ML20009G783
| ML20009G783 | |
| Person / Time | |
|---|---|
| Issue date: | 07/24/1981 |
| From: | Palladino N NRC COMMISSION (OCM) |
| To: | Gorsuch A ENVIRONMENTAL PROTECTION AGENCY |
| References | |
| NUDOCS 8108040653 | |
| Download: ML20009G783 (22) | |
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UNITED STATES 8'
NUCLEAR REGULATORY COMMISSION g
WASHINGTON, D. C. 20555 PM July 24, 1981
\\kl CHAIRNtAN NLl). {t ") Kf (I? {Y
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Ms. Ann McGill Gorsuch
'4 Administrator
- tt JUL 2 91981 > 12 U.S. Environmental Protection Agency h'k u.s. mm nowm 401 M Street, SW, A-100
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Washington, D.C.
20460
Dear Ms. Gorsuch:
W Enclosed for your consideration are the Nuclear Regulatory Comission comments on the proposed " Federal Radiation Protection Guidance for Occupational Exposure," published on January 23, 1981 (46 FR 7836).
While we agree in principle with many of the proposed recomendations, we suggest a number of substantive changes.
Although we do not suggest adopting all of thf recomendations in ICRP Publication 26, we recommend adoption of the system of dose calculation as recommended by the ICRP.
That system is logical and self-consistent, and appears to be based on the best scientific information available.
The proposed ICRP guidance endorses summation of external dose and internal comitted dose equivalent, as does the EPA cystem.
Chairman Palladino and Comissioner Ahearne request that EPA adopt the ICRP system of dose limitation intact as a sound scientific basis for quantifying relative risk, regulating exposures to radiation, and as one which would be consistent with that used in other countries.
Comissioners Bradford and Gilinsky recomend the ICRP system for dose calculation and generally for dose limitation except where it leads to higher permissible organ dose limits or higher permissible radioactive isotope concentrations than current regulations.
In those cases, they would retain current standards as EPA recommends.
They believe there is clearly no difficulty in meeting these limits since they have been met by licensees for many years.
Regarding exposure of the unborn, the Comission believes that the lower ICRP exposure limit should apply.
Commissioner Ahearne's views on recomendation 8 are included with our detailed comments.
On the matter of employee notification of radioactive exposure, the
'Comission prefers an alternative scheme to the one proposed by EPA.
The Comission intends to implement in its regulations a system that requires yearly notification of a worker's annual and accumulated lifetime dose. We suggest EPA include in its guidance criteria for such notification in order to enhance uniformity of Federal practice.
8108040653 810724' PDR MISC l
Ms. Ann McGill Gorsuch t In its Federal Register notice (46 FR 7836), EPA requested views on (1) the desirability or necessity for a reduction of the 5-rem radiation protection guide (RPG) on effective dose equivalent and (2) the provision of additional EPA guidance that would establish more explicit requirements on exposure of individuals.
The Commission does not consider any reduction in the 5-rem RPG or additional guidance by EPA to be necessary at this time.
The NRC staff has reviewed the available new information on the dose estimates at Hiroshima and Nagasaki and concluded that it would be premature to draw quantitative conclusions with respect to these dose estinates.
The NRC staff will continue to monitor closely any developments regarding the Hiroshima and Nagasaki dose estimates.
However, our current assessment of the potential impact of these dose estimates on radiation protection standards and risk estimates does not justify any delay in the development and implementation of EPA guidance or revised NRC regulations.
Enclosed are both general and specific coments on the proposed EPA guidance.
The specific comments are numbered to correspond to the numbered recommendations as they appeared in the Federal Register notice.
Sincerely, Y
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V (Gl(AfftyL-f funzio iladino
Enclosure:
As Stated mm M
CHAIRMAN PALLADIN0 AND COMMISSIONER AHEARNE'S COMMENTS ON PROPOSED FEDERAL RADIATION PROTECTION GUIDANCE FOR OCCUPATIONAL EXPOSURES PUBLISHED JANUARY 23, 1981 (46 FR 7836)
A.
GENERAL COMMENT
S The NRC's evaluation of the propo.ad EPA guidance ras identified a number of issues that would introduce substantial problems for the NRC--and perhaps, for other agencies.
One of the key issues is the propcsed adoption of a system of dose limitation resembling the ICRP system of dose limitation, but which includes a number of departures that, in our view, would impair the usefulness of the system.
The NRC endorses the adoption of the :CRP system of dose limitation.
Our endorsement of the ICRP system is in recognition of some very desirable features of that system.
The ICRP system:
(1) is based on a contemporary radiation protec: ion philosophy that would require (a) justifying why persons are to be exposed to radiation (b) ensuring that any exposures are as low as reasonably achievable, and (c) using appropriate dose limits; (2) is based on an " acceptable risk" rationale !nat is derived from the statistics of job-related risks to workers in the " safer" industries, excluding nuclear; (3) provides a method (a) to combine doses to nultiple organs, doses from multiple radionuclides, and doses from internal and external exposures and
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(b) to express these doses in terms of a whole-body dose equivalent on the basis of risk considerations, which may be compared to the dose limits;
(4) incorporates the state-of-tne-art knowledge of biological, physical, and dosimetric information in deriving " annual limits of intake" (ALI) and
" derived air concentration" (DAC); and, (5) provides appropriate dose limits for normal working conditions, which are generally more restrictive than previous limits; but provides flexibility for exceptional operational difficulties when it is in the public interest to exceed the primary limits.
The new ICRP analytical models are so complex that sophisticated computers are required to calculate those quantities (such as ALIs and DACs) needed to implement radiation protection programs and to regulate the use of radioactive material by industries and others.
Owing to the complexities of the calcula-tions and the interdependence of the features of the ICRP system of dose limitation, it is not possible to arbitrarily change some selected parts of the system without destroying the continuity and coherence of the whole, which would be the'effect of the proposed EPA guidance.
If the proposed E?A guidance is promulgated in its present form, all of the calculations and tables provided by the ICRP must be replaced, and the implementation by all U.S. agencies would be made extremely difficult.
In addition, communication with radiation scien-tistsofessentiallyailothercountrieswithradiationprogramscouldbe extremely difficult because the U.S. would have different definitions for the same concepts.
The ICRP system has been adopted or is in the process of being adopted by the IAEA, the Commission of European Communities, the OECD Nuclear Energy Agency, and most countries with radiation programs.
The selecticn of a
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specific system of dosc linitation has a direct imcact on international agree-ments, cooperative efforts, and guidelines, related to radiation doses to workers and members of the public.
Another area of concern to us is ;that so.e of the differences between the ICRP system and the E?A recommendations are changes that E?A justiff'es on the basis of demonstrated practicability.
We believe that the current experience does not demonstrate practicability, but does cemonstrate technical feasibility.
This difference is significant.
Primary dose limits and CACs must be met regardless of the costs which mignt be involved.
In contrast, practicability (in the scnse of "as low as practicable"--now "as icw as reasonably achievable")
recuires consideration of the costs for achieving a particular level of radia-tion prctection.
This distinction is tne heart of the ICR? system of dose limitation, and we believe that many of our proolems with tne proposed E?A guidance stem from mixing of ALARA issues with the issues cealing with selection of primary dose limit values.
An additional problem that we have identified is one of semantics.
Terms such as "should," wher used in regulations, usually indicate a substantial amount of flexibility (i.e., that options are afforded to those regulated);
the term "shall" indicates that action is required without options.
- However, when the E?A recommendations appear in the Federal Register over the President's signature, tha wcrd "should" may hava the impact of the word "shall" for Federal agencies.
With this in mind, we have notea that several of the proposed EPA recommendations, that would seemingly permit substantial flexibility for affected Federal agencies, might actually result in de facto limits and require-I ments that were not intended.
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5.
SPECIFIC COMMENTS Rec:mmendation 1:
Ei-A's first recommendation would require the justification of all occupa-tional exposure.
This is consistent with ICRP recommendatior..,
.I we concur in this recommendation.
Recommendation 2:
The second recommendation would require that collective doses be as low as is reaconably achievable.
This is aise in agreemen witn ICRP recommenda-tiens, and we concur in this recommencation.
1 Re::mmendation 3:
Rec:mmendation 3, would provice adiation pr:tection guides (RPGs) that are not consistent with ICRP recommencaticns.
In our view, recommendation 3 censtitutes a major and undesirable de:arture frca the ICRP system of dose limitation.
Key differences between the ICRP system and that prooosed by the EPA are as follows:
1.
Differences between EPA and ICRP recommended dose limits are shown in the following table:.
Oroan Agnual Dose Limit EPA ICRP Gonads 5 rems
-- (a)
Others 30 rems 50 rems (E)No value given by ICRP, but 20 rems may be inferred from the weighting factor for gonads.
(b)The ICRP providas these dose limits to avoid r.on-stochastic effects.
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As shown in the table of weighting factors below, EPA is proposing the exclusion of the risk to gonads in calculating the weighting factors, but is proposing the inclusion of skin.
Tissues Weicntinc Factors (Wt)
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ICRP Gonads 0.25 Breast 0.20 0.15 Red bone marrow 0.15 0.12 Lung 0.15 0.12 Thyroid 0.04 0.03 Bone surfaces 0.03 0.03 Skin 0.01,")
Remainder (other organs) 0.40 0.30(*)
l 3.
The EPA guidance states that the value of an ALI (or equivalent) currently in use is not to be increased in regulations governing work situat ons identical with or similar to those currently in existence although information provided in ICRP Publication 25 and its companion volume, Publication 30, woula support increasing some ALIs as well as decreasing others.
The ICRP system of dose limitation would (1) combine the doses from inter-nal and external exposures, (2) add contributions from several internal organs in a " weighted" manner, and (3) impose an overall comoined limit for the whole body of 5 rems or its equivalent in terms of dose to body parts or organs.
The ICRP system of dose limitation makes.use 'of a series of " weighting factors,"
J, by which the dose to each organ would be multiplied to give an effective i
dose that would be equivalent to a whole body dose with respect to risks.
The ICRP system requires that the " effective dose equivalents" for each organ be (a)Five other organs with highest dose.
The f' actor for each of the other organs is then 0.06 (ICRP) or 0.08 (EPA).
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summed (along with any external whole-body doses) and that the sum should not exceed 5 rems.
The ICRP does not recommend an annual dose limit for a single internal argan.
However, an annual dose limit for a sir.gle organ may be inferred from the ICRP W. values if it is assumed that (1) nere is no external exposure and I
that (2) no otner organs receive any dose during intake, transport through the body, and elimination of the radionuclide.
In this case, the dose required to yield a risk equal to that associated with wncia-body irraciation might be so high that some nonstochastic (prompt, nonrandom) biological effects might occur.
In order to avoid these nonstochastic effects, w.. Oh are related to dose in a-
" threshold" manner, the ICRP recommended a ccr.straint that the annual doses to any internal organ not exceed a conservatively establisned value of 50 rems.
Thus, 'he 50-rem dose constraint should not te comcared directly with the dose limits for " critical organs" that are urrently being used.
The ICRP limits for the lens of the eye and for skin are also based on avoidance of nonstochastic effects.
Since the 30-rem dose constraint proposed by EPA for all internal organs presumably would be used to avoid nonstochastic effects, and since the 50-rem dose constraint of the ICRP system add the 30-rem dose constraint of the EPA are both below the threshold for such effects, it would appear that the lower dose value selectec by EPA v;mid represent an unnecessary added factor of con-servatism that is not supported by either biological information or cost-benefit analyses, and would cause confusion in relationship to practices in other countries.
This is also true of the differences in doses to the lens of the eye and the dose to the skin, which EPA chose to include in the W table.
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t While the ICRP system of dose limitation, which comoines doses from exter-nal and internal doses, would, in general, be more restrictive than the current standards, some derived air concentrations based on the ICRP system would be somewnat higher than the current values in 10 CPR Part 20 (based on FRC guidance) for a variety of reasons.
For example, the ICRP values are based on quantifi-cation of risks; they are derived using contemporary otological models; and some organs are less important radiocarcinogenically than others.
The ICRP system of dose limitation, which incluces justification, ALARA requirements, and dose limits, is based on a logical scientific rationale that is internally consistent.
Comoared to current E?A (:RC) stancards, scas annual intake limits (and their reflection in the derived air concentration values) would increase, scme would decrease, and others would emain essentially uncnanged.
The primary dose limit of 5 ems per year would no change.
We believe that the E?A guidance should ref'.:ct the new values for ne intaxe limits and DACs indepen-dent of the direction of the change." We celieve that any restrictions on exposures below the basic limits, particularly those that would be selected based on operating experience, are ALARA issues.
Such matters, can best be handled by the regulatory agencies who can judge whether any adjustments are needed, and if so, by how nuch, and the justification for doing so.
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l By removing " gonads" from the list of organs that are included in the derivation of W. values, the proposed E?A guidance would increase all but one i
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"!n exceptional circumstances, the RPGs may be exceeded, for cause.
Provision for doing so may be established on a generic basis by the Federal agency having jurisdication where clear and specific criteria are provided as a basis for pennitting such doses, including the requirement that such doses are permitted for the purpose of mitigating i
circu stances that might, otherwise, result in greater harm to other workers or the general public."
C.
NOTES CLARIFYING RECOMMENDATIONS:
We have two suggestions concerning the notes following ne recommendations.
The first concerns the manner of compliance with subitem e of recommendation 4 4
(individual monitoring and recordkeeping), and the second certains to recommendations 2 and 3 and the implementation of the ALARA concept.
1.
Note Cla rifying Recommendation 4.e:
The most direct, and perhaps the most desirable, way of determining committed internal dose is by means of detennining the amount and location of internally deposited radionucifdes by bioassay methods.
However, bioassay methods (including whole body and organ counting; breath, urine, and feca'.
analyses) are not always practicable at exposure levels encountered in the workplace.
In order to clarify EPA's acceptance of other more indirect methods for estimating and controlling interral exposure, we request that an
_ additional note, 'perh[ps designated 2.a., be inserted between notes 2 and 3 to read:
"With respect to the requirement in subitem e of recommendation 4 for the provision of individual monitoring and recordkeeping, it is recognized that, under some conditions of exposure, monitoring
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individual exposures by means of bioassay procedures will not be feasible or necessary.
Therefore, regulatory agencies may provide for alternative monitoring and recordkeeping procedures such as monitoring and recording of concentrations of radioactive materials in air to which the individual is exposed and the duraticn 'of that exposure."
Even this alternative might prove to be difficult *.o implement in Range P where levels might'be as-low as 10-percent of the RPG from both internal and external exposures.
2.
Imole. entation of ALARA We a-e concerned that the EPA proposed guidance may be read as requiring.
a rigorous quantitative implementatn n of ALARA.
The difficulties involved in a rigorcus quantitative approach to implementation of ALARA are c
recognized in ICRP Publication 26.
The TEC has studied this orcblem and concluded that, while quantification of the cost-benefit analyses associated with reducing the exposure of workers to radiation and optimization of radiation protection provisions are desirable goals, the implementation of ALARA should not be delayed while the problems associated with such a quantitative approach to ALARA implementation are solved, but should proceed on a qualitatiye basis.
Th.at is,.the elements of ~ optimization
- analyses, which would include the costs as well as technical practicability and benefits, would be considered in judging ALARA.
A quantitative optimization analysis can be costly.
Some applications are' too trivia's to justify quantitative analyses.
In these cases, qualitative analyses are adequate.
What is important is that the elements of an optimiza -
tion analyses be factored into the decision-making process.
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We therefore, request that EPA clarify its guidance wi h respect to t
ALARA implementation by adding a note to the effect that ALARA implementation should not be delayed while a rigorous, quantitative implementation procedure is perfected, but should proceed on a structured qualitative basis.
D.
OTHER C0!FENTS:
1.
EPA requested comments on approaches to further restrictions on the exposure of workers in Range C, which is defined in EPA recommendation 4.
As indicated above, we have serious reservations concerning the overall value of the proposed set of graded minimum radiation protection requirements as proposed in recommendation 4.
It does not appear that EPA guidance that would require further restrictions on exoosures within any range below the RPG could be justified on a rational cost-benefit basis.
It is our view that each individual regulatory agency is in the best position to determine the justification for and the specific nature of any such requirements.
As expressed above, it is our position that the 5-rem annual RPG as proposed by EPA and as recommended by ICRP will result in l
radiation protection that provides an adequately low level of risk relative to those found in other safe industries.
With the requirement fer justification and ALARA efforts at all levels of exposure, any further restrictive requir.ements seem to be without merit and yerging on
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s tultification.
2.
EPA requested comments on the possible reduction of the 5 rem annual RPG.
The NRC has published proposed amendments
- to 10 CFR Part 20 that would eliminate the 5(N-18) formula and the 3 rem per quarter
- 44 FR 10?88, Published 2/20/79.
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Standard that allows up to 12 rems per year.
We see no reason to reduce the annual dose standard (RPG) below 5 rems at this time.
The staff has done an extensive analysis of the pros and cons associated with a proposed dose-limiting standard reduction.
It was concluded that any significant reducticn would result in very substantial costs and that a reduction to 0.5 rem per year would result in wholly unacceptable impacts, including, for some activities which liRC regulates, a significant increase in collective (person-rem) dose, when considered in light of the theoretical benefits.
Further consideration of any such redt: tion by EPA should include a thorough and carefully developed cost-benefit analysis.
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