ML20133G800
| ML20133G800 | |
| Person / Time | |
|---|---|
| Issue date: | 07/25/1985 |
| From: | Dircks W NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | |
| References | |
| TASK-PII, TASK-SE SECY-85-147A, NUDOCS 8508090080 | |
| Download: ML20133G800 (76) | |
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POLICY ISSUE July 25, 1985 SECY-85-147A (Informat. ion)
For:
The Comissioners From:
William J. Dircks Executive Director for Operations
Subject:
REGULATORY-EXEMPT RADIATION LEVELS (DE MINIMIS LEVELS)
Purpose:
To inform the Comissioners of developments in other countries which are related to the Commission's consideration of the de minimis concept in the revised 10 CFR Part 20.
Sumary:
During the May 15, 1985 Comission Meeting on the staff's. proposed revision of 10 CFR Part 20 (SECY-85-147), the staff comitted to providing the Comission with a summary of the recent advice
- issued by the United Kingdom's National Radiological Protection Board regarding exempt dose levels.
This paper provides that information.
TheAtomicEnergyControlBoardofCanada(AECB)alsorecentlyissued a proposed regulatory policy statement (May 6,1985, Consultative Document C-85) on exempt quantities for disposal of certain radioactive materials.. A sumary of the AECB proposal is also included.
A comparison of the staff's Part 20 recomendation and the UK and Canadian recomendations is also included (Enclosure 1).
Discussion:
A.
Types and Applications of Exempt Dose Levels This paper concerns the concept of a dose or risk whose magnitude is so small that it is insignificant compared to other everyday risks
- This " advice" is more binding on other UK agencies, such as the Nuclear Installations Inspectorate, than might be indicted by the term " advice."
It is issued under the UK Radiological Protection Act of 1970 and is similar to the Federal Radiation Guidance prepared by EPA and issued by the President.
Contact:
H. T. Peterson, RES (427-4578) geo90$0 850725 85-14k PDR
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and need not be subject to regulatory concern. This has commonly been called "de minimis."
_There are two major applications for such levels:
1.
The first type provides a level based upon risk, dose or radioactivity level (e.g. curies) below which there is no need for acquiring formal regulatory approval. An example would be license-exempt quantities (such as Appendix C to 10 CFR Part 20).
Levels expressed as individual risk or dose or radionuclide t
concentration could be used to define levels for the unrestricted disposal of radioactive waste below Class A.
i 2.
The second establishes ~a cutoff level to define a lower limit for the evaluation of collective (population) doses.
This applic-ation is related primarily to impact assessments.
4 The Part 20 proposal in SECY-84-147 is of the second type - a cutoff for collective dose evaluations.
The proposed Canadian guidance is of the first type, an exempt level for evaluation of alternative LLW disposal options.
The UK advice contains levels pertaining to both applications.
B.
The UK NRPB Advice On May 2,1985 the UK National Radiological Protection Board issued formal advice on the treatment of small radiation doses to members of 1
the public.
This advice is contained in policy statement, ASP 7 (Enclosure 2).
The principal points of the advice are:
1.
Effective dose equivalents of 50 microsieverts per year, 50 uSv/y (5 millirem /y*) are insignificant as far as the individual is concerned. This means that the total contribution to the dose to an individual-from all practices [ sources] may be disregarded if it does not exceed 50 microsieverts per year (5 millirem /y.)
i
[emphasisadded].
f
- These British and Canadian publications use the SI unit for dose equivalent, the sievert, Sv (1 Sv = 100 rem).
In this paper the conventional dose equivalent unit rem is used except in statements of policy where the SI unit is used and the equivalent conventional unit is shown in parentheses.
i
3
-4 a.
Using a risk factor of 2 x 10 per em the risk of harm is abogt1chanceinamillion(5x10- rem x 2 x 10'4
=
10- ).
b.
The level corresponds to 1% of the annual dose limit for members of the public of 500 millirem per year.
c.
The value is small in relation to natural background radiation in the U.K. per year. 0.1 to 1 rem.
2.
When only one practice [ source] is under consideration, the level of concern for a single individual should be reduced by a factor of 10 to 5 uSv per year (0.5 millirem /y.)
[This presumes than it would be unlikely for any] individual to be exposed concurrently to as many as 10 sources.
a.
The portion of the collective effective dose equivalent commitment
- by contributed individual doses less than 0.5 millirem should be separately identified and costed.
b.
Based upon previous U.K. NRPB guidance (ASP 4 and reports R-120 and R-132), the value assigned to the portion of the collective dose, comprised of individual doses in the range of 0 - 5 millirem is about $25 per man-rem.
3.
Practices which result in individual dose equivalents of 5 uSv per year (0.5 millirem per year) or less and which produce a detriment cost of less than about X2,000 ** (at 42,000 per man sievert) or a collective dose less than 1 man sievert (100 man-rem) if undiscounted (more if the collective dose is discounted ***) should be of no concern to regulatory authorities.
- collective
- population effective
- risk-weighted whole-body equivalent dose equivalent - absorbed dose modified (multiplied) by a quality factor, e.g.
rem as opposed to rads commitment
- future dose from radioactive material released into the environment and those incorporated into the human body.
- About $ 25 at $1.26 per pound sterling (June 7, 1985 exchange rate).
- Earlier NRPB advice (ASP 4, NRP8 Reports R-120 and R-132) permits discounting future detriments using discount rates of 0-3% per year and specifies ranges for the monetary equivalent of the detriment depending upon average individual doses.
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a.
The exclusion level of 100 man-rem is a level which should produce no health effects; the probability of any health effect being 0.02.
b.
The detailed assessment of the collective dose or consideration of the need for further measures to reduce the public health detriment need not be undertaken if costs would exceed the levels specified above.
In a press release (Enclosure 3) that accompanied the issuance of this guidance, the NRPB noted that this advice does not classify radiation i
sources as being of no regulatory concern on the basis that they have no associated risk.
It requires a decision to be made based upon the characteristics of the source. They also note that on the basis of these criteria, it will not be possible to exempt the disposal of large quantities of radioactive material, either in dilute form or in i
small portions over extended periods. Also it will not be possible on the basis of this advice to exempt radiation sources with the potential to give large individual or collective doses as the result of unlikely or low probability events.
The NRPB also issued a technical report, NRPB-R175 (Enclosure 4) that contains an expanded discussion of the rationale for the policy statements and examples of the application of the cutoffs.
Comment:
The issuance of this advice by the UK NRPB represents a significant step.
These levels will have application in government approvals and l
resource expenditures.
They will also effect design and planning, operation controls, waste disposal (note the proposed Canadian level in the following section) and decommissioning.
This UK action will undoubtedly provide incentive for other countries to establish similar levels.
C.
AECB Consultive Document C-85 i
On May 6, 1985, the Atomic Energy Control Board of Canada (AECB) issued a consultative document * (Enclosure 5) regarding proposals for 4
exempting the disposal of certain radioactive materials from i
licensing.
The report notes the regulatory utility of such levels and discusses the factors that could be used to justify a negligible level of risk such as natural background levels, risks from other
- This might be viewed as a draft policy statement for public comment.
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activities, Federal [ Canadian] Dose Limits and Federal Provincial Drinking Water Guidelines. On the basis of these factors, the AECB proposes:
1.
A de minimis dose criterion of 50 microsieverts per year, 50 uSv7y (5 millirem per year).
As with the U.K. NRPB advice, the AECB document noted that this represents:
a.
1% of the existing dose limits.
isk of 10-6/per year (using a dose-to-risk factor b.
Anannual_g/ rem).
of 2 x 10 c.
And is well within risks generally experienced by individuals from other causes.
2.
This level would be used by the AECB staff in case-by-case analyses of applications for license exemptions for radioactive waste disposal. AECB licensees wishing to gain exemptions would provide to the AECB detailed information on the waste materials, radionuclides and activities, monitoring procedures and disposal methods.
C.
Comparison of Various Recommendations provides a tabular comparison of the principal features of the NRC staff's "de minimis" recommendation in SECY-85-147 and those of the UK NRPB and Canadian AECB.
As noted, our recommendation does not involve a regulatory limit but is limited to a calculational cutoff for use in impact evaluations.
The Canadian AECB's proposed policy is intended to be a level for regulatory approval of alternate disposal methods of low-level radioactive waste.
The UK advice has much broader applications and addresses both individual and collective dose cut-off levels.
The level of 1 millirem per year proposed by the NRC staff for Part 20 as a cutoff for collective dose calculations is a factor of two higher than the UK NRPB individual dose criterion of 0.5 millirem per year. The dose-to-risk coefficients used are slightly different (160 versus 200 fatal cancers per million man rem.) This accounts in part for the difference in the annual dose criteria.
The lifetime risks of cancer death which are associated with these angual dose levels are very compagable: a lifetime gisk of 0.7 x 10-for the NRPB value (0.5 x 10 rem /y x 2 x 10- effects / man rem x 70 years) i
b 6
and 1.1 x 10-5 fo the NRC staff proposed cutoff value (1 x 10-3 rem /y x 1.6 x 10' x 70 years).
These differences in the risks or risk / dose coefficients are well within the uncertainty bounds of these values.
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c' _. ~,,_..__..ss William J. Dircks Executive Director for Operations 1.
Comparison Table 2.
UK NRPB Advice ASP 7 3.
UK NRPB Report R-175 4.
UK NRPB Press Release 5.
AECB Consultative Document C-85 DISTRIBUTION:
Conunissioners OGC OPE OI OCA OIA OPA SECY
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4 ENCLOSURE 1 f
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ENCLOSURE 1.
COMPARISON OF "DE MINIMIS" LEVELS ADOPTED OR PROPOSED BY NATIONAL STANDARD-SETTING REGULATORY BODIES Proposed UK Advice Canadian AECB 10 CFR Part 20 (ASP 7 and NRPB R-175)
Consultative SECY-85-147 Document (C-85)
Status:
Staff Recommendation Formal Advice (similar to Statement of Proposed 4
to Commission US Federal Guidance)
Policy Scopp:
Limited to evaluation Applicable to most Limited to case-by-case of population doses decisionmaking evaluation of waste disposal exemptions l
Action Permitted:
Annual doses below Sources of doses less Disposal practices yielding j
designated level need not than these levels need individual doses below be included in collective not receive regulatory limits may be licensed
[ population] dose attention after case-by-case review
]
evaluations Colle;ctive Dose Evaluation:
Permits portion of a.
Collective doses less Does not directly address collective dose resulting than 100 man-rem collective doses l
from very low individual comprised of individual j
doses to be neglected doses less than 0.5 arem per year need not be subject to regulatory I
concern.
1
)
b.
Portions of collective l
dose from individuals I
with doses < 0.5 mrem per year are to be evaluated separately.
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c.
Partiens of callectiva dose due to individual doses less than 5 millirem per year have a lower detriment cost, about $25/ man-rem.
[ Prior NRPB Guidance ASP 4 reports R-120, R-132].
Individual Dose Leval(s):
1 mres/ year a.
Individual dose from Individual doses from exempt all sources < 5 mrem disposal practice < 5 mrem per year.
per year.
b.
Individual from single source < 0.5 mrem per year.
I e
i ENCLOSURE 2
k Advice given by the National Radiological Protection Board 7
under the Radiological Protection Act 1970 A,SP E National Radidogical Protection Board
^
Smallradiation doses to members of the public General 1 The Board had endorsed the system of dose Ilmitation recommended by the International Commission on Radiological Protection as given in their Publication 26, while indicating that it would need to give advice on interpretation of specific points from time to time'.
2 Members of the public are exposed to ionising radiation because of the existence of a natural background of radiation and radioactivity, and also as the result of many human practices.The magnituce of the resulting doses from single practices or classes of source often vary very widely-factors of many thousands are not uncommon.The suggestion is often made that small doses to individuals from a single practice or class of source should be deliberately disregarded if they fall below some defined value because,it is claimed, this might reduce the concern now exhibited about small doses and might avoid an unnecessary depf oyment of resources in the assessment and possible further reduction of such small doses.
3 The Board now considers that it is able to give advice on the treatment of such 2
exposures. In a supporting document factors influencing this advice and the i
l practical implications are discussed in more detail.
Exposure of individual members of the pubile 4 The Board considers that effective dose equivalents up to 50 pSv per year,le,1%
of the annual dose limit for members of the public, are insignificant as far as the
. individualis concerned.Using the risk factor of 2 x 10-2per Sv for the incidence of deleterious health effects, this level of Individual dose rate corresponds to an annual risk of harm to the individual of about 1 chance in a million (a risk of 10-8peryear). I I
This level of risk is not usually taken into account by individuals in arriving at decisions as to their actions.
5 Further, a dose of 50 pSv is smallin comparison with the variation in annual effective dose equivalents from natural background radiation within the United l
Kingdom.These are commonly in the range 1000 to 10,000 pSv per year.
l 8 The Board therefore recommends that the contribution to the effective dose
[
equivalent received by an individual from all practices may be disregarded if it does not exceed 50 pSv per year. individuals can justifiably regard such annual doses to themselves or to their families as being no cause for concern.
Exposure of many individuals from one source 7 When many individuals are exposed as a result of a given practice, or a single class of sources of radiation exposure, assessmentsinvolve the estimation of the f
quantity collective effective dose equivalent commitment. This quantity involves the summation of all the related individual doses, no matter how small. Even if some of
b tne lhdividual doses are so sm all that they need be of no concern to the Individual, national authorities may wish to be aware of the total collective dose so as to assess the overall health consequences. However,the Board recognises that for some,',
purposes, and where data allow,that portion of the collective effective dose equivalent commitment made up of very smallIndividual doses might be separately identified as an aid to reaching decisions,for example,in the allocation of resources to applying control. measures.
l 8 Most assessments of collective effective tifose equivalent commitment do not involve any appraisal of the doses to individuals from sources of exposure other than that under immediate consideration.To allow for the possible exposure of one
' Individual to several practices or classes of source,the Board suggests that the level of dose considered to be of no concern to a single Individual,when assessing a single source, be further reduced by a factor of ten, to 5 pSv per year.
9 The Board recommends that,where possible,that portion of the collective dose equivalent commitment contributed by doses of less than S pSv per year to Individual members of the public should be separatelyidentified and costed.This recommendation supplements, without modifying, the Board's earlier recommendation' that the evaluation of public hostth detriment for optimisation studies should have a besetine value of C2000 per man Sv for allindividual doses in the range from zero to 50 pSv per year.
Optimisation of protection for a defined source giving rise to small doses 10 Where a pre!Iminary assessment of exposure resulting from a single source shows that both the individual and collective doses are small. it is possible to select a value of collective dose below which the source can be regarded as being of no consequence. At some point, the cost of assessing the collective dose in detail or of considering the need for further measures to reduce public health detriment will be greater than the cost of that radiation detriment.The Board considers that. in such situations,the rigorous use of cost benefit procedures for optimisation may represent an unwarranted allocation of resources.The cost of such procedures is unlikely to be less than a few thousand pounds.
11 The Board recommends that, provided a practice involving exposure can be shown to lead to individual effective dose equivalents of less than 5 pSv per year and a collective effective dose equivalent commitment having a vafue of less than C2000, having regard to the build-up of doses over time from continued use of the source of exposure, the source should no longer be of concern to regulatory authorities.
Without discounting this corresponds to a collective effective dose equivalent
. commitment of 1 man Sv. lf the doses are widely distributed in time and any form of discounting is used, the corresponding collective effective dose equivalent commitment will be greater.
Referencee 1 National Radiological Protection Board, Recommendations of the International Commission on Radiological Protection (ICRP Publication 26): Statement by the National Radiological Protection Board on their acceptability for application in the UK. Harwell, NRPB, ASP 1 (1978) (London, HMSO).
2 Fleishman, A B,The significance of small doses of radiation to members of the public. Chilton, NRPB R175 (to be published).
3 National Radiological Protection Board, Cost benefit analysis in optimising the radiological protection of the public: a provisional framework. Chilton, NRPB, ASP 4 (1981)(London, HMSO).
asete.
$ ind[du7lNe'rNostoo m of ertemel dosee plus thoes committed from Intakee during eie year.
National Radiological Prataction Board Chilton, Didcot,0xon OX110RQ s
January 1985 Her Msjesty's Stationery Office, price 30p ISBN 085951240 f
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ENCLOSURE 3 l
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f THE SIGNITICANCE OF SMAI.L DOSES OF RADIATION TO MEMBERS OF THE PUBLIC A B Fleishman l
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ABSTRACT The suggestion is often made that small radiation doses and associated risks to individuals from a single practice or class of radiation source should be
[
deliberately disregarded if they fall below some defined value.
The Board has i[
issued formal advice on the treatunt of such doses, establishing radiological can be used to reassure individuals and as a basis for h
protection criteria that h
exempting source related exposures from regulatory consideration.
Some of the b'
factors influencing this formal advice and its practical implications are n',
discussed in more detail in this report.
3 D'l
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.E National Radiological Protection Board Chilton Didcot 0xon OX11 ORQ 8
March 1985 HMSO, E4.00 ISBN 0 85951 241 X e
CONTENTS Pate No.
1 1.
INTRODUCTION 2
2.
HISTORICAL DEVELOPMENT 3.
INDIVIDUAL RELATED ASPECTS 3
4 4.
SOURCE RELATED ASPECTS 4.1 Cost-benefit analysis in the optimisation of
~
4 radiation protection -
4.2 An alternative approach to source related exemption 6
levels
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5.
DERIVATION OF EXEMPTION LEVELS 8
5.1 Definition of a source 9
i 5.2 Assessment of the radiological 1spect 9
10 5.3 Discounting 10 6.
CONCLUSIONS 11 7.
REFERENCES APPENDIX - Practical implications of Board advice 13
.I FIGURES 4:
f.
1.
Schematic representation of procedure for implementing criteria 8
l on exemption levels k
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l 1.
INTRODUCTION Problems in risk management and regulation are of different levels of importance.
Regulators have limited resources and need to assign priorities sensibly so that these resources are not dissipated on trivial problems at the cost of neglecting major problems.
Practically all of those with responsibilities for rirA management adopt some type of pragmatic policy to to ignore very small risks and to use their resources effectively.
enable them In radiation protection the working hypothesis is that any increment of dose carries some probability of harm however low the level of exposure.
It is t
therefore not possible to classify sources as being of no regulatory concern on the basis that they have no associated risk.
A decision has to be made on the characteristics of the source that render it of no further regulatory concern.
f fairly pragmatic grounds, i
These decisions have been made in many instances on particularly in respect of exemptions for waste management.
One purpose of the advice published by the Board in AS?7( } is to provide a more consistent basis for decisions of this type.
While a linear, no threshold, dose response relationship for low-level irradiation is generally accepted as the working assumption for radiological
{
there has been a protracted debate as to whether or not it protection purposes, is reasonable to sua very small individual doses, additional to those acessnulated in the calculation and use of collective dose from natural background radiation, j'
estimates.
This issue has assumed considerable importance in the field of I
radioactive waste management, as m.tch of the collective dose arising from the dispersion of effluents or low-level solid waste disposal is delivered at very 9
(
l low individual dose rates.
A widespread feeling has emerged within the
.i radiological protection cousminity that this procedure may over-emphasise the k
7
. significance of low-level exposure and, in particular, promote undue public anxieties over those vaste management practices that result in essentially As an alternative, it has been suggested that a level of l
trivial levels of risk.
,a
- p individual dose or risk should be established below which there would be no I
3 further need for regulatory cone'ern. Such dose levels or corresponding levels of risk are often termed 'de minimis' by analogy with the legal expression
'd.e, This minimis non curat lex', meaning the law is not concerned with trivialities.
concentration on the legal analogy and on a trivial individual dose level has tended to obscure the purpose for which this concept has been most commonly used, that is in the setting of exemption levels, or in the granting of exemption's from Residual levels of risk associated with auch particular regulatory requirements.
exemptions should be viewed as being of suf ficiently low importance not to need regulation, rather than being acceptably low in any absolute sense.
In this such risks will be called " insignificant" and the concept will be called
, report
" triviality".
UI establishes radiological The advice given by the Board in ASP 7 pratsetica critoric that can be ussd as tha basis for dscisicns en exsaptiano, and includes recommendations concerning insignificant levels of both individual and collective doses. The purpose of this report is to explain the f actors that were taken into account in formulating the Board's advice and to discuss its practical implications.
2.
HISTORICAL DEVE1.0PMENT Application of the concept of triviality within radiological protection is by no means new, and proposals on this topic were first considered by Board staff I)
)
in 1977 As with all early work in this area
, this concentrated on the definition of insignificant levels of risk or dose from the point of view of affected individuals. The rationales most frequently adopted for the purpose of this definition were comparison with other risks which individuals consider of no
~~
concern, or at least those that do not cause people to change their courses of action, and comparison with the levels, or particularly the fluctuations, in natural background radiation.
Thus, for example, in a survey of comparative risks experienced by the population, Webb and McLean concluded that an annual
(
probability of death of the order of 10 per year is not taken into account by
[
individuals in arriving at decisions as to their actions. The annual individual whole body dose equivalent of the order of 100 pSv corresponding roughly to this level of risk was also shown to be appropriately small in relation to variations in individual whole body dose equivalents arising from natural background radiation.
Given the continuing interest in regulatory exemptions, it is not surprising that the concept of triviality has remained under active consideration internationally, by a number of competent authorities
, and has been the o
subject of an increasing number of reports and scientific papers Recent proposals by some authors and bodies, such as the US Nuclear Re gulatory Commission still concentrate'on the individual risk related aspects.
However, there are two features which cause difficulty with this approach. One is the likelihood that a particular individual will be exposed to many sources, each of which may have been dismissed as of no concern, and the second is that one source, which any have been dismissed on an individual basis, will in fact expose many individuals.
These aspects have been recognised and discussed by some previous authors.
To account for the potential u ltiplicity of radiation sources, it has been suggested that the insignificant individual dose equivalent for a single source would need to be lower than that regarded as insignificant for all relevant sources taken together.
Reductions of a factor between 10 and 100 have been proposed in the literature for this purpose The choice of factor depends on the way in which a single source is defined.
However, even where due allowance is made for this, there remains the question of whether or not it is valid to regard as insignificant the total of many individually insignificant -.. -
The individual doses are not, in feet, sero.
Nor, it is presuasd, cre doses.
It has been noted(16)that "to take a hypothetical example, the resulting risks.
a 10-' per year risk to a 1000 people produces 10-3 expected f atalities per year, This same risk equivalent to an expectation of one f atality per thousand years.
of 10 per year applied to the entire US population of 230 million produces an If a judgement of whether these were dg expectation of 230 fatalities per year.
miniais risks hinged on the individual risk, the regulatory response (or non response) is likely to treat these risks comparably. Yet common sense tells us certainly a poor use of saf ety resources to address the first that it is almost Consequently, it has been argued ( 0) that risk, but not necessarily the second."
the societal impact of radiation sources, for radiological protection purposes, It is expressed in terms of collective dose estimates, must also be considered.
implicit in this proposition that all the relevant individual doses must be included in the estimate of collective dose.
forward by the International Under the systes of dose limitation put Commission on Radiological Protection (ICRP)( U, it is clearly necessary to account for both individual related aspects and source related or collective These are considered in the next two sections.
3 -
aspects.
h 3.
INDIVIDUAL RELATED ASPECTS The definition of an insignificant level of risk from the point of view of a
~
conceptual dif ficulties.
It is serely a matter of single individual poses no choosing a level of risk likely to be videly accepted for this purpose.
Many radiation exposures routinely encountered by members of the public are very small by comparison with either dose limits or natural background radiation j'
and are well below dose levels at which the appearance of deleterious health As has been indicated in the previous section, has been demonstrated.
effects studies of comparative risks experienced by the population in various involuntary an annual probability of death of the ceder of 10~' per activities suggest that taken into account by individuals in their decisions as to year or less, is not On this basis, and using a risk factor.,
actions that could influence their risks.
!/.-
7 of 2 x 10-2 per Sv for the% incidence of serious deleterious hesich effects following irradiation of the whole body, a risk of harm to an individus1 of e,
an effective dose equivalent of 50 nSv per year.
10-' per year corresponds to This dcse corresponds to 1% of the annual dose limit for members of the public in comparison with the variation in annual effective dose and, also, is small These are equivalents from natural background radiation in the United Kingdom.
commonly in the range of 1000 to 10,000 pSv per year.
On this basis, the Board therefore recommended in ASP 70)that the received by an individual from all contribution to the effective dose equivalent (excluding natural background radiation and medical sources of practices exposure) should be of no concern to that individual if it does not exceed 50 usy The value in defining an insignificant level of dose from the point of per year.
i i
j view sf a singlo individus1 is in giving rocesurcnce to the individuol end his family.
This reassurance may be needed in relation to one or several sources.
J The figure of 50 pSv per year may be used in relation to all such sources or to the single source that is causing anxiety.
Regulatory exemptions are tot likely to be needed in situations relating to single individuals, but there are some re gulatory contexts in which the insignificant dose level for an individual may be of value.
yor example, in undertaking critical group assessments to ensure compliance with a dose limit, or with the upper bound associated with a single source of exposure (22), individual doses below the relevant insignificant dose level may be automatically disregarded by regulatory authorities.
This situation is already reflected in the field of occupational radiation exposure where, in accordance with ICRP advice on recording levels, doses to workers of the order of 1 mSv per year are not measured and are rarely assessed.
4.
SOURCE RELATED ASPECTS The system of dose limitation recommended by ICRP(21) and adopted for use in the United Kingdom clearly embraces two main components, those related to individual protection and those related to the total exposure caused by the source under consideration.
4.1 Cost-benefit analvsis in the optimisation of radiation protection
/
To deal with these source related aspects of population exposures within its l
system of dose limitation, ICRP have suggested the use of cost-benefit analysis procedures to carry out the optimisation of radiation protection (
)
Cost-benefit analysis has received increasing attention in recent years as a L
seans of examining whether or not the total detriment to society from a specific source of radiation exposure is "as low as reasonably achievable taking economic and social factors into account" or "ALARA".
This examination, using cost-benefit analysis, requires a monetary valuation of radiation-induced health detriment under various circums tances, so that the benefits from reduced radiation exposure can be directly compared with the costs of protective
,i measures. Since it is assumed that 'this health detriment is proportional to the collective dose (or more strictly to the infinite time integral of the collective dose equivalent rate, the collective dose equivalent conniement) delivered in an irradiated population, this valuation is generally expressed in terms of a cost per unit collective dose equivalent, eg, in I or $ per man Sv.
The choice of this costing is not necessarily independent of the magnitude and time distribution of the individual dose equivalents. Nevertheless, the optimisation of protection has sometimes been regarded as being solely concerned with collective dose, irrespective of the individual dose levels involved.
Given this, there appeared to be two potential mechanirms f or co-ordinating the idea of insignificant individual dose levels with the need for optimisation of protection.
One would be to exclude individual doses below the insignificant 6
6 b
r This vauld have ths level from assessments of collectivo dose.
individual dose of simplifying such calculations by restricting both the size of the ld need benefit population and the time over which the accumulation of collective dose wou It Some of the counter arguments were discussed in Section 2.
to be considered.
as it would result international and professional criticism, would also attract in the omission from collective dose estimates of dose equivalents deliver long distances (often in other countries) and af ter long periode (to future generations).
An alternative procedure would be to distinguish, in the that is made up of individus1 dose l
calculation of collective doses, the component equivalents below the insignificant dose level.
This component can then be If this component were separately identified as an aid to reaching decisions.
ffect would assigned a zero valuation for use in cost-benefit analysis, the net e to do this in a transparent way.
j small individual doses, but be to ignore the l
The decision would be clearly identified as one of policy and would not be pa Both procedures reflect a view that if the risks of the radiological assessment.
f involved are of no significance to affected individuals then it does not matter how many such risks are added up, the result is of no significance to society.
Rather they suggest Neither the Board nor ICRP have adopted the above view.
h.
societal health consequences of say, one predicted cancer, is the same
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that the d people each exposed to whether it arises in a population of one hundred thousan E
10-5 risk, or a population of one hundred million people exposed to a 10-s risk.
This is reflected in the recent publication by ICRP on the a
h detriment",
optimisation of protection (23) by the concept of " objective healt F
which is solely related to the collective dose couaitment, irrespective of individual dose levels, and is therefore invariant no matter wherever or whe U'
't Nonetheless, ICRP noted that other aspects of health f
are received.
the doses including the concern and anxiety of individuals exposed to radiation, higher risk levels, and can be detriment,
,5 '
linearly with risk at say increase more than as a function of the individual dose levels involved.
The ICRP expressed for the valuation of health detriment therefore consists of formulation components, accounting for collective and individus1 dose e.
separate
~
considerations, respectively(23)
These concepts have been included in the latest International Atomic Ene inter-Agency's Basic Safety Standards (
In order to ensure a minimum,
- ldwide, nationally acceptable degree of' pr'otection for all exposed populations wor of collective dose commitment (based on IAEA has established a baseline value applied to all regional and global exposures to be objective health detriment)
It may, arising from the transfrontier dispersion of radioactive effluents the introduction of the concept of triviality, in a therefore, be concluded that form that either precludes the calculation of collective dose arising from would be in conflict it a zero cost, individual doses or assigns d if part of insignificant with the ICRP recommendations on the optimisation of protection an, - - - -
' ' ^ ^ ' ' ' '-
e---
ith ths part of the collective dose is delivered out41de the country of origin, w IAEA efforts to control transfrontier exposures. I ) in 1977, the Board has been Since the appearance of ICRP Fublication 26 into a scheme for working to develop the cost-benefit framework for optimisation The first consultative document-on this subject 7) practical application in the UK.and was followed in 1981 by formal advice (2 in 1980(26) published during concerning the protection of the public from routine radioactive releases was normal operations.
The consultative document included the option of a zero cost for a It was recognised that collective dose made up of very small individual doses.
i osts, in terms of the adoption of this option would ignore the direct pecun ary c associated f
and increased expenditure on medical treatment, D
lost economic output with the finite number of radiation-induced health effects whic collective dose even if it were made up of statistically predicted per unit insignificant individual doses.to the consultative document opposed the zero cost Many of the responses the Board therefore rejected this in developing its formal advice, option and, finite value based on an analysis of the direct option in favour of a small, but o
pecuniary costs noted above(28)
This is reflected in the costing scheme by the
- j..
baseline valuation of 12000 per man Sv which may be taken to correspon ICRP formulation of the cost of objective health detriment, and is applicable I
levels in the range from zero to 50 pSv all annual individual dose equivalent It is intended that this aspect will be (ie, below 1% of the public dose limit).
retained in any further advice by the Board about cost-benefit analysis f I ').
Finally, it should be noted that optimisation of protection of the publiccollective dose to an annual individual d r
application of this value of unit cost of only 20.1 per
[!,
of 50 pSv would result in a health detriment The adoption of equivalent annual sua for an individual.
e clearly an 2significant i.
this easil pecuniary cost within the Board framework for optimisation is year; therefore entirely consistent 'with the proposition that such doses are
.f.)
insignificant from an individual viewpoint.
An alternative approach to source related exemption levels Si Although the Board has not accepted the idea of ignoring insignificant 4.2 has been t -
individual doses in the estimation or valuation of collective dose, it the provision of data for optimisation studies may increasingly recognised that Thus, where the collective be costly in -itself in terms of time and resources.
of performing the optimisation is sufficiently small, the cost coussiement costs. In such situs-dose may outweigh any potential reduction in health detriment s for optimisation may in itself f
d
, tions, the rigorous use of cost-bene it proce ure The cost of such procedures is represent an unwarranted allocation of resources.
unlikely to be less than a few thousand pounds, so that a collective dose equivalent commitment valued at less than this would not be worth ex
If it w2re also made detail for the purpose of the optimisation of protection.
up of individual dose equivalents of less than 5 uSv per year (allowing a factor to a number of sources), it to account for the possibility of exposure of 10 would also be insignificant from the point of view of the exposed individuals.
In ASP 7( }
Board therefore recommends that, prov.ided a practice the involving exposure can be shown to lead to individual ef fective dose equivalents of less than 5 pSv per year and a collective effective dose equivalent commitment valued at less than 12000, having regard to the build up of doses over time from continued use of the source of exposure, the source should no longer be of concern to regulatory authorities.
In formulating its advice on the optimisation of protection of the public, the Board considered that it was reasonable to assign less weight to doses It decided that the arising in the future as a result of present-day practices.
discounting procedures generally used for the purposes of investment appraisal should be applied in evaluating the temporal distribution of doses to determine the ' pres ent-value' of health detriment costs.
However, given the long to reflect the timescales commonly encountered in radiological protection and r
the Board recommended an unusually low range of concern for future generations, UI discount rates from zero, which assigns the same weight to doses whenever received, up to a value of 3% per year These recommendations preclude the unique definition of an insignificant since they require the recommended sum of level of collective' dose commitment, 22000 to be compared with a discounted present value, which is a function of both the temporal distribution of collective dose and the discount rate applied.
However, if a 0% discount rate is employed cautiously, together with the j
valuation of 22000 per asa Sv for individual doses below 50 pSv per year, then this sum will correspond to a collective effective dose equivalent commitment of c.
It is also worth noting that this collective effective dose equivalent 1 man Sv.
the associated f
of I san Sv is unlikely to produce any health effects; commitment Y
probability is about 0.02.
is therefore proposed 'that where maximum individual dose equivalents are It commitment of less than than 5 pSv per year, a collective dose equivalent less be arising over the operating lifetime of a given radiation source,
.1 man Sv, automatically regarded as insignificant.
If, however, the present value of the maximum rate of 3% per year exceeds the health detriment costs discounted at sum of E2000, the source will not be regarded as insignificant and formal will be required.
For intermediate results, ie, where the optialsation collective dose equivalent commitment exceeds 1 man Sv but the present value when the maximum rate of 3% per year is less than E2000, the decision of discounted at rate.
formally optimise will depend on the selected discount whether or not to This aspect is cent.idered further in Section 5.3.
i 5.
DERIVATION OF EXEMPTION LEVELS The key steps in assessing whether a particular source can be exempted are I
to define the source under consideration, to assess the individual and collective doses from the source, and to compare them with the criteria in the Board's advice.
The results of this sessment can, if required, be expressed in a such as the specific activity of particular vaste categories, by practical form, saking some further assumptions.
The general framework of such a scheme is shown in Figure 1 and illustrative examples of its application are given in the appendix.
DEFINE RADIATION
~
SOURCE UNDER CONSIDERATION If IS THE MAXIMUM FUTURE ANNUAL INDIVIDUAL DOSE LESS THAN No 5 10-' Sv7 Yes 3,
CRITERIA FOR CRITERIA FOR EXEMPTION ARE NOT cI EXEMPTION ARE SATISFIED. FORMAL SATISFIED. NO OPTIMISATION STUDY FURTHER REGULATORY REQUIRED i
Q CONSIDERATION REQUIRED
)
h t-A h
if l
IS THE TOTAL COLLECTIVE DOSE pf COMMITMENT LESS THAN Yes t'
I san Svf i
1 f!.
7 No If No A
IS THE COST OF HEALTH DETRIMENT P,j DISCOUNTED AT 3% y-1 LESS THAN f20007 jj u.
Yes 37 i
CONSIDER AN APPROPRIATE DISCOUNT RATE, I i
If No Yes IS THE DISCOUNTED PRESENT VALUE 0F HEALTH DETRIMENT COSTS LESS THAN E2000 AT THE DISCOUNT RATE I?
Schematic representation of procedure for implementing criteria on Figure 1 exemption levels b. _.
1 D2finition of a saureo i
~
The basic requirement in defining a source froa a point of visv of exmpt cn 51 is that this process follows an assessment of detriment.
There is still a For example, low-level there may be a number of similar sources.
wastes any be generated in similar composition and quantity by hosp problem in that A relevant question is then whether all of throughout a city or a larger region.
these wastes constitute 'one source' or whether each hospital constitute separate source.
from the point of view of The Board considers that as a minimum requirement, treated as each site _ should be exemption, of the radionuclides released and the pathways to man.
assessed taking account
- tion, In a similar way, a-_ site _for deposition of waste may be considered for exemp 8
j municipal landfill site accommodating small quantities of treatment k
for example, a A site may also comprise a particular waste radioactive materials.
facility such as an incinerator.
the criteria If an exemption is being considered for a particular site, l
The existence of other similar sites would site.
should be considered for that If the exemption is being considered not make the site more or less significant.
reference to the individual sites, h :'
for all the vastes from many sites, without The number of sites is should be appifed to the total situation.
be given to the apportionment of the the criteria because consideration must then important, f
overall exemption level between the relevant sources.
the duration of the is essential in defining any of these sources that the case of a f acility such as a It In source be taken explicitly into account.this would be the expected life f
aunicipal landfill site, f the building 3: -
it was filled; in the case of a hospital it would be the lifetime o An aspect of the continued operation of a facility, which has to
+.
h build up of and facilities.
be taken into account when it is being considered as a source, is t e collective dose commitment from successive releas years during which the facility is operational.of such sources which Furthermore, in the case.
taken by national authorities to particular care kill need to be individual environment, the assumption made in setting the level of insignificant exposed to more than a few exempt ensure that a particular individual is not is still valid.
This requirement suggests that regulatory authorities dose, ie, that h
xemptions and subject
- sources, who are granting axemptions should keep a record of t ese e them to periodic review.
Assessment of the radiological impact _
the Standard environmental modelling procedures can often be used to a 52 llective dose commitment maximum individual doses and time distribution of the co from a given source, or to provide estimates of quantities o dose levels. In carrying arising radionuclides or wastes corresponding to insignificant
_9_
out these assessments, it is ossantial to take secount of tha total relocess f rom the source, bearing in mind the number of years for which it is operational.
It is also necessary to consider the full range of environmental pathways back to man, and thereby determine to what extent it is possible to derive generic exempt quantities that are insensitive to site-specific assumptions made.
In this context, specific assessment methodologies for examining compliance with
'de,
)
minimis' criteria are actriely being developed
, and some may already be found in the literature for such sources as disposal in municipal landfill sites, incineration and wastes from decommissioning nuclear plant ( 0,31),
It should be noted that the application of the advice given by the Board to the derivation of exemption levels does not explicitly take account of accidents
?
or other 'probabilistic' events which may occur to the source or facility. It is
)
assumed that the doses and dose distributions being compared with the insignificant dose levels will actually occur in the exposed population.
If there are events of moderate probability which could give rise to doses, such as human intrusion at shallow land burial sites, then these should be treated for the purposes of assessment and comparison as doses that will occur (ie, with an assigned probability of unity). The system does not include rules for exemption j
of sources with the potential to give high doses as a result of unlikely events.
j 5.3 Discounting i
The use of discounting procedures, implying an increasing devaluation of i
doses delivered progressively further into the future, remains a subject of controversy within the radiological protection community.
The Board has always clearly recognised that discounting of all costs is a formally correct procedure in cost-benefit terms. However, the range of discount rates referred to earlier in Section 4.2 has not been extensively used in practice and is now considered to broad ( ')
In the context of public exposure fron long-lived be too radionuclides, public perception of the timescales involved and conce rns for future generations have effectively precluded the use of normal discount races.
Instead, the rates most commonly accepted for the purpose of sensitivity analysis d
assessments tend to fall within a range of 10-2 go go per in vaste management i
cent per year.
The implications of the choice of discount rate are explored in the examples given in the appendix.
6.
CONCLUSIONS The advice given in ASP 7
, coupled with the practical guidance in this 1
document, is intended to assist those with responsibilities for radiation protection of the public, to provide justifiable reassurance to those individuals exposed.to insignificant levels of dose, and should enable national authorities to derive a range of exemption levels for particular types of radioactive waste under the appropriate circumstances.
By establishing radiological protection criteria for the purposes of exemptions, based on quantitative risk considerations, it is hoped that priorities for regulatory action can be more..
involving ionising ths broed rango of activitics consistently specified across the On the basis of the Board's criteria it will not be possible to exempt radiation.
form or in disposal of large quantities of radioactive material, either in diluteS small portions over extended periods of time.
i l to give large individual or to exempt those radiation sources with the potent a collective doses as a result of unlikely or low probability events.
7.
REFERENCES b
of National Radiological Protection Board, Small radiation doses to mem Chilton, NRPB, ASP 7 (1985) (London, HMS0).
1.
the public.
levels of dose: a practical
,j Insignificant C A M and McLean, A S, Harwell, NRPB-R62 (1977) (London, HMS0).
- Webb, 2.
suggestion for decision making.
3.
Davis, J P, The feasibility of establishing a "de minimis" level of radiation dose and a regulatory cut-off policy for nuclear regulati f.
Maryland, USA, General Physics Corp., GP-R-33040 (1981).
IN Proceedings of the 16th of de minimis dose.
annual meeting of NCRP on Quantitative Risk in Standards Sett Eisenbud, M. The conewpt 4.
g, Washington DC, NCRP (1981).
203, 320 (1979).
- Science, a pragmatic de minimis_ approach.
Comar, C, Risk:
5.
Health Phys., 39,, 370 (1980).
Rossi, H H. What are the limits of ALARA.
6 A M, An approach to setting radiation standards.
i Adler, H L and Weinberg, 7.
Health Phys., H, 718 (1978).
"de minfais" International Atomic Energy Agency, Consf krations concerningdumpin 3:'
quantities of radioactive vaste suitable for 8.
'j.
Vienna, IAEA-TECHDOC-244 (1981).
permit.
y i
vaste Internationsi Atomic Energy Agency, De minimis_ concepts in radio y
Vienna, IAEA-TECHDOC-282 (1983).
9.
disposal.
radiological protection objectives for I
for the NEA Radioactive
- 10. Nuclear Energy Agency, Long-term
- f. '
radioactive vaste disposal.
Expert Group reporton Radiation Protection and Committee and the Committee Waste ManagementParis, NEA (1984).
4, Public Health.
11 Radioactive Waste Management Advisory Committee. Third A
- [
y
,E' London, HMSO, p43 (1982).
Radioactive Waste Management Advisory Committee, Fifth 12.
London, HMSO, p3 (1984).
- London, A study group report.
Risk assessment:
13 Royal Society of London, Royal Society (1983).
R Part 20.
IN Baker, R E, Cool, W S and Mills, W A, NRC Revision to 10 CF Industry, NU Proceedings of Conference on Radiation Issues for the Nu 14.
orleans, October 1982.
F L, EPA's view on de minimis_ limits for nuclear Guimond, R J and Calpin,Realth Physics Society, New Orleans, 3-8 June (
15.
radiation practice.
' i
- Whipple, C,
Application of the de minimis concept in risk managssent.
16.
Health Physics Society, New Orleans, 3-8 June (1984).
Health Physics Society, New Meinhold, C B, Criteria for a de minimis_ level.
17.
Orleans, 3-8 June (1984).
of de minimis levels of l
R H and Fleishman, A B The establishment of
- 18. Clarke, of the 6th International Congress radioactive wastes.
g Proceedings l
IRPA, Berlin, May 1984.
protection aspects of exemption levels in the
- 19. Clarke, R H, Radiological E Seminar on Interf ace Questions in Nuclear Health a nuclear fuel cycle.
Safety, NEA, Paris, 16-18 April 1985 (to be published).
- 20. Lindell, B and Beninson, D, ALARA defines its own limit.
Health Phys.,
H, 684 (1981).
the International Commission on Radiological Protection, Recommendations of f
International Commission on Radiological Protection (adopted January 17, 21.
1977).
Oxford, Pergamon Press, ICRP Publication 26.
Ann. ICRP, 1, No.3 (1977).
A compilation of the International Commission on Radiological Protection,Oxf ord, Pergamon Press, ICRP 22.
major concepts and quantities in use by ICRP.
Publication 42, Ann. ICRP, H. No. 4 (19b4).
Co st-benefit analysis V
International Connaission on Radiological Protection, Oxford, Pergamon Press, ICRP
)
23 in the optimisation of radiation protection.
2/3 (1983).
Publication 37, Ann. ICRP, g, No.
Agency, Basic safety standards for radiation 24.
International Atomic EnergyVienna, IAEA, Safety Series No.9 (1982).
protection, 1982 Edition.
International Atomic Energy Agency, Costing transboundary radiation exposure h
(the minimum value applied to unit 25 benefit analysis). Vienna, IAEA (1985).
4:
National Radiological Protection Board The application of cost-benefit consultative the radiological protection of the public: a 26.
ff' analysis toHarwell, NRPB (1980) (London, HMS0).
document.
analysis in optimising National Radiological Protection Board, Cost-benefit provisional framework.
2-27.
the radiological protection of the public:
a h *,
Chilton, NRPB, ASP 4 (1981) (London, HMS0).
28.
Clark, M J and Fleishman, A B. Technical Appendix E: the application of the radiological protection of the public: a cost-benefit. analysis toHarve11, NRPB (1980) (London, HMS0).
A consultative document.
of keep radiation exposures as low as f1
- 29. Webb, G A M.
The requirementProof of evidence to the Sizavell B Inquiry, reasonably achievable (ALARA).
NRPB/P/3 (October 1984).
Ortunali, O I and Roles, G W, De minimis waste impacts analysis methodology.
Vashington DC, Nuclear Regulatory Commission, NUREG/CR-3585 (1984).
30.
l 31.
Clark, M J, Smith, G M, Hemming, CR and Chapius, A M, Methodology for 7
l evaluating radiological consequences of the management of very low-level of Nuclear Power Plants.
Graham and
{
3 Decommissioning solid waste.
Trotman for CEC, EUR 9474 (1984).
i t
i Appendix Practical Implications of Board Advice involves an advocated for deriving exemptions clearly While the procedure assessment of health detriment, it is noted that the use of sophisticated environmental models will not always be necessary for this purpose.
In many practical situations, having determined that the individual dose equivalen d
criterion of 5 pSv per year is satisfied, and with knowledge of the half-life an l
residence time in the biosphere of the radionuclides involved, it may be read that the collective dose equivalent commitment does not exceed I
}
established Both of the conditions regarding insignificant dose levels will then 1 man Sr.
be fulfilled, and no additional regulatory consideration will be required.
i involves individual cases where the overriding constraint Furthermore, in such
(.
will be possible to establish exemption levels of doses to critical groups, it in a manner directly analogous to the
[-
activity or quantities of radionuclides, limits for members of calculation of derived limits corresponding to ICRP dose c.
I the public.
In some specific situations, particularly those involving long-lived the collective dose become regionally or globally dispersed, radionuclides that cost crueria vill be the overriding or discounted health detriment r[ '
commitment I'
constraint.
For these cases, a range of derived exemption levels may be rates within the range of zero to 3% per corresponding to discount 5
determined, The final choice of exemption level will then depend on the judgement ma k
year.
on the appropriate discount rate.
l, The overall procedure and range of possible outcomes for a selected series of radionuclides is illustrated in the following examples, giving notional (f '
f
[
routine liquid discharges to I
calculations for routine atmospheric discharges, respectively. In and solid waste disposal to umanicipal landfill sites, a derived exemption level corresponding to the individual
- rivers, each specific case, j
?
dose equivalent criterion of 5 pSe per year is first assessed, together with and discounted health detriment associated collective dose equivalent commitment costs.
The implications of this derived level are then examined in terms of M
h formal
(
whether this satisfies the constraints of the other criteria, or whet er a optimisation study would notionally be required.
Finally, for those 4
overriding (ie, where i
individual dose criterion is not radionuclides where the exceeds 1 man Sv), a revised range of the associated collective dose commitmentillustrating the relative importance of derived exemption levels is calculated, these different criteria in specific instances.
Example 1 - Routine atmospherie discharges II) of a derived level of discharge, Table 1 presents illustrative results corresponding to the individual dose equivalent for each of four radionuclides, The total collective dose commitment is for the criterion of 5 nSv per year.
discharge continuing over a 30-year period, and of health detriment cost at 12000 per man Sv.
Tablo 1 Routine atmospherie discharges lesding to 5 uSv y-1 to individuals i
Cost of health detriment (2) 30-year operating lifetime Nuclide Discharge level Collective effective Zero discount Discounted (Bq s-1) dose equivalent rate at 3% per commitment year (san Sv) 4 4
3 22 10 1
5.72 10 4.05 10s 2.86 10 85Kr 2
129I 3.70 2.26 101 4.52 10" 2.95 10 1
4.38 10-1 8.76 102 137Cs 3.46 10 2
3.32 10-1 1 60 10-1 3.20 10 239Fu 137Cs and 239Pu clearly It can be seen from this that such discharges of satisfy the insignificant collective dose equivalent commitment criterion of both of which are globally dispersed, e5
- 129I, 1 man Sv, while those of Kr and exceed this criterion by a factor of approximately 25.
However, given its costs associated extremely long half-life, the discounting of health detriment 1291 discharges has a substantial impact, reducing the present value with rates in the range of 1 - 10%
relative to undiscounted costs for annual discount of magnitude (2)
On this basis, the discounted health by about two orders 129I is found to be well below the insignificant health l
detriment cost for and would 'therefore preclude the need for any further h
detriment cost of 12000, In contrast to this, k
optimisation where finite discount rates are to be applied.Kr are relative I
tha results for the short-lived s5 although further reduction and exceed the insignificiant health detriment cost, of the discharge may still not be warranted on the basis of an optimisation c.
study.
overriding, For those nuclides where the individual dose criterion is not 1291, a range of insignificant discharge rates may be calculated 85Kr and O
le, The bottom of this range is determined by b
which satisfy the Board's criteria.
the collective dose equivalent commitment criterion of 1 man Sv (corresponding to V
a zero discount rate judgement), and is derived by dividing the relevant 45Kr or 22.6 for 1297, l
[*
discharge level in Table 1 by a factor of 28.6 for Kr, the top of the range is constrained by the health 85
[,
Similarly, in the case of which 3% per year meeting the criterion of f 2000, detriment cost discounted at dischstge level in Table 1 to be reduced by a factor requires the insignificant 129I the discounted health However, for of approximately 16 (ie, E32,200/22000).
detriment cost is below E2000, and the individual dose criterion remains the overriding constraint, thus the top of the insignificant discharge range remains lf unchanged from the value in Table 1 The overall position may therefore be summarised as in Table 2. *
.=
Table 2_
atmospheric discharges _
Revised levels of insignificant
^
int Range of revised discharge level (3q s'l) and overriding constra Nuclide 7
1 42 107 - 2.52 10 85 r (collective dose)
(discounted cost)
K i
1 64 10 3.70 129I (collective dose)
(individual dose)
Example 2 - Routina ifquid discharges to rivers discharge of t
for illustrative purposes, this example considers a continuousint
[
f five radionuclides, over a 100-year period,*1, taking du tion.
7 3 of 1.3 10 3 y Table 3 presents results(3)of a derived level of dischargecriterion of 5 pSv
')
corresponding to the individual dose equivalent sessed, including h
relates to the most significant individual pathway from t ose asThe results drinking water, freshwater fish, farming and marine pathways.
the associated collective dose equivalent commitment and to the total received from all such relate distribution (as given in Table 4) pathways.
Table 3_
1 to individuals _
Routine liquid discharges leading to 5 uSv y*
Cost of health detriment (C)
-Nuclide Discharge level Collective effective dose equivalent Discounted at Zero discount f
commitment 3% per year 1
(Bq y'l)
(aan Sv) rate 3
.?
1 2.63 10" 6.56 10 li 10 1.32 10 89 c 4.54 10 2
T 4.03 10-1 8.06 10
.I 137 s 1 61 10 6.29 10" 1.45 10" 8
C 1
8 3.14 10 4
s 1,41 10 237Np 1.43 10 2.25 lo t,13 to2 239 u 2.5 lo 4.90 10" 1.39 10" h
s P
(! ~
1 s
2 45 10 241 m 2.5 lo A
137Cs would such from Table 3, that only in the case of satisfy the collective dose equivalent commitment 9
It can be seen For the other, relatively long-lived radionuclides, this derived discharge levels criterion would be exceeded by a factor of between one criterion of 1 man Sv.
magnitude.
Table 4 indicates that the collective dose equivalent co and is therefore more is particularly protracted over time, undiscounted health 239Pu arising from ie, relative to significantly affected by discounting, 3% per year are reduced by a f actor of 16 those discounted at for other radionuclides.
detriment costs, f actor of approximately 4 239Pu, compared with a
for Table 4 Time distribution of collective ef fective dose equivalent for liquid discharges Time, t Percentage of collective effective dose equivalent commitment (years) delivered after t years 99 c 137 a 237Np 239 u 241 m T
C P
A i
1 2.45 10-1 9.6 10-1 7.27 10-1 1.98 10-1 9.08 10-1 10 4.48 9.60 7.27 1.98 8.98
}
102 86.2 96.0 72.7 19.8 89.8 103 100 100 86.4 22.2 98.0 104 100 100 100 51.1 100 5
105 too too too 97.8 100 106 100 100 100 100 100 However, for none of these relatively long-lived radionuclides would the discounted health detriment costs comply with the criterion of E2000.
It may 137Ca, a formal optimisation therefore be concluded that, with the exception of study would be required for all the discharge levels in Table 3, irrespective of e
k judgements on the choice of appropriate discount races.
the Alternatively, if insignificant-level discharges were redefined to meet s
collective dose commitment criterion they would certainly meet the individual g
2 dose criterion, and therefore be legitimately considered trivial.
This revised range of insignificant discharge rates has been calculated for these long-lived i
j, radionuclides. The results are presented in Table 5, which shows that the bottom of this range of discharges is determined by the constraint of the collective
~
dose equivalent commitment criterion of 1 man Sv, while at the top, the need for I'
discounted health detriment costs to meet the E2000 value is consistently f*
overriding.
Table 5 Revised levels of insignificant liquid discharges l
Nuclide Range of revised discharge level (3q y~l) and overriding constraint i.
3.44 109 - 1.38 1010 99Tc (collective dose)
(discounted cost) s 7
4.55 lo _ 1,97 10 237Np (collective dose)
(discounted cost) 2.22 106 _ 3,55 107 239Pu (collective dose)
(discounted cost) 1.02 107 - 3.60 107 241Am (collective dose)
(discounted cost) l
1 lendfill sitas_
Example 3 - Solid vaste disposal to municips
'instentensous' this example considers an with an illustrative purposes, icipal landfill site disposal of quantities of'five radionuclides to a munTable 6 presents resu For I
5 m.
area of 300 m x 300 m and a depth of sponding to the individual derived level of activity for each radionuclide corre associated the together with criterion of 5 pSv per year, costs.
detriment discounted health dose equivalent commitment and The normalised temporal collective dose equivalent drinking water pathway.
commitments These relate solely to the dose equivalent i
distribution of the respective collective ef fect ve I ).
are presented in Table 7 Table 6_
l to individuals Solidvastedishosalleadingto5uSvy' Cost of health detriment (E)
Collective effective Level of dose equivalent f Discounted at Nuclide Zero discount activity (Eq) cossaitment 3% per year rate (man Sv) 3 3
1.52 10 3.87 10 2
15 1,93 4
1.47 10 1.82 10 4.98 10 38 1
13 2.49 10 3
37310 2.66 10" 2.75 10
(
14C 1
13 1 33 10 6
o
Tc 2 30 10 9.12 10 3
14 4.56 10 6
o 239 u 2.01 10 9.48 10 P
4,74 to3 16 I
281 m 1.26 10 A
I L
Table 7_
dose equivalent.
Time distribution of collective effective for solid vaste disposal _
l t commitment Percentage of collective effective dose equiva en delivered up to t years Time, t I
241 m A
I 239 u (years)
P 99 c T
f
,l"C i,
3H 0
0 0
0 101 3.3 10-1 0
0 17.8 0
0 0
1 87.9 38.4 5 10 0
0 0
2 99 93.4 10 68.0 0
0 2
100 99.5 7.6 10-1 5 10 96.9 3
100 0
10 100 100 64.0 3
100 0
5 10 100 100 100 100 10" 100 100 a
l 100 10' 100 f
for nsns of tha rcdicnuclidas considsred hsro can be seen from this that the disoosal of such derived activity levels satisfy the insignificant It 239 u P
Indeed, in the case of would collective dose equivalent commitment of 1 man Sv.
d
- However, this would be exceeded by over three orders of magnitu e.
rise within the
- 241Am, and given that doses from these latter radionuclides do not sta.r re 14C 3
3H and first 3 10 years, costs for the discounted detriment Furthermore, cost of f.2000.
Only in the case of effectively zero.
also comply with the' reference lly so.
It may would now Tc would this criterion be exceeded and, even then, only margina therefore be concluded that judgements on the choice of appropriate d 99 239Pu and especially with regard to in this case, rates are highly significant results given in Table 8 for a revised o-241 m.
This is also reflected in the criteria and, in activity levels satisfying the Board's A
range of insignificant h span over three orders i
particular, the range for these latter radionuclides whic be applied.
of magnitude depending on the judgement for the discount rate to o
Table 8_
3 solid waste for landfill disposal _
- {
Revised cuantities of insignificant i
Range of revised level of activity (Bq) and overriding constra nt Nuclide 15 14 - 1.82 10 9.43 10 3H (collective dose)
(individual dose) 1 12 3,73 1o13 1.50 10 1"C (collective dose)
(individual dose) l.'.
1.73 1012 - 1.67 1013 99 c (collective dose)
(discounted cost)
T f.
~.
1 10 - 2.01 10 "
4.41 10 239 u (collective dose)
(individual dose)
P 16 2 66 1012 - 1.26 10 241 m (collective dose)
(individual dose)
A
,a i
s.
References Jones, J A, NRP3, Personal Communication (1984).
from radioactive 1.
Fleishman, A B and Clark, M J, Evaluating future detriment I
Chilton, NRPB-R132 (1982) (I.ondon, IDfS0).
2.
discharges.
Smith, G M, NRPB, Personal Communication (1984).
3 l
Remaing, C R, NRP3, Personal Communication (1984).
4.
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ENCLOSURE 4 e
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Nationa Racioogico rotection 30 arc 3
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Chilton, Didcot, Oxon OX11 ORO Telephone: Abingdon (0235) 831600 Not for publication or broadcast before 00.01 hrs on Thursday 2 May 1985 Small doses of radiation to members of the public Advice
- on criteria to be used to exempt from regulatory action sources leading to small radiation doses has been published by the National Radiological Protection Board.
In radiation protection the working assumption is that any radiation dose, however small, carries some probability of harm.
It is therefore not possible to classify radiation sources as being of no regulatory concern on the basis that they have no associated risk.
A decision has to be made on the characteristics of the source that render it of no further regulatory concern.
These decisions have been made in many instances on fairly pragmatic grounds, particularly in respect of exemptions for waste disposal. One purpose of the new NRPB advice is to provide a more consistent basis for decisions of this type.
The NRPB considers that radiation doses up to 50 microsieverts (pSv) per year, ie,1% of the annual dose limit for members of the public, are insignificant as far as the individual is concerned.
This level of individual dose rate corresponds to an annual risk of harm to the individual of about one chance in a million.
This level of risk is not
- NRPB, Small radiation doses to members of the public.
Chilton, NRPB, ASP 7 (1985) (London, HMS0).
Fleishman, A B, The significance of small doses of radiation to members of the public.
Chilton, NRPB-R175 (1985) (London, HMS0).
No 3/85
9 usually taken into account by individuals in arriving at decisions as to
[
their actions.
}
Further, a dose of 50 pSv is small in. comparison with the variation in annual effective dose equivalents from natural background radiation within the United Kingdom. These are commonly in the range 1000 to 10,000 Sv per year.
This level of trivial individual dose is most helpful in putting radiation risks into _ perspective.
However, one source can irradiate many individuals and the NRPB advises that regulatory authorities should only ignore small doses from that source if the cost of assessing the collective dose in detail, or of considering the need for further measures to reduce public health detriment, is greater than the cost of the health detriment itself.
To allow for the possible exposure of one individual to several practices or classes of radiation source, the NRPB suggests that the level of dose considered to be of no concern to a single individual, when assessing a single source, be further reduced by a factor of ten,.to 5 Sv per year (1 chance in 10 miElion).
On the basis of the NRPB's criteria it will not be possible to exempt the disposal of large quantities of radioactive material, either in dilute form or in small portions over extended periods.
Similarly, it will not be possible to exempt those radiation sources with the potential to give large individual or collective doses as a result of unlikely or low probability events.
Press Enquiries:
NRPB Information Office: Abingdon 0235-831600 -
\\
Matt Gaines Ext 410 (Home: Oxford (0865) 52459)
Gill Wilkinson Ext 514 (Home: Abingdon (0235) 21211) s
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e 9 t-s ENCLOSURE 5 l
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Consultative Document Document de consultation I+
Atomic Energy Commission de contr6le Control Board de l'6nergie atomique CONSULTATIVE DOCUMENT C-85 Proposed Regulatory Policy Statement THE BASIS FOR EXEMPTING THE DISPOSAL OF CERTAIN RADIOACTIVE MATERIALS FROM LICENSING Issued for cocument:
May 6, 1985 Canads
This Consultative Document is issued in order to provide an opportunity for public review of the proposal it contains before formal issue as a Regulatory Document. Comments are encouraged and should be directed to the address below before AUGUST 6,1985.
Unless otherwise requested by the submittor, a copy of all comments received will be placed in the AECB public documents room.
Direct comments to:
Health Effects and Regulatory Documents Section Atomic Energy Control Board P.O. Box 1046 Ottawa, Ontario CANADA K1P SS9 O
m._.
~
THE AECB RECULATORY DOCUMENTS SYSTEM i
1.
Siting, design, manufacture, construction, commissioning, operation, and decommissioning of nuclear facilities, or the production, possession, use and disposal of prescribed substances, in Canada or under Canadian control, are subject to the provisions of the Atomic Energy Control Act and Regulations administered by the Atomic Energy Control Board (AECB).
2.
In addition to the Atomic Energy Control Regulations, three other categories of Regulatory Document are employed by the AECB.
These are:
Generic Licence Conditions - standard sets of conditions that are included in particular AECB licences of a common type, unless specific circumstances indicate otherwise; Regulatory Policy Statements - firm expressions that particular
" requirements" not expressed as Regulations or Licence Conditions be complied with or that any requirements be met in a particular manner but where the AECB retains the discretion to allow deviations or to consider alternative means of attaining the same objectives where a satisfactory case is made; and Regulatory Guides - guidance or advice on any aspect of the AECB's regulatory process that is given in a manner less rigid than that intended by Policy Statements.
3.
In developing Regulatory Documents, the AECB publishes its proposals as Consultative Documents in order to solicit comments both from the nuclear industry and from the public. This is done prior to releasing any Regulatory Document in final form.
In certain cases, after the period for public comment, a Consultative Document may be issued for " trial use".
This is done for a limited period of, time to gain practical experience.
Following the period of trial use, the revised document is re-issued for further public comment prior to release in final form.
4.
Comments on Consultative Documents and suggestions for new Regulatory Documents and for improvement to those that exist are encouraged and should be directed to the Health Effects and Regulatory Documents Section of the AECB.
5.
Copies of Consultative Documents, Regulatory Documents and related index lists are available in both English and French on request from the Office of Public Information. Requests for technical information on and interpretation of documents should be addressed to this office.
6.
The Atomic Energy Control Board may be contactec as follows:
Postal address:
Atomic Energy Control Boarc P.O. Box 1046 Ottawa, Ontario
)
CANADA KlP SS9 Telephone
)
General Inquiries:
(613) 995-5894
THE BASIS FOR EXEMPTING THE DISPOSAL OF CERTAIN RADIOACTIVE MATERIALS FROM LICENSING 1.
INTRODUCTION Section 25 of the Atomic Energy Control Regulations requires that any prescribed substance associated with the development, use, application or production of atomic energy shall not be abandoned or disposed of except in accordance with a licence or with the written instructions of the Atomic Energy Control Board (AECB).
This requirement means that a regulatory judgement must be made in every case where it is proposed to dispose of radioactive vaste from nuclear fuel cycle operations or from the use of radioisotopes no matter how low the concentration or quantity of radionuclides present.
Some materials have such low radionuclide content that the radiological health risks as a result of their disposal without special radiological precautions would be so small that AECB licensing of the practice is not necessary.
From a practical point of view, it would be advantageous to identify such waste materials, often referred to as de,minimis wastes, in terms of concentrations of radionuclides in, or on the surface of, contaminated materials or, alternatively, in terms of the total quantity of radionuclides present, depending on the case.
These numerical criteria would apply to the various methods of disposing of the waste materials, such as those commonly used for the disposal or recycling of conventional wastes or garbage.
It is difficult, however, to define numerical criteria of practical use which can be applied generically to all of the possible disposal situations.
The alternative and more fundamental approach would be to define a negligible, or de,minimis, level of individual radiological risk that is insignificant and that would form the basis for exempting the disposal of materials from AECB licensing control.
They could then be disposed of by conventional means.
Formal recognition of this approach would foster efficiency and consistency in the regulation of radioactive wastes.
It would also help in establishing regulatory priorities and would thereby simplify and expedite the decision-making process. Furthermore, it would be in the public interest to permit better utilization of resources by diverting them away from examining or implementing measures for the further reduction of negligible risks associated with the disposal of certain wastes.
Clearly, the concept of a dji minimis risk or dose is generic in nature in that it is in principle broadly applicable to all situations involving exposure to ionizing radiation. While the practical application of the concept to other situations is being evaluated, the AECB will use the concept as described in this document for deciding when to exempt the disposal of certain contaminated materials from licensing control.
The introduction of the de minimis risk or dose concept is not foreseen to affect the licensing of currently designated radioactive waste management facilities, for these contain wastes or involve operations for which nuclear regulatory controls are still considered necessary.
On the other hand, some waste materials that are presently being sent to licensed facilities may prove to qualify according to the concept for recycling or disposal by conventional means.
.. 9 2.
POSSIBLE BASES FOR DERIVATION OF 'DE MINIMIS" DOSE 2.1 Natural Background Radiation Mankind has been subjected to natural background radiation throughout history and has adapted to this exposure. The individual dose received in a year from natural background radiation varies significantly from place to place depending on a number of factors such as elevation above sea level and the amount and type of ncturally-occurring radionuclides in the soil and other In some locations in other countries, the annual natural background ma t t e r.
radiation dose exceeds the dose limits for man-made radiation established by the AECB for individual members of the public.
No measurable effects have been detected in populations living in areas of high natural background radiation.
In Canada, individual doses f rom all natural sources generally lie in the range of 1 to 2 millisieverts per year and variations of 0.1 to 0.2 millisievert per year in a geographical region are common.
For further perspective, the increase in the cosmic radiation dose component of natural background radiation that is received during a trans-Canada return flight by an individual on a commercial jet aircraf t is approximately 0.05 mil 11 sievert.
An incremental annual dose resulting from the disposal of certain materials exempt from licensing as radioactive waste might be considered insignificant if it is a small fraction of the annual dose due either to natural background radiation or to the variation in natural background radiation.
In the latter case, a de,minimis dose rate would be indistinguishable from the background variation in dose rate.
Moreover, its statistical effects would be smaller than those due to the background variations themselves.
However, it is not clear what the small fraction should be in deriving a de minimis dose criterion.
2.2 Risk Risk is a factor present in all human activities. There is always some chance of serious injury or death, even if the chances are very small. Attitudes towards riska vary from person to person and can be influenced by such factors i
as whether the risks are voluntary or involuntary, whether they are unusual or l
not and whether they are likely to occur soon or far in the future. Aversion to an elevated risk is sometimes overcome if the person involved perceives that there are adequate compensatory benefits. Also, risks over which people feel they have some control tend to be accepted more readily than risks that they feel are beyond their control.
The following paragraphs illustrate the different degrees of acceptability of risk under different circumstances.
The International Commission on Radiological Protection (ICRP) in formulating its recommendations on dose limitation determined that individuals generally I
accept occupational risks of fatalities in the range 10-5 to 10-3 per year (i.e. I to 100 deaths per year for every 100,000 workers).
Indeed, some individuals in their occupations or recreational pursuits accept voluntary I
risks that are even greater than 10-3 per year. Background radiation constitutes a risk of fatal cancer of about 10-5 per year, but despite the fact' that the background level varies widely, people generally are not influenced by the relative magnitude of this risk when they decide where to live.
' making.
This gives rise to the following policy statement:
"The Atomic Energy Control Board recognizes that, for practical purposes, the disposal of certain contaminated materials should be exempted from AECB licensing control.
The AECB will use a de minimis dose of radiation to individuals of 0.05 millistevert in a year Tor deciding such exemptions on a case-by-case basis, provided that the radiological impact is localized and that the potential for exposures of large populations is small. Approval for licence exemption will be given if it is satisfactorily demonstrated that the de,minimis criterion is met, using methods and procedures no different from those that would be applied to the corresponding uncontaminated materials."
This policy statement is based on current attitudes to risk and on the current and foreseeable future use of atomic energy.
Should these factors change in the future, then the policy statement would be reviewed.
5.
APPLICATION OF THE "DE MINIMIS" DOSE CONCEPT The de minimis dose criterion applies to the individuals in the group most likely to receive the highest doses as a result of the disposal or recycling of slightly contaminated wastes by conventional means in which no particular precautions are taken beyond those for dealing with sibilar uncontaminated wastes. The concept therefore requires that an analysis be conducted to determine whether a particular method of disposing of a given waste results in individual doses that satisfy the dji minimis dose criterion. Clearly, the rigour and comprehensiveness of the predictive analysis should be commensurate with the scale of the potential hazard but should nonetheless use mathematical models that are formulated from experimental and field data where appropriate and that use realistic assumptions.
I I
In considering applications for approval for licence exemption based on the de minimis dose, the AECB will consider all licence-exempt disposal practices contributing to the dose received by the critical group.
If the group is already receiving some contribution f rom an existing exempt practice, this will be taken into account in approving any new practice. Furthermore, the Board will periodically review all approvals it has issued, in order to ensure that the relevant parameters of the situation have not changed significantly, and will require proponents to submit information to assist in these reviews.
In due course, as experience is gained in applying the concept, criteria and guidelines will be generated that more explicitly define vastes that qualify for various types of conventional disposal and recycling.
In the meantime, licensees that choose to take advantage of the de minimis dose concept must provide to the AECB such of the following information as necessary:
(a) a detailed description of the waste materials, including their origin, chemical composition, physical state, volume and mass; (b) the concentration or contamination levels, half-lives, and identities of the radionuclides present;
l
.e.
From information reviewed by the ICRP concerning risks that are regularly encountered by members of the public in every day life, it seems that individuals are likely to accept risks of fatalities in the range 10-6 to 10-5 per year. Furthermore, surveys of risks associated with various activities have indicated that risks of 10-6 per year may be the threshold for risks that are considered insignificant by individuals in their decision-saking.
Such information provides a logical basis for deriving a de, minimis dose criterion.
The necessary conversion from risk to dose for this purpose is sufficiently well understood, even though there may be uncertainties in extrapolating from mortality risk factors determined at high doses to effects that may occur at very low doses.
2.3 Federal Dose Limits The Atomic Energy Control Regulations administered by the AECB currently specify maximum permissible doses and exposures for atomic radiation workers and members of the public. These dose and exposure levels do not apply to natural background radiation or to ionizing radiation received by a patient in the course of medical diagnosis or treatment by a qualified medical practitioner, or received by a person carrying out emergency procedures undertaken to avert danger to human life.
The dose limits are 50 millisieverts per year for occupationally exposed individuals and 5 millisieverts per year for any other person.
In view of the assumed non-threshold nature of the dose-response relationship, these dose limits do not represent absolutely risk-free levels of exposure.
There is, in fact, an additional requirement applied in practice that all doses be kept as low as reasonably achievable, economic and social factors being taken into account.
The dose limits thus place a limit on the risk of radiation-induced fatal cancer and serious genetic effects, that may be judged acceptable in relation to benefito, and prevent acute and identifiable non-cancerous radiation injury. The selection of a de minimis dose criterion on the basis of a fraction of the federal dose limits would therefore be somewhat arbitrary and judgemental.
2.4 Federal-Provincial Drinking Water Guidelines Federal provincial drinking water guidelines have been published by Health and Welfare Canada in regard to the radiological characteristics of water supplies to the public in large communities.
Radioactive contaminants in water supplies arise principally from natural sources, and to a lesser extent, from industrial and research ac.tivities. The guidelines are based on arbitrary f ractions of the dose limits recommended by the ICRP in its publication ICRP-26 and are expressed in terms of maximum acceptable and target concentrations of radionuclides. Maximum acceptable concentrations in an average daily intake of 2 litres of drinking water correspond to an effective dose equivalent of 0.5 millisievert per year (i.e.10% of the ICRP recommended 1
annual limit for members of the public). Target concentrations correspond to an effective dose equivalent of 0.05 millisievert per year (i.e.1% of the ICRP recommended annual limit for members of the public).
While the. target concentration is intended to be a guideline for life-long continuous consumption, concentrations between this level and the maximum
- acceptable concentration on a continuous basis may also be judged acceptable, provided they are kept as low as reasonably achievable. However, the establishment of these levels should not be regarded as condoning the degradation of drinking water supplies to the specified concentrations.
As mentioned above, the drinking water guidelines are based on arbitrary fractions of the dose limits recommended by the ICRP.
This, together with the fact that drinking water represents but one environmental pathway that may contribute to the radiological impact from waste disposal, limits the appropriateness of basing a di minimis dose criterion on the drinking water guidelines.
3.
PROPOSED DERIVATION OF "DE MINIMIS" DOSE CRITERION Low levels of exposure to ionizing radiation associated with natural background radiation, nuclear fuel cycle operations and radioisotope uses all carry with them an attendant risk of radiation-induced health effects.
Such radiological risks can be appreciated in relative terms when compared with conventional risks that individuals in society face and accept in certain circumstances and consider insignificant in others.
The concept of risk is proposed as the basis for deriving a det minimis dose criterion, a risk of 10-6 per year being used as an upper bound for deriving an annual individual dose for this purpose.
In converting risk to dose, the ICRP in its publication ICRP-26 indicates that the mortality risk factor for radiation-induced cancers is generally accepted as being approximately 10-2 per sievert as an average for both sexes and all ages.
However, to properly account for the genetic risk to subsequent generations, the overall risk factor becomes approximately 2 x 10-2 per sievert.
In this case, the proposed reference individual risk of 10-6 per year can be expressed as an annual individual effective dose equivalent of 0.05 millisievert. This level of annual dose may therefore be taken as the Shi minimis dose criterion.
In comparative terms, the de minimis dose level is well within the range of variation of natural background radiation in most parts of Canada, it is equivalent to 1% of the federal regulatory dose limit for members of the public and it is equivalent to the federal provincial target concentration guideline for the radiological characteristics of drinking water.
Even though the $bt minimis individual dose, and hence individual risk, is very low, the AECB recognizes the importance of limiting the number of people so exposed in order to restrict the overall impact on the population.
It is anticipated that the radiological impact of disposai practices that are exempt from licensing will be localized, and hence that the potential for exposures of large populations will be small.
l 4
AECB POLICY STATEMENT A numerical de minimis dose criterion of 0.05 millisievert has been derived on the basia of a risk level that is well within the range of risks generally accepted by individuals and that corresponds to the upper end of the range of l
risks considered insignificant by individuals in their personal decision-t
n.
I
_3_
making.
This gives rise to the following policy statement:
"The Atomic Energy Control Board recognises that, for practical purposes, the disposal of certain contaminated materials should be exempted from AECB licensing control.
The AECB will use s de minimis dose of radiation to individuals of 0.05 millisievert in a year ~ Tor deciding such exemptions on a case-by-case basis, provided that the radiological impact is localised and that the potential for exposures of large populations is small.
Approval for licence exemption will be given if it is satisfactorily demonstrated that the de minimis criterion is met, using methods and procedures no different f rom those that would be applied to the corresponding uncontaminated materials."
This policy statement is based on current attitudes to risi and on the current and foreseeable future use of atomic energy.
Should these factors change in the future, then the policy statenant would be reviewed.
5.
APPLICATION OF THE "DE MINIMIS" D3SE CONCEPT The de minimis dose criterion applies to the individuals in the group most likely to receive the highest doses as a result of the disposal or recycling of slightly contaminated wastes by co1ventional means in which no particular
)
precautions are taken beyond those f or dealing with similar uncontaminated wastes. The concept therefore requiris that an analysis ba conducted to determine whether a particular method of disposing of a given waste results in individual dossa that satisfy the de tainimis dose criterion.
Clearly, the rigour and comprehensiveness of th~~fredictive analysis should be commensurate with the seale of the potential hazard but should nonetheless use mathematical models that are formulated from experimental and field data where appropriate and that use realistic assumptions.
In considering applications for approval for licence exemption based on the de minimis dose, the AECB will considor all licence-exempt disposal practices contributing to the dose received by the critical group. If the group is already receiving some contribution from an existing exempt practice, this will be taken into account in approving any new practice. Furthermore, the Board will periodically review all approvals it has issued, in order to ensure that the relevant parameters of the a:.tuation have not changed significantly, and will require proponents to submit information to assist in these reviews.
In due course, as experience is gained in applyin,g the concept, criteria and guidelines will be generated that morn explicitly define wastes that qualify for various types of conventional disposal and recycling.
In the meantime, licensees that choose to take advantar,e of the de mininds dose concept must provide to the AZCB such of the folloving informa, tion as necessary:
i (a) a detailed description of the waste materials, including their origin, chemical composition, physical state, volume and mass; (b) the concentration or contamination levels, half-lives, and identities of the radionuclides present;
b (c) details of the monitoring, analytical and decontamination procedures undertaken at the nuclear facility or premises to characterize the waste materials and to minimize the preennce of removable contamination on internal and external surfaces; f
l (d) the initial destination of the waste material upon release from the nuclear facility or premises and any additional information regarding its ultimate disposition; (e) in cases where it is necessary to ensure that the waste materials are disposed of or recycled as proposed, details of administrative procedures that could be implemented to achieve this assurance; j
(f) details of the proposed disposal or recycling scheme and an assessment of the radiological impact on members of the public.
Where long-lived radionuclides are involved, exposure pathways in the long-term should be taken into account including, for example, the re-use of disposal sites.
In certain cases, the AECB may perform its own impact assessment for the purpose of deciding whether to grant an exemption from licensing.
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UNITED STATES
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NUCLE AR REGULATORY Commission
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g W ASHINGTON. O. C. 20555 r.
i i,.....f JUL 2 51985 MEMORANDUM FOR:
Chainnan Palladino Comissioner Roberts Comissioner Asselstine Comissioner Bernthal Comissioner Zech FROM:
William J. Dircks Executive Director for Operations
SUBJECT:
REVISION OF SECY-85-147, PROPOSED REVISION OF 10 CFR PART 20 At the May 15 briefing on the subject proposed rulemaking the staff told the Comission that it had received from EPA proposed Federal Radiation
. Protection Guidance for Occupational Exposure. The staff stated that the proposed revision of 10 CFR 20 was consistent with this proposed Federal Guidance. This statement was conditioned, however, on the subject of protection of the embryo / fetus, in that we interpreted the proposed Federal Guidance to allow implementing agencies latitude in balancing contradictory stated requirements. We told the Comission that we had submitted coments to EPA on the proposed Federal Guidance and had requested clarification on certain points.
We recently received this clarification in the form of a letter from Sheldon Meyers to W. J. Dircks, dated 7/16/85 (enclosure 1) which states that our interpretation of the requirements for protecting the embryo / fetus was not correct. The EPA letter is very clear that a specific exposure limit of 0.5 rem during the entire pregnancy of a declared pregnant worker is to be established.
It also clarifies other points that we raised in our comments on the proposed Federal Guidance.
The protection of the embryo / fetus, including these EPA clarifications, will be one of the issues addressed at the July 30, 1985 Comission briefing.
Contact:
Robert Baker, RES 42-74579
a The Commissioners 2
l We have made the necessary revisions to the Federal Register notice that was included as enclosure 1 to SECY 85-147 to reflect these EPA clarifications of the proposed Federal Gui. dance. Copies of the affected pages, in comparative text, are provided as enclosure 2.
William J. Dircks Executive Director for Operations
Enclosures:
1.
Ltr fm Meyers to Dircks, dtd 7/16/85 2.
Comparative Text cc: SECY OPE OGC s-
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9
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UNITED STATES ENVIRON 31 ENTAL PROTECTION AGENCY
(*% w$j WA5HINGTON, D.C. 20460 JUL 161985 William J. Dircks Executive Director for Operations Nuclear Regulatory Comission Washington, D.C.
20555-
Dear Mr. Dircks:
Thank you for your letter of June 7, 1985, to Mr. Charles L. Elkins, I
Acting Assistant Administrator for Air and Radiation. We appreciate the Nuclear Regulatory Comission's support of the submission of revised Federal Radiation Protection Guidance to the President for approval and promulgation as guidance to Federal agencies. Your staff has continued to be most helpful in this endeavor.
Your letter requested clarification of the proposed revised guidance in two areas. The first concerns protection of the unborn. The guidance recomends that the limit for protection of the unborn be achieved
"...without economic penalty or loss of job opportunity and security to workers." You inquired whether this recommendation is intended to be interpreted as permitting a balancing judgment vis-a-vis full regulatory implementation of the limit for dose to the unborn.
Such a balancing is not intended. That is, implementing regulations should require that the limiting value of 0.5 rem be satisfied (subject to coments below on prior doses and the significance of small additional doses). The issues of economic penalty, job opportunity, and job security are additional matters that are independently addressable, by the employee or others, under such statutes and orders as Title VII of the Civil Rights Act of 1964, as amended; Executive Order 11246, as amended; and the Pregnancy Discrimina-tion Act of 1978. These additional matters may or may not also be within the aegis of the Atomic Energy Act, and therefore addressable or not addressable in NRC regulations. However, in either case, it is not the intent of the guidance to compromise the protection of the unborn on such grounds. In this regard, it is perhaps useful to note that all of these recomendations apply as guidance to Federal agencies only to the extent that they have ren1 story or administrative jurisdiction. We will clarify these points in the final recomendations, as you requested. We note also that, in the absence of a statement regarding possible discriminatory actions, the existence of a limit for protection of the unborn might be misinterpreted by some as prima facia evidence of a basis for such discrimination.
Since this is clearly not the conclusion reached in forwarding these recomendations, we have concluded' that a clear statement is warranted in the guidance itself.
8$1363 ESCL:$'.'RE 1
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2 Two other matters regarding Recommendation 6 also warrant some clarification. The draf t language is capable of interpretation regarding who say " declare" that a woman is pregnant.
It was the intent of the interagency group that this be reserved to the woman herself, and the final guidance will clarify that this is so.
It may also occur that a significant dose has been received by an unborn following conception but prior to a woman declaring her pregnancy.
If this dose is close to the limit for the unborn, a difficult regulatory situation could develop if no working location in the facility is completely " dose-free."
In such situations it would be completely within the spirit and intent of the guidance to permit doses not significant in comparison to the recommended' limit, such as those already customarily not large enough to record, during the balance of the pregnancy, so as to facilitate the development of reasonable implementing regulations. If the dose prior to "declara-tion" already exceeds the limit, a similar regulatory solution would be appropriate, i.e., doses deemed not significant in comparison to the recommended limit could be permitted during the balance of the pregnancy, and, of course, there is no regulatory solution or obligation to redress any excess dose prior to declaration.
Your second point concerns the lack of a defini' tion of " workers" to whom this occupational exposure guidance is intended to apply. Your assumption that this is intended to be lef t to the implementing agencies is correct, and we will clarify this in the guidance.
We will be glad to provide any further clarifications if this is necessary. Thank you again for your continuing support.
Sincerely yours, Sheldon Meyers, Acting Director Office of Radiation Programs (ANR-458) i 1
.K 4
4 REPLACEMENT PAGES FOR SECY-85-147 FEDERAL REGISTER NOTICE STATEMENT OF CONSIDERATIONS AND PROPOSED RULE i
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REPLACEMENT PAGES FOR STATEMENT OF CONSIDERATIONS
TABLE 1.
(Ccntinued)
Issue Present 10 CFR Part 20 Proposed Revision Embryo / Fetus Not addressed.
[ Specific-limits-considered--but-not-included-in proposed-revision-] 0.5 rem (5 mSv) during the entire pregnancy due to occupational exposure of the " declared" pregnant woman.
ALARA Recommended.
ALARA program required.
Occupational None Investigation level--set by licensee below reference level annual limit.
BASIS FOR LIMITS diological damage or health effects
" Acceptable" risk (10 4 per year for workers, would not be statistically observable.
10 8 to 10 5 per year for members of the public) based on estimated radiation-induced fatal cancers and serious hereditary disorders.
Upper limit of organ dose set to avoid non-d stochastic (threshold) effects, such as cataracts.
p:TERNAL 00SIMETRIC METHODOLOGY Irradiation Dose to the most irradiated organ, Dose to each organ is calculated, weighted by i.e., " critical organ," used to limit a factor equating risk from dose to that organ intake via " Maximum Permissible Con to risk from S rems (0.05 Sv) of whole-body centrations" (HPC).
irradiation, and then the products are summed.
Values for ALIs and DACs have been calculated for each radionuclide.
Doses from radionuclides deposited Weighted doses to organs from radionuclides in non-critical organs are ignored.
deposited anywhere in the body are summed.
J C.
g Lung model 1959 ICRP-2 model used.
Improved 1966 model of ICRP Task Group on Lung g
Dynamics used.
a Retention in lung Aerosols ranked " Soluble" or " Insoluble."
Aerosols ranked by translocation and elimina r
tion rates, i.e., 0 (days), W (weeks), and Y (years).
5 j
I
^
TABLE 3.
SUMMARY
OF DOSE LIMITS Occupational Exposures of Individuals Dose Limits Sum of deep dose equivalent and com-5 rems (0.05 Sv)'in
~
'mitted effective dose equivalent
- one year Deep dose equivalent (external only) 3 rems (0.03 Sv) in one quarter Any organ or tissue, extremities 50 rems (0.5 Sv) in and skin one year Lens of the eye 15 rems (0.15 Sv) in one year Minors 1/10 of annual limits for adults Embryo / fetus 0.5 rem (5 mSv) durino entire preonancy period Planned Soecial Exposures Annual limit from all events 1 x annual limits Lifetime limit from all events 5 x annual limits Exposures of Members of the Public Sum of deep dose equivalent and com-0.5 rem (5 mSv) in mitted effective dose equivalent
- one year aThe sum of weighted 50-year dose commitments from the intake of radio-active material and (external) deep dose equivalent.
" Deep dose equiva-lent" used in this summation is the highest dose equivalent at a tissue depth of 1 cm to the head, trunk, arm above the elbow, or leg above the knee.
(See 5 20.3.) For intakes of certain long effective half-lived radioactive mater.ial, annual rather than committed effective dose equivalents may be used.
(See $ 20.205.)
Combined Internal and External Doses A limit of 5 rems (0.05 Sv) in a calendar year would be established on the sum of the doses from sources internal and external to the body.
The deep dose equivalent from external sources and the product of the weighting factors and the 50 year committed dose equivalent to the organs would be sumted.
The quarterly limit of 3 rems (0.03 Sv) deep dose equivalent from external sources in the present Part 20 would be 26
E to occur, the individual could receive 3 rems from the internal deposi-tion each year and would not be permitted to receive any additional intake of long-lived radionuclides which might add to the annual dose.
- However, it is unlikely that metabolic behavior of such nuclides will remain so stable over a lifetime that this dose would not decrease somewhat in time.
In addition, ALARA efforts should be adequate to keep internal depositions well below the limit.
The Commission believes that these conditions are practical, reflect state-of-the-art health physics practice, and permit adjustment of the committed dose equivalent estimates as better data become available.
XII.
MINORS AND PREGNANT WOMEN In developing the proposed revision, consideration was given to regulating the exposure of classes of workers who might be at a rela-tively higher-than-average risk from radiation exposures, e.g., minors, fertile women, pregnant women, and embryos / fetuses.
For minors (persons less than 18 years of age), the annual limits are 1/10 of those for an adult worker.
The present NRC regulations in 10 CFR Part 19 reouire that all indi-viduals who might be exposed to radiation in their workplace be informed about the potential risks associated with the exposures.
As a matter of policy, the NRC has used a single annual limit for both sexes and has relied on information provided in Regulatory Guide 8.13 (" Instruction Concerning Prenatal Radiation Exposure") to all workers regardino risk to an embryo / fetus.
The susceptibility of the embryo / fetus to damage by radiation is well established and recent information suggests that the period from 10 weeks to 17 weeks in development may be especially critical.
In view o'f the greater sensitivity, it is generally considered d'esirable to limit the dose to the embryo / fetus to not more than 0.5 rem (5 mSv) during the entire pregnancy.
To avoid possible greater damage at higher exposure rates, particularly at some critical time during the development of the embryo / fetus, efforts should be made to avoid substantial variation above 37
v a uniform monthly exposure rate which would satisfy this limit.
Unfortunately, during one of the critical periods of embryonic organ development (the first two or three months of pregnancy), a woman might not realize that she is pregnant.
In order to protect an embryo / fetus before a woman is aware of her pregnancy, a lower dose limit for all fertile women might appear to be desirable.
However, establishment of a lower dose limit for all fertile women would result in undue restriction when there is no embryo / fetus to protect and could, therefore, restrict the employment of virtually all women in the nuclear workforce.
1 37a
1 The NCRP recommended in Report No. 39 (1971) that "During the entire gestation period, the maximum permissible dose equivalent to the fetus from occupational exposure of the expectant mother should not exceed 0.5 rem."
The ICRP recommended a constraint on the dose to the pregnant woman by selecting working conditions so that she would be unlikel'y to receive more than about 1.5 rem per year.
Because of the shielding pro-vided to the fetus by fluids' and the mother's overlying tissues and fluids and the duration of the pregnancy, it is likely that the fetus would receive less than 0.5 rem under such selected working conditions.
[ Exposure-of-the-enborn was-one-of-the-issues-censidered-by-the Environmentai-Protectien-Agene'y-(EPA 3-in proposed-Federai-Radiation Protection-Saidance-for-Occupational-Exposure published-en-danmary-ES-1981 perseant-to-Sectien-274h-of-the-Atemic-Energy-Act-ef-1954--as-amended (46-FR-78363-(see-XXIII:--iMPbEMENTATISH--Federai3 --Feiiewing-tensidera-tion-of-the-comments-en-the preposed guidance-and-ali-ether-aspects-of that-matter--EPA-is-likely-te-inciede-in-the-recommendatiens-fer-Federai gui d a n c e-li mi tati o n-o f-th e-des e-e qui v ai e nt-to-an-e n b o rn-c hii d-to-8: 5-rem
- (5-mSv3-as-a-resait-of-eccopationai-exposure-of-a-weman-declared-to-be pregnant ] Under its legal authority to deveico recommendations for the President concerning guidance to all Federal agencies for the orotection of workers exposed to ionizing radiation, the Environmental Protection Agency (EPA) has proposed recommendations for protection of the embryo /
fetus.
The updated (March 25, 1985) draft guidance includes a recem-mendation that the dose equivalent to an embryo / fetus as a result of occupational exposure of a woman declared to be pregnant should not exceed 0.5 rem (5 mSv) during the entire aestation period.
[ft-is expected 3-that] This recommendation [wiii-be] is accompanied by a further recommendation that conformance to this limitation should be achieved without economic penalty or loss of job opportunity and security to workers.
As with previous Federal quidance, the NRC, as a matter of policy will imolement the final Federal quidance on protection of the embryo / fetus in its regulations.
[The present-NR6-regeistions-in-10-6FR-Part-19-require-that-aii-indi-videais-who-might-be-exposed-to-radiation-in-their workplace-be-informed abeet-the petential-risks-associated with-the-exposures:--Aii-workers 38
d s houl d-b e-s p e ci fi c atiy-i nf o rmed-ef-the-ri s k-te-an-emb rye / f e tes:--Hewe v e r-there-are policy-constraints-against-regeistions which-establish-different dese-iimits-for-men-and-wemen---As-a-matter-of policy--the-NRE-has esed-a single-annuai-limit-for-both-sexes-and-has-relied-en-informatien previded i n-R egei sto ry-Sei de 13-f u f ns tructi on-E e nc e rni ng-Pre natsi-R adi ati o n-Expe-sure 3.te-aii-workers regarding-risk-to-an-embrye/f etus-]
u
[The-Eemmission-has-censidered-incieding-in-the proposed-revisien-a 5-20-Ese-that-weeld-read-as-fe44ews-]
38a
I
~
[$-20:208--Bese-te-en-embrye/ fetes]
)
[(a)--Except-as-noted-in paragtsph-(c3-of-this-section--a ficensee-shali-ensure-that-the-effective-dese-e'quivalent to-an embrye/ fetus-due-to-eceupationai exposure-of-s
~
deciated pregnant-weman-dees-net-exceed-0:5-rem-(5-mSv3 during-the-entire pregnancy:--Efferts-shecid-be-made-te avoid-substantiai variation-above-a-uniform-monthly expe-sure-rate which-would-satisfy-this-iimit --(Fer-record-keeping-requirements-see-5-20:l106:3]
[(b3--The-effective-dese-equivaient-te-an-embrye/ fetus-is-the sem-of--]
[(13--The-deep-dese-equivaient-to-the-deciated pregnant woman;-and]
[(23--In-the-absence-of-age-specific-transport parameters for-the radionuclides-invnived -two-times-the-cemmitted i
e f f e cti v e-de s e-e q ui v ai e nt-th at-wo ni d-b e-e the rwi s e assessed-due-te-the-intake-of-radiencelides-by-the pregnant woman '--The-ficensee-may-ese-facters-ether than-2-when-they-become-available-for-specific-radio-naciides:--Further--the-ficensee-may--for-intakes-of 84 ass-Y-materiais--calculate-the-dese-to-the-embrye/
fetus-en-the-basis-of pheten-dese-to-the-embrye/ fetus (target 3-from-ether-(searce3-organs plus-the-dese equivaient-to-the-embrye/ fetus-frem-that portien-of the pregnant woman s-intake-of-Eiass-Y-meteriai-that i
is-transportable--eppiying-either-the-facter-of-E-er age-specific-facters-applicable-to-the-transportable fraction-involved:]
[4This-facter-of-E-recognizes petential-differences-in-bielegicaf-facters that-cecid-rescit-in-the embrye/ fetus-receiving-an effective-dese-equiva-4ent greater-than-that-of-the pregnant woman-as-a-resuit-ef-intake-of radioactive-materiai-by-the pregnant-weman ]
39
.e Consistent with the proposed guidance to Federal agencies, the prooosed revision of Part 20 would reouire the licensee, following a voluntary declara-tion of pregnancy by the emoloyee, to limit to 0.5 rem (5 mSv) the dose to an embryo / fetus from occupational exposure of the declared Oregnant woman through-out the -period of pregnancy unless, as noted below, the embryo / fetus may have already received a dose in excess of the limit prior to the declaration.
To provide adeouate radiation protection for the embryo / fetus, and to minimize the restriction on employment, the Commission recognizes the importance of female workers voluntarily informing their employers of their pregnancy and the estimated date of conception, so that arrangements can be made to restrict potential exposures.
Licensees would be required to use, as dose to an embryo / fetus, the sum of the external radiation (deep dose equivalent) and two times the effective dose equivalent assigned to the expectant mother from the radionuclides which enter the mother's body.
The factor of two is the same age-soecific factor which is being used in the assessment and summation of radiation doses to the public.
The Commission would not consider the licensee in violation of the proposed revision for exceeding the 0.5 rem dose limit if the embryo / fetus had received 0.5 rem, or more, before the pregnant woman notified the licensee of her pregnancy.
In order to permit continued emoloyment of the pregnant woman during the remainder of the pregnancy, and recognizing that it is not possible to avoid some additional exposure in a nuclear facility, the prooosed revision would permit an additional 1% of the annual dose limit for workers, e.g., 0.05 rem, to be received by the embryo / fetus during the remainder of the pregnancy.
39a
.s
[(c3--Hetwithstanding-the-iimit-in paragraph-ta)-of-this-section; i f-the-des e-to-th e-eme rye /f e tus-i s-f e end-to-hav e-exc eede d 8:5-rem-(5-mSv3-by-the-time-the weman-declares-to-the-iieen-see-the pregnancy-and-the-estimated-date-of-conception;-the licensee-is-in-compliance with paragraph-(a)-of-this-see-tion-if-the-licensee-dees not-assign-the woman-tasks which rescit-in-the embrye/ fetes-receiving-an-additionai-dese e x c e edi n g-6 : 05 - rem- ( 0 : 5 - mS v 3 - d e ri n g - th e - r e m ai n d e r-o f - th e pregnancy ]
[Th e-E emmi s s i o n-d eci d e d-no t-to-i n ci ede-a ny-s p e ci f i c-de s e-l i mi ts - o r other-censtraints-en-the-embrye/ fetus er-en exposure-of pregnant-wemen in-the proposed-revision-of-Part-20-bat -rather;-to-await-any-Federai i
gui danc e-dev el ope d-by-E P A-o n-thi s -i s s ee-and-to-co nti nce-i ts-reli ance-on Regeistory-Seide-8:13-as-a-searce-of-informatien-and-instruction-en-riskr]
Consistent with [this-decision] the Federal cuidance prooosed by epa for protection of an embryo / fetus from occupational radiation exposure of female workers, the proposed amendments to Parts 19 and 20 published by the Atomic Energy Commission on January 3, 1975 (40 FR 799) regarding maintenance of doses to an embryo or fetus as low as is reasonably achievable would be superseded.
[The-Eemmission-is particciariy-interested-in-comments-en-this decision-to-limit-the-scope-of-this-reiemaking preceedingr]
l XIII.
PLANNED SPECIAL EXPOSURES 4
Removal of the 5 (N-18) '! dose-averaging" provision in the present Part 20 could limit the flexibility in the management of some occupational exposures necessary to accomplish tasks in high radiation areas.
In order to provide some compensating flexibility, the proposed revision contains a provision for " planned special exposures." However, the provision is designed to be used only in exceptional situations when alternatives which might avoid the higher exposure are unavailable or impractical.
In the proposed provision for planned special exposures, an indi-vidual's dose due to all such exposures in a calendar year may not exceed an increment equal to the annual dose limits.
Thus, an individual could be permitted to receive 5 rems (0.05 Sv) from planned special exposures in a given year in addition to 5 rems (0.05 Sv) from routine activities 40
e the exposure.
This approach was not proposed because the risk of suffer-ing health damage from these limited exposures is small and the justifica-tion for having the planned special exposure feature is the recognized s
need of the licensee to accomplish important occasional tasks vital to continued operations.
The revision is believed to contain adequate features to permit the licensee to have the assured labor resources when they are needed while providing' adequate worker protection.
Consideration also was given to prohibiting fertile women from parti-cipation in planned special exposures.
A planned soecial exposure could result in a whole body effective dose eouivalent of 5 rems at the limit, plus an additional 5 rems received during normal working conditions.
This theoretical dose equivalent of 10 rems for a possibly pregnant woman could represent a significant increase in risk of damace to the embryo / fetus above the risk from the 0.5 rem limit specified for declared pregnancies.
However, this prohibition has not been included in the revision because of consideration of the following factors.
The prohibition would require licensees to either exclude all women from planned special exposures or to question, with the associated invasion of privacy, the reproductive capability of female employees.
The prohibition could unnecessarily restrict the work opportunities for women who could choose not to become pregnant during the time intervals involving the higher planned special exposures.
The avail-ability and effectiveness of birth control methods now available provides a reduced probability of an unplanned or unexpected pregnancy.
Moreover, the dose limit that would be specified for the embryo / fetus would prevent declared pregnant women from carticipating in planned special exposures.
[Finafiy--in addition-to-the-reistively-encommon-ese-ef planned-speciai-exposures-and-even less-likely psrticipatien-of pregnant women-in-the-activity--there-weeld-be-a r el ati v ely-s mali-i nc reme n t ai-i n c r e a s e - d e e-to-ra di a ti o n-ex p o s ur e-i n-th e-o v e rali rtJk-that-the-embrye/ fetus-norma 44y-incers-(see-NRE-Regeistory-Seide-8:13-uinstructien-Eencerning-Prenatai-Radiatien-Exposere ):]
u 42
a XIV.
OVEREXPOSURES The present Part 20 does not specifically address overexposures of workers.
However, the present Part 20 does restrict the further exposure of a worker who has exceeded the quarterly limits (1.25 rems per quarter or 3 rems per quarter if the 5(N-18) " bank" has not been "used up") only for the remainder of the quarter in which the overexposure occurs.
The proposed revision would limit the dose equivalent for workers to 3 rems (0.03 Sv) in any quarter and 5 rems (0.05 Sv) in a year.
If f
l l
a 42a
REPLACEMENT PAGES FOR PROPOSED RULE I
)
l
SUBPART C - OCCUPATIONAL DOSE LIMITS 20.201 Occupational dose limits for adults.
20.202 Compliance with requirements for summation of external and internal doses.
20.203 Further provisions external exposure.
20.204 Further provisions - internal exposure.
20.205 Further provisions - internal exposure involving radionuclides with very long effective half-lives.
20.206 Planned special exposures.
20.207 Occupational dose limits for minors.
20.208 Dose to an embryo / fetus.
l SUBPART 0 - RADIATION DOSE LIMITS AND REFERENCE LEVEL FOR INDIVIOUAL MEMBERS OF THE PUBLIC 20.301 Dose limits for individual members of the public.
20.302
[ Reserved.]
20.303 Reference level for the exposure of individual memoers of the public.
20.304 Collective dose evaluations.
SUBPART E - (RESERVED]
SUBPART F - SURVEYS AND MONITORING 20.501 General.
20.502 Conditions requiring i dividual monitoring of external and internal occupatie.I dose.
SUBPART G - CONTR L OF EXPOSURE FROM EXTERNAL SOURCES IN RESTRICTED AREAS 20,601 Control of access to high radiation areas.
20.602 Control of access to very high radiation areas.
1 80
" Calendar week" (See Week)
" Calendar year" (See Year)
" Class"-(or " Lung class" or " Inhalation class") means a classification scheme for inhaled material according to its rate of clearance from the pulmonary region of the lung.
Materials are classified as 0, W, or Y which applies to a range of biological half-times for 0 of less than 10 days, for W from 10 to 100 days, and for Y greater than 100 days.
" Collective affective dose equivalent" (See Oose terms)
" Commission" means the Nuclear Regulatory Commission or its duly author-1:ed representatives.
" Committed dose equivalent" (See Dose terms)
" Committed effective dose equivalent" (See Oose terms)
" Controlled area" (See Area terms)
" Declared pregnant woman" means a woman who has voluntarily informed her employer, in writing, of her pregnancy and the estimated date of conceotion.
" Derived air concentration" (See Dose control terms)
" Dose" terms (1) " Dose" or " radiation dose" is a generic term which means absorbed dose, dose equivalent, committed dose equivalent, or committed effective dose equivalent, as defined in other paragraphs of this section.
(2) " Absorbed dose" means the energy imparted by ionizing radiation per unit mass of irradiated material at the location of interest.
The units of absorbed dose are the rad and the gray (1 gray (Gy) = 100 rad].
86 l
.:e (3) " Dose equivalent" means the product of absorbed dose, quality factor, and all other necessary modifying f actors at the location of interest in tissue.
The units of dose equivalent are the rem and the sievert [1, sievert (Sv) = 100 rem].
l l
l 1
l l
l 86a
75K-K (3)
" Derived air concentration" (CAC) means tne concentration of a given radionuclide in air wnich, if breathed by reference man for a orking year of 2,000 hours0 days <br />0 hours <br />0 weeks <br />0 months <br /> under conditions of lignt activity (innalation rate 1.2 cubic meters of air per hour), results in an inhalation of one ALI.
(OAC values are given in Table 1, Column 3 of Appendix B of tnis.6 art.
Note consideration of submersion dose; see 5 20.203.)
(4)
" Dose limits" means the permiss!ble upper bounds of radiation doses.
They apply to the dose equivalent received during the period of time covered (generally a calendar year), the committed effective dose equiva-lent resulting from the intake of radioactive material during the same period, or the effective dose ~ equivalent received in' a year.
" Dose" or " Radiation dose" (See Dose terms)
" Dose equivalent" (See Dose terms)
" Effective dose equivalent" (See Dose terms)
" Embryo / fetus" means the develooing organism from conception until the time of birth.
" Exposure" terms (1)
" Exposure" means being exposed to ionizing radiation or to radioactive material.
(2)
" Natural background exposure" means exposure to cosmic and terrestrial sources of naturally occurring radioactive material, including technologically enhanced radi, active material, such as plasterboard and fertilizer, but not including byproduct material or l
~
radioactive' material specifically intended to be a radiation source.
(3)
" Normal exposure conditions" means the conditions '*here expo-l sures can be limited by control of the radiation source and by control l
of the individual exposed to the radiation source.
l 59 Enclosure i
(4) " Planned special exposure" means an exposure that oc::urs infre-quently during normal operations when it is necessary to permit a few workers to receive cases in' excess of the annual dose limits.
Oose limiting provisions for planned special exposures are separate frqm, and e
in addition to, the dose limiting conditions for normal exposure conditions, l
l l
89a l.
X 0
(c) Before a planned special exposure, the licensee ensures that the individuals involved are--
(1) Informed of the purpose of the planned operation; (2) Informed of the estimated doses and special radiation or other.
conditions that might be involved in performing the task; and (3) Instructed in the measures to be taken to keep the dose and other risks ALARA.
(d) Before a planned special exposure, the licensee ascertains the dose equivalent from all previous planned special exposures and all doses in excess of the annual limits for each individual involved in accordance with 5 20.1104(a)(2),
(e) Subject to S 20.201(c)(2), the licensee does not authorize a planned special exposure which would cause an individual--
(1) To exceed, numerically, one times the annual dose limits speci-fied in S 20.201(a) from all planned special exposures and all doses in excess of the annual limits in a calendar year; or (2) To exceed a total lifetime dose from all planned special expo-sures and all doses in excess of the annual limits by that individual of five times the annual limits specified in S 20.201(a).
(f) The licensee provides respiratory protection to ensure that the intake by inhalation will be within the appropriate annual limit of intake (ALI).
(g) The licensee maintains records of the conduct of a planned special exposure in accordance with 5 20.1105, and submits a written report in accordance with S 20.1204.
(h) The licensee records the dose resulting from a planned special exposure in the individual's record and informs the individual, in writ-ing, of the dose received within 15 days following determination of the dose.
However, this dose will not be considered in controlling future occupational dose to the individual under 5 20.201(a).
)
$ 20.207 Occuoational dose limits for minors.
The annual dose limits for occupational exposure for minors are 10%
of the annual dose limits specified for adult workers in S 20.201(a).
The dose limits for minors are not exceeded if the inequality in the reference for S 20.202 in Appendix E of this part is equal to or less than 1/10.
10e 1
5 20.208 Dose to an embryo / fetus s
{al Except as noted in caracraph (c) of this section, a licensee shall ensure that the effective dose ecuivalent to an embryo / fetus due to occuoational exposure of a woman declared to be pregnant does not exceed 0.5 rem (5 mSv) during the ' entire pregnancy.
Efforts should be made to avoid substantial variation above a uniform monthly exposure rate which would satisfy this limit.
(For recordkeeping requirements, see 5 20.1106.)
{bl The effective dose equivalent to an embryo / fetus is the sum of--
{1l The deep dose equivalent to the declared pregnant woman; and
{21 In the absence of age-specific transport parameters for the radionuclides involved, two times the committed effective dose equivalent that would be otherwise assessed due to the intake of radionuclides by the pregnant woman. (']2 The licensee may use factors other than 2 when they become available for specific radionuclides.
Further, the licensee may, for intakes of Class Y materials, calculate the dose to the embryo /
fetus on the basis of photon dose to the embryo / fetus (target) from other (source) orga'ns plus the dose l
equival.ent to the embryo / fetus from that portion of the pregnant woman's intake of Class Y material that is transportable, apolying either the factor of 2 or age-specific factors applicable to the transportable fraction involved.
[']2This factor of 2 recognizes cotential differences in biological factors that could result in the embryo / fetus receiving an effective dose eouiva-lent creater than that of the pregnant woman as a result of intake of radioactive material by the pregnant woman.
1 108a
M Notwithstanding the limit in caragraph (a) of this section, if the dose to the embryo / fetus is found to have exceeded 0.5 rem (5 mSv) by the time the woman declares to the licen-see the pregnancy and the estimated date of conception, the licensee is in compliance with paragraoh (a) of this sec-tion if the licensee does not assion the woman tasks which result in the embryo / fetus receiving an additional dose exceedin; 0.05 rem (0.5 mSv) during the remainder of the pregnancy.
s
)
108b
)
(3) Records of the results of surveys used to evaluate the release of radioactive effluents to the environment.
S 20.1104 Determination of prior occupational dose.
(a). The licensee shall determine--
(1) The occupational radiation dose received during the current calendar year by each individual who enters the licensee's restricted or controlled area and is likely to receive in a year an occupational dose requiring provision of individual monitoring devices or services pursuant to S 20.502; and (2) Prior to permitting an individual to participate in a planned special exposure, all planned special exposures and overexposures (including doses received during accidents and emergencies) received during the lifetime of the individual.
(b) The licensee shall determine the exposure history, as required by paragraph (a) of this section, and record on NRC Form 4, or other clear and legible record, all of the information required in that form.[2]s The form or record must show each period in which the individual received occupational exposure to radiation or radioactive material and must be signed by the individual who received the exposure.
(c) The records on NRC Form 4 shall be retained until the Commis-sion terminates each pertinent license requiring this record.
Arrange-ments may be made for transfer of the records to the NRC upon termination of the license.
The licensee shall retain records used in preparing NRC Form 4 for two years after the record is made or until completion of the fi,rst inspection of the radiation protection aspects of the licensee's program, whichever'is longer.
[3]3 Licensees are not required to reevaluate the separate external dose equivalents and internal committed dose equivalents or intakes of radio-nuclides assessed under the regulations in effect before Further, occupational exposure histories obtained and recorded on NRC Form 4 before would not have included effective dose equivalent, but may be used in the absence of specific information on the intake of radionuclides by the individual.
126
T.
. iaa f 5 20.1106 Records of individual monitoring results.
(a) Each licensee shall maintain records of doses received by all individuals for whom monitoring was required under normal operating conditions, and all doses due to overexposures, planned special expo-sures, accidents and emergency conditions.
(b) Each licensee required by 5 20.502 to provide individual moni-toring devices to assess external dos'e equivalent shall maintain records of the results.[3]1 (c)
Each licensee required by 5 20.502 or a specific license condition to assess individual internal effective dose equivalent shall maintain records of the results that contain--
(1) The estimated amounts of the radionuclides providing signif-icant exposures as a result of an intake; and (2) The total effective dose equivalent' assigned to the intake of radionuclides.
(d) Each licensee shall add the assessments of individual external dose equivalent and internal effective dose equivalent resulting from the intake of radioactive material for individuals for whom monitoring is required by 5 20.502 or a specific license condition.
The licensee shall enter this sum and maintain the records specified in paragraphs (a) and (b) of this section on NRC Form 5, in accordance with the instructions for NRC Form 5, or on clear and legible records containing all of the information required by NRC Form 5.
(1) Where specific information on the physical and biochemical properties of the radionuclides involved and their behavior in an indi-vidual is known and differs from the instructions for NRC Form 5, the licensee may use that information.
If specific information on an indi-vidual is used, the licensee shall document or reference in the individual's record the information and the calculation techniques and models used.
~
[3]1 Assessments of dose equivalent (rem or sievert) and records made using units in effect before need not be changed.
128
_s (2) The licensee shall enter on NRC Form 5, or equivalent record--
(i) External deep dose equivalent doses for periods of time not exceeding one calendar quarter; and (ii) Dose equivalents resulting from the intake of radioactive material, and the summation of dose equivalents from external sources and from intake, for periods of time not exceeding one year.
{3} The licensee shall maintain' the records of dose to an embryo fetus with the records of dose to the mother.
(e) Each licensee subject to S 20.501(c) of this part, in addition to preserving personnel monitoring records in accordance with this section, shall also pres.erve with these records copies of pertinent personnel dosimetry processor accreditation certif-icates from the National Voluntary Laboratory Accreditation Program as necessary to demonstrate compliance with 5 20.501(c) after February 1986.
(f) The licensee shall retain each required form or record until the Commission terminates each pertinent license requiring the record.
S 20.1107 Records of release of radioactive material in effluents.
(a) Each licensee shall maintain records of the identity and quantity of radioactive material in effluents released to unrestricted areas, within the constraints in SS 20.301 and 20.303, except that the identity of the individual radionuclide in effluents need not be docu-mented if the total concentration of such unknown radionuclides is less than 10% of the limit for unknown mixtures.
(b) The licensee shall retain the records required by paragraph (a) of this section until the Commission terminates each pertinent license requiring the record.
S 20.1108 Records of waste disposal.
(a) Each licensee shall maintain records of the disposal of licensed materials made under SS 20.1002, 20.1003, 20.1004, 20.1005, and disposal by burial in soil, as authorized before January 28, 1981.[']5
[']iA previous S 20.304 permitted burial of small quantities of licensed materials in soil before January 28, 1981, without specific Commission authorization.
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(b) The licensee shall retain the records required by paragraph (a) of this section-until the Conunission terminates each pertinent license requiring the record.
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.ar-5 20.1206 Reports of personnel monitoring.
Each person described in 5 20.1207 shall, by August 1 of each calen-dar year, submit to the Director, Office of Nuclear Regulatory Research, U.S. Nuclear Regulatory Commission, Washington, DC 20555, the reports specified in paragraphs (a) and (b) of this section, covering the preced-ing calendar year.[3]s (a) A report of either (1) t'he total number of individuals for whom personnel monitoring devices or services were required under 9 20.502 or 5 34.33(a) of this chapter during the calendar year; or (2) the total number of individuals for whom personnel monitoring devices or services were provided during the calendar year:
Provided, however, that such total includes at least the number of individuals required to be reported.
under paragraph (a)(1) of this section.
The report shall indicate whether it is submitted in accordance with paragraph (a)(1) or (a)(2) of this section.
If personnel monitoring devices or services were not required to be provided to any individual by the licensee under 9 20.502 or $ 34.33(a) of this chapter during the calendar year, the licensee shall submit a negative report indicating that such personnel monitoring devices or services were not required.
(b) A statistical summary report of the personnel monitoring infor-mation recorded by the licensee for individuals for whom personnel moni-toring devices or services were either required or provided, as described in paragraph (a) of this section, indicating the numbe'r of individuals whose total effective dose equivalent recorded during the previous calen-dar year was in each of the following estimated ranges:
[8]sA licensee whose license expires or terminates prior to or on the last day of th'e calendar year shall submit reports at the expiration or termination of the license, covering that part of the year during which the license was in effect.
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