of radia- tion safety professionals and technicians of a size and level of expertise appropriate to the activities of the program An effective on-the-job training program is essential for all employees Continu- ing education programs relying on expertise within the organiza- tion as well a s opportunities provided by professional societies, universities and other organizations should be used to maintain high skill and knowledge levels Management should support and encourage staff members to become certified by appropriate orga- nizations such a s the American Board of Health Physics, the Amer- ican Board of Medical Physics, the American Board of Radiology, or the National Registry of Radiation Protection Technologists

3.4 Radiation Safety Program Policies

and Procedures

Radiation safety policies and procedures should be clearly stated in a radiation safety manual Specific procedures should be written by operations groups and the radiation safety staff to implement the radiation safety policies for various tasks that are performed in the course of operating the facility It is important to distinguish operating procedures employed by the radiation users and the radiation safety staff from the policies and procedures that are promulgated in the overall facility radiation safety manual

3.4.1 Radiation Safety Manual

The radiation safety manual should include a comprehensive statement of policy and the principal administrative and program procedures established by the RSC Significant technical support of the RSO is needed for writing this manual

The radiation safety manual is provided to help workers use radiation and radioactive material safely in compliance with the organization's policies and in compliance with regulatory requirements

The radiation safety manual should include:

1 management's commitment to proper radiation safety practice

2, description of the RSC, the radiation safety staff, and the radiation safety program

3 specific policy and regulatory requirements

4 specific procedures on how to comply with these requirements

Management should support periodic revisions of the manual including appropriate contributions from the RSC and the RSO

3.4.2 Radiation Safety Operating Procedures

Radiation safety operating procedures that govern the radiation safety staff are prepared by the RSO Lead managers or supervi- sors with the assistance of the radiation safety staff prepare spe- cific operating procedures that govern activities and processes that involve the use of radiation or radioactive materials Procedures are instructions that describe actions and steps necessary to con- duct a particular task, actions and protective measures to conduct the task safely, and steps necessary to document performance of the task Procedures provide a means for enabling consistent, repro- ducible work and may range from relatively simple instructions to complex manuals Within the radiation safety staff, for example, there should be procedures covering instrument calibration and use, laboratory sample counting, radioactive waste handling, and the calibration and use of personnel dosimeters as appropriate Depending on the complexity of a particular task and the train- ing and experience of the individuals involved, procedures for work that involves radiation or radioactive materials should include the following elements a s appropriate:

i

1 a description of the work t a t is authorized

2 a description of the potent ? a1 hazards that will be encoun- tered in performing the work, including potential radia- tion dose rates, identification of the sources of radioactive material, potential radioattive contamination levels, and the potential for intake of nadioactive material

3 the identification of indididuals responsible for making

sure that the work activitiks are conducted in accordance with the safety procedure

4 the safety controls and procedural safeguards that are necessary to prevent or limit exposure including require- ments for

protective clothing

3.5 RESPONSIBILITY / 17

respiratory protection

internal and external dosimetry

radiation surveys

worker time and dose limitations

limiting conditions for either radiation or contamina- tion levels

health physics or radiation safety coverage that is required during the task

5 required worker qualifications including any specialized training

6 actions to be followed in the event of a n emergency

7 a description of contamination control requirements

8 a description of required training and tasks that should be completed before beginning t h e task a t hand

9 a description of the method for authorizing deviations from the specified procedure

10 references to records and reports to be completed

11 a description of acceptable results and of actions to be

taken i n response to unsatisfactory results

Procedures can be simple and brief, but those that govern the use of high activity radiation sources or the use of large quantities

of radioactive material are usually detailed and complex Proce- dures should always be based on established policies, good prac- tices, and regulatory requirements Sources of information helpful

in developing procedures include the recommendations of the NCRP, the ICRP, the International Atomic Energy Agency (IAEA);

the consensus standards of the ANSI, the American Society for Testing and Materials (ASTM), the American Conference of Gov- ernmental Industrial Hygienists (ACGIH), and the American Industrial Hygiene Association (AIHA); the suggestions from NRC

regulatory guides and t h e guides of the Conference of Radiation Control Program Directors; and other guidance documents

3.5 Responsibility

Ultimately, workers are responsible for their own safety How- ever, supervisors and managers are responsible for providing a safe workplace and for promoting an attitude of responsibility for safety among all workers Compliance with radiation safety procedures and demonstration of individual responsibilities described i n the overall program policy should be a n established performance expectation for every individual involved, both workers and man-

agement The RSC and RSO are accountable to management for developing and implementing a radiation safety program that meets the radiation safety policy and regulatory requirements, and that supports the implementation of the ALARA principle Man- agement is responsible for establishing and funding a radiation safety organization that includes independent quality assurance checks and that is adequate for the complexity of the operations utilizing radiation and radioactive material

3.6 Quality Assurance

Management should ensure that there is a quality assurance program in place to provide oversight of the radiation safety pro- gram A quality assurance program should encourage and support self-assessments within the work group to ensure that the radia- tion safety goals are met Independent audits should be developed when necessary to gain a n outside perspective of any aspect of the radiation safety program The overall goal of a quality assurance audit program should be improvement of performance The pro- gram should never be an adversarial or fault-finding activity Quality assurance is a systematic evaluation of activity to mea- sure outcomes against expectations Audits, inspections, surveil- lance and statistical evaluations (quality-control checks) are all basic quality assurance tools used to make systematic evaluations

A radiation safety program should contain quality assurance assessment to evaluate the adequacy of:

1, basic control of radiation-producing equipment and radio- active materials

2 conformance with organizational policies and regulatory requirements

3 contamination and effluent control, and protective measures

4 health physics assessment in the workplace and surround- ing environment

5 health physics assessment of dose to workers and the public

6 incident and accident investigation and corrective actions

7 training

8, record keeping

3.6 QUALITY ASSURANCE / 19

3.6.1 Management Goals

Management has a responsibility not only to assure that corpo- rate goals are met, but also to assure that operations are performed with safety, reliability and cost effectiveness The assurance of safe, reliable and cost-effective performance depends on management, including the RSO Managers and supervisors have the responsibil- ity to provide a safe work environment and to ensure good work practices in the areas that they manage Reviews of operating records and personal interviews with the staff are necessary com- ponents in the discharge of this responsibility

3.6.2 Surveillance

Radiation safety surveillance is a quality assurance activity, although it may also be necessary to demonstrate regulatory com- pliance and increase worker and public confidence I t depends on training workers to establish a high quality of performance in proper handling, controlling and monitoring of radiation and radio- active material Area surveys and personal monitoring are signifi- cant aids for determining the adequacy of facility design, operating procedures, and worker training A high-quality surveillance pro-

gram depends on the availability of functioning and calibrated instrumentation (see Section 10)

The RSO should expect prompt, accurate and consistent reports

of the results of routine area surveys and personal monitoring These reports can provide a n indication of serious inadequacies in the facility procedures and training Records of off-standard condi- tions should be written clearly on the survey form or in the survey log book, and confirmed by the responsible health physicist Any corrective action that is recommended and implemented should be documented and considered to be provisional until reviewed by a health physicist or the RSO

Routine surveys and personal monitoring are usually done on a regular schedule, but may be relatively infrequent (weekly, monthly or quarterly) For this reason, it is important that super- visors understand their essential role in controlling radiation expo- sure and in recognizing the implications of changes in operating conditions This is especially critical when high-dose rate radiation sources are being used Supervisors and workers should be well trained in the detection and control of radioactive contamination when it is a possibility in the workplace

Follow-up and special surveys should be performed to:

1 confirm the findings of a routine survey that identified off-standard conditions

2 assist in the investigation of individual exposures that are greater than expected

3 confirm unexpected findings of radioactive contamination, assess any mishandling of radioactive waste, or locate missing radioactive material

4 assure success of decontamination efforts

5 verify adequacy of shielding

6 verify measurements made during regulatory inspections

7 provide training for new radiation safety staff

In addition to the above, special surveys may be required as part

of a n investigation of a major radiation accident or a s a result of concern on the part of any worker These investigations require the active participation of the radiation safety staff A thorough inves- tigation report should be prepared and is usually required by the responsible regulatory authority

3.6.3 Program Audits

A radiation safety program audit is a deliberate examination of

the program to determine if it is effective The audit is an integral part of any quality assurance effort and should not be confused with the entire radiation safety effort

Two common types of audits are those that are done by the RSO and persons within the radiation safety program (self audit), and those that are done by persons from outside the program (indepen- dent audit) The major advantage of the self audit is that problems can be identified and promptly corrected by the workers, supervi- sors and radiation safety staff The self audit should be a n activity performed by a team selected from the workforce, the RSC, super- visory health physicists, and the RSO who have the knowledge and experience to identify and correct any problems or deficiencies Self audits should be scheduled to provide a systematic annual review

of the entire radiation safety program Problems identified and defined from self audits should be corrected in a timely manner and lessons learned should be examined for applicability to other parts

of the radiation safety program

An independent audit should be scheduled as needed to assess the overall program Because this audit has the advantage of a n independent perspective, deeply entrenched work methods that may be overlooked during self audits can be identified Further, in

3.6 QUALITY ASSURANCE / 2 1

auditing measurement procedures and results, the independent auditor may suggest improvements or changes in standards and techniques The independent audit should be preceded by adequate notification, which includes the time and purposes of the audit, the work areas to be covered, the persons to be interviewed, and the records needed for review Ideally, an independent audit should find

no deficiencies that have not been identified by self audits

Both types of audits require preparation, observation, evalua- tion and communication Audit reports should be factually correct and should emphasize the relative importance of the various find- ings Fault-finding, blaming and adversarial relations should be avoided The overall goals of an audit are to ensure that the intended work quality is being maintained and that possible improvements are identified and fostered

3.6.4 Incident and Accident Investigations

The investigation of incidents and accidents must be timely Both internal reports for management and reports to regulatory bodies may be needed in preliminary form within hours or days and

as final reports within days or weeks These reports are the respon- sibility of the RSO and the supervisor who is responsible for the operation that was involved in the incident or accident

Incident and accident investigations should include a thorough examination of the scene, interviews with the people involved, a review of pertinent records, and a complete and accurate report of the incident or accident and subsequent investigation The location

of the event should be completely surveyed with appropriate instruments as needed to determine and document the radiation levels and the extent of radioactive contamination Personal moni- toring devices should be collected and evaluated, and bioassays should be performed as needed An inventory of all radioactive material and waste should be made Any records or logs that have been maintained should be examined

Workers and others in the area should be interviewed early in the investigation A photographic record of the area may be impor- tant to reconstruct the incident or accident, e.g., in the case of a

serious individual exposure

Although incident and accident investigations are important both legally and for program improvement, avoiding unnecessary

interruptions of important activities (e.g., medical service, produc-

tion and research) is also important However, in some cases the

RSO may decide to suspend work in an area to allow an immediate

and thorough investigation Expeditious completion of the investi- gation would permit an early resumption of work When important activities are interrupted, appropriate notations in the operating records are necessary The records should always be sufficiently detailed to allow future review I t is also important to remember that incident and accident reports could be made available for pub- lic scrutiny

3 work objectives, priorities or efficiency

4 technical knowledge or support

is a clear understanding of responsibility, a reasonably uniform approach to safety, and a well-documented response to the identi- fied deficiency

Changes or corrective actions must be communicated to the

RSC and to appropriate employees This is especially important when common services such as personal monitoring, waste man-

agement, training, and emergency response are affected Records help to limit the confusion that may arise during independent audits and ease the quality assurance efforts of the RSO Good records are important for effective tracking of changes by the RSO and management

3.8 OCCUPATIONAL MEDICINE / 23

3.7 R e c o r d s M a n a g e m e n t

The amount and detail of the records that the RSO should main- tain has become substantial and their maintenance represents a n appreciable portion of the effort of the radiation safety staff The main records are "master" copies of the radiation safety policy man- ual and the radiation safety procedures

Included in the records that should be maintained are those

t h a t detail administrative actions that affect the program, report internal and external audits, and record deficiencies and corrective actions Operating procedures, personal monitoring and survey

records, instrument calibration records, waste management records, and records of worker training should be maintained in a readily retievable form The NCRP has provided guidance for maintaining radiation safety records i n Report No 114 (NCRP,

1992)

3.8 O c c u p a t i o n a l M e d i c i n e

The health of the worker is essential to the effective functioning

of the organization Therefore, a good occupational health program should be provided Special health evaluations and monitoring may

be needed for occupationally exposed individuals working in spe- cial environments, e.g., high temperature areas or high airborne contamination areas Special health services should be available to provide care to workers accidentally exposed to high radiation doses or to high internal or skin contamination

While no special health care is needed for workers who receive normal occupational exposure, concerns about radiation exposure

may occur under special circumstances, e.g., assignment to an unfa- miliar job, a necessity to receive more radiation exposure than usual, exposure to unfamiliar conditions that involve sources of radiation and pregnancy For this reason there should be persons available who are knowledgeable about the risks of radiation expo- sure and who are trained to address these concerns Management and the staff of the radiation safety program should be sensitive to the concerns of the workers

3.9 Recommended Additional Reading

A Compendium of Major US Radiation Protection Standards and Guidelines: Legal and Technical Facts, ORAU 88/F-111, Oak

Ridge Associated Universities, Washington, 1988

Dose Control at Nuclear Power Plants, NCRP Report NO 120,

National Council on Radiation Protection and Measurements, Bethesda, Maryland, 1994

The Handling, Storage, Use and Disposal of Unsealed Radionu- clides i n Hospitals and Medical Research Establishments,

International Commission on Radiological Protection Publica- tion 25, Annals of the ICRP 1, Pergamon Press, Elmsford, New York, 1977

Limitation of Exposure to Ionizing Radiation, NCRP Report

No 116, National Council on Radiation Protection and Mea- surements, Bethesda, Maryland, 1993

Management of Radioactive Material Safety Programs at Medical Facilities, Draft Report for Comment, Camper, L.W., Schlueter,

J., Henderson, P., Bermudez, H., Fuller, M., Jones J., Campbell, V., Montgomery, J and Allen, K., NUREG-1516, U.S Nuclear Regulatory Commission, Washington, 1995

Occupational Dose Reduction at Department of Energy Contractor Facilities: Bibliography of Selected Readings i n Radiation Pro- tection and ALABA 5, DOEIEH-0364T, BNL-43228, U.S Department of Energy, Washington, 1994

Occupational Dose Reduction at Department of Energy Contractor Facilities: Study of A U R A Programs - Good Practice Docu- ments, DOEIEH-0278T, BNL-47339, U.S Department of Energy, Washington, 1992

Occupational Dose Reduction at Nuclear Power Plants: Annotated Bibliography of Selected Readings i n Radiation Protection and

ALARA 8, NUREGICR-3469, BNL-NUREG-51708, U.S Nuclear Regulatory Commission, Washington, 1996

Operational Radiation Protection: A Guide to Optimization, IAEA

Safety Series No 101, International Atomic Energy Agency, Vienna, 1990

Operational Radiation Safety-Training, NCRP Report No 71,

National Council on Radiation Protection and Measurements, Bethesda, Maryland, 1983

Optimization and Decision-Making i n Radiological Protection,

International Commission on Radiological Protection Publica- tion 55, Annals of the ICRP 20, Pergamon Press, Elmsford, New York, 1988

3.9 RECOMMENDED ADDITIONAL READING / 25

Provision of Operational Radiation Protection Services at Nuclear Power Plants, LAEA Safety Series No 103, International Atomic Energy Agency, Vienna, 1990

Quality Assurance for Diagnostic Imaging, NCRP Report No 99,

National Council on Radiation Protection and Measurements, Bethesda, Maryland, 1988

Radiation Protection i n Occupational Health, IAEA Safety Series

No 83, International Atomic Energy Agency, Vienna, 1987

Radiation Protection i n the Mineral Extraction Industry, NCRP

Report No 118, National Council on Radiation Protection and Measurements, Bethesda, Maryland, 1993

Radiation Safety Training Criteria for Industrial Radiography,

NCRP Report No 61, National Council on Radiation Protection and Measurements, Bethesda, Maryland, 1978

Radiological Control Manual, DOE5H-0256T, U.S Department of

Energy, Washington, 1992

Radiological Protection i n Biomedical Research, International

Commission on Radiological Protection PubIication 62, Annals

of the ICRP 22, Pergamon Press, Elmsford, New York, 1991

Ra'diological Protection of the Worker i n Medicine and Dentistry,

International Commission on Radiological Protection Publica- tion 57, Annals of the ICRP 20, Pergamon Press, Elmsford, New York, 1989

Recommendations for the Safe Use and Regulation of Radiation Sources i n Industry, Medicine, Research and Teaching, IAEA

Safety Series No 102, International Atomic Energy Agency, Vienna, 1990

Suggested State Regulations for Control of Radiation, Volume 1,

Ionizing Radiation, Conference of Radiation Control Program Directors, Frankfort, Kentucky, 1997

Properly designed facilities allow for a much higher degree of safety than can be obtained by dependence on administrative rules and procedures in inadequate facilities While good design can never eliminate the possibility of accidental radiation exposure or contamination, the probability and magnitude of such occurrences can be greatly reduced Proper facility design is also the most effec- tive approach in reducing unnecessary occupational exposures or releases to the environment Attention to the radiation safety and control aspects of facility design can minimize later operating difficulties

The planning and design of new or modified facilities should include review by qualified experts to ensure that appropriate radi- ation safety features are incorporated Competent input and review in these stages will facilitate operation within established safety standards and maintain radiation exposure a t levels that are ALARA with minimal adverse operational effects

4.1 Site Selection

There are several factors that should be considered in the site selection process for a facility designed to handle radioactive mate- rial or to use radiation-producing equipment Many of these factors are based on radiation safety considerations and relate to the radi- ation doses that could be received by workers or members of the public outside the facility during routine operations or accidental conditions

A facility for handling radioactive material or using radia- tion-producing equipment must be located and designed so that the radiation doses to persons outside the facility can be maintained below applicable limits and are ALARA While proper design can preclude or minimize the release of radioactive materials and the emission of direct radiation from the facility, the site itself can pro- vide a n additional margin of safety The potential risk posed by activities within a facility to persons outside the facility will dictate

2 the physical and chemical forms of radioactive material

3 the type of work to be performed

4 the potential for dispersal of radioactive material to the environment during routine operations or accidental conditions

5 the potential pathways for release of radioactive material (airborne, liquid, contaminated solids)

6 the levels of direct radiation that could exist outside of the facility during routine operations or accident conditions For facilities where radiation-producing equipment will be oper- ated, the specific factors to be considered in site selection include:

1 the types of radiation to be produced

2 the energy and intensity of the radiation

3 the levels of direct radiation that could exist outside of the facility during routine operations or accident condtions

4 the potential for the production of activation products

5 the potential for the release of activated material to

the environment during routine operations or accident conditions

6 the potential pathways for release of the activated mate- rial (airborne, liquid, contaminated solids)

It is not uncommon for facilities both to handle radioactive material and to use radiation-producing equipment In such cases, all of the above factors need to be considered in site selection

If the quantities of radioactive materials that could be released from either type of facility under normal or accident conditions could result in exposure a t significant fractions of dose limits to individuals outside the facility, the meteorological, hydrological and seismological characteristics of the site must be evaluated These factors always have to be considered for large facilities like power reactors, and radioactive waste processing facilities Also common to both types of facilities is the need to consider the spatial and temporal distribution of potentially exposed individuals That

is, the density of the relevant population a s well as the associated occupancy factors should be considered

Other factors that need to be considered in the site selection pro- cess include economic considerations, public or commercial access, the risk from hazards related to chemicals, explosives, carcinogens and other such materials, zoning and other regulatory require- ments, and public acceptance For example, it may be economical to locate a radiation oncology suite in the basement of a building, since i t is likely to need less additional shielding than one located

a t ground level Similarly, a large high energy accelerator located

in a n isolated area might require less shielding to limit doses to members of the public than one located on a crowded campus, because a greater distance could be maintained between the source and potentially exposed individuals

Facility layout is a n important aspect of design and a n inherent aspect of the implementation of the ALARA principle Radiation safety must be recognized a s a n integral part of any operation that uses radiation sources or radioactive materials, and space for this function should be allocated within the facility, a s appropriate Areas designated specifically for radiation safety functions, e.g.,

storage of monitoring instruments and supplies, analyzing and recording of surveillance samples (air filters, wipes, etc.), instru- ment calibration, decontamination of workers or equipment, pro- cessing and packaging of radioactive wastes, etc., should be integrated into the overall facility layout

Functional portions of the facility need to be located properly, relative to each other - for efficient operations, for ease of move- ment of people and materials into and out of processing areas, and for effective maintenance When practical, the facility should be designed with zones based on gradients of potential external radi- ation exposure, potential airborne or surface contamination, and similar considerations For example, lunch rooms, offices and con- ference rooms should be located in clean zones Zones with minimal risk of exposure include sample counting rooms and low-level radioisotope laboratories Laboratory or processing areas contain- ing the largest quantities of radioactive materials should be the most isolated from the clean areas High-intensity radiation sources should be surrounded by low-occupancy areas to reduce the risk of inadvertent exposures Persons going from one clean area to

4.3 EQUIPMENT AND SYSTEM DESIGN / 29

another, or between low-risk areas, should not be required to pass through zones of greater risk of exposure or contamination

Protective clothing change rooms and areas for personal con- tamination monitoring and decontamination should be established

a t points of access to areas used for handling significant quantities

of radioactive materials Attention must also be given to control of potentially contaminated persons in the event of an accident requiring rapid egress from the facility At least one area for per- sonal contamination monitoring and decontamination should be accessible without requiring individuals to pass through an area that may have become highly contaminated as the result of an accident

To the maximum extent compatible with facility operations, uses of radioactive materials should be segregated from uses of hazardous chemicals Waste management and disposal of mixed wastes is much more difficult than dealing with either radioactive

or hazardous chemical wastes separately

4.3 Equipment and System Design

In addition to the facility layout, it is important to design or select specific f ~ t u r e s , equipment, systems and components for effectiveness in relation to radiation safety and operational effi- ciency Equipment and components that may become highly radio- active or contaminated should be designed for accessibility, ease of maintenance, ease of installation and removal, and ease of decon- tamination (ASTM, 1991) The provision of fixtures designed to support removable shielding or containment enclosures can reduce the time spent in the vicinity of activated or contaminated equip- ment At accelerator or reactor facilities, it is prudent to choose materials that will not become highly radioactive for use in areas where exposure to particle beams or neutron radiation is likely A decommissioning plan should be developed in the facility design stage to guide the selection of materials for the facility and equipment

The operations planned for the facility should guide the selec- tion of installed monitoring and surveillance equipment Installed radiation monitoring systems are generally necessary in facilities

in which operations can cause the radiation levels in potentially occupied areas to reach dose rates that would be of concern They can also be useful for remote monitoring of highly radioactive fil- ters, ion exchange resins, tanks and other equipment These instru- ments must be carefully chosen based on the radiation fields and

dose rates that they will be required to monitor For example, while Geiger-Miiller detectors would be appropriate for radiation fields produced by sources emitting gamma rays, ionization chamber detectors would be needed for pulsed x-radiation fields In some facilities, neutron detectors may be required

Installed monitors may be needed in some facilities a t the exits from areas in which loose radioactive material is handled These monitors can be designed to detect radioactive contamination on hands and feet, or they can check the entire body as the individual leaves the area In some cases installed monitors may also be required for checking equipment that is being removed from an area in which it could have become contaminated or activated These monitors may also be useful for detecting radioactive mate-

rial that may have been put into normal trash If the dispersal of radioactive material is possible, installed monitors for detecting airborne radioactive material may be needed

At facilities in which extremely high or potentially lethal doses

of radiation can occur, a n access control and warning system is nec- essary Such a system should be designed to address the hazard that is present These systems can be quite simple, such as warning signs, a locked door, or a radiation detector alarm They can also be very complex key-controlled or computer-based programmed logic interlock systems Recommendations on the specification and design of these systems are contained in NCRP Report No 88

(NCRP, 1986)

4.4 Shielding

This Section is not intended to be a manual for shielding design However, some of the important considerations are briefly dis- cussed Shielding may be necessary to reduce the potential for exposures to workers and visitors a t the facility and to the public

in the vicinity of the facility Because individuals may be exposed to multiple sources of radiation, it is recommended that shielding for any single source be designed to limit radiation exposure to some fraction of the recommended dose limit (NCRP, 1993b) Designers should recognize the uncertainties inherent in estimating the potential radiation levels and in calculating the transmission of radiation through the shielding material These uncertainties are

larger when the radiation field is complex, e.g., where there are

mixed neutrons and gamma rays or where there is a wide spectrum

of energies involved Composite shields, i.e., shields made of

of increased use of the source or future design changes that would increase access near the source should be taken into account The field of shielding design includes considerations of radiation physics, materials properties, and structural engineering Impor- tant references dealing with shielding include: Blizard (1962),

Blizard and Chilton (1968; 1970), Burchsted et al (1976), Chilton

et al (19841, Goldstein (1959), Jaeger (1975), McGinley (1993),

Price et al (1957), Profio (1970), Rockwell (1956), and Shultis and

Faw (1996) Data necessary for shielding design and recommenda- tions concerning shielding techniques are also contained in several NCRP reports (NCRP, 1976a; 1977; 1978a; 1983b) and ANSI stan- dards (ANSWANS, 1985; 1991; 1997)

In summary, various materials can be used for shielding, depending on the type of radiation, its energy and intensity, and the attenuation required Typically medium and high atomic number materials such as iron and lead are effective for shielding x and gamma rays For moderating fast neutrons a material with a high hydrogen content, such as water or polyethylene, must be included

in the design When thermal neutrons are captured in hydrogen, cadmium or other elements, high-energy gamma rays are emitted and must be considered in the shield design Concrete is suitable for shielding both photons and neutrons and is a cost-effective material of choice when space is available Earth is also a n effective and inexpensive material that is widely used a s shielding in vari- ous types of facilities In addition to meeting radiation protection goals, the selection of shielding material is dependent upon engi- neering factors such a s weight, cost, structural stability and compatibility

Shielding design should be an integral part of the initial plan- ning for the facility Ultimate removal and disposal of shielding should also be considered during the design phase For example, lead shielding may create a hazardous waste disposal problem upon removal In some experimental facilities the need for