ML20244C456
| ML20244C456 | |
| Person / Time | |
|---|---|
| Issue date: | 08/30/1983 |
| From: | Dircks W NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | |
| References | |
| TASK-PINC, TASK-SE SECY-83-362, NUDOCS 8309080120 | |
| Download: ML20244C456 (152) | |
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xuost 30. ne3 POLICY ISSUE s m _e3_3e2 (NEGATIVE CONSENT) a :
For: The Commissioners From: William J. Dircks Executive Director for Operations
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Subject:
EMERGENCY PLANNING - PREDISTRIBUlION/ STOCKPILING OF POTASSIUM IODIDE FOR ThE GENERAL PUBLIC
Purpose:
To concur in developing a federal polf cy statement recommending against requiring the redistribution or stockpiling of potassium iodide (KI) as a preplanned emergency protective measure for use by the general public during potential reactor accidents.
Discussion: On March 5,1981, the Commission requested the staff to cor.tinue the source term technology studies to a point where decisions could be made on alternative protective actions for puolic use in a nuclear plant emergency. As has been well noted, there are large uncertainties regarding source tem issues. Nevertheless, the staff believes that there is currently enough information in hand to make a defini-tive statement concerning the stockpiling or redistribution of potassium iodide as a protective measure for general public use during potential reactor accidents.
For the following reasons, the staff recommends against the stockpiling or redistribution of KI in the vicinity of nuclear power plants as a condition of a license to operate a nuclear power plant. Further, the staff does not believe that stockpiling or redistribution of KI should be a part of government sponsored emergency planning requirements for nuclear power plants. The principal reason for this staff position is the extremely high cost / benefit ratio that would be associated with the implementa-tien of a KI stockpiling or pred1stribution program for the general public. This is derived from a reevaluation of infomation (as described in NUREG/CR-1433; Enclosures B and C) on considerations
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Contact:
g f'oh Rocer M. Blona, RES/DRA 4 637633 'l
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The Commissioners concerning the benefit and cost associated with potassium iodide stockpiling. A cost / benefit uncertainty analysis performed by the i staff conclusively shows that potassium iodide offers extremely l small be.nefit in relation to its costs and is not cost effective l
as a preplanned emergency protective measure for the general public.
A detailed analysis of thes'e factors is presented in Encleture A. A short summary of the current status of the source term aspects of the issue is also included in Enclosure A. It should be emphasized that the analysis in Enclosure A does not depend on new or projected reductions in the radiciodine source term.
Recommendation: Based upon this analysis and with Commission approval, the staff will proceed to recommend to the Federal Radiological l Preparedness Coordinating Committee that the Federal policy l
in this area should be against recuiring the preplanned stock- ,
l piling or predistriDution of KI for the general public for potential reactor accidents as indicated in SECY-82-396A.
/
William rcks Executive Director for Operations
Enclosures:
A - Perspective On Potassium Iodide (KI) As A -
Preplanned Protective Measure B - IAEA-CN-39/102, Radiation Protection:
An Analysis of Thyroid Blocking C - NUREG/CR-1433, Examination of the Use of Potassium Iodide (KI) as an Emergency Protective Measure for Nuclear Reactor Accidents D - ACRS' Comments E - Dr. Beyea's Comments
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SECY NOTE: In the absence of instructions to the contrary, SECY will notify the staff.on Wednesday.,
Se tember 14, 1983 that the Commission, by negative consent, assents to the action proposed in this paper. ,.
DISTRIBUTION:
Commissioners OGC ,
OPE OCA OIA OPA REGIONAL OFFICES EDO ELD ACRS ASLEP ASLAP SECY .
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ENCLOSURE A 1
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A .. Enclosure A i .
Perspective on Potassium Iodide (KI) As a Preplanned Protective Measure Introduction In August 1980, the NRC published in the Federal Register the final revisions to Appendix E of 10 CFR Part 50 concerninfj emergency planning. At present, the emergency planning philosophy of the NRC includes the following basic protective action considerations to be implemented by licensees and State and local agencies (NUREG-C654/ FEMA-REP-1, Rev.1, Apper. dix I; IE Information Notice No. 83-28:
CRITERIA FOR PROTECTIVE ACTION ~ RECOMMENDATIONS FOR GENERAL EMERGENCIES, itay 4, 1983):
- 1) Recognition of the course of events by the plant. operators and likely outcomes;
- 2) Predetennined decision criteria to initiate emergency actions on-site early in an accident sequence;
- 3) Prompt notification capabilities for authorities and the public;
- 4) Development of predetermined in-plant action levels for:
Sheltering by the population,
- Early evacuation by the population in nearby (a few miles) areas in the event of potential severe accidents; and
- 5) Ad hoc evacuation or prompt relocation by the public wherever and whenever warranted in the event of an actual major release of radioactivity, based predominantly on offsite measurements (e.g., areas of high dose rates).
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With regard to KI, the current NRC and FEMA guidance calls for the provision of KI for energency workers and for institutionalized persons within the plume exposure EPZ (10 mile radius) whose immediate evacuation may be infeasible or very difficult (NUREG-0654)/ FEMA-REP-1, Rev.1, pp. 60, 63).
i Further, it is noteworthy that the U. S. Food and Drug Administration has provided for the over-the-counter, non-prescription sale of KI for use during radiciodine releases.
Since the publication of the regulatiets on energency planning and specifically the Commission information paper on K146ftY-80-257A, September 18,1980), one question has remained unresolved--should Iodine blocking agents be required to be immediately available to members of the general public in the event of a reactor accident? This question is the central issue in the development of a Federal policy en KI by a subecmmittee of the Federal Radiological Preparedness Coordinating Committee made up of FEMA, NRC, FDA, EPA, DOE, and USDA represent-atives (see SECY-82-396).
Whether to stockpile or redistribute XI comes down to a few basic questions:
o What are the potential benefits of administering XI to the general public?
o What is the impact of distance from the reactor on the benefits of KI?
o How can KI effectively be administered to the general public?
o What are the costs associated with administering KI to the general public? ~
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o What are the potential adverse impacts of administering XI to the' general public?
o Do we have enough certainty in the results to make a decision?
The' decision for requiring the administering of KI to the general public must weigh' all of the answers to these questions. The methods for pulling together all of the ans,iers into a readily understandable fom is cost / benefit and uncertainty analysis techniques.
Cost / Benefit Uncertainty Analysis At the request of the Commission in 1979, Sandia National Laboratories and the NRC Research staff conducted a study on the use of potassium iodide as an emergency protective measure for nuclear reactor accidents (NUREG/CR-1433, March 1980).
A copy of the report and a summary paper is attached.
The risk to the thyroid of exposed individuals posed by potential accidents is especially great for several reasons:
Radioactive isotopes of iodine are produced in abundance by the fission proces s.
Inhaled or ingested iodines are quickly absorbed into the bloodstream and concentrate preferentially in the thyroid.
Iodines are eliminated from the thyroid with a relatively long biological hal f-l i fe.
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- C As a result, the radiation dose to the thyroid is likely to exceed the dose
. to the rest of the body, and thyroid damage.is likely to affect more individu61s than any other accident-induced health effect. Taken in large enough quantities prior to exposure, KI acts to block the absorption'of radiciodines by the thyroid, reducing the' thyroid dose.
There is considerable' uncertainty concerning the effects of radiation exposure on the thyroid. Thyroid nodules are the effect of primary concern and would typically be observed from 10 to 40 years after exposures. A nodule is an abnormal growth that could be either benign or malignant (cancerous). Nodules that are thought to be possibly malignant would most likely be surgically removed.
Most thyroid cancers are well differentiated, slow growing, and relatively I
amenable to therapy. Their associated mortality rate is therefore much lower than that for most other forms of cancer. WASH-1400 conservatively assumed a l 10 percent mortality rate for malignant thyroid nodules.
Sufficiently high radiation doses (3000-5000 rem) would result in ablation of the thyroid with no subsequent risk of either benign or malignant nodules.
I However, because of the high doses required, thyroid ablation is unlikely to occur except for persons very near the reactor following the most severe accidents. Ablation would probably require surgical removal of the thyroid, and the affected individual would need to take substitute hormone pills on a daily basis.
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The Cost / Benefit Uncertainty Analysis was perfomed using a modified version l of the Reactor Safety Study (WASH-1400) consequence model.- Four categories of potential accidents were studied: release of gap activity
- to the containment, release of gap activity without containment isolation, core melt with' a.
melt-through release; and core melt with an atmospheric release. Thyroid dose calculations show tnat gap release to the containment would not pose a significant health hazard to the public at any distance from the reactor.
For a gap release without containment isolation and melt-through categories, doses in excess of. recommended protective action guidance levels (PAGs)-
(5-25 rem to the thyroid) would be confined to areas within approximately 10 to 15 miles of the reactor. For a low likelihood core melt with a direct atmospheric release, however, thyroid doses could exceed plume pathway PAGs at distances of hundreds of miles. The results of the KI study were based upon the same infomation as the results of the NRC/ EPA task force report on the recommended planning basis for offsite emergency preparedness (NUREG-0396,
" Planning Basis for the Development of State and Local Government Radiological Emergency Response Plans in Support of Light Water Nuclear Power Plants").
The potential tenefit of KI was measured by assessing the possible reduction in the total numbers of thyroid nodules that would be expected to occur in the event of a reactor accident. The units used to express this benefit is "thyrcid nodules prevented". Costs were estimated conservatively by assuming
- Gap activity is the limited amount of radioactive gaseous material which collects within the tube which holds the uranium dioxide fuel pellets during nomal reactor operation.
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only capital cost of the drug--distribution, replacement, monitoring and public l
- education costs were ignored. The results of the cost-benefit analysis for the use of KI are summarized in Table 1. Cost-benefit ratios ($/ thyroid nodules prevented) were given assuming that no other protective measures are.taken.
(KI would protect- only the thyroid, not other body organs, and only from radiciodine. In addition, KI would only be effective if ingested within about 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> after radioicdine inhalation, or within about 12-24 hours before radio-iodine inhalation.) Other key assumptions made in performing the analysis-are noted in Table 1.
Uncertainties due to health effects parameters, accident probabilities and costs were assessed, as well as the effect of other potential protective measures on the predicted cost-benefit ratios, such as evacuation and sheltering. The potential impact en children (most susceptible population) was also evaluated.
Estimated cost-benefit ratios were found to be high, and it appeared that dis-tribution of KI to the general public would be, at best, marginally cost-effective even close to a nuclear power plant.
~ Finally, a simple risk-benefit analysis, based upon the FDA published Federal Register Notice (43 FR 58798, December 15,1978) showed the risk of adverse physical reaction posed by KI to be small at the recommended action levels and dosages.
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, ?i Throughout the KI study questions of the uncertainties associated with such. .g analyses were raised and sensitivity studies were presented to provide insights into the importance of the uncertainties. The NUREG/CR-1433 report concluded $k aith the following statement: , 'WM.
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.m To some extent, the large uncertainties in the above assumptions fjj[
hinder our ability to provide definitive guidance. Nevertheless, ,;
';c for the assumptions made, the calculated cost-benefit ratios are fr% ,
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high; even-including uncertainties, KI appears to be only marginally h cost-effective, at best.
The KI report presented-its summary analysis using conservative assumptions which would bound the benefit of ' distributing KI (favor the distribution of [$
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Kl). Even with the conservative assumptions, the actual costs appear very ;
large compared to the potential benefit. Instead of presenting a conservative estimate, it is far more meaningful to show a realistically based central .
estimate and the range of uncertainty or bounds about the central estimate. I-d In this way, a better perspective is obtained on the relationship of the con-servative estimate (upon which the original conclusion is based) to the range ,
e of. answers that could be expected. In addition, the uncertainties in the s' calculation are explicitly identified and efforts can be undertaken to reduce Only through a full uncertainty analysis and such a pre- :
the uncertainties. .
sentation can the final question, concerning the level of certainty needed to .
make an informed decision, be answered. ['
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. Thyroid Effects Versus Distance f. .
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'One of the questions' which needs to be evaluated is the relationship of thyroid g p
effects as a function of distance for potential reactor accidents. Based upon IN[$;
pgp.E current source tenn assumptions (i.e., WASH-1400j, detailed studies of these }M57 relationships have been perfonned (WASH-1400, Appendix VI, Figure 13-5, -6; $pg
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910 REG /CR-2239, Figure 2.6-6; and NUREG/CR-1433, Table 10) which show that in VI. ?
bg the. case of potentisl . accidents which are a clear threat to the public health E,4,M
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calculated to occur beyond 10 miles from the reactor. Given the occurrence of r ?
the very low probability severe core melt accidents, the majority of the thyroid nodules occur beyond fifty miles from the reactor. In addition, for these .[
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potential severe accidents it would be expected that the thyroid dose would be -
greater than 10 rem out to more than 100 miles. Therefore, in order to sub- [
stantively reduce the number of thyroid nodules from a potential severe reactor accident, KI would have to be immediately available to the general public for ~
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significant distances from the reactor (i.e., much areater than the 10 mile EPZ). .-
J' In addition to the thyroid effects versus distance relationship, it is essential - I i to realize that for the severe core melt accidents, the thyroid dose within 10 [
- r F miles would be expected to be on the order of thousands of thyroid rem. At .
these doses the thyroid would probably be ablated (destroyed) and thus the #-
_ thyroid could not develop nodules. (The effectiveness of KI in reducing these ;, j doses is measured in NUREG/CR-1433.) Further, when ablation is likely, the dose -l to other organs, such as the bone marrow (see WASH-1400, Appendix VI, Figures 3-5 and 6), would be approaching lethal levels. For these cases the thyroid
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con'templated. Sheltering, evacuation, and/or respiratory protection should hcg be. emphasized as the preferred emergency response measures. j
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i dose would not be expected to exceed 10 rem beyond a couple of miles. Because ,
of the importance of these relationships to the extent of the need for KI, the [
0 thyroid effect distance relationships need to be factored into the decision of whether to stockpile or redistribute KI for the general public. -
Stockpiling Versus Redistribution of KI
. The next issue which must be addressed is the question of methods for effec- -
tively providing KI to the general public. Two strategies have been discussed:
stockpiling and redistribution. The main technical issues which have. to be addressed are: (1) how much time is there available in which to administer KI compared to the time required for each strategy?, and (2) is either strategy detrimental to other protective measures?
As shown in NUREG/CR-1433, only in the case of the major atmospheric releases (i.e., severe core melt accidents) is there an appreciable chance of exceeding the 10 or more thyroid-rem protective action criterion proposed by the Food and Drug Administration for KI administration. For these accidents, the time avail-able for sufficient warning is of significant importance. Currently, short warning times before a major release are assumed for risk dominant accident
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.x sequences. If there is the potential for significant warning, there will be ((
i relatively little radioactive iodine released. Further, increased warning time j v.
would increase the potential efficacy of evacuation as a protective measure.- [w For this evaluation short warning times (e.g., one hour) for risk' dominant ;
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Xf KI is going to have appreciable benefit, it must be taken within a very short period of time after inhalation of radiciodine, e.g. , about two -hours. Because~ ;
the prompt administration of KI is critical to its effectiveness as a protective [
measure, some method of rapid distribution to the public would be necessary.
Stockpiling supplies of KI in regional distribution centers or even in local .l centers such as schools, police stations, or firehouses most likely would not .
provide the drug to the public in a timely manner. Moreover, there is the potential for significant detrimental impact on other protective measures if the public is told to immediately obtain a KI pill from the nearest distribution center instead of immediately taking shelter or evacuating. .
l There do not appear to be these same problems _ with the redistribution strategy.
Dr. von Hippel, in his memorandum to the Commission on November 18, 1980, writes, "there is no real alternative to redistribution. If you wait until the event, _
then telling people to go to their local police or fire station to get thyroid protection medicine may create panic, may be too slow, and may result in increased exposures because a larger fraction of the population would be outside."
for these reasons stockpiling KI does not appear to be a viable alternative s trategy. Therefore, redistribution of KI will be the strategy examined in the f
remainder of this analysis.
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_11 Cost / Benefit Results Before proceeding with this analysis, the results of the previous' cost / benefit study need to be understood. Table 1 presents the summary table from NUREG/CR-1433. It is reproduced with all assumptions highlighted. Cost / benefit ratios as calculated in NUREG/CR-1433 range fran $300 thousand dollars per thyroid nodule averted within five miles of the plant, to $40 million dollars per thyroid nodule averted between 150 to 200 miles from the plant. The extremely large values are caused by the dominance of the low probability of the accidents in the cost / benefit ratio. The costs of KI predistribtuion on a per year basis are not very large. ( A cost / benefit ratio of one indicates that XI costs equal potential KI benefits. Larger cost / benefit ratios indicate that KI is potentially -
less beneficial; conversely, smaller cost / benefit ratios indicate that KI is-potentially a more beneficial protective measure.) Because the costs and the potential benefits are direct functions of the number of people in the vacinity of a power plant, the actual population distributions are not important because it cancels out of the calculation. Although not shown in this table, it is noted that the cost / benefit ratio would be largest for the smaller, more likely, postulated accident scenarios.
Table 1 bases the previous results upon sets of assumptions concerning the following five areas:
- 1) Source Term;
- 2) Probability of Release;
- 3) Effectiveness of Potassium Iodide;
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i 4)' Adverse Impacts;-and 5), ' Costs , of KI Program.
Appendix'.1 of this report' focuses on each of these areas' and associates upper and lower bounds and central estimates to, each. The' appendix then propagates the ur. certainties to. indicate how muc'h the results .in Table 1 should be modified to give a. realistic appraisal of the bounds on the potential value of KI.
Iodine Source Tem Considerations Accident. source .tems have received significant attention as a, potential area of conservatism in current technical evaluations. As such the treatment of the iodine source term in the remainder of this analysis'is now featured.
The probability, magnitude, timing, and physico-chemical form of releases of fission products to the environment, i.e. , the accident " source' tenn", have a direct- influence on emergency planning considerations. . The source term issue is presently under intense investigation by the staff. On December -17,1982, the Executive Director for Operations, EDO, sent to the affected office directors an inter-office program plan which describes the nature and schedule of the staff's activities de' signed to resolve the many technical issues connected with accident source tems. In January 1983, the EDO established an Accident Source Term Program Office to focus the implementation of the source tem program plan in a single program office.
Although the issue of accident source tems, and particularly the timing and quantity and fom of iodine likely to be released in an accident, has been discussed extensively in the last two years, it is premature to speculate quantitatively on the resolution of this issue. There ik general expectation
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that there will be reductions in the source tems developed in earlier risk i e
studies, but there is uncertainty in the amount of these reductions. In this !
context, " reductions in source tems" means lower probability, increased time j i
before a tajor release and/or reduced release fractions of the core inventory to ,
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the atmosphere, or combinations of these which would reduce the risk (probability times consequence). These issues are not expected to be resolved until at {
least the summer of 1984 when the compilation of the results of ongoing studies is expected to be completed.
Therefore, the assumptions made in this cost / benefit analysis are that:
- 1. The high and central estimate source tems for iodine release are those contained in the Reactor Safety Study (RSS), and
- 2. The low source tem is chosen a factor of 10 lower than RSS values to reflect the expectation summarized above, and to indicate that the current state of knowledge permits any estimates of such reduction factors to be expressed as orders of magnitude only.
It is noted that the radiciodine release fraction for the risk dominant accident sequences is currently of the order of seventy percent of the radiof odine in the reactor (e.g., for PWR-2 of the RSS), so the potential for a significant increase in release fraction is negligible.
Results of Uncertainty Analyses The results of the uncertainty analysis indicate that the central estimate for the cost / benefit ratios given in Table 1 is increased by about a factor of forty, with an uncertainty range going from a lower bound of about one quarter of the numbers nivan in Table 1, to an upper bound of about a factor of more than 6,000
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... d times higher than the values in Table 1. Thus, the range within five miles is
$70,000 per thyroid nodule averted to $200 million~ per thyroid nodule averted, with a central estimate of about $10 million per thyroid nodule averted. These results do not account for the following assumpt' ions, all of which would drive the cost-benefit ratios 'even higher and make KI distribution a'less effective protective measure:
- 1. No adverse impact on other protective measures assumed, such as the 1
potential for the public to believe they are immuna to radiation (i .e. , " placebo" effects);
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- 2. No consideration that KI is good only for reducing thyroid rea;
- 3. No_ consideration of nonlinear extrapolation at low doses; and
- 4. No adverse health impacts of the drug assumed.
Table 2 presents a modified Table 1 (summary table from NUREG/CR-1433) with I central estimate values and uncertainty bounds around the cost / benefit ratios.
The cost / benefit ratios of dollars per thyroid nodules averted should not be l
confused with the costs to implement a KI program. probabilities, effects and J
costs are all included in the numbers. As indicated on page 73 of NUREG/CR-1433, the minimum cost to implement a KI redistribution program in the entire U.S.
would be about 20 million dollars per year (10e per KI tablet times 200 million people) . In contrast, at some reactor sites in the U. S. the costs for the tablets for the residents of the 10 mile EPZ could be less than $1000, excluding distribution periodic replacement, monitoring anc public education costs.
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Costs Associated with Thyroid Treatment The final piece of information necessary to make a decision on the stockpiling or redistribution of KI is the actual costs associated with' medical treatment f for thyroid removal. An estimate of an upper bound for medical costs of $17,000 ll I
was given in NUREG/CR-1433. Tnis number was inferred for an average hospital *
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care cost of $2,000; which is 60 percent of all direct costs; plus indirect costs which are assumed to be four times higher than direct costs.
Dr. Frank von Hippel in his memorandum to Commissioners Ahearne, Bradford, Gilinsky, and Hendrie dated November 18, 1980 indicated that estimates of average costs of $6300 to $9400 had been made for thyroid removal by the New York City Department of Health. Costs associated with medical screening, also mentioned
' by Dr. von Hippel, would not be eliminated by KI administration since the exposed ,
population would still need medical screening with or without KI medication, especially for other radiation effects. Therefore medical screening costs should not impact the cost / benefit analysis.
Conclusion A substantial amount of information has been presented concerning the decision l
on whether or not to recommend stockpiling or redistributing KI to the general I
public.
. 1 The. estimate of ten million dollars per thyroid-rem averted for the 0-5 mile interval is the lowest central estimate cost / benefit ratio for any distance. !
Comparing this ratio to the $10,000 to $17,000 cost associated with thyroid removal indicates that potassium iodide is plearly not beneficial in relation to its costs. The lower bound (most optimistic) e' stimate is still significantly higher than the cost averted. Within 50 miles, the best estimate cost / benefit ratio increases by more than an order of magnitude over the 0-5 mile ratio to i
more than 140 million dollars per thyroid nodule averted. It is noted, however, that a substantial fraction of the collective dose (thyroid person-rem) could
. accrue beyond fifty miles from a release point. For t,he current large release accident scenarios, over half the thyroid nodules could be' induced beyond fifty miles.
The final question to resolve is whether or not there is sufficient information available to indicate that a considered decision concerning XI public distribution l can be made. Another way to phrase the question is to detemine the confidence l
i we have in the comparison of the cost-benefit results based upon the uncertainties in the analysis. Thus we need to ask two questions:
-1) How much confidence do we have that the costs associated with thyroid damage are less than the benefits of reducing the number of thyroid nodules from administering the KI?; and
- 2) What confidence level is necessary to make a decision?
It is now possible based upon the uncertainty analysis to answer the first question. The second question is left to the decision maRer.
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. Table 2 of'the analysis presented estimates of the 95 percent confidence-interval about a central estimate for'a series of distance intervals. Based upon these numbers we can compute (see Appendix B) the confidence we have in the estimates. For example, we can be 99 percent cor.fident that the actual cost -
would exceed $20,000 per thyroid nodule potentially averted within 5 miles. We
. can also be about 50 percent confident that the actual costs would exceed 10 million dollars per thyroid nodule potentially averted within 5 miles. As the intervals get further from the plant we become much more confident that the cost /
benefit ratio will become very large, to the point that we are about 95 percent confident that the costs-per thyroid nodule averted will exceed 10 million dollars beyond 100 miles.
These confidence statements are the final statements that can be made concerning the risk, cost, and benefit of Potassium Iodide and the associated uncertainties.
Based upon these statements the staff believes that the following statement can be made:
Redistribution or stockpiling of potassium iodide to the general public is not cost beneficial and should not be recommended as a protective measure appropriate for emergency planning.
Comments on Paper Two letters were received concerning draft versions of this analysis: the ACRS and Dr. Jan Beyea of the National Audubon Society formally commented.
These letters are attached. All substantive comments were factored into the final version of the analysis. -
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Ll l .One question was raised by the ACRS which requires specific discussion. The concern was' raised that cost-benefit uncertainty ' analysis has never been
.J performed before on any decision concerning other aspects of-emergency planning. l
'The cost-effectiveness of the conduct of emergency drills, installation of j i
warning sirens, and justification of analyses for population evacuations were j.
I raised as examples of candidates -for similar analyses. However, decisions have !I i
been made to implement these measures without such quantitative statements.
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, i The staff believes that such analyses are needed to make informed decisions ,
concerning safety areas (such .as emergency planning)' of significant complexity and uncertainty. The Committee to Review Generic Requirements demands such analysi: for all changes to the present regulations. As a minimum all of the issues and questions are highlighted. The relevant infomation is brought out in 'a form which is consistent and meaningful to the question at hand. Fu rther, the results of the analysis are presented so that the decision becomes much more defined. In the case of KI there should not be a doubt left about the decision.
From the central estimate point of view, the decision is obvious. When all of the uncertainties are factored into the analysis, the decision is still obvious.
All of the infomation confirms that KI should not be redistributed or stockoiled for the general public. Unfortunately, most decisions will not be so clear cut.
Uncertainties in the analysis will tend to overlap the comparisons thus making the decision much more difficult. When this occurs either more information is required to reduce the uncertainties or better define the problem, or a decision mill have to be made based upon ill-defined criteria and information. Such is not the case for a redistribution policy concerning Potassium Iodide.
f' '
.39.
' Table 1 Summary Table for KI . Cost-Benefit Analysisa ,b.c Distance Interval Cost-Benefit Ratio
( kilometers) (miles) (US'$/ thyroid nodule prevented) 0-8 0-5 , 3 x 10 5 8-16 5-10 4 x 10 5 16-40 10-25 7 x 10
- 40-80 25-50 2 x 10 6 l 80-160 100 6 x 10
!. 160-240 100-150 2 x 10f l 240-320 .150-200. 4 x 10 a '
Xey Assumptions
- 1. 99 percent effective XI (i.e. , all persons take drug before cloud ~
passes).
- 2. No other prctective measures are taken.
- 3. WASH-1400 accident probabilities. '
- 4. ' Estimated cost of KI program = $0.10 per person per year.
Assumed cost includes only the purchase price of KI, i.e.,
no costs for distribution, monitoring and administrative expenses.
- 5. . Only one reactor (3200 MWt PWR) within 200 miles.
- 6. WASH-1400 dose-effects coefficients (no 0.1 effectiveness factor for I-131 dose),
b uncertainties are large and scale approximately linearly with assumed KI effectiveness, accident probabilities, cost, multiple reactors, and
- dose-effects coefficients.
c From NUREG/CR-1433
1 Table 2 '
Summary Table for KI Cost-Benefit Analysis Distance Internal Cost / Benefit Ratio Miles ($ / thyroid nodule prevented) b Central Estimate a , Upper Bound Lower Bound b
0-5 1 x 10 7 2 x 10 9 7 xx10 10f 5-10 2 x 10- 3 x 10 9 10-25 3 x 10' 4 x 10 910 2 x 10 55 25-50 8 x 10 07 1 x 10 5 x 10 50-100 2 x 10 4 x 10 1 x 10 6 100-150 8 x 10 9 1 x 10 ll 5 x 10 6 150-200 2 x 10 3 x 10 9 x 10 a
Key Assumptions on Central Estimate
- 1. Source term for I-131 equal to that in WASH-g400
- 2. Probabilities of largest accidents about 10~
- 3. WASH-1400 dose effectiveness factors
- 4. 1-131 1/10 as effective as other radiation for thyroid effects
- 5. KI is about 50 percent effective in blecking iodine i
- 6. Other protective measures implemented (reduces benefits by factor of 4) ,
- 7. No adverse impact on other measures because KI oeing taken assumed 1
- 8. No consideration for KI only good for thyroid and iodine
- 9. No consideration for nonlinear extrapolation at low doses
- 10. No adverse impacts of drugs assumed
- 11. Costs assumed to be $0.20 per person per year
- 12. Redundancy of location increases costs by 50 percent ]
- 13. Shelf life assumed to be 3 years
- 14. Multiple site locations reduces costs by factor of 3 b
uncertainty bounds are based upon estimates assuming a log normal distribution at the 95th percentile. Standard error propagation techniques were usec to generata upper and lower bounds.
I i
_-___-_--_________m_
Appendix A Detailed KI Cost / Benefit Uncertainty Analysis As Table 1 of NUREG/CR-1433 indicates, many assumptions were made which directly impact the cost / benefit ratios. Each of the assumptions have uncertainties which would modify the results. By specifying the central estimate and range of values that the assumptions can take, a more realistic estimate of the cost / benefit of KI will be obtained. '
The following factors in the NUREG/CR-1433 analyses have large uncertainties which could significantly modify the results:
- 1) Source Tern (WASH-1400 source term assumed in the summary table of NUREG/CR-1433) - Factors as low as 2 and as high as 100 have been indicated as the potential reduction in radioactive iodine in various severe accident sequences. Pending the resolution of this issue, in this analysis we have chosen to use central and lower bound estimates of unity ( no change) and an upper bound estimate of ten (ten-fold reduction in iodine release fraction). No changes in release timing were assumed.
- No change in potential KI benefit assumed; a range of one to ten reduction in release fraction assumed possible. ***
- 2) Probability of Release (WASH-1400 probabilities assumed in summary table of NUREG/CR-1433) - Critiques of the Reactor Safety Study have consistently indicated that the uncertainties associated with the probabilities were understated. Since the Reactor Safety Study was published in 1975, several probabilistic safety analyses have been performed on specific reactors. These studies indicate
- These sentences highlight the relationship of the best estimate and range discussed in the section to the benefit or cost of KI as measured in the summary table of NUREG/CR-1433. ***
o .
S .
A .
that the frequency of a large atmospheric release 'of iodine lies. '
I between 1 x 10-3 and 1. x 10-6 'per reactor year (RY) with uncertainty '
i
' bounds of about a factor of ten associated with these values.
Not, all of these studies utilized-detailed modeling of the containment c
~
perfonnances; the' studies conducted _under the. Reactor' Safety Study Methodology Applications Prograrh and the Interim Reliability Evalu-ation Program used a methodological approach similar to that used in the Reactor Safety Study. Improved analyses recently performed by the industry and NRC relative.'to the Zion.'and Indian Point facilities: indicate that containment is stronger'than previously 'I assumed and the frequency of early containment failure is lower than that predicted in the early studies. Considering the early studies in this light we have selected a frequency of a'large iodine' release as 10-5/RY with an upper bound of 10-3/RY, and'a lower bound of 10-7/RY.
I Dr. Frank von Hippel, in his comments on KI , has indicated that the probabilities are seriously underestimated, and uses a 10 year recurrence interval for large release accidents. This is equivalent to a one in a thousand probability per reactor year for a large atmospheric release in the U. S. Operating experience would indicate that the probabilities given in WASH-1400 can be at most a factor of about 10 to 100 too low.
On the other hand, Dr. Harold Lewis, Chairman of the Risk Assessment 2
Review Group (NUREG/CR-0400), has written that he believes the Reactor I"The NRC and Thyroid Blocking - One Excuse After Another," Bulletin of the Atomic Scientists, October 1980, p. 44.
2"The Safety of Fission Reactors," Scientific American, March 1980, Volume 242, Number 3.
A-3
. . .i Safety Study is conservatively biased throughout; which would: counter the underestimate claim of von Hippel. A range of a factor of 100 on both sides of the. central probability estimates is assumed in this analysis.
- Potential KI benefit not changed; major accident probability range of 10-3 to 10-7 assumed.***
- 3) Effectiveness of Potassium-Iodide - There are many. issues which have been raised concerning the effectiveness of KI in preventing thyroid nodul es, o Dose Effect Relationship -
The first assumption concerns the incidence of thyroid nodules, cancers and cancer fatalities from exposures to radiciodines.
The summary table from NUREG/CR-1433 assumed 334 thyroid nodules per million person-rem to the thyroid--with 60 percent benign, 3
and 40 percent cancerous. Beyea has assumed an upper bound of about a factor of 5 higher thyroid nodules for the general population and a factor of 20 higher for children. He also assumes about a factor of 2 lower estimate for a lower bound.
The BEIR-III4 committee however, states in its risk estimates for 3
See Enclosure E
- "The Effects on Populations of Low Levels of Ionizing Radiation,1980,"
National Research Council,1980, p. 304.
_ . . - . . . - _ . _ . . . . _ . . _ . _ - _ . .--.-....--.a
.o , ,
A-4. ,,
thyroid cancer that there is "no significant data to substantiate
!. an age-at-irradiation effect..." According to BEIR-III,'(pp. 289 and 292), only about 5 percent of the cancerous nodules were assumed to be fatal. ~ A factor of 5 increase and 2 reduction will be used for the effectiveness issue.
- Potential KI benefit not changed; range of 0.2 to 2 assumed.*** -
o I-131 Effectiveness -
The question of the effectiveness of I-131 thyroid-rem in causing nodules, etc. as compared to external irradiation is raised. (The same dose effectiveness factor for I-131 as .for all other radio-nuclides was assunied in the summary table.of NUREG/CR-1433.)
Factors of 10-80 too high for the incidence of I-131 have been given in WASH-1400 and the BEIR-III report based upon animal data.
Since only 2/3 of the dose to the thyroid is from I-131, a factor of 2 reduction will be assumed, with an upper bound of a factor of 3.
- Potential XI benefit decreases by a factor of 2; range of 1 to 3 assumed.***
i
1, f
L -
A-5 1
=- . !
o KI Effectiveness - l L ,
l-
'In the summary table of NUREG/CR-1433, KI was assumed to be 99 per- l t
cent effective in reducing the:radiciodine thyroid dose. Realis-tically, based upon not having the drug available and long response :
[
times, this is a factor of 2 or more too high. b a
- Potential KI benefit decreased by a. factor of 2; range of 1 to 3
{
t assumed.*** ;:
, L l' i o Other Protective Measures - [
t Benefits of other protective measures such as' evacuation, shelter-- l ing, or respiratory protection were not included in NUREG/CR-1433 summary table. There other measures, as is shown in ~ sensitivity studies in NUREG/CR-1433, would reduce the effectiveness of KI by factors of 1 to 10.
- Potential KI benefit decreased by a factor of 4; range 1 to 10 assumed.***
o Adverse Impact On Other Measures -
No adverse effects of KI were assumed in NUREG/CR-1433 summary table.
There are possible adverse impacts on the effectiveness of other protective measures caused by a KI policy. These occur both in emehency planning, where resources could be diluted, and in an actual emergency response, where the effectiveness of other measures could be reduced because time would be taken to locate and take the drug. Factors of 1 to 2 too high could be realized by such adverse actions.
- Potential XI benefit not changed; upper bound factor of 2 assumed.***
A-6 .
KI 'Only for Thyroid -
o There is also the perspective that KI will block radioiodine from only the thyroid. It has almost no other effect on_ the more severe potential radiation. hazards, . such as from.all other radionuclides..
exposure pathways, and organs, for effects such as early fatalities, injuries or non-thyroid cancers or genetic effects.for which emer-gency protective measures should be focused. There is no factor which can be applied to this consideration, but it should be recogn-ized as a limitation of KI which other protective measures do not have.
- Potential KI benefit would be reduced, however influence not included in analysis.***
o Linear Extrapolation -
The last effectiveness issue deals with the use of the linear l extrapolation on the incidence of thyroid nodules at low doses.
1 BEIR-III cautions that there is little or no data to support this assumption at low dose levels, and specifically indicates that there are no data for doses icwer than 6.5 rad to the thyroid.
1 l
Again no specific factor can be applied to this consideration, but it should be kept in mind when considering recommendations, especially at far distances.
- Potential KI benefit would be reduced, however influence not included in analysis.***
l
I
- l . >
.. A-7
- 4) Adverse Impacts - No adverse inpacts of KI were assumed in the summary table of NUREG/CR-1433. There has been significant discussion on the adverse impacts or risks associated with potassium-iodide usage by the general public. The question remains unresolved, with substantive l arguments made on both sides. ,In addition to the potential risks asso-ciated with the drug as discussed in detail in SECY-80-257A, another adverse impact could be the perception on the part of the public of an immunity to radiation effects after they have taken KI. This " placebo" effect could further reduce the effectiveness of other protective measures by having the public believing they have been immunized and thus have no further concerns from the radiation. Another adverse impact would be caused by overdesage of KI due to some members of the public, in a state of fear, takinc all of the KI available to ward off radiation.
Or, in the opposite sense, even greater fear or panic could be inspired if the pills are lost or not otherwise available. The potential for extensive training and education of the public to prevent such occur-rences is uncertain. Finally, there is some concern that if the pills are redistributed to the public, they will be lost or people will mis-use them. It is difficult to quantify these uncertainties but the potential adverse effects could be enough to preclude the use of KI as an emergency protective measure.
- Potential KI benefit would be reduced, however influence not included in analysis.***
- 5) Cost of KI Procram - There are many costs which would be associated with the stockpiling or pre-distribution of KI:
H g
l' A-8~ .
o Purchase. Distribution, Storage, Monitor and Public Education -
(A cost of $.50 per. person assumed in NUREG/CR-1433.) This cost -
only accounts for the original purchase or replacement costs and ,
approximates the costs associated with one 14 tablet bottle of' the_ medication as currently available from the manufacturers.
1 l Other additional costs would include distribution. -storage, L monitoring, training, and public. education. A factor of 1 to 3 increase in cost could be anticipated to cover these items.
- KI cost increased by factor of 2; range of- 1 to 3 assumed.***
o Redundancy of Location -
No redundancy. of location was assumed. in the summary table in NUREG/CR-1433. There may be a need to have a redundancy of the medicine in various locations. This could amount to an additional factor of 2.
- KI cost increased by factor of 2; range of 1.5 to 2 assumed.***
o Shelf-Li fe -
A five year shelf-life for KI was assumed in the summary table in NUREG/CR-1433. A three year shelf-life is prescribed currently by the Food and Drug Administration. This would increase the costs by a factor of 1.67. I
- KI cost increased by factor of 1.67; range of 1 to 1.67 assumed.***
l
-___ ____ __- _ 1
ri
^
. -l .
.- .. A-9 o' Multiple Site Locations -
~
Single reactor sites was assumed in the NUREG/CR-1433 summary table.
On the other hand, there are many reactors at-locations which would overlap _one another for distributions to large distances and so a cost saving would accrue. This. would account for a-factor of 1/2 to 1/5 reduction in the cost, with a best estimate .
of about 1/3.
- KI cost decreased by a factor of 3; range of 2 to 5.***
Propagation of Uncertainties Ranges of values and best estimates have been presented above for the major uncertainties associated with the assumptions in the cost / benefit ratios.
Table A-1 presents the upper bound, best estimate, and lower bound estimates for each of the factors previously discussed. By combining these factors, an estimate can be made of the range and best estimate of-the overall cost / benefit ratios for the redistribution of KI. The method used to combine the factors is the standard uncertainty propagation technique assuming log-nomal distri-butions at the 95th percentile about the median or best estimate" modifier.5 For the cost / benefit ratio of $300 thousand per thyroid nodule averted within 5 miles of the plant, as given in Table 1, a more realistic central estimate value would be about 40 times higher which equals $12 million per thyroid nodule 5
Manor, Schafer, Singpurwalla, Methods'for Statistical Analysis of Reliability and Life Data, John Wiley and Sons, Inc. ,1974, p. 264.
4
_________m_ _ . . . . _ _ _ . _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ _ . _ _ _ _ _ . _ _ _ mm_-
A-10 -
averted. An upper bound would be about 6300 times higher which is about $2 billion per thyroid nodule averted, and even the lower bound is $70,000 per thyroid nodule averted. As noted earlier, however, elimination of thyroid nodules within five or ten miles would not significantly reduce the total number of thyroid nodules for risk dominant accNent sequences.
l l
u_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ . . _ . _ _ _ _ _ _ _ _ _ _ _ . _ _ .
1 1 ', - -
A-11 4
Table A-1 Uncertainty Bounds for Cost / Benefit Analysis Assumptions Modifiers of Cost / Benefit Ratios Given-in Table 1 Uncertainty Consideration Upper Bouna Central Estimate- Lower Bound
- 1. Source Term * ?)07 ?l? 71 7
- 2. Probability of-the Accident 100 1 0.01
- 3. -Effectiveness of KI
- a. Dose Conversion 2 1 '0.2'
- b. I-131 Effectiveness 3 2 . 1
- c. 99% Effectiveness 3 2 1
- d. Other Protective Measures 10 4 1
- e. Adverse Impact on Other Neasures 2 1 1
- f. KI Only for Thyroid x? x? -x?
- g. Linear Extrapolation x? x?- x?
- 4. Adverse Impacts x? x? x?
Drug Risks, Placebo -
Effects, Misuse
- 5. Costs of KI Program Purchase, Distribution, Storage, Monitoring, Public Education 3 2 1 Redundancy of Location 2 2 1.5 Shelf Life / Losses 1.67 1.67 1 Multiple Site Locations 0.5 0.3 0.2 Combined Uncertainty Range Assuming Log-Normal Distributions '+
the 95th Percentile 6,300** 40** 0.23
- The uncertainties in " source terms" are extremely large. 'The values listed between the question marks were used in the derivation of the bounds shown in the bottom line of the table.
- Times the unknown factors for 3.f 3.g, and 4 above.
___- -------___-___--____-___---,-,---a-- --_-------_-___---,__~___--.-__--______,--__---_--_____-,._-------------______----_----__----,-----_-_a
e .
- i I- , .
l Appendix B l-I Confidence Statement The stockpiling or redistribution of potassium iodide as a preplanned protective measure for public use is beneficical if e<e*, where e is the unknown cost /
4 benefit ratio frequency and e* is some griterion (e.g., e* = 2x10 ). Let e denote the cost / benefit ratio estimate resulting from the uncertainty ar.alysis.
We are interested in the following probability:
Pr(e <e *l e )
~
Where we are assuming a median unbiased estimation scheme.
To evaluate the above expression two major assumptions are made. The true (but unknown) cost / benefit ratio 15 assumed to follow a logr.ormal prior distribution and the sampling distribution of the uncertainty analysis estimate is also assumed to be a lognormal distribution. Based on these assumptions the results of these calculations are provided in the table below.
4 Note that if our criterion is 2x104 (e* = 2x10 ) and our median estimate of 7
the cost / benefit ratio resulting from the uncertainty analysis is lx10 for the distance interval 0-5 miles, then the probability is .99 that our criterion will be exceeded.
B-2 Distance Tnterval' 00 Pr(e<eo je) '
i (miles) 0-5 2x10f 1.0x10-f 5x10 2.6x10~2 5 -
1x10 4.8x10 ;
5x10- .15 D
1x10 .23 1x10 .57 4
5-10 Ex10 6.19x10-3 1.62x10-2 5x10f 1x10 3.11x10 ' ,
5 5x10 *II 6
1x10 .17 7
1x10 .46 4
10-25 2x10 2.67x10-3 5x103 7.95x10-3 1x10 1.67x10-2 7.07x10-2 5x10f 1x10 .12 7
1x10 .40 4
25-50 2x10 6.98x10~4 4
5x10 5 2.39x10-3 1x10 5 5.57x10-3 5x10 3.00x10-2 6 -
1x10 5.51 x10-2 i
1 1x10 .26 4
50-100 2x10 4 3.03x10-4 5x10 1.07x10-3 1x105 2.56x10-3 5x10*6 1.50x10-2 l 1x10 2.88x10-2 7
1x10 .16 4
100-150 2x10 4 1.77x10-5 1 5x10 8.43x10~4 1x10!3 2.52x10~3 5x10 2.39x10 3 6
1x10 5.57x10~2 7
1x10 5.51 x10-7.72x10~6 150-200 2x10l 5x10 3.75x10,4 1x10! 1.14x10~3 5x103 1.15x10 3 D
1x10 2.76x10 2 7
1x10 3.11x10-
4 e
' 4 9 e
s$
e- e . .
e 9
' g9
=
b ENCLOSURE B e
f 6
l l
Enclosure B
- I^.e** e. , l W. , * .. . :
4
. . l INTERNATIONAL ATOMIC ENERGY AGENCY
, ]
g,) INTERNATIONAL CONFERENCE ON CURRENT NUCLEAR I POWER PLANT SAFETY ISSUES
_; q- - -
Stockholm,20-24 October 1980 IAEA CN-39/ 102 RADIATICH'PwndION:
AN AEYSIS O? DIY.:CID ELOCICDC David C. Aldrich Sardia National Laboratories Puel Cycle Risk Analysis Division 4413 Albogaergae, New Mexico 87185 USA rpger M. Blord US Nuclear Fegulatory C:Inission Division of Syste.:s & kliability Research Washirgton, DC 20555 USA
\
This is a preprint cf a paper intended for presentation at a scientific rneeting. Beeswse of the provisional nature o content and since changes of sutstance or detait rney F.aw to be trace tefore publication,the preprint is rnade a understanding that it will not be cited in the literature or in any way be reproduced in its present form. The vi the staternents r aoe rernsin the responsibility of the narned author (s); the views do not necessarily reflect these o rnent of the desagnatirs Mer-cer State (s) or of the designating organization (s). In particu/ar, neimer the IAEA nor an orpenization or bocy sponsoring this inerting can be held rewonsible fur any rnoterialreprotfaced on thu propritst.
_ . . ~ . _ _ .
g
INTERNATIONAL ATOMIC. ENERGY AGENCY .
^
. \'
INTERNATIONAL CONFERENCE ON CURRENT NUCLEAR "
- POWER PLANT SAFETY ISSUES
-7 + Stockholm,20-24 October 1980 IAEA CN-3c/ 102 Radiation Protection: An Analysis of tyroid Blocking Abstract An analysis has been performed to provide guidance to policy-makers concernim the effectiveness of potassian iodide (KI) as a thyroid blocking agent in potential reactor accident situations, the distance to which (or area within which) it should be distri-buted, aM its relative effectiveness conpared to other available protective measures. L e analysis was performed using the Reactor Safety StMy IRW1400) consegaence no$el. Four categories of accidents were addressed: gap activity release accident (GS),
GJ without contalment isolation, core melt with a melt-through release, and core melt sith an atmos #eric release, Cost-benefit ratios (US S/ thyroid redule prevented) are given assuting that '
no other protective nessures are taken. Uncertainties due to health effects parameters, accident probabilities and costs are assessed. me effects of other potential protective measures, such as evacuation aM sheltering, aM the d: pact on children (critical population) are evaluated. Finally, risk-benefit considerations are briefly discussed.
- 1. Introduction Follcwim the recent accident at tree Mile Island, there has been a resurgence of interest in the use of thyroid blocking as an emergency protective measure for reactor accidents. m is paper sur.ari:es .a stMy [1] performed at the regaest of the U.S. Nuclear Regulatory Consnission to provide technical guidance on t%t issue.
Se objectives of the stp were to determine 1) the effectiveness of potassium icdide (II) as a thyroid blockim agent in realistic 1 Radiological emergency plans in Great Britian inclufe thyroid blocking using tablets of potassian iodate which, in the British l'
experience, have an appreciably longer shelf-life than iodide l tablets. De iodate form could be ec:picyed in the U.S. only by ccepliance with Food and Drug M= ministration (F::A) requirements f that inclu$e gathering pertinent clinical data on the use of the drug.
3 This is a preprint of a paper intended for presentation at a scientific rnseting. Becawse of the provisional r,ature of content and since :f.arges of subriance or detail rney have to be rnade tyfore publication, the preprint is made available e understanding that it will not be cited in the literature or in any way be reproduced in its present form. The views exp the staternents r".ade remain the resooruibility of the narned author (sh the views do not rmenarily reflect these of the 9evem fnent of the oesigr. sting Meanber State'.sl or of the desig4 tire organization (s). In particular. neither the IAEA nor any other Otp&n5E& tion Or bO$V sipOnscring this tnettitsg can be held responsible fOr Sr:y material reproduct' din th:2 preprin
accident situations, 2) the distance to which (or area within which) it should be distributed, 3) the corditions urder which it should be implemented, and 4) its relative effectiveness corpared to other available protective measures. Be analysis was performed using the Beactor Safety Sttdy (K7ds-1400) consegaence model [2,3], CRAC, for i a range of potential reactor accidents; from fuel pin gap activity l release accidents to complete core meltdowns with containment fail- '
ure directly to the atmosphere. 2ere is a great deal of uncer-tainty la our knculedge of these releases ard their probabilities, as well r 3 dose-health effect relationships for the thyroid. To sore extent, these uncertainties hiri$er our ability to provide .
definitive guidance. Bowever, they are addressed to the extent possible in our analysis.
- 2. Background 2.1 Potassium Icdide (KI) as Protective Feasure 2e risk to the thyroid of exposed individuals posed by potential accidents is especially great for several reasons:
- Radioactive isotopes of iodine are produced in abuMance by the fission prccess.
- Iodine and iodine cocpourds are nor:r. illy q31te volatile.
terefore, a sizeable fraction of core radioicdine inven-tories could be available for release to the atnicsphere.
- Inhaled or ingested radiciodines are gaickly absorbed into the bloodstream and concentrate preferentially in the thyroid.
- Icdines are eliminated from the thyroid with a relatively long biological half-life.
As a result, the radiation dose to the thyroid is likely to far exceed the dose to the rest of the bcdy, aM thyroid damage is likely to affect rcre iMividuals than any other accident-iMuced health effect. Taken in large ercugh gaantities, KI acts to block the absorp roid dese.gion Forofthis radioicdines reason, KI by hasthe thyroid, been reducing discussed for many the thy- years as a potential protective measure for use in the event of a serious reactor accident [4]. Bowever, use of KI is not the only protec=
tive action that will reduce thyroid dose, nor is it without its difficulties and problems:
2 The effectiveness of the block is strongly influenced by how rapidly the K! is administered. Essentially complete curtail::ent _
(90% or greater) of radioicdine uptake by the thyroid regaires that the drug be administered shortly before or 1::nediately after the initiation of exposure. A block of 50 percent or mere l
is attainable only during the first fe bours af ter exposure [4] .
C .
p,
- The drug is not ccepletely risk free; adverse reactions are
- l. possible.
- Making KI available would involve a cost to society; dollars i that perhaps could be used to reduce risk more effectively elsewhere.
- tere are serious logistical problems associated with ensur-ing that the public would receive the drug in sufficient time to be effective.
4
- It must be assured that any KI distribution strategy imple-mented would not reduce the effectiveness of other protective actions taken.
l There is presently no definitive cuidance in the U.S. concern-I ing when, er under what corditions, KI should be used as a blocking agent. Re NCRP recomerds that it be considered for use if the projected thyroid dose to an irdividual in the general public exceeds 10 rem [4] . Protective Action Guides (PAGs) promulgated by the EPA for projected thyroid dose range from 5 to 25 rem [5] .
Protective action is recorrended at the lower level for sensitive populations (pregnant wmen, children), er if there are no local constraints to providing protection at that level. Protective actions wuld be warranted in all cases if the projected dose exceeds the higher value. However, only evacuation ard controlled area access were discussed in the EPA docment, aM the use of KI was not specifically cited as an appropriate protective measure.
Because the prompt administration of KI in the event of an accident is critical to its effectiveness as a protective mee-sure, some method of rapid distribution to the public is res: ired.
W ere is lit'tle current definitive planning for such methods.
Stockpiling supplies of KI in " distribution centers" such as schools, police- stations, or firehouses has been recommeMed.
An alternative would be to. provide each household with a suffi-cient supply for all mer.bers of the household. 2 e feasibility, effectiveness and implementation costs of these ard other alter-native strategies should be investigated.
2.2 Thyroid Eealth Effects h ere is considerable uncertainty concerning the effects of radiation exposure on the thyroid {2,4,6] . Syroid nodules are the effect of primary concern aM would typically be observed from 10 to 40 years after expcsure. A nodule is an abncrmal growth that could be either benign or malignant (cancerous). Nodules that are thought to be possibly malignant muld nes likely be surgically recoved.
iest thyroid cancers are well differentiated, slow growing, and relatively amenable to therapy. Their associated mortality rate is therefore nuch lower than that for rest other for:rs of i
____________m. _ _ _ _ _ _ _ _ _ _ _ _m__m__ _______ -
PL
.. j . .
cancer. 1ESB-1400 conservatively assmed a 10 percent mortality -
rate for malignant thyroid nodules.
k Based on the results of animal experiments and clinical data for htnans, WAS&l400 asstraed that internal irradiation of the thyroid by I-131 would be only 1/10th as effective as nal x-rays in producing both benign and malignant nodules.gxter- mis -
factor' of 0.1 for I-131 dose was disputed by the American Physical Society (APS) stix!y group on reactor safety [6], which assumed a range of factor s from 0.3 to 1.0. Because.this issue remains unresolved, calculations were performed in this analysis both with and without a 0.1 factor for I-131 dose effectiveness.
Sufficiently high radiation doses 4 would result in ehlation of the thyroid with no subsepent risk of either. benign or ralig-nant nodules. Bewever, because of the high doses reg ired, thy-roid ablation is unlikely to occur except for persons very near the reactor folicwing the nest severe accidents. Ablation would probably require surgical renoval of the thyroid, and the affected individual would need.to take substitute hormone pills on a daily basis.
r per 10p5-1400 assumed an incidence rate of 334 thyroid nodulesperson-rem are ralignant, te dose-effects coefficient for a child's thyroid can be derived from WASS-1400 data to be approximately a factor of 2 higher. Others [7] gave asstraed incidence' rates as high as 650 thyroid-nodulegper10 persorprem for adults, and. 6500 thyroid nodules per 10 persor> rem for children. S e calculations per-
, formed in this sttx!y assq. the 1GSE-1400 risk coefficient of 334 thyroid nodules per 10 person-rem. S e effect of uncertainty in the thyroid dose-effect relationship was assessed by repeating some calculations using the highest incidence rates proposed.
2.3 Accident Beleases Considered Release magnittx!es for potential accidents of offsite significance rarse from relatively sull releases of gap activity to the large releases predicted for full core-melt accidents in which the containment fails directly to the atmosphere. WASH-1400 grouped this spectrtn of reactor accidents into nine release categories for pressurized water reactors (PWR) with large dry containments and five for boiling water reactors (BWR) with Mark I containment.
3On a purely radiological basis, it is thought that the more uniform distribution of dose within the thyroid from external irradiation might increase the efficiency of inducing clinical hypothyroidism =.
40n the order of 3000 to 5000 rem [1] .
i eWGuns 4m+ -
___ _ __ _w
- 5 For the purpose 'of this stu$y, the NR accident release spectrtra was further grouped into four categories: - !
MASB-1400 Release Cateceries
- 1. Gap Activity Belease Accident (GAP)
- 2. Gap Activity Release Accident without M9 Containment Isolation (GAP without
~Isolaticn)
- 3. Core Melt with Melt-trough Belease M38 (Core Melt Melt-Through)
- 4. Core Melt with At:nospheric Release WR6-7 (Core Melt Atmospheric) hh5 WR9 represents a gap activity release accident in which pellet aM cladding would be released into the containment. All engineered safeguards are asstned to function properly. WPS 1isate theproperly same as on n?9, demaM. except that the containment fails to is>
incitriing containment sprays, are asstraed to function properlyAg .
NR categories asstrx-d 1 through 7 are accidents in which core melt is to occur.
WR 6 eM 7 are dcminated by acciden: sequences
. involving containment failure' by containment base mat mel:-throo;h.
ML5, on the other hand, consist of accidents in which contain-ment failure is assried to occur directly to the atm'ositere as a result of either inadequate isolation of containment openings or penetrations, or overpressure. a reactor vessel steam explosion, hydrogen burning, tatien, %7 accidents were not censidered specifically analysis. in thisTo redu Ecwever, the information and conclusions presented .
for large dry containment W as should be roughly applicable to other ER designs and for BWRs as well, give.. a similar type of accident and mode of containment failure. -
- 3. msults an$ Conclusions tt ,
3.1 2hyroid Dose Calculations to dete: nine 1) the magnitude of the threat to the thyroid ofA ser '
exposed individuals, 2) the distance to which that threat is likely to be of concern, and 3) the relative contributions of different exposure pathways and radioisotopes to the thyroid dose, l.
for each of the four accident categcries defined in the previous section.
All calculations were performed for a 3200 E't WR using ,
one year of meteorological data taken frca a single reacter site.
Frcn the year.'s data, 91 different weather sequences were selected by stratified sa:gling [2] and used to generate probability dis-tributions of thyroid dose versus distance. 2:eathing rate and __
shielding were parameters appropriate for a ;ergen located outdoors assr.ed: 3 breathing rate = 2.66 x 10" m /s, shielding facters me e ees -
- w . -o- .
> .. . i
+ .
1 P .
= 1.0 (clod exposure) and 0.7 (ground exposure). myroid dose cloud (cloM exposure), 2was estimated as the sum of 1) external dose from external dose from contaminated ground (ground ex;osure),)3) internal dose during the first 30
{
days from all inhaled radionuclides except I-131, and 4) inter- -
nal dose during the first 30 days from inhaled I-131. S yroid ;- i dose from ingestion via the grass-cow cilk-man pathway ard chronic exposure was not included because those pathways w:)cid not require an irrediate emergency response in the event of an accident. i We probabilities of exceeding thyroid doses of 0.01 ard 1A, conditional on the ~rcurrence of a gap activity releas accident (GAP).
i are far lower than ag *eccreerded action levels, and ares e Eretted j!
still confined to aree.r w ry close to the reactor. :.
it is evident cant hacard tothatthethe' GAP accident does not pose a signifi-Berefore, public.
!j l}
i
'i roid doses of 1, 510 and 25 rem versus distance for the GA +s without Isolation and Core Melt Melt-Through accidents.
te 5, 10 and 25 rem dose levels represent the rarse of action levels that haveprotective emergency been recommended reasures. in the US for the initiation of i lower bourd for doses of interest.Se It is 1 rem level evident fromwas theseadded as a :"
results that, for all practical purposes, projected thyroid doses of concern are confined to areas within a few 10's of {~
. kilometers (10's of miles) of the reactor for these types of i accidents, and in rest cases to areas considerably closer. {.
For the GAP without Isclation accidents, doses in excess of 5 ;[
rem are confined to about 16 kilometers (10 miles); those in -
excess of 25 rem to alcut 8 kilcneters (5 miles). Se same dose levels are confined to approximately 24 and 11 kilometers (15 and 7 miles), respectively, for the Core Melt stit-Brough category. ~
We conditional probabilities of exceedirs thyroid doses of shcwn 1,10inand 25 rem Figure ID. fcr the Core Melt At aospheric category are S e thyroid dose levels of concern are likely to be exceeded at very large distances from the reacter (ard corresperdirgly ever very large areas) if this type of .
accident were to occur. -
Further analysis indicated that the thyroid dose is domi- .
nate? by the inhalation of raficiodines for each of the four accident categories. Inhalation of I-131 alone accounts for anotherpercent 60-80 of the total dose, ard other icdines contribute 10-25 percent.
Inhalation of non-radioicdines, clots i expcsure thyroid dose. ard ground exp:sure are all small contributors to total -
i a
8 J a 9
..~
l 3.2 Cost-Benefit Analysis -
The decision to use KI as a protective measure should be based,. at least-in part, on-its cost-effectiveness relative . .
to other available protective or. safety measures. To analyze 4the costs'and potential benefits of KI,'the following informa-tion is needed:
-- Costs;
- Potential reduction in accidenb inpacts afforded by the use of KI; and ,
- Accident probabilities.
.The cost of implementing a KI program would include: the pur-chase price of the KI in tablet or liquid form (both original aM Nriodic replacement costs); costs for stockpiling, distri-buting and monitoring the status of the drug; and administrative
- i. expenses associated with the program. 2 e potential benefit of KI would be a reduction in the nunber of thyroid nodules' that would occur following a major release of radioactive material.
Accident probabilities are expected occurrence rates per year of reacter operation. By combining the costs with the accident probabilities and the estimated reduction 'in effects, a cost-benefit ratio is generated. Se cost-benefit ratio for.KI is interpreted as the expected ntnber of dollars required to pre-vent a single thyroid nodule. i
- The results of our ' analysis are strxrarized in Table I in - i ter:r.s of ecst-benefit ratics (US S per thyroid nodule pre- !
vented) for selected distance intervals from a single.3200 MWt j-AGR.
2e uncertainties in the estimated ratios are very large. t Key assumptions made in their derivation are noted in the table. I Calculations were performed using CRAC in the same tranner as described in the preceeding section. Se KI was conservatively asstrned to be 99% effective in reducing thyroid dose from ire-haled radiciodines (i.e., all persons take the drug before or 1:renediately after the cloud passes). Tealistic effectiveness values could be significant probabilities were asstraed.gy s. Probability aller. WASB-1400 accident uncertainties have been estimated to be at least an order of magnitude [1]. Stock-piling, distribution, monitoring and administrative costs for a KI program would depend on the specific strategy of implementation 5
NASB-1400 probabilities: CAP (PhPS) 4x104 , GAP without Isole-tion (PWR8) 4x10"", Core Melt Melt-Through (PW36-7) 4.6x10*",
and Core Melt Atmospheric (PWRl-5) 1.4x10 5 per reactor-year.
Note that even though the probability of the core Melt At=cs- _
pheric (diIl-5) category is sr.all, it dominates (95-100%) the risk of thyroid nodules.
~
', 3 hm
. - i
, h.'
"and are difficult to esti: rate. B erefore, only the original purchase and rgplacenent costs of the drug were included in h
this analysis. S e ratics presented in Table I are appropri-ate if there is only a single reactor within 200 miles. Many . n$
i l
actual locations would be influenced by several reactors, and g);d cost-benefit ratios could be reduced by factors as high as 5 Mj in the US [1]. gI w
Uncertainties in dose and health effects parameters are also large and could result in either higher or lower cost- h iM benefit ratios. Re values in Table I assme W$5-1400 dose-effects coefficients without a 0.1 effectiveness factor for I-131 dose.
range from 6x10 If 5the 0.1 factor is assmed, the estirated gatios #hlD S/ nodule prevented within 0-8 6 to 2x10 S/ ;tfff nodule prevented within 240-320 h. Using the upper bound risk coefficient of 6500 thyroid nodules per 106 person-rem for chil- iQ dren 17] (no 0.1 I-1315 dose effectiveness factor), the estirated $s3 ratics range from 5x10 S/ nodule prevented within 0-8 h to .
h y;.
2x10$ S/ nodule prevented within 240-320 6. r-:x Finally, the cost-benefit ratios in Table I assme that no other protective actions are taken. Sewever, other protective 7 -
neasures, inclu$ing both evacuation aM sheltering, can also act -
to reduce thyroid dose. Evacuation has the potential to be 100%
effective in reducing all dose if accoglished before arrival of the radioactive cloud. On the other hand, it could be ineffective if not initiated until after the cloud'has passed. Sheltering '
might also provide sme reduction in thyroid dose an$ could poter>-
tially be implemented at much larger distances than evacuation [8]. -
2 erefore, in either case, the thyroid dose reduction afforded -
by the supplemental use of KI could be reduced, and the KI cost- .
benefit ratics presented in Table I could be correspondingly increased.
To sme extent, the large uncertainties in the above assrp- -
tions hinder our ability to provide definitive guidance. Never- '
theless, for the assmptions rade, the calculated cost-benefit ratios are high; an$ even including uncertainties, KI appears to be only trarginally cost-effective, at best. ;
3.3 Risk-Benefit Considerations '
m ere is considerable experience with the use of KI as a therapeutic drug [4] . It has been used for a nm.ber of years in high doses, and on a long-term basis, for the treat ent of vari-ous pulnenary disorders. Se reported incidence of adverse reactions to the drug is low, and the risk posed by the short-6 2e estimated cost of 50.10 (US) per persen per year assines ~~ i a purchase price of 50.50 per individual (14 tablets in a bottle) i and a shelf-life of five years.
l e
a
[
if term use of the relatively low doses that would be involved " '
$ with respnse to an accident has been jtziged by sane to be '
A minimal. S e NCRP j to be between 1x10"j4] estimatp and thedose, 1x10~ per adverse andreaction concluded rate that h the administration of KI would not result in significant ime- 4 diate side effects, even if given to large segments of the 3 ppulation. Using the values proposed by the NCRP, a si:gle 4 risk-benefit analysis showed the risk of a$ verse reaction p sed by KI at the reco= ended action levels and dosages to be small g
Q conpared to its potential benefits .[1] . Bowever, several recent k reprts [9,10] suggest that there may be, a significantly higher , q risk associated with use of the drug a~ong certain, segments of ' / f y
the population. If this is confirmed, the risk-benefit conclu-sien for KI w uld have to be reassessed. ik y'
- 4. Coments and Recocrnen$ations IU Based on the above analysis, the following additional ,Q coments and recamendations are made: f;p Although the effective use of K! could significantly '
f.
reduce the ntnber of thyroid nodules resulting from a serious accident, it would have no, or only minor, '
inpact on other accident consequences; inclu$ing ime-diate deaths or injuries, delayed cancer deaths, and long-term land contamination. Berefore, the avail- <
ability of K! would provide only a supple. ental strategy to be considered along with other possible protective ;
measures, a
me risk of thyroid nodules was shcw to be dominated by the large releases associated with core melt acci- -
~
dents in which the containment fails directly to the atmosphere. terefore, if design modifications, so:h- .
as filtered containment venting systems, are implemented ,g; i
'~
to reduce the likelihood of those releases, the poten-tial benefit of KI could be substantially reduced.
Before any KI program is implemented, specific -
alternative strategies for stockpiling and distributing I' j the drug should be examined to reduce costs and assure .- 1 effectiveness. l We use of ca=cn household items (e.g., handkerchiefs and towels) as respiratory filters may provide signifi- ~'
cant additional protection against dose due to irhaled radionuclides and should be considered further in the ,,
developent of protective strategies.
If a KI program is implernented, resmnsible government ,
4 agencies should give priority to establishing guidance l (e.g. , PAGs) concernire when, er under what conditions,
, the drug Octnd be used.
y __ _ -___ _ . - - _ _ _ _
- g. A
+Q. 4 x
p
. Finally, whether or not a public KI prcgram is imple- f mented, it might be wise to have sufficient quantities 9, of the drug availab2e at or near reactor sites for use T by 1) site personnel, 2) offsite emergency response
- T personnel, aM 3) control 2ed populations in offsite E institutions (e.g., hospitals, prisens) where inmediate y evacuation would be difficult or infeasible. -
References he. '
- 1. Aldrich, D. C. aM R. M. Blond, Exami' nation of the Use of
- -l. [?
Potassic: Iodide (KI) as an Emercency Protective Measure
((p, for Nuclear Raactor Accidents, SAE60-0961, NUREG/CR-1433, '
Sardia National Iatcratories, Albuquerque, NM, March 1980. e E
- 2. Reactor Safety Studv AcceMix VI: Calculation of Reactor jh Accident Consequences, WASH-1400 (NUPE-75/014), U. S.
Nuclear Pegulatory Commission, Octcber 1975. ! jj i ( *-
- 3. Wall, I. B. , S. S. Yaniv, R. M. Blond, P. E. M:Grath, H. W. iII
, i;E Church, and J. R. Wayland, CVerview of the Psaetor Safety i,:
Study Consequence Model, U.S. Nuclear Jegulatory Corr.lssion, e1.
NUPE -0340 (1977).
- 4. Protection of the Thvroid Gland in the Event of Releases of Radiciodine, NCEP Te;crt No. 55, National Council on Fadia- .
tion Protection and Measurements, August 1977. !R ,
i-
- 5. Manual of Protective Action Guides and Protective Actions k For Nuclear Incidents, EPA-520/1-75-001, Septemoer 1975, i .E U.S. Environmental Protection ;sency.
!Q .
- 6. "Fepert to the Arerican Physical Society by the Study Group on Light-Water Teactor Safety," Review of Modern Physics, 47, 1975. ,~
- 7. Jan Beyea, Some Icrc-Term Consequences of Ev:othetical Major Paleases of Radioactivity to tne Atrosecere frcm Three Mlle '
Island, Draft Te;crt to tne President's Council on Envircr>- ~
mental Quality, Center for Enercy ard Environmental Studies, Princeton University, September 1979. -
- 8. Aldrich, D. C. , P. E. M:Grath and N. C. Rasmussen, Examine- '
I s
tion of Offsite Radiological Emercenev Protective Measures *?
for Nuclear Peactor Accidents Involvihc Core Mit, SAC 76- .
0454, NUFIG/Chll31, Sandia National Iacoratories, Albuquerque, NM, June 1978.
- 9. Curd, John G. , et al, "Potassitn Icdide Sensitivity in Four
Patients with Bypocomplenentemic Vasculitis," Annals of _
Internal Medicine, December 1979, vol. 91, No. 6, pp. 853-857.
l 1
s ,
L- ,
L -
- y. .
. c 1
[ -10. . . Rosenstein, Beryl J. , et al. , " Iodide-Induced Hypothyroidism-. f-Without a Goiter in an Infant with Cystic Fibrosis," Journal.- +
q of Pediatrics, August 1978, Vol. 93, No. 2, pp 261-262. :.
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Conditional Probability of Exceeding Indicated Byroid ?l Figure 1. .-
l Doses for an Exposed Adulta Iccated Cutdoors. Prot-abilities are Conditional on Either a Gap A::tivity J '
Belease (GP) (lA), G2 without Isolation (1B), Core '.
Melt Melt ':hrough (lC), or Core Melt AtJos?.eric (lD)
Accident. ,
i "Ine cose for $h exposed child would be approxir.ately a factor of -
l 2 higher becaise of differences in thyroid :r. ass, breathing rate, .
fractional iodine uptake, ard ::etabolic rate [2] . ;
b n .
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+ _ . 4 1 . .
l[' Summary Table for KI Cost-Benefit Analysisa ,b' Table I. ,,
L: -Distance: Interval Cost-Benefit Ratio -
(kilometers) (miles) (US S/thvroid nodule prevented) 0-8 0-5~ 3'x 105 8-16 5-10 4 x 105 16-40 10-25 7 x 105 40-80. 25-50 2 x 106 80-160 50 100 6 x 106 2 x 10 7 160-240' 100-150 ,
240-320 150-200 4 x 107 aKey Assts:ptions
- 1. '99% effective KI (i.e., all persons take drug before clotx5 passes) .
- 2. -No other protective measures are taken.
- 3. 9 515-1400 accident probabilities.
- . 4. Estimated cost of KI progra.m = S0.10 per person per year.
Asstred cost incitdes only the purchase price of KI, i.e.,
no costs for distribution, monitoring and administrative expenses.
l- 5. Only I reactor (3200 MRt PWR) within 200 miles. *
- 6. WSE--1400 dese-effects coefficients (no 0.1 effectiveness ~
factor for I-131 dose).
btfacertainties are large ard scale approx 2r.ately linearly with assmed KI effectiveness, accident probabilities, cost, multiple reactors, ard dese-effects coefficients.
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.. EXAMINATION OF THE USE OF.F.OTASSIUM [0DILE (KD .. .4 5..? M. ,M.. ,$f$.u , ..y. i .:* . ~~
p:
- 9. p,.m1:,4-.;G.5 M.w.9...M.
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- k . .AS AN EERCENCY . PROTECTIyEf...EASURE F,0R cNUCLEAfLi....,. . c.
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Unlimited Release -
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.N EXAMINATION OF THE'USE OF'P'OTASSIUM IODIDE (KI) AS AN g _'5
.g:
EMERGENCY PROTECTIVE MEASURE FOR NUCLEAR REACTOR ACCIDENTS . s David C. Aldrich .
Sandia National Laboratories 'm 4 '
Albuquerque, New Mexico B7185 Roger M. Blend U.S. Nuclear. Rec.ula:O rv. Commission Washington, CC 20555 Date Publisned: March 1980 .
Sandia National *abcrat: ries Albuquerque, New Mexico 37185 cperated by Sandia Corporation for the U.S. Cep=r: ment of Energy Prepared for of fice Of Nuclear Regula:Orf Research Probabilisti: Analysis Staff U.S. Nuclear Regula: cry Commission Washington, D.C. 20555 Under Memerandum of Understanding OOE 40-550-75 _
NR2 F'N No. A1042 ..
3i
._._______m_ . . _ _ _ _ _ . . . _ - _ _ _ . - _ _ _ _ _ _ - _ _ _ - _ _ _ _ - _ _ _ _ _ _ - _ _ _ _ . _ _ _ _ _ _ . - _ _ _ _ _ _ _ . - _ _ . - - _ _ _ . _ - J
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ABSTRACT - :.' ' D. , .
'n 7y
. Following the recent accident'at Three. Mile Island, there has been a resurgence 'of interest in the use of thyroid block- )..
V ]i sing -as an' emergency protective measure ' fo.r reactor accidents. ,c. -
<An analysis has been performed to provide guidance to policy-makers concerning the effectiveness's of potassium iodide -(KI) . ., .,
as a blocking agent in realistic accident. situations, the dis- .;.
tanca to which (or area within which) it should be distributed, . ... k and its relative effectiveness compared to other-available -
T protective measures.- _,
.. 2,
^.
The analysis was performed using the Reactor Safety Study , f
.(WASH-1400). consequence model. Four categories of accidents ~
were. addressed: gap activity release accident (GAP), GAP '
without containment isolation, core melt with a melt-through release (Melt-Through), and' core melt with an atmospheric release (Atmospheri:). Thyroid dese calculati:ns show that the GAP catec.o..r does not e.cse a si.e.nifican: health hazard to the publi: at any distance fr:m the reac:::. F: the GAP
.without containment isciation and. Melt-Through categories,- -
coses .n
- 4 excess of recommended protective action gu.4cance levels (PAGs) (5-25 rem) are confined to areas within approx-imatelv 10 ~ and -15 miles of the reae::::r, resr.ectivel'v. , For .
the At.5cspheric categcry, however, thyroid doses are likely to exceed PAGs cut to 100's of miles.
o A' cost-benefit analysis for the use of K: was also per-f:rmed. C s:-benefit ratics (S/ thyroid nodule preven:ed) are given assuming that no other prote: ive =easures are taken.
Uncertainties due :: health effects parameters, accident pr==-
abilities and ces:s are assessed.- The effects en predi::ed retics of ether potential protective measures, such as evacu-ntion and sheltering,'are addressed. The impac: On cnildren (criti a1 population) is also evaluated. The estimated ces:-
cenefi: ra:ics are high, and i appears tha: the distrihuti n of KI is eniv. mar.inally cost-effective, at best. .
Finally, using statistics provided in NCRP Reper: No. 55, a simple risk ':enefi: analysis shewed the risk of adverse re-action posed by K! at the recommended action levelsEcwever, and desages to be small compared to its potential benefits. several recen: repor s suggest that adverse reaction rates for some segments of the pcpulatien may be higher than these e :imated -
by the NCRP. _
5-6
a., . ... _ . . . . .. . . - . - . . -.. - .
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4.-
o l
5 N
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- l -
CONTENTS lt a.
". 4. '-
Page
- E Figures ..............................~........ 8 Tables .................'...................... '9 4
o Acknowledgements ............................. 11-12 Prologue ..................................... 13
- 1. Introduction ................................. 15
~
18
- 2. KI as a Protective Mease e .......'.. .........
- 3. Accident aelease: Considered . . . . . . . . . . . . . . . . . 22
- 4. Thyroid Dose and Health Effects 25 Calculations ..............................
- Thyroid Dese ............................... 29
- Thyroid Dose Calculations . . . . . . . . . . . . . . . . .. . 29 39
- 5. Other Protective Measures ....................
Cost-3enefit Analysis ........................ 42 6.
- Costs ......................................
- Fotential Impac: Of the Accidents . . . . . . . . . . 46
- Potential Reduction in Thyroid Nedules . . . . . 46
- Accident P:ccacilities . . . . . . . . . . . . . . . . . . . . . 51 Cost-Benefit Ratic ......................... 53 1:
I~
Sensitivities .............................. 54 l
Risk-Besefi: Analysis ........................ 59 7.
Summary, Conclusicas and Recc. emendations ..... 61
, B.
~.
References . ................................. 6 7 _.
I
? 9
___________m_m___.- . _ - _ _ _ _ _ _ _ _ . _ _ _ _ . _ _ _ _ _______ _ _ _ _ _ _ _ _ _ _ _ _ _ ______._.______m___ _ ___._._._____. __ n -
= -_n t . 6
. g U
a
( -l , .
. g. -
.s Figures . iet Ib a Pace : s :i -
No.
u
~
~t 1 Percent of Thyroid 31ccking Afforded by 100 mg of Stable Iodine as a Function of Time (in hours) of Administration Before or After 19 a 1 pCi Slug Intake of I-131. c.
, t 4
2 Conditional Probability of Exceeding Thyroid Doses of 0.01 and 0.2 rem versus Distance for an Exposed Adult Located Outdcors. Probabili-ties are Conditional on a Gap Activity Eelease - 36 accident.
3 Conditional Probability of Exceeding Thyroid Deses of 1, 5, 10 and 25 rem for an Exposed Adcit Located Outdoors. Probabilities are 37 Conditional en a GAP w/o Isolaticn Accident. .
4 Conditional Probability.of Exceeding Thyroid Doses of 1, 5, 13 and 25 rem f:: an Exposed
~
Adult Located Outdoo:s. Probabilities Melt-Through are Conditional on a Core Mel 35 Acciden:.
5 Conditional P::bability of Ix:eeding Thyroid Doses of 1, 10 and 25 rem for an Expcsed -
-.a,a. ,,
n ... .
. . c ., ,. ,. ;
.u m.... . . -. .:cn,. 2....- -...
a t .. - . .
Conditional on a C re Mel: At=cspheri: 40 A: ident.
8 . - - - - - . -- - - - - - - - - . . . - - . - .
h.mm_m--_____ --____mm_ _ _ _ - _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ . _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ . _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _________.________.________d
, , ,s l
f, Tables ; .! ~
a ayt -
e Pace : >-
do . : - ".
1 Summarv. of Release Categories Representing 1" Hypothetical Nuclear Reactor Accidents (f:om Ref. 1). ,
23 2 RSS Calculation of Expected Cases per Million Person-Rem of Benign and Cancerous Thyroid Nodules (from Ref. 1).
- 28 3 Mean Thyroid Dote (rem) versus Distance for Exc.osed Adult L0cM ed Outdcors. The mean thyroid dose for a child would be approxi-matel.v a factor of 2 hic.her. 31 4 Conditional Probability of Thyroid Damage versus Distance for Expossd Adult Located Outdoors. Probabilities are conditional o n t.". e a - .. - d d. e .". *. o c .- "..." * .i .3 "~. P .- o ". .= ." .' '. .# '. . der .
wo.,- ... e..
w, ., r- r o ., 4 ., a . a. '. .v . . . .
=
. ." . . 4 .". .: e .
for a enild. 32
= z... ..e.2v...,,. . e . ,.. : . ... r .a.. ..e .r. v. e a .. . .w.
... y . , 4 2 s ., e for Exposed Individual Located Outdoors. 34 ea
- e.,
an. .a/
. o,. . ..
4.n. w
. .:: . . .. .; .. .. a ,. .,. ,e . . v. .. . .... e..
of "hyroid Nodules Witnin Selected Distance
.a.. .. y,.,e. . p. ,. . . 4 .s . -.- . , r- r. , u 3. ....4 - . .ee.c.4.y ... .. . .e 100 persens/ mile'. is assumed.- Risk
- . .., ......a. : - c., ....
- .. ~.e6 a w o e .e .a .a . 4..e . . . .. ...: . . . .
4-
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e ..? M ,. E ..
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2 form toculation
- densitv of .,.. 100 rersons/
- mile 4s a,s..;e.. . .~
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.' nodulet per l'o persen-re to thyrcid. 49 80 w*
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- s. .V O.
geni .,,4 my e .m , e yegw_
m e e e e,s ppha, y -ggggsy p p ga spap a e.P.-..,-enem m & *M. wse p age mas G-.e m__ m__-______s_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . . _ _ _ _ . _ _______._________.m_ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ __ _ _ _ _ _ _ _ _ _ . _ _ _ _ _ _ . . _ _ _ _ _ _ _______________m. _ _ . _ ___ __-______.__m _____m_ _ _ _ _
A-
. 1 ;
. 2.".
~
. -4 l'de Tables (cont'd)~ -> '$**) - '
No. Pace
- 8~ Potential Reduction'per Year of. Reactor 4 Operation in Mean Mumber oflThryoid Nodules by Use of KI. 99%. effective KI is assumed.
RSS probabilities are assumed'. 52 -
'9 Estimated Cost-Benefit.LRatios for Use of KI
' (S per nodule prevented). -99% effective KI is assumed. RSS probabilities are assumed.- 55
-10 - Cost-Senefit Analysisi for- Use of KI by .
~
Children. Assumptions: risk coefficient =
. 668 thyroid noduelssper 10 person-rem to ~
thyroid, no'O.1 dose effectiveness factor for I-131, Core Melt Atmospheric accident catescry only, RSS accident probabilities. 5E 11 Cest-Benefit Analysis for Use of KI by.
Children. Assu=p: ions: APS cpper-bocnd risk coefficient.fo; chil.dren.cf 5500 thy-roid nodules per.10 person-rem to thyroid, no 0.1 dose effectiveness fae ce for I-131, Core Melt Atmospheric accident category only, RS5 accident probabilities. .
58
c c= mary Table for K: Ces:-Seneft: Analysis (frcm Ta=le 9). 63 O
e 4
10
~ ... . . . - - . - - .- .. .- - . - . . . . . . - . - - . - - - . . - - . - - - - - - - -
- - a__m m _ . -_ - -m_m_-__.__m___ __ --___mm..___ma_ ____._..___mm_ _u__u -__i__._a__.___ u__,_______w_ _ - * - _ ______u_____m____________ _ _ _ _ _ . _ _ _ _ _ _ . . _ _ _ _ . _ . _ . _ _ _ _ -_ _____ - _ _ . _ _ _
,, l 1.
9 .
! 4 ii '.. .-
'i 3 ,
4
..A . s sj .
.-3 '
. .- ACKNOWLEDGEMENTS -
j ",
4 *
,i .- The authors are indebted to their colleagues, D. M.
Ericson, N. C. Finley, J. D. Johnson, J. M. Taylor (Sandia),
.' ~
B. K. Grimes, J. A. Martin (NRC) and B. Shleien (FDA), fc,
.g their many helpful discussions and suggestions.
J' s
e I
e 4
4
-e.
8 .
1 1-! *,
___-________m_ _ _ _ - _ _ _ _ - .-______-__.--_-____----__w
m__ _. .. .y
. .- ..__. .r.____ - --._ -
,. {
i- .'
. dl J 1 4 ' . . . 6 =
~' 'O n
.: l E4
,4 Hc . - ..
- ) -
I
!, l
. , , . /- -
4-
~ 2 .
PROLOGUE id
,t -.
?
a r. ~:
- I
- ,
s, . . ..1, During the'first few' critical days of the. accident at Three t, s .e Mile Island, many spontaneous decisions were made concerning ,
P offsite emerc.ency orotective measures. . .
The sense'of the, moment , .
dictated action. Plans were conceived and isolemented with -
4 little or no time available to determine the potential-benefits .
c.
and.cests associated with alternatives. Specific plans were .
developed to evacuate the population within 20. miles of the re-actor; the Governor.crdered a five mile precautionary evacuation of pregnant-women and small children; and Potassium-Iodide medi-catien-(KI) was manufactured and shipped to the area for possible
.distributi n.
l To provide an adequate planning basis for potential future accidents o it is necessarv. to determine hew frec.uen:1v thev wecid . .
1 occur; to estimate their anticipated impa::s en the surrounding
.occ. ula tio n ; and to evaluate -he potential benefits Of alternative protec:ive measures. Several studies have focused en these imper-tant questiens.1,2,3 - :t is also i=portant to estima:e the ecs:s associated with varicus protective seasure strategies. ~4ith this information (i.e., o.r:bability . of accident ec=urrence; i::a : en .
1 l
public; benefit of various protective seasures; and associated ces:s), a rational basis would be available :: make planning decisions.
It is the intent of this reper: to focur en one emergency ,
protective measure (?ctassium I0dide) and present information n
--e.~..--.-.- . - . . -
-..,*-gemen- -o-me==*w--
-- ** ew.w e ew - +e e
- - ' - - - - - . - - . . _ . _ _ _ _ _ _ __ ' ~ ~ ' ^ ' ' ' - ~ -- - - - - - _ , , _ _ _ _ _ , , _ _ _ , , _ _ , _ , _ __ _ _ _
' 7-~ --
- f. ,
4
. . f j
needed to make a decision concerning a program for its use. g
~
There'are many uncertainties associated.with the information, ' ' .1 :
s {
methods, and techniques which are used in this analysis. As ,.
our knowledge and experience e::pands, the results and conclu-sions of this type of s'tudy shoulc be reevaluated and, if necessary, changes should be madel to the emergency planning strategy.
e f
i 9
0 e.
m .
..- f
+
v'-t r i
/ -
l - 1 i 1. Introduction ;
i
..wf j .- Potential acc4. dents at nuclear reactors, however unlikely, I. '
t l
< i 4 . could result in substantial offsite radiation expcsures, and I i ..
- 1 pose a serious threat to the health and safety of the surround- '
ing public. If an accident were sufficientiv severe, the re-4 sulting radiological consequences could include immediate deaths and injuries, delayed cancer deaths, thyroid nodules, and icng-term contamination of land and property.1 Any immediate effects, even for the worst accidents, would probacly be confined to areas relatively close to the reactor (a few tens of miles), and could be significantly reduced by implementing immediate protective mea-sures. Eowever, cancer deaths and thyroid ncdules : ulf Occur ever mucn larger distances (100's cf miles) and would therefere te less af fected by immediate protective measures taken near the site. -
..u.,. . a..,..r . o . . e . u.y
. . t a. ..
n:
- w. ,x cse'. .... ' '. ' v '. . .'"
.= ,~' .~. ~ _c c. '_ ""
potential ac:idents is especially great for several reasons:
~
- Radica::ive ise:: pes of icdine are produced in abundance e .. . . c , , ,.
w
.y . ..e
... .4 ,. .. ... . ___
_ .-ga,,
. . . .< . g .a ..,. . ... y c u..= _c = . - = . . . o . ...a .' ~..'.'.c_
.'. v.. y.1..'.'=.>.
. .s. e.... , s - . ,. , .
, z..,...,,
.... z. . ,n. .. 4.n -:v.- .. . ,. .,a.. .c.4 ~aa.n ,. a.../ ,. . . .
tories eculd be available for release to the a:mesphers.
... ., , ,. c: : ., .. ... ..,.... .. . 2. 2 4
. , . . . .,, _..e .m.4 _r; . ..-..e;
...e w.7ccce.
- w . . ., . . ,'* A .. n C a. .r.. .. .. . . e - . ,. . ,. .. ., .. .4. ... . .* o;
- 4. ..,.
I
.. th.vr c i d .
g
. wC . I.t g
. ag.. g...t...t.h . . . =
.g
. . ..Pe a.. ...b.. g.. ..9[.,..n s
- g e .. .g . .
g
.p . *g . a...j g...
- e7 .*..e, .. n..
. .. .*.g.mg*
5
' . g .i .f _ *.58g. .
!5
~ - " _ _ - . __ . _ ,
.< 2 . . _
9 2 I
L f- .
,/
7b a result, the radiation dose to the thyroid is likely to f ar- ,,1 i il 1
1 exceed the dose to the rest of the body, and thyroid damage is t.
~ -
p.
t 'likely to affect more individuals than any other accident-induced '
. ~
~
> health effect.1,3 Taken in large enough quantities, potassium
- I
' iodide (KI) acts to block the absorption of radiciodines by the 4
' For'this reason, KI has
',' thyroid, reducing.the thyroid dose.
been' discussed for many years as a potential protective measure for'ase in the event of a serious reactor accident.4*
^
l The availability of KI would provide a supplemental strategy to he considered along with other possible protective measures.
Ecwever, KI shculd not be considered a panacea for reactor acci-dents.
Altheegh its effective use could significantly reduce the it would {
nu=cer of thyroid nodules resulting frem an accident, .
have no i=pe et en long-term land contamination er immediate health I effects, and eniv a sederate isoact en delaved cancer deaths. f the only protective actien that wi.11 reduce Use of K! is also no:
its difficulties and preclems:
thyre.d dese, nor is it withcut
- The drug is net ecepletely d risk free; adverse' reacticns are possicle.
to society; .
- Making KI available would involve a cost
. dollars that perhaps could be used to reduce risk more ,
I
' ef f ectively elsewhere. )
?
- Potass m 10date, a drug similar to KI, has been distributed Britain.3 A for use within a few miles Of reactors in Greatrecommends 3 planning recen analysis by Seyea and von Hippe1 U.S., en the for the use of KI ever muen larger distances in :ne Order of 100 cr mere miles frem all reae:crs.
16
- - - . . _ . . _ . . *** # - m ess aem,,,
- - - - . - - - - - _ . _ _ - . - - - . - - - - . _ - - - - . - - - - - - - _ - - .--,-,----_,a--_- - ,------ - - _ - - - - - - - - - - - - - - - - - - - . - - - - - - - - - - - - _ - - - - - - - - - - - - - .- --~~u' - , - - - - , - - _ - - - - - - - - - , _ , i
1 .
% 3
\
I
.. .. .'L 7
- There are seri,ous. storage and distribution logistical ,
problems associated with ensuring that the public would d((
receive the drug in sufficient time to be effective.
- - It must be assured that any KI distribution strategy
- implemented would not reduce the effectiveness of other protective actions taken, e.g. , if people are required to receive KI at a distribution center, they may be
" c aug h t" by the cloud while outdoors, and receive a higher dese than if they had stayed at home.
A timely decisien on the potassium iodide issue is required of responsible coliev. makers. .
This report summarizes a studv.
. .+,. t.e-,.
n...e;- .. -,ya, t 4. ,..a g .a... .... ., . u. n. . .i .., , -u.t.gg. ..- e .. . - . .---.
re .. .- . -- . :
.. .i .e ... :
- n. . g e ;- r.y
, .n
.y
-- .cy.a. z
-e ...g.z
. ..c.e...,
. . .., ,. .-n. . e-. v,.-
s ness of K- in potential accident situatione, (2) t o. he le. determin
,. a.m o=. K, ,s a. ..e ..e e .y. -. . ,r. . , . .e . . :. ...., n r- ...n.. a.., i,)
- s. .. c e =. .-- . e. -
... e . ... .
2
,2.., .u.e y.7n 6.,,.:.. -a s .- . . . , . 24
- . .e .. g n - ., .-
g ..u .: u. . :.-. g .- ,. ,. y .a. ..u. .: . .
..m. .. . . . . - . .
a .= . ... a. n G. . .A
..~g. g s.
-a s c ,-,1- - 2 A 3 5-u- .a.- ~ .t e.c-
.un. n) 2. . --
. .e . e - .4 - , .s .e
~ A ( n* >s . . .
s .a. .n ..a--. sA
$ a. ...c. *. a. . m -.. e .
" a
.Cnpt.to ... . s .t. . -e.u. -m L, - .: e .t . r *. a. . g. ..-a A . .
.4- e g w e .. o. .r .. d* .e e-e -'e ve -u..n. -a a o. . #.-- e. ..a. #- se a-. .. o#. . .a. .is .: .". #- v. .
. .s . .m'v_ g -.
..s.:.-..s.. s-~
s s . ,.. . :. . .c ..w ....a.., s --
e.,e. -- s e , e. n.w.n u. -sg a.ys- ~A
..u.e ,. ..a .a.n. 4..a.
-e .
- g. . ... ..a.
see2ee.A se
- e .1 '. . : e e. .l .# .3 .- -mi. - . a . 7. a . . v a .: . . - s*
. =. : ..' .m s u.. e . *. m . .J . :. , a .- a.
. - - c- -- -y
. .~ a
.s - w.a... .~ et w .. . .. .,
.;e-
---.s.----, ee.e
.. s.ocxy..,.4 4
. , 44s....L. 4u,.4.n: .
mc.t sA see--
.s.
,. *. . .n.. o ,a n .u. .+,.
youi A- - u.a a---c e a .e...-- . a s' .. . e n. A. .-- . n o. -- ---
. effectiveness before making K available.
The analysis re,c:ted nere was .:erformed using -he Reacr;: ,
, l
". Safetv. Studv. (RSS) consec.uence model,' CRAC, for a range Of pcte.-
.;. s...s.
w - . g .e.... e . r e g.e . .3
. .;-c. e .-.s.-e m .e
. s- . . .e. s. e. .-
.a
. - s . a. s e c e s
.. - - c. \
..a. .:..C...
. = .~. . l l
l
)
17 I
)
g' . _ . - - - - - -
-w ,
<At..
- % l t ,,
c . . . .,. ..
z ,sx- -
l cxamined; from fuel pin gap activity release accidents to com- ye L . :r' plete core meltdowns with containment failure directly to the '--
l
. .. F %
stmosphere. It is important to note that6 there is a great deal i s
of uncertainty in our knowledge of these releases and their .
probabilities, as well as dose-health effect s relationships for the thyroid. In some cases, these uncertainties hinder our ability to crovide . definitive guidance. 'owever r d they are l
l addressed to the extent .cossible in our anal.vsis.
- 2. KI as a Protective Measure Inhaled or inc.ested iodine is rac.idiv. and almost comc.letelv .
..u
, e,
..e - .a . . o . . , . . o c a... ,,
. . ... . c..... ,,,
... - ene .u...- - ..u.,. 4 - e a.
. - .-- .. =
concen: rates in the thyroid where it has a biological half-life of a Oroximatel.v 120 da.vs. ..
The absorption of radiciodines by the d
- ..k.v . o .' ' ' = ,- . =. .= . ' .v - -a. d u c a. d.
. - . ' . ' -'od" ' ' " . " " . . = _= e s a *. . ." _= . e d w..'
a a .... .a .i ,. 4..- d .4 . . =. .... '- -- ~3
- -- a. x re s ". . =. . ' '. .'. e " ..' a. c k. .' . . , e '. .' =. c . ' ". a. . a. s a- . . -.
.... g .e. ,. .s g.a e .ag a .
e- .. eu.. .z . .r i , . . ,.
s a < ... - a..e.z
. . w. .... , . .4...,.
u,em .4 . 4..... .. 4. . e. . .
e..s . =. . a
. .e."or. *.> - =x: .. s".=.,
. ..' . e ...a , o . ' .v .
.. ,e4. 3 .--w2 4 .e ...r.. , . q. , y
. .. ..,. ... . ...-i2:.+ e- .. ~.4.. . .4.. . ., _. , ,. . .. o u, a. ,
3.e .. . . .. , . 4 . 4. ..4..
. -. 34...4
. .. ._... ......u 4-- .
< , . .---3 eg .e ..e, _,
c, e . ..
4 ..
. e.._,
v 1 .' . ..' a. v a _' "_ e -a. vo .u: ,
.".a.
. '.4.- e. e.s s e .a. . .da .' _' ,v
. -.._'a.*.=
. r . .-"..._=_'_'-
..e . . ( 0. 0 % . . - ., *. .= *. a. . ' o .# . .= d. .' a.-i r d 4 ..e " r t .= k e "v. '. .". e '. .'. v. . w .' d -
requires that stacle iodine be administered sner:17 cefore or
.d~.- .,e - d d. .= . =. .' v. . = . ' . = . . - ' . . ' . =4...4.4.=~..d
. . r. #. a.xe ce".e.
-- r'. b' - ek #. .0
.Cercen: or more is attainable only during the first few hours after expcsure.
1$
- w. ~ - - . - - - - - - - - - - , - - - - - - - - - - - - - - - - - - - - - - - -- .__. - - - --
g.. - . , -
p: '
a
- j '-
4-
. 4 1
t i .i ,;*
,. 4-
. e. s..
G
- , . e '.
- ' '-
- t . ,
1 s ..
a ..
,j:..
TCDL l*1 g - l0l
- s
-l 30-',2
\ s .,
70 - [t
\\ $, ^,)o
. \ 60 - ?
,. \ .
sg- ~
r
.i t* \
. si s p 40-
\ f ,, sg.
$ \\\ ..
\ ' to- [,
10-
-+0 -10 -20 -70 0 10 29 la +a Figure 1. ?ercent of ~'hyroid Elecking Afforded by 100 mg of Stable :cdine as a Functien of Tin-e (in hcurs) of Administration Eef:re er After a 1 +;ci 51:g Intake of :-131.
Ref: Radicaccite Icdine in the Preblem of Radia :en Safety (USSR) (19 72) , USAIC Translatsen Ser:.es, AEC-tr-7536. Available from NTIS , US Cepart-ment of Cer::.e ce , Springfield, VA 22151.
9 4
e 19
_ - - - _ - - __-----___---.._-_--.1----.-_____ - - . - - . _ _ - - - - - _ . - -
- W o I, r
a .
l
.4
..i.
. /
- t 3... - l us Several chemical compounds of stable iodine are suitable i- j
~.
as blocking agents, including potassium iodide (KI) and potas- .'.
1..
\
slum iodate.* The Food and. Drug Administration (FDA) has ,
recommended and approved oral administration ' of potassium iodide .
(KI) in dosages of 130 mg (tablet or liquid form) as a blocking agent.4,6 Continued administrate.on of this daily dose appears 1 to maintain an essentia11v. complete block. A minimum of three and to seven days administration would probably be required, i
use of the drug is not expected to exceed 10 days.6 .
i There is presently no definitive guidance concerning when, or under hat conditions, KI should be used as a blocking agent.
'+- " s u> ' . ' ~.'..e f.o-
.e .,..,...e.ee *"c-*. .i . ",e c o ...
. . ; d a. .- =. d. ... .
... y.c
. w. . . . . . - - . . .
jected thyroid dose =* o an individual in the general public exceeds 10 rem.4 Protective Action Guides (PAGs) p,romulgated n'
.# a.. - y r o";e r. .**. ' " v. .e -- .i d. . doce .a.. ; e '..m.
. . '. .*. . .-a.m.
b.v . w.. a. r :. .A e
.e..ez.. a; .s .. . ..u. a. 1. .. w e . a.. .. =. *. .z..
2.. o . e- .w.. . < V a. an.:..on .s 2
.a.
. .m m r y--. e c. . = .. . wc .a c n , .
.-*...'.'-.a...'o, i '
.. .. .*'.e - =.
7 o o, "..' = . # m. n e-a e . . = .' . 3 7 =. .
3 - r..- , y .2 2 4 ... .- ....4-..
. . ... .= . . .."a . . a. v a. .' .
a . n, ..oc.,.
. . 3 n. e. . . . i + ......... .
-4 .........; 4 ,,,
... ....,ees .e s. ...
. o ........
. . , . 2 .. . ., . . a.o.s ..
..o,..2
-e ..........
Eowever, only evacuati:n jected d:se exceeds the higher value.
- m . a d . .' o c. ' .= '.. . =.ce-.ea...v.
. . - ' .. *- .... = '. a. - = . . = ~.. 3 '. *. .= .3. ... .'n .'ude ..".v. . o. ' ' -
c since in -he olocking using 100 mg tablets .e..
u ,. .,
of. ..otassium
.s ; c ,sc. . .e z...ieda:e, c ., .
.. , .z .a ,. ,, ,..,n. a ., ..,
B ,. I >.. -<. ., u .xce
- a. ,. . -n e , . e . . . .... ..
longer than that of icdide :aclets. The iodate form could be
.^.w.'.i.=...=.
r w ' . *. 7. " e'. .-*."."s.i.-=.-a.....=
e.ao.1
- v. a. d. '..n '.k. e U . c~ . ^ 7. .' v. " v.
tnat include gathering :ne ,ertinent :linical data for the iodate.
'-c* ..".a . w ~ ~. .' '. 'e
- e##.'.*...=.=. ~.' .v.. .. ~ ' '. ' s e 's .+e =.c'..'-a.=^
received wi:nin a f ew days f o' lowing :ne release if no .::::ec-
...4 .J e . . 2...
A.g
'*'*'~ ~ ~'
===e**- * * - " * * - * * * " * ' " " " * * * ~ ' * * - ~ * ' ~ *' '
....==-euar
< :. a F
,.4 .
~~
g w *' -
~and controlled area access were discussed in the EPA document,' :
and the use of KI was not specifically' cited as an appropriate l'
,, protective measure.
1
]i -
_There is~ considerable experience'with the use of KI as a therapeutic drua. 4 It has been used for a number,of years in .6 high doses,-and on a long-term basis, for the treatment of vari-
{
4i ous pulmonary disorders. The reported incidence of adverse
.[ reactions to the drug is low, and the risk posed-by the short-
] i term use of the relatively low doses that would be involved with l
response to an accident is judged to be minimal. The 'ICRP 4 estimates'the adverse reaction rate to be between 1 x 10~7 and 1 x 10-5 per.dese, and cencludes that the ad= ministration ef K would not result in significant immediate side effects, even if given to large segments cf the pcpulaticn.*
Because the prcmpt administration of K! in the event Of an accident is critical to its effectiveness as a protective mea-sure, seme methed of rapid distribution to the public is required.
There is little curren: definitive planning for such methods.
Stockpiling supplies of K: in " distribution centers" suen as schools, pelice stations, or firehouses has heen recccmended.'
An alternative would ce.to provide each household with a suffi-cient supply for all members of the household. The feasibility and effectiveness of these and other alternative strategies, as 9
. well as their likely implementation costs, should be investigated.
e
" Note :nat wtrning would be given cautiening agains: the use cf K: by individuals who are sensitive to iodine.
21 t__.______ __m.____ . _ _ _ _ _ _ _ _ . _ _ _ . . _ _ _ _ _ _ . _ . _ _ _ . _ _ _ _ . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . __ _________________.__ _ __ _ _ _ _ _ _
b .
J. . . .
a o ..
- jj . 3. Accident Releases Considered q
\
, d.
r a Release magnitudes for potential accidents of offsite *
- :~
l]s significance' range..from relatively small releases of gap ,
6 q 4 ,'.
- I l
activity to the large releases predicted for full core-melt accidents in which the containment f ails directly to the atmos-1 #
phere.* The RSS grouped.this spectrum of reactor accidents ,
] into nine release categories for pressurized water reactors (P'JR)
I'i.- with large dry containments and five for boiling water reactors j-(BWR) with_ Mark I containment. These categories are presented
- s
! in Tableil along with their estimated probabilities of occurrence, release magnitudes, .and other parameters that characterize the j . release. It shculd be noted that, because cf the lack cf complete understanding of the physical processes asscciated with core-melting and the resulting release of radioactive material to the environment, there is.a large degree cf uncertain:y and overlap in these grcupings. There is also a significan: uncertain y associated with their estimated probabilities,I a point which will be discussed later in inis report.
I "A-lar:e ligh: water pcwer reactor typically centains about 13 oillion curies of radioactive material. The spectrum of pc:en .
tial accidents addressed in this study would release frem 10-'
(1000 curies) to about one half (5 billion curies) of this radio- I active ma:erial directly to the a:mesphere.
da's
1 , :'
s . i M
Mm.
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=
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a e
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w w. _ tr nese rte rtx l
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dp nohe ,
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'w. 4.. 'w. nw ..
N~
a.-
- . s ..
.u .
c mi e at rml rc'
,ot ,
b f
- l aeiau , .
a " e tticys .
c . hea rcgu .
i
~ e * ' . .
4 thmdeorh t
e . w w "* w .
.w. t et et h
.uuu.*..-
f oovcioe, et atn i r
t ti e n d o .- n tje en p .
oecovsha y - ".. ....a*w.w .
..u.. . w ". -
i i rariet l
f " .- . . .
t uopto s g .~
.! . . ati cdde i cdea t u a h o 'g a i ns n
i u i rrti n .r t . . .. nt die n '.. ' "u . .. . . . .. .w.ww.aw
. w".4 ..
i shsat se e .
. ...e . . . . - ..... .
. . cirl am s ........* ..... .
eti eeu e ..
hnhnf ml l r . t ewoo ep p . . .
. m l er e* . nngl er e uu.www ... . .
uu t
ei n a s o f h I ) .
1 . . = .
. a. .
e ai n a c o t s .
wt rce
- e. ..-
. , l nial hth t i f ..
. .- eodvechc re . .
. hc e r i gi oI t
~., . . . ., ,. ., . . .
e hih emrewew g .
.. .... a
. l em ...
n
. ahioh h t o . .
. .. . vttf t n o ar . . ,
. r iet cf( . . .
emt ed
. . . h
. t oomnst t e .
n........ n.nn. n nr at n ,h
. . i ss .
i fdt g at .
. . o t e yi en .
el i gl dl e l e marneil h ed .
.. .. . i i eimca Hi c
. . u . . . .," .,. . .
o .. u ,..
. w.. . ... . t rt'n cne e reaih f c
. et ear 'l t oA .
.. .. . .. hahwoe
... cs yr ro . .
~. n. a.
4 - mt e o .ec
.uu...... . . ....
u uu ... .
. seshyhen n
at . . .. ...
. ... . . i viTit mee mc .
.. . . i i i ut ma ..
... n.
. . . ~. .. n.
et e .
drtl i ue ...
scs .no f s SH .....
..u. .
u..u. .....
.. u
... .. aaaee'l gn
.....w.... ...
n o . .
. . . eoerp nie li l em i h
.- . . . edehi . net grm rarp 1 . .
r
- n. me. .. '. w . w w st naur 4..w- 4.. .. .w . - .
e 4. ~.. .
l 4 4.
f of om f ooiwl a pe d
b ......... ..... . . . .... . .. o l s l,h n a .. e
. - n a si e d T .. ...
meo eut es i sienbcun
.u .. .
.. t ath e eao
..z..m-
. . eat rtjes
.. ... el r r h e u o .a .ereenol Trdt mml o t p B
s.t o
- i i j . .l,1 > 2) ;i - :6 j ie l;lg; i
.ij. .. .j . l ; I:i .i}!!
,l' >!;;,l!ll!Ill i'i i!.llllllll!lIl ,lt.tl li>l;l;l;l.' ik
' ~' _ _ _ _ _ _ _ -- - - - -
1 A
g j . l o .
(- l
. . . I, r
L
- t.*
For the purpose of this study, the PWR accident release a17 !
1 i spectrum has been. grouped into 4 categories:* -
IJ Y ..
Y RSS Release -
Catecories .
- 1. Gap Activity Release Accident ,(G).P) PWR9 ,
- 2. Gap Activity Release Accident without Containment Isolation (GAP w/o Isolation) FWR8
- 3. Core Melt with Melt-Through Release (Core Melt Melt-Through) FWR6-7
] 4. Core Melt with Atmospheric Release PWR1-5 (Core Melt Atmospheric) 0
. WR"s . =. - .- a. .e e.. . * * ,a ,. = c . '3< . .v .
. .= . =. = = e a . . .' d. a. . . . 4 .s w". 8 c.. c r..' ;"
."e.
ac.d. v .i .v. i.n .i . .' a ' .' v. - .. .. . .= .' .J. e #- '.4..*..i..
. - . ..".e c. a .' e "- e a. n ..h. a. .
fuel pellet and cladding would be released into the containment.
.'". . . e . d n .c -
n' _' .' e .. 3- .' . e a. ..= 4 o a c. e. ". a . .'s c . a. a s - "-. a. .# -- --
re . .' v. .
- we..e '= ..". e
. . .. .c a...a. a s O. W'..c . , a. x . a. - - ~..'.a...".es-^w....=.'...=.... -=-.'s
.o
.a,.. , , ,y r. aeg: n- . ., .2 . . , ... ,,-
.... .... .eg .. - - . . . -n.. .u. e. ..., . , .a . , , . , ;....... ,.gze-
,"a . d=,
.i . . ^. .' ". d .' . :.-- n . = .' . . = . *. .c - - =. v s , a . a. aes". . .a.#
. o .' ". .n . *. .' e r.
. e.,.v. .
- gy.
. . .. .,,- . ..4,s .' .."..-u.".~i.>.-e
.=....a....a 4.. '"'.c.
... w c^.-=.
..a.'. . ' ,-
. =.e.="=.'.
. .. . c.". . . .S W'.6 =. .. ..'
~
.= . =. #...^ ...' .a . =. d. ".v .= .' .'e...
.d..v ..' vd... ,- .--n ..= .. e.n..
. e 3u C.. . e =
. ' = . ' . ' " . = . _"v --....='...e.2.
"- a .=. e ...a .
melt-through. PWR1-5, en the other hand, consis od accidents l
.< n w -n:. ..u. n. . n... . _: ...e.... ... . : , a . . . ... ,--i, g _e _e .- ..,. . .-
c...;:,c..,.o.,
, . me..r
. e - h e . =. _= _= a . a s "..' . ^e.# a. .d . .". e . ' ... a d. e _ u .= . a. - ~=^ ~ .' .= . .' o r.
4 ^
- .-n..=.'.- .
...e . . . - ^ re . . .i . . .e - .
e..e.-= -- .# - ns, - .==.. = - . - .. ve s .e e .' .c.=..=~.., ax-'re' r-----. n, -
s m. .h...C ee. 9 .. gen..
...g w ,e.. 3,,
we . . a..m y..w 4 .g.w, ; :. . u. .. C : C
..w .C
- ,',,c-
......C . .m..;w* ,- - . .' ,. e.
.- . y u. .a . . . .. g g ,., a,:a---..., --;
... ,,..u. w e. .: . .. . =. >. ... a..
..a .,g.,,..a,.
. . e g wu .4. ' .J.,.y
.gw,.
,e J *C-
.w .e.s..-.,.3.,4 .. . .e. e..u. .p .% = C .
I 1 L . . - - . . ....... . . . . . - - - - - - - - . - - - - - - - ~ - - - - - -
hn$lpA;&if .:nS5:O %r.r- a: e.n.J0: O
~
G,j --y;l a
N.- ; uAk, '
o 1
. t
. .. ,I ~
. . c
+
' i t
hydrogen burning, or overpressure.
To reduce the required time ;i ...
.4 e and cost of computation, BWR accidents have not' been considered. . 1 ; 2-specifically in this analysis. Ecwever, the information and
~
conclusions presented for large: dry containment PWRs should be roughly applicable to other PWR designs and for BWRs as well, given a similar type cf accident and mode of containment failure.*
'4. Thyroid Dose and Health Effects Calculations Dose to the thyroid is estimated as the sum of 1) external dose frem the passing cloud'(cicud exposure),' 2) external dose frem contaminated ground (ground exposure), 3) internal dese during.the first 30 days from all inhaled radionuclides except.
, I-131, and 4)-internal dose during the first 30 days from i'nhaled I-131. Thyroid dcse from ingestien via the grass-ccw-milk-man pathway and chronic exposure has not been included in this analysis because these pathways would not r'cuire e an'immediate emergency respense in the event of an accident.
" SWR 5 represents the SWR gap activity release accident. SWR 1-4 are accidents that involve core-melt. For the specific B'AR design investigated in the RSS, the probability of containment f ailure by containmen: vessel melt-througn is essentially :ere, i.e., the containment is assumed to alwavs . fail direc:1v. to :ne .
atmosphere. 3WR4 is dominated by accident sequences involving \
'~
e containment isola:icn failure in either the drywell or wetwell, whereas SWR 1-3 are dcminated by accidents in which the centain-ment fails frem either a steam explosion in the reactor vessel or containment, er frem overpressure resulting in release through the reactor building or directly to the atmosphere. Other con-tainment designs (e.g. , ?WR ice condenser, SWR Mark II or SWR Mark !!!) would have semewna: different precacilities fer the various containment failure medes.
,e sa
. __. . ..: . . - - - ~ . . . - ~ ~ ~ - ~ ~ ~ ~ ~ ~ - ~ ~ = ' * ~ ' " ~ ~ ~ ~ * * ~ ~ ~ ~ " " * * ' '
J. ;
E-i s
.,, 5 k
The dose ' received by a child's. thyroid is likely to be 3-
- 4. .R . 2, different than that received by an adult for several reasons, f'.
. including differences in thyroid mass, breathing rate, frac- _
tional iodine uptake, and metabolic rate. The RSS assumed age dese. factors
- of 1.0 for' children of age,s 0-1 years, 1.9 for
. ages 1-10 years, and 1.6'for ages 10-2h years. Somewhat higher' factors-(up to 5) have.been assumed in other studies.3,9' There is considerable uncertainty concerning the effects of radiation exposure on the thyroid.1'4'9 Thyroid nodules are the effect cf primary concern and would typically be observed i
frem 10 to 40 years af ter exposure.' A nedule is an abnormal grew:h' hat : uld be either benign er malignant (cancerous).
Nodules that are thought to be possibly malignant would mest likely be' surgically removed. .
Most thyroid cancers are well differentiated, slew gr: wing, and relatively amena 1e to therapy.* Their associated mortality rate is theref:re much icwer than that for mes: cther forms cf 1
cancer. The RSS1 conservatively assumed a 10 percent mortality n=e for =alignant thyrcid nodules.
Based en the results cf animal experiments and clini:a1 data for humans, the RSS 1 assumed that internal irradiation of s
the thyroid by I-131 would be only 1/10th as effective as exter-nal'x-rays in producing both benign and malignant nedules.** ,
" Ratio of en 16 to adult inhalation dese.
- 0n a purely radiological basis, it is thougn: tha: the scre uniform distribution of Icse within the thyroid from enternal irradiation sign: increase the ef ficiency of inducing clinical hypothyroidism.
26 1
~ "
' " " * ~ ~***~~~~~~~~~""'
.. ,,+-,n+.e - ee. - -.- *~-~~ * ~ * = - ~ ~ ~ ~ ' * " *
-- -- __.- --_-.--_-_________---___A___ _ _ _ _ . _ _ _ _ . _ . _ _ _ _ _ _ _ _ - _ _ _ _ _ - _ _ _ _ _ _ _ _ . _ _ _ - . _ _ _
~# - - - - .
g ;__g .
. c N ,
'2;*1 *. .
m x <.
'.W: 'A 9
This factor of.0.1~for I-131 dose was disputed b.v the American ..
k.....yuN. .
.; y su Physical' Society (APS) study-group on reactor safety,9 which i !. F. [.s:,k,, j i *p'd % .
assumed a range of factors from 0.3 to 1.0.- Because this issue N M
<!{} .
remains unresolved, calculations have been performed in this .t!J
. -e U
i analysis both with and without a 0.1 factor for I-131' dose .,
. ./4 F ,7+
4
- W
. effectiveness. -
Q Sufficiently high radiation doses
- would result in j'.O. ,;
s.
7 ablation of the thyroid with no subsecuent risk of"either u;-
Q benign or malignant nodules.1 However, because of : the high .
H doses required, thyroid ablation is unlikely to occur except .
for persons very near the reactor following the most severe v accidents. Ablatien Sould probably require surgical removal of the thyroid,.and the affected individual would need to.take _
substitute hormone pills on a daily basis. Thyroid damage, including both ncdules and ablation, has been addressed in .
this analysis.
The RSS calculation of the expected number of thyroid nodules per millien person-rem ** is reproduced in Table 2.
6 The assumed total incidence rate is 334 thyroid nodules per 10 l
person-rem, cf which 60 percent are beni,gn and 40 percent are l
malignant. Althcugh not specifically computed, a dose-effects coefficient for a child's thyroid can be derived from the RSS 9
" ~ "Tse ass assumed that doses in excess of 5000 rem (50,000 rem
.from I-131) would result in thyroid ablation. A value of 3000-o- rem has been assumed in this analysis.
- Number of cases per millien pcpulation per rem ON 44
- - - - - - - - -~~'"*'-'-~~~~~~~~~
- l.. , _. .. -. - - . . -* - - . - . . - - - - -
e c
n h t .
a n s C e ki -
u sc 3 3 3 3 3 3 3 3 3 3 o ii r Rf 4 4 4 4 4 4 4 4 4 4
- e f c e n o ,
a c C -
d -
n d ,
a ec .
t s 4 6 3 7 2 9 0 3 1 g
n ce i spa es 3 6 5 9 4, 9 6 2 0 0 0 6 7 1 1 n exC -
0 2 1 e l E D f u e f
h c o n t
ht e m n r t
e g n f e
i . e I
- nk c e n esi 8 1 8 4 4 4 4 r
o 1 4 4 4 Bif n s
t i f r e i e o 8 P C -
n 9 o a d l
r 1 o n 1
eet 0 9 6 a I guc M A>ak 1 1 1 1 1 1 5
1 1 1 I -
ir -
8 r ,
e t
T r s V a s r k '
6 5 1 1 e e at s 0 0 0 0 0 2 s y s eat 3 3 3 4 7 1 0 e 3 3 2 1 a . Y e i
l t
C )
la n 1 i d T e . t m t f tt xs e e c ie nir e r e el a 0 S t
t t re 1 0
1 0
1 0
1 1 0 0 1 1 0 n 0 0 r x m a. \ y3 i 1 1 e
E o f t j e
. t r ,
f f s n .
o ( o o m yL d l e
n s c n t r o e ns a -
i li ear 3 , 4 6 3 0 6 5 5 o l n t
h f t a .
1 1 i i n o a I. ce 9 0 2 2 t
a l s l
h f ey 1
7 6 6 1
5 4 3 4
2 7 1 6 o p
r u t t(
1 1 l a e
_ c x n
I l
a d
i E _ h n o n
_ C o i i l
o r i S y f t l l on i
G I
l I
i o
l h
i m
l i
m
- ni a r
_ ot 4 6 6 4 8 9 4 0 4 0 e r
. l a 1 4 9 6 0 0 1 2 o p
- 2 tl 0 1 1 1 1
1 1 1 0 1 4 0 0 e c'a t t
_ e ar 0 0 0 0 0 0 0 0
s t
r a 0 0 d e s
_ i PP l s e
- la i a s T h c a c c p f
_ uL9 9 os 0 0 0 0 0 0 0 0 f
o o
r d
e r r t 0 1 2 3 4 5 6 7 1 o e c G g 1 e - -
I t h e ey - - - - - - - A t m t i r n x ta Ag (_
0 l 1 1 1 1 n y 2
1 1 1 I
i E
1 3 4 5 6 7 f i t I
' " h '
i i . {:j .{I :
tliil t . !i t I ,
1
4 d
\ 1,,
s
)
r . . .
- i
. t data to be approximately a factor of 2 higher.* Beyea 3 assumes *j the RSS values as lower bounds, and upper bounds of 650 thyro 4d '
i l nodules per 10 6 person-rem for adults, and 6500 thyroid nodules l p r 10 6 person-rem for children.
e t
Unless otherwise stated, the calculations perf ormed in this a
d
'l study assume the RSS risk coefficient of 334 thyroid nodules per
- q. 106. person-rem. This corresponds to an assuded risk, or prob-
'I a
i ability, cf a thyroid nedule for an individual of 3.34 x 10-4/ rem, 1, 1.e., 100 rem to an individual implies a probability of contract-ing thyroid nodules of 3.34 x 10 n'. For this assumed coefficient, a dose to an individual of 3000 rem gives a thyroid nedule pr:b-ability of appr:ximately.1.0. Therefore, the following is assumed:
~
Thyroid Dese r -
< 3000 rem p(thyroid nodule) =
(3.34 x 10-4/ rem)(dese in rec)
> 3000 rem p(thyroid nodule) = 0 p(ablated thyroid) = 1.0 1
1 The effect of uncertainty in the thyroid dese-effect relation-l l
shic is assessed t.v re.ce a t i nc. sete calculati ns using the
- er bound values propcsed by Seyea3 and the AFS.c "
Thyroid Oose Calculations 1
1 i l
A series of calculations was performed using CRAC,-'-} to determine 1) the magnitude of the threa: :o the thyrcii of _
'For age group 1-10: (years at risk) (age fcse fae:Or) (risk coeffigien:) = 30 x 1.9 x (5 - 4.2) = 707 :nyreid nedules per 10 5 person-rem (see Table 2) .
29
- 4 1;
i ,<
l0 .
- r. '
y . !
4 -
a . i 1
l exposed individuals, 2) the distance to which that threat is ;3 l .-
3 a-j likely to be of concern, and 3) the relative contributions of 2' j cifferent exposure pathways and radioisotopes to the thyroid ,,
a . .
dose, for each'of the four accident categories definec in the previous section. All calculations were performed for a 3200 l 4 l Mdt PAR using one year of meteoro'ogical l data taken from a sinc.ie reactor site.* From the . year's data, 91 different weather secuences were selected by stratified sampling 1 and used to generate probability distributions of thyroid dose versus distance. Breathing fate and shielding parameters appropriate fer a person located outdoors,,2,,, are assumed:
~
, , , a . u. .:.;.
... e- x.
.0- .a/s,
. su
.. .t ..
, . a. .: . . : :,c.,..,..
.. .... . v, (cicud exposure) and 0.7 (ground exposure).
For each accident category, Table 3 persents'.the mean thyroid cose that woulc be'receivec by an exposed adult located o u.a..co a. .c. . .ee.e..e;. a.t .
. . . . . ..e. .s .-
.m ..e
.. ea....
. ... . ~. .u. e e c... ..,s-pending dose to a child's nyroid would ce approximately a f ac: r 4
o .' 2 .". 4 . .". a. . . ~..= .* .1 a. 4 .o c. a. s a. . . s .". a. .a s s c . .= . =. A.
.- +. a b i .' .i .v. a . .'
thyroid damage f:: :ne same individuals. The values shcwn ecual
- "e dosee
. . . . . 3.. *..= . - ' . = . .-"...4-'.'a.'.
.r. ."v . ". a.
.s.c -c .-.' .=k -. . e. .' .' ... i 4 =. . . . .* .'
I 3.34 x 13-4 .cer . erson-rem to the thv. r o id .
- k. #. e w P. O. .. f . b. O.
...I..N. ( . . . ". . O O.
.. . Y. O..ON.
v; . I. M
....C..P..M.C. ."..f'O. . $. [. .
shewn
-n i. .t ., w to, have seli :le
.. o. . 7 . w...
e T"T.ec:
...e..
cn the predi::icn of long-tern a.+.. , e. .s - " * , *"e ".*.e ^# . e *. *. *. ." o .' *. C, # .= .'
- y. . . . - . .. ... .. .. ..
Sw.- c . . . c .4 .sq pA. 3e '
Ag.s
. .. ...m .s .c
. . R g
..;.. .. . s.
. c. .6.. . . . ..
. Z ..2 4 .g 4 . .e. .. . . . . . . . i .c .g . ... . , A .y .
l 1
I i
i I
l 20 i
1
-- .m. .e. ..~. ..--.. .~-~.- we. . - - n.- - . ~ . -- - * - ~ . *. ~=
l
_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . _ . _ ___________o
1 m 4 3 3 3 2 2 m t .
t 0 0 0 0 0 0 )
A 1 1 1 1 1 1 e e e 6 6 u r
~
t l
x x x 'x x x 3 1 % d u s
e 8 0 e o
- d. 2 3 8 1 M . s p
. cr 1 5 3 1 3 1 e o x se e c d e rh r n og o a l d oi C t a n dh s n u t i r o u2 d e r O f - t g h x (
do ' c e e a 7 t r h ' e s ao s u 0 ct t t l nc o ,
a p !
s I a r r f e ,
a t . %- '
s e it a 1 2 2 3 3 3 o g )
t t - - - - - - d a e s
Mlye l M
e 7 0
1 0
1 0
1 1 0 0 1
0 1
f o
s a
r) u3 s
dt 5 1 x x x x x x p on ea t 2 n po sm oi l
e 2 6 0 9 0 0 i
o 1 xt xi et px y M 5 7 2 5 2 1 t o x o r u l l e Er o e b c vS t
p g r i r n o rp e o a.lc f
oa t a
C t s rn( s e C i f o eb c t d
y st i 0.0 nd n ea1 1 al e t d n t u d n i i.i a1 so i cc o l i
l n casd iw i basnnog.l t r e D t i d A a 1 2 2 3 I sl l - - - - - b noot a ui o 0 0 0 0 0 ool cc ri l an sh s 9 1 1 1 1 1 1 pt adf e r c i .
e va 5
5 3 l x x x x x ali urn und
) r
/o w 7 2 1 0 9 er erl i doi l mo ef P 1 4 1 3 1 ttl gd h asa l c r A l i h oe
( e G udnti r s c I ho b o l e s eSf ed asir s couuhr s .
od Di dr o
2 3 3 4 5 5 6 f' t
otf f e n/s1 t
r;-
i y - - - - - - - - d os emo oh 0 0 0 0 0 0 0 0 e o rt 1 1 1 1 1 1 1 1 snd f-y ua e-x x e
%ane x x x x P x x l 0t
- . em:
r eI m1 c C 7 0 1 7 2 1 0 9 xf an n 5 4 1 1 4 1 3 1 eel wht ss ae ti u6 e s
MWe eenpcl 6 cri 2d na i 3
}
e i d p
sn=p eo
. s < esl ea l
e l e etbct ad sn<
b i e gre T
a
(
m 1 5 0 5 0 0 0 0 rsl i n a eeel hrt sis t pasl s i
'. e 1 2 5 0 5 2
0 a ah a c 1 1 esaipt l
n a wec sl eeS t
s 1 oah t J' dCt ui i
D _ " b Cd 1 { . t l
,t(i t L , ., . I {' , Ill l l
h d p e s i o 1 2 2 3 l p
m - - - -
t 0 0 0 0 i A d d d d 1 1 1 1 t 6 l d t
l t
l O 7
0 7
0 4,
p x x 'x x u m
l u
u . e 3 3 2 3 f o .
dg M 1 3 1 5 3 owwo A n- e j e ' yel gm r
derr c. o l
b a
rue elb sud C ,
np ocl ' T s e
pci d xoh n d el E c i
.o i ehu ht o t
rna sdr t w oe h , eiy ,
g soh ,ss fd r see i o u ort nss ecf o dy oao cc r hd nar i lt e i cd a e l
'l a t t t eh - 3 4 4 5 6 6 7 7 uea qh l i ed dsi shg t - - - - - - - -
iti l 0 0 0 0 0 0 0 0 etb a
neo D h y e 1 1 1 1 1 1 1 1 ohr ct y n M do so2 r x x x x x x x x etd h i
o t t n rnt i
slf g l 4 7 7 5 7 0 7 3 nma ee ei
.g rao e e sr) h n
en t a
M 0 5 1 2 6 2 6 3 e- s t
vor e r nu a .i i o C r poo eet wsl h tt sr eic t o iu ql a n C sr e i x r s at i
e eec n e n os f d upn aer ku ca l a n s r i
I ey c c
c thn d idrl A h 1 i v n e
p a, ae o . r a v
dt ,
o t i de inr r sa t epn cao y e m, a n g cit i i i l 2 3 4 5 5 6 6 7 e l
o si acc
'l fl r t x i o I s
0 1
0 1
0 1
0 1
0 1
1 0
0 1
1 0 men sl e ef e ia oip aab mir bp o x x x x x x x x d on d iaa fw isoh sue l h yl 0 3 7 7 4 7 3 3 nt i t oe w rat i rb P 1 1 3 5 1 3 1 6 edt o l P A si( f nr i
d G oo d r s e ia e
b l ye st n a . u 1 hl i l b so 3 t u t
aus or w 1 l csl r o - 4 x eea P os 1 3 u br n d e 0 3 a
i.
l t i r
ait nOi i 5 6
7 0
0
~
9 9
1
- ofi f oo d
1
- 0. tolv i o l 0 0 0 0 0 0 0 0 i di 1 1 1 1 1 1 1 1 r hl v t eb rt y ngi it a P x x x x x x x x onh ail A t et hh u ab l
3 3 ci t f o G 9 3 7 7 4 7 acs yo o 'x i
s r ul t I P 1 1 3 5 1 3 1 6 fi e fl a st s sf t end
. sei l ea 4 eoc ncn ech ie e e i ri vk e l
b
)
s ise ti g3 sut
.af f h a e cra es T i l
e mni r m fdaot se
( f ediii v 1 5 0 5 0 0 0 0 en tl o e 1 2 5 0 5 0 nd cie i
c 1 1 2 1 sieh nl n sos ioew a 0 ar yeol a l ev t
s oyhet ei j
l b 't SP rt i
l "f I "d U !' ! .
t i i';
8l . l
- i! 1 I '.l ll l
. _-. . . - .. S e t.
gk
^ :
. . . 1 r.
r eD i;
The probability of thyroid damage to an individual follow- .e
-1 ing a gap activity release accident (GAP) is extremely low, 4h1'.
. .t ranging from less than 2 x 10-* (1 in 50,000) 1 mile downwind i
- c. .
~ of th'e site to less than 4 x 10~9 (1 in 250,000,000) at 100 ,
miles. Probabilities are somewhat higher for the GAP w/o Isolation and Core Melt Melt.Through accidents. Thyroid damage probabilities for the Core Melt Atmospheric accidents are much .
higher, and such accidents could pose significant health ba:ards to persons at distances of more then 100 miles from the site.*.
These results agree with these of previous studies.2,3 Fractional compenents of the mean thyroid dcse are pro-vided in Table 5 for selected distance intervals: 0-25 miles,25-100 miles, and distances greater than 100 miles Within these intervals, the relative contributions to thyroid dose will not differ significantly. The dose is divided into ccm-
- 4 ^ ' e d 4. . .a. s , 4 ...5. .= .' .= . '..a. r. #. . c . --
o n. a. .. . s .' -- . ..'.e 4...".a . - = .' r. c #.
. . .=.
radicie' dines, cicud expcsure and ground expcsure. Radici:di..e inhalation is further divided into cO :cnents for :-131 and other iodines. It is evident from Table 5 that the thv.reid dose is dominated ':y -he inhalatien of radici dines f each of the four accident categories. Inhalation of -131 alene "C=u.. . n ..us. "a. "w s a. d .i.'...*.*...=.*..i..,*.".e'..=.,e#.'.=..=.a..= . . ' - # d. -
1 cated. The RSS consequence medel assumes an invariant wind direction fellowing the release of radioactive material. Ecw-ever, because of the time required cy the cloud to travel 'large
,. 4 k. e ' v *." = ~. ~.".. e w '. n e d . . a. w- . . - . . v '. .' .i , 3. . -=c.,
a, s.,nc.s, 4. - - .
- .- . .. t . . . .
shift and that the predicted dose levels would r.ct ce ecserved n,.,3. . - . . s i ., ,. .= a e. ...e ,,..w, . , a.s...... .2,,
. . . . D...6.
-. u. -W . ,. 7 v w .G-. .-. . . . . .w . .
.' ce e .' v, --
.. . e # .' s . .= . . . e = ' -. . . ..'.a. *-=
...; e. -.,i - -#. . . . a.
. o v. a. . -- .
released :lcud.
3 m_____-_m________
e d r : - -
nu 322 322 333 422 us 000 000 000 000 oo rp e 000 0O0 000 000 Gx -
s E
- r o
o d
t u .
O -
b d e e r t du 342 222 696 11 a us 000 000 0. D.1 00 c oo o l p 000 000 O00 000 l Cx .
E l
a u i d
i i
v d a ,
. n ' s I e
. n
_ d i e d s d o o
el '
p l o 223 222 009 755 x ai 000 000 110 000 E hd r
na 000 000 000 000 I r .
o - 7 f n e b i
0 o '
=
b l r t
o d
i a s c o se a r
y en f ni 526 536 659 1 06 j
h i d 221 221 1 1 0 221 v
't. dn . r oI 000 000 000 000 i n l d a or l e
r l e .
M ihw tz t 0.hi 1 S f iO o
d =
's t
e .
l 1 1w n n a3 707 u1 0 533 727 t o .
e h1 677 '677 666 677 oi n
n- 000 000 l t
,ca I I 000 000 p 3 n n 7oi o 3 t n a
C m et l 4 r n a - uo n . 0 sc )
o hj 1 x
i x c xx n id t t i c o r eu a r e 6 o r l n h h 6 rr P a vr _ i o 't p
s 2f og t t o )
. e- a l m = rt S t) l e t o ns o M A et e e I e s l 0 t 0 t cr aau l l 0 I 0 b ei 0 0 l 0 l 0 rf s a ce n(
51 0
/o 51 0 M
e 51 0 M
e 51 0 .
T 2 - 0 2 - 0 2 - 0 2 - 0 jjt v v a - 51 w 51 - 51 - 51 r ix t
02> 02> e 02> e 027 il e
s P
- t r r hd l
A A o o t l y aea i
t G G C C eid rh -
. . . . 0Sl A 1 1
C D 8bC t ,
l'
_R,,
.. a t
. y y, A -
3, . .
t -
h r5 accounts for 60-80 percent of the total dose, and other iodines g'I
- au.. 4 4
e contribute another 10-25 percent. Inhalation of non-radio- 29 *
\?r.
2 iodines, cloud exposure and groun.d exposure are all small v contributors to total thyroid dose. [
t j
The probabilities of exceeding thyroid doses of 0.01 and 0.1 rem versus distance frem the reactor are shown in- Figure 2, conditional on the occurrence of a gap activity release accident (GAP). The probitbilities are calculated f or an exposed -
adult located outdoors.- The selected dose levels, 0.1 and 0.01 rem, are far icwer than any recommended action levels, and are
-still confined to areas very close to the reactor. Therefore, it.is evident that the GAP. accident does net pose a significant hacArd to the public.
Figures 3 and 4 show the probability of exceeding thyroid doses of 1, 5, 10 and 25 rem versus distance for the GAP w/o Isolation and C0re Melt Melt-Through accidents. The 5, 10 and 25 rem dese levels were chosen because they represent the range of action levels that have been recommended for the initiation of emergency protective measures. The 1 rem level It is evident was added as a lower tcund for doses Of interest.
from these results that, for all practical purposes, pro;ected thyroid doses of concern are confined to areas within a few 10's of miles of the reactor for these types of accidents, and in
- most cases to areas considerably cleser. For the GAP w/c Isolation accidents, deses in excess Of .5 rem are confined te l
.' about 10 miles; these in excess of 25 rem to abcut 5 miles. The 35
'l J
- .4 4
t *
. ' i,
.4
...~4 ,
a, ,-
on t .
.J -u
. s
)
., a !.
-'t s,.
N 4
.5
- 1. 0 -_ .. . . . . . .
.j , .. .
N . s at
~ , .
..e w
=
C. 01-c - -
w a 4 o z ..
._.J e
= m -
< =
= m -
v y -
= w e.
,c = -
O ._ e
~
E.
-~ .._ D 0. 01 .r- -
.. i u i
.a _- r i
W u -
l X l L J 1
. G.~v -
D.001 O.1 . ! 10 !00 l
DISTANCE *
(miles )
l l
l
.r .a -.. e 4' . *w..--
- * # # '. .# '.'.. " a ' ~
.~.~..X '* *.--* # # .M. , ..* ~. V .* -* 4 .#. .'. w'* e* ..
' ,'7w .#
.O *" " " d " ' ,#
C* g.g~i aA
- .. ,* t .1
. g ... . e . e ..--es .4m.e. ~. .s . p. ---
, w s- s .n.
- Tg eegA -- -
p,s.... n . svg-
- v. s- a; v a c,.3. : .'.,gb "an.a a .e.
-- v ... .. -- - 3. .- a 1.e.. ..
.a c ..a7 . .,,. ,- C.ra . e.c.....: -
a .,4 ; e e...s.
1 e. e m. .a
. --. e.a
. . ( c-n .t ) .
36
7_ ,
- a ; .
- . :a .-
- :-, - - ~ . ~
~
- 4. . .,
.s. _
- 4; . 1
- a. '..
. .m.
. ,- a. -
I.
L :.
l' . .1. 0 . _
4 _ ..
- j. ,
4 .
t
, w E 1 rem e
- 5 rem -
et N e
. z 10
.m o < 0,1 _
rem -.
e -
3
- 25 rem _-
e x. -
a_
= :
=a o
=
o .
' m w . .
W c
- s. a oe i ,
t
=o a ~
- 0. 01 - -
m z 3_:
,o, _
1
~~ 1
- r. ~
e
_z_ .
c w . -
M a .
GAP wie 150LAil0N .
1
- * * I * * * ' ' ' ' ' ' ' '
0.001 '
O.1 1 10 100 DISTANCE ( miles )
l -. ' Figure 3. C:nditional Pr:5 ability of Exceeding *hyroid Ocser i
o f 1, 5 , 10 and 25 re= for an Expcsed Adul. Located.
. Octdecrs. Pr:babilities are C nditional en a GAP
. v/o Isolati:n Accident.
37 m______ . _ _ _ _ _ _ _ _ . _ _ _ _ _ _ _ _ _ . . _ _ _ _ _ . _ _ _ _ . . . . . _ . _ . . . _ _ .
- . .~,
.i .
T
]
p.
e e, .
.e a.
s-x.
J .:
- 1. 0 . .
i . .
w c:
n .
N O
s z 25 10 5 . I rem b < 0.1 .
>e 3
+. .
=- .
o E= c - l
-a
.m ze= -
.o.
.e z o 0.01--
.nsd v .. .I r-
- 9 L -i e -
2 l. l
= ;
6.4 I' ,
l 5 t CCRE MELT MELT - THROUGH 0.001
- I - -
- 3. I 1 10 100 DISTANCE t miles )
e t . w. 6 at . v . p-.: z.. g.,
.. . ..e...a...,*
- . . - ,-;- ..s
- r.<.g,.
. 2.. .. .. .m. ...w
,..aa w Cwes c
C .J 7 sy .i n.! 3 s
4 .O,r gm
.. .# .= .z n. .v< r C.eG4 ..A.,.*.
- =
-wC.y g...4 *
.o r 9M. .dl.
. C, w A .g. 5 . A.lt .e, E m., . . . gp gg g DO w .M .$h4. . S. Sh
. .g. E A. pg 15 P g g
. A . &. . 4 . b e . .. .W wA H ;Il r. . . .E .. ...*
- J 3 e a ...e , o w e, ~ e. a.- e. ee e .m e- m o .ouw w + * * * * * * + = ' - * * * = ** so = . * * * *"* * ' ' * ' ' ~ " * ~ " " ' * " '* ' ' ' ' ' *
- _ _mtm_-- - - .m_ _ _ - - - - -- - - - - --
'; ~ n.
- b. a:--
Dt.
- i
- y
. . ; 1 C u, . .
- e
-( i (; -
h {'
.T same dose. levels are confined to approximately-15 and 7 miles, :a r.. -
t.j'4,. d p respectively, for the Core Melt Melt-Through category. D.,s-o The conditional probabilities of exceeding thyroid doses of ;
- g. . 1, 10 and 25 rem for the Core Melt Atmospheric category are shown in Figure 5. . The thyroid dose' levels of concern are likely to be ,
exceeded at very large distapce's from the reactor (and correspon-
- 1 dingly over very large areas) if this type of accident were to f .
I occur. h
- 5. Other Protective ' Measures It was shown in the previcus section that, for each of the four accident categories addressed, the thyroid dose is dcminated by th6 inhalatien cf radioicdines. Therefore, in ceder to be effective in reducing the thyrcid' dose and resulting health im-reduce the inhalation dose, KI l- e. a cts , a .orotective measure must dees this by blocking the abscrptien cf inhaled radioicdines by the thyrcid. Ecwever, cther protective measures, including both evacuation and sheltering, can also act te reduce inhalatica dese.
Evacuation, which is the expeditious movement of the 1 i
.occulatien, is considered :: be the c.rimarv. c.re:ective measure in most radiological emergency planning within the United States.13,14,15,16 Evacuatien could potentially be 100 percent j
. .1
,.n reducing a,1 c.c se .a :. acccmpl:. ..sne ..ce: ore arr:.va.
l 1
ef,_ective On the other hand, it could be in-l l
1.
= of the radioactive cicud.
i I
i l 39 l
l
= f
~ l
- h. e,
- b. '
- 4, .
i g-s .'
. 1 J
A l .
=
4 -
y .
a- .:
r
, - 1. 0 ---- - . .
~
s% . . .. ..
N 1 rem .
10 rem .
- E -
.; W- 25 rem
. m .
N . .
e 8 -
z' -
- 5 =:: . 0.1 -
. >. e r- .
__. c .
= -
<W-
- =. - - _ l ow
.=-
- . ,a _.
o ae ze -
.o_ e ,
==-
c >._ %
z-c -e0.01 u p ,
_z_ C i
c, r
- -l u L X
- CCRE MELT ATMOSFEERIC l E001 1 10 100 1000 DISTANCE ( miles )
Figure 5. Conditional Pr:5 ability Of Exceeding hyroid Ocses of 1,10 ar.d 25 rem for en Exposed Adul: I,ocate d -
Outdecrs. Probabilities are C nditional en a Core Mai A::cspheri: A :ident.
40 p y,wae e. w,..,,e ow eser *- 89up* * * * * * ' *
- a gu ese
__ __ _____________________.-__._-___m - _ _ _ - _ _ _ . . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
ww _
+ a :. : , . . . . 2. -
-- - - - - = - - - - m
- V.. .
. a
- L 3 . ;
l e l r -
~ i,
. i c, :
affective in reducing inhalation doses if not-initiated until ~" . .
- . l
,. a,. ;,
o "
after the cloud has passed.*
- i. g LI o ui i Sheltering might also provide some reduction in thyroid :
s i dose and could potentially be implemented.at much larger dis- '
u
' tances~than evacuation. Sheltering is the deliberate action hy 1 the public to take advantage,of the protection against radiation 'l exposure af forded by remaining indoors, away from doors and win- I dows, during'and after the passage of the cloud of radioactive !
material. The shieldinc. inherent in normally .
inhabited rtructures ,'
offers some' degree of .crotection against external penetrating I 2
i rad,iation frem airborne and s,urface-deposited. radionuclides. ]
Furthermore, the exclusion cf a significant amount of airborne I radioactive naterial from the interior of a structure, either li
~
by natural effects or by certain ventilation strategies, can re-duce the amount of inhaled radionuclides as well.17 A recent study 13 sugges:s that a factor of 2 reduction in inhalatien dose can te assumed for sheltered individuals. That factor has been j assumed in the followinc. ecst-benefit analv. sis. :
I 1
Finall.y , other cotential measures such as creathine. th ro uc.h
. 1 I
either respirators er commen household items, e.g., handkerchiefs ,
and towels,19,20 may provide additional protecti:n against dose 1
l 1
"Even :n situatiens where the radica :ive 1 cud has passed, eva-l cuation could be valuable to reduce expesure to ground centamina-tion. However, since thyroid dese is deminated by radicicdine inhalation, it would not be reduced significantly in this case.
It is also pessible that evacuating persens : uld receive increas inhalation deses if, for examp'e, they renained in :ne :1 cud for longer .ceriod of time or mcved :: ward, rather than away fr:m, the reactor wnile in the plume.
A!
,n ~.. .-_ -
._c
]
. s
. 2
.. s
. s , . *
. i
- . , , i i I from' inhalation'of radionuclides. : .j However, further research'is ' ,D requiied to determine their effectiveness!in realistic accident
- k. !. ' ,.
situations, and they-have not been addressed in this analysis. . .
?.
D
- 6. Cost-Benefit Analysis ,
~
(
{
The decision.to use potassium icaide (KI) as'a protective i imtasure.should be based, at least in part, on its cost-effective- ... .
neco relative to other available protective er safety measures.- .
t.
To analyze the costs and potential benefits of KI, the following ,,
information is needed:- -
- Costs;
- Potential impact of accidents;
- Potential reduction in accident impacts; and
- Accident probabilities. .
l-l The cost.of implementing a K! program would include: the purchase
- c. rice of the K! in tablet or liquid form (both ori=.inal and per- .
, iodic replacement co s ts ) '; costs for stockpiling, distributing and monitoring the status of the drug; and administrative expenses I
associated with the program. The potential impact of the accident is measured here by the mean nu=her of thyroid nodules that wculd
-occur within selected distance intervals. The reducticn in acci-dent impact is measured as the difference between the number of l
.thv.roid nodules .credicted if no pro ective actions ar2 taken .,
.(normal activity) and the number predicted if various protective .
~
Accident probabilities arc expected 1 actions are implemented.
occurrence rates t.e year Of reactor operation. By combining the costs with the accident precabilities and the estimated reducticn ,
8'
- a. . -.
- %4
/
in effects, a cost-benefit ratio is generated. The cost-benefit I"
ratio for KI is interpreted as the expected number of dollars i
. required to prevent a single thyroid nodule.
The' cost *-benefit ratio has been evaluated for the GAP w/o Isolation, Core Melt Melt-Through, and Core Melt Atmospheric v
accident categories over selected distance intervals out to 200 miles frem the reac'tcr. Because few, if any, thyroid nodules are likel.v for the ga.o activitv .
release accident (GAP), that category has not been addressed. Calculations were performed for a 3200 MWt FWR using CRAC in the same manner as described in Section 4. Several additional assumptions were made to facilitate the analysis and to elicw the presentation of results
~
in a concise and easily interpretable .anner. All calculations assume that K! is 99 percent effective in reducing the dose to the thyroid frem inhaled radiciodines. This is cbviously a limiting case since it assumes that all affected individuals take the drug before er immediately after the cloud passes.
A uniform population density of 100 persons per square mile was also assumed. " Results for real, or site-specific, pcpulation l
distributions can be estimated by scaling the 100 persens/ mile 2 l
results within each distance interval. Finally, calculations were perf0rmed both with and without the 0.1 dose effectiveness factor for I-131 discussed in Section 4.
t
. "Because costs are aise assumed to be prcportienal to .cceu- .
lation density, this assusprien dees not i= pac- the ecs:-
cenefi: ratics calculated.
. 43
e , .
l
. Costs The1 stockpiling, distribution, monitoring, and administrative. "ii,~. i costs of'a KI program would depend on the specific strategy of ,.
l implementation and are' difficult to. estimate. Therefore,,only l
the orig'inal purchese and replacement costs of the' drug'are addressed in this analysis. The following assumptions'are made:
- 1) Cost of KI per individual (14 tablets.in a-bottle) =
l- 50.50.*
- 2) KI is replaced every five years ( i . 'e . , 5 year shelf- .s life).**
- 3) KI is'available for all persons within a.given distance l interval.
- 4) No redundancy of KI locations (i.e., no extra tablets
~
, are available).*** ,
, N.
1 l-The cost per year to provide KI for all persons within an interval is therefore equal to the number of persons in the interval x 50.50/ person x 1/5 years.
- Tnts value is consistent with the price range (50.41 to 0.75, depending on quantity) quoted by a U.S. drug firm that manu-factures KI.
- KI tablets and solutien currently approved by the U.S. Food and Drug Administration (FDA) for marketing tear 2-year expira-tions. Ecwever, improved product stability should be possible.
Therefore, a 5-year shelf-life is assumed here. --
- Considering the importance Of prompt distribution and administra-tion of KI, some redundancy of storage locations would =e desir-able. However, the extra cos: f rom this redundancy has nc: been included here.
As 1
_. __ . - _ __- _ _ _ . _ - - - . . _ = ._ .__.
L_
_:._ : .., a .
- .. 4.
?. .. b.
, .s c.
For the uniform pcpulation density of 100 persons / mile 2 .
ed . .}
I assumed in this analysis, the number of persons / located within r} -
- ~
o-. selected distance intervaln are as follows:
Distance Interval No. Persons in Cumulative No.
(miles) I'nterval Persons 0-5 7,900 -7,900 5- ? 23,600 31,400 i 10-25 165,000 196,000 l 25-50 589,000 785,000- i 50-100 2,360,000 3,140,000 100-150 ,
3,930,000 7,070,,000 !
150-200 5,500,000 12,600,000 4
Using this information, the estimated annual cost. for a KI program )
i within each interval is given below. l l
i Distance Interval (miles) Cest(S/yedr)
.1 0-5 790 :1 5-10 2,400 10-25 16,000 1 25-50 59,000 50-100 240,000 100-150 390,000 q 150-200 550,000 1 At the assumed cost of 50.10 per person per year, the annual ces:
to implement a KI program for the entire,U.S. would be abou S20 million.*
i e
'Otner distribution strategies, such as regicnal s:crage, could' substantially reduce this cost. Ecwever, because of longer implementation times, the ef f ectivenss cf these strategies may also be reduced.
an*
45
--_--._------_.e. _ _ . . _ _ - - _ - _ . - - . - - - . - - - -
g- _ _ _ _ _ _
~: u ..
c u .a =--- m--_.- - - _-.
, 6
\ .
, -7 l, (*',
,e' p ,
1
- .c
- Potential Imcact of the^ Accidents b
The mean number..of thyroid nodules
- that.would occur-within' [y . , ,
'celected distance intervals for the'three'ac:ident categories. ...
fm.
y Results are pre- ,.
addressed:are given in Tables 6a, 6b and~6c. . ~'
- sented separately for four protective. measure combinations: ;
- 1) normal activity ,. i.e. , no prote'eti've actions ' taken, * * ,
. c.
'y
- 2) normal activity plus 99 percent effective KI, 3) sheltering ***,
and.4) sheltering plus 99. percent effective KI. Although results c'
.are not.specifically presented.for evacuation, they would range from zero within all distance intervals to approximately those 1.
values shown for normal activity (see Section 5).
Potential Reduction in Thvroid Nodules 4 l The potential
- reductions in the mean number of, thyroid nodules that'would result by the use of KI are presented in Table 7. The values provided were determined from thosa given
~
in Tables 6a, 6b and 5c. As an example, for the GA? w/o Isola-tion accident, the mean-number of nodules in the 0-5 mile interval is 1.77 for normal activity and 0.09 for normal activity plus l
l
- For :ne Core Melt Atmospheric accident category, thyroid doses can be sufficiently nigh to result in aclated thyroids as well as nodules. Mean numbers of ablated thyroifs in 6c.
each distance interval are given in parentheses in Table '
- Shielding facters = 0.75 (cloud exposure) and 0.33 (ground -
exposure). 1-day exposure to ground contamination (see
~
~
reference 1).
- 5hielding factors and ground exposure time are the same as fer normal activity. 50 percent reduction in innalation dese.
1 1
46'
8!) jll 2 l ,
i
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=
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t
_ d r o c
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612111 512111 r a n rK g f t e 000000 000000 ds t%
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mip l9 3 ut a9 3 r Nas m r ,
o l e nul o 0 f apu 1 l
f i s eod 3 Mpo 1 n a n - 1 a l m 1 3
)
e n
ard 1 noi r - e a of o o 1 r s ii r f ay u t ny r s e i uh r t o o r d t o i f p u nA v x s o 4 t
c i r e o p
C 1 a t 7532671 o 6361 253 i x 3 f c 734331 1 t 61 1 11 00 A c . . n e
.s= s 1O00000 a 0000000 o nl s l f l d oat e a c n i vn n m s ( u t re e r s o r
aei v o e n
5 7 g lt c i N e oni t i sIf c v 0 m
I f e i
= a ee f f
t c
/o c onc e e s s watk l f r r e a f o o Pss s vr e t . t Aii o cnc GI ) t d e e aoa I
t) s fif 1 ns 050050 000 d
o 050050 000 jaj t
a 0
I e l 51251 12 51 251 1 2 nnrv i 6 ei - - - - - - - 1 i ii t
u cm n(
0505000 0
0505000 12505 i
l nd al e a 1 2505 l et e l o t 1 1 h
11 f nt b h ioh a t s t I i
T i i i W 5 8 ct W D I lilll!!llfI. Ir l
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t c i v
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s s l 0000000 0000000 .
rs e e 5290028 ea n h 4600035 b e S 1 80374 n s n v 1 1 i i i N t I c nK e a f ee f 1 Mvi e3 1
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te u l 1 000000 1 000000 o a 21 90006
_ I
. h m 31224 61
_ l I t r 19974 9 i
aK i W h t
1 21 tf no e .
t e bsU -
. h c t
xt i
i o
_ r e
. r
_ 7 l n h hp a
o
_ I
_ e v i
'- s l r t t o
_ b e a l -
m a t l 000 e 000 t 000
_ T n) o 050050 M 050050 A 0500 50
_ I s s 51 251 1 2 51 251 1 2 51 251 1 2
_ e I - - - - - - - t - - - - - - - t - - - - - - -
_ el 0505000 l 0505000 l 0505000
_ ci o 1 2505 e 1 2505 e 1 2505 nm a( /w 1 1 M 1 1 M 1 1 t e e
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A o o
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= - - ~;'
~
1
- 99 percent ef fective KI (Table 6'a). The difference between these .
^
two numbers (1.68) is the reduction afforded by using KI. i4- --
Accident Probabilities The probability of occurrence estimated by.the RSS1 for the accident categories addressed in'this analysis _can be obtained from the data'in Table 1.
~
Estimated' Probability.
RSS Catecories (cer reactor-year)-
4 GAP PWR9 4 x 10~'
GAP w/o Isolation pWR8 4 x 10~5
. Core Melt Melt-Through PWR6-7 4.6 x'10-5 Core Melt Atmospheric . PWRl-5 1 4 x.10~"
a The RSS probabilities were.used with the results in Tacle.
7 to determine the pctential reduction in the mean number of thyroid nodules per year of reactor _eperatien by implementing a-KI strategy. These values, which are shewn in Table 3, include contributions freu all 3 of the accident categories censidered.*
Note that the contribution frcm the Core Melt Atmospheric categerf dominates (95-100%).
o I "The expected reduction per Eeactor year = L (potential ~
reduction)t (accident probability)i, where i is the acci-dent ca tege rf .
51
t i 0 0 0 0 t r 1 1 1 c
e 1 1 1 1 a
a f
l t x x 'x x x x x c t
~
e 7 3 8 5 6 5 s
s 0 n e
h S 1 1 4 4 5 2 1 e d d e n -
i m e ,
c u v c s i a s t a c y e d e1 h ie f3 t t i
or ra f1 e-I v + s y i 3 2 3 3 i hs e t c
3 3 3 1 e sr - - - -
0 0 0 0 i
' i oo A 0 0 0 1 1 ft df l 1 1 1 1 1
e r
oi l 1 a 'x x x x x x x e ri m , 4 5 1 1 0 eb 0 r 4 1 ba o 1 5 3 4_
N 1 3 8 9 mb h ,
uo t i )
g Nr p n
W x t
y aS i eS l t
i MI ' b n a i . b d
r o
r
~ ne o 3 3 2 2 2 2 3 p onn t J
w - - - - - - -
i i 0 0 0 0 9 0 0 t s c t 3 1 1 t as a r 1 1 1 1 n
r a f e x x x x x x e e t x d ps s l 0 4 i Oi s e 0 3 3 6 9, c e h 1 1 1 6 c rI n S 2 4 1 a
oK e ~
(
t v -
ce i t av t c
)
n tei t e o c
I f i f e f1 . t of e3 7 c f 1 u re e- e d a sI l e ea o y b r Y 9' d r o t T a l 9
a r
e . 1. f i v
3 3 2 2 2 2 2 n i t
p 0 i i
I t - - - - -
0 0 n d K t c 0 0 0 0 0 1 1 s e u A 1 1 1 e
1 n o 1 t o
of x x x x x x x u p i
o h t
l a
l a (
_ t 2 0 9 0 3
_ ce i m 5 7 v us W r 2 5 2 3 3 2 1 i dU e y b
t m
o r
[ d s
il b l
f i o
ah d r
_ i s e = y t e t h nl a n t
_ eu l o l td u ir o
uoN l a l c t a ce t t
vr a uy a c d - l b
_ . e er a
_ 8 t s rot n) n eac e I s 0 0 0 o l s l e 0 0 5 0 i e el 0 5 t t e l
b ci 5 1 2 5 1 1 2 c cr a
- h nm - - - - - -
0 u e i
_ t a( 0 5 0 5 0 0 0 5 d pr c t 1 2 5 e x !
n u 1 1 t 0; 1* i l di h D
O t
_ l l ;
n __. ._ _ _ _ _ _ _ _ _ _ .
1
- i
~
. 1 i .
1 The uncertainties in the probabilities used above are larce. .
).
Error bounds of factors of 1/5 and 5 on the
. i values above were I.-
6-estimated in the RSS. In 1978, the risk assessment review group (Lewis Committee)',8 chartered by NRC to review the Reactor Safety i 0
. Study, concluded "We are unable to determine whether the absolute probabilities of accident sequendes in WASE-1400 are high or low, but we believe that the error bounds on those estimates are, in generalr greativ . understated." Operatina. exoerience
. data for light water reactors (LWR) can also be used to estimate ~an upper bound for the e.robability of core melt.21 Throu9h the end of 1979, there had been approximately 450 years of LWR experience in the O.S., without a core melt event.*2' Assuming a X' distribution f or such potential events, it can be shown that the probability of core melt is less than 1.5 x 10-3 with 50 percent confidence, and less than 6.7 x 10-3 with 95 percent confidence.**21 These co.c.er cound . probabilities are approximately factors of 25 and 100 times the RSS values above (4.5 x 10-5 _ 1,4 x ig-5 = 6.0 l
x 10~#).
Cost-Senefi: Ratio Combining the estimated ecsts and the results in Table S, estimated cost-benefit ratios for the use of KI are presented
- de O
"Althouen the accident at Three Mile Island involved serious core ~
damage, it was not a core melt event.
- Worldw je ~2iR experience through 1979 was closer to 1000 reau or-d l years.2- Using this value rathe; than 450 years results in precability, estimates of 7 x 10 ' with 50 percent confidence, and 3 x 10~~ with 95 percent confidence.
-:)
_____________________-__-a. . . _ _ _ _ _ _ _ _ . - _ _ _ - _ _ . _ _ -
w t
m i.e. , the expected. .
Lin Table 9 in' terms.'of'S_per nodule prevented, .
~~7 ,-
number of dollars required to prevent a. single thyroid nodule. '
. ~
~ .
,t.;
a-
- Thd estimated.ratics' range from 3.2 x 10 5 S/ nodule prevented- .r
- y; 1 s ..
(for the.0-5! mile interval,' normal activity, and no 0.1 dose - . s. . .
8 S/ nodule prevented effectiveness factor for I-131) to 3.7 x 10 (for the. 150-200 mile ~ interval, shelter,ing and 0.1.I-131 dose.
effectiveness factor). . e 4 J Sensitivities Table 10 summarizes a cost-benefit analysis. performed speci- .
fically for the use of KI by children. The risk-coefficient assumed, 663 per 106 . pe rs o n-r em ,
- is a factor of 2 higher than that assumed'in Table 9. Other ass' unctions include: no 0.1 .
dose ef festiveness f actor fer I-131, RSS accident probabilities, normal activity, and a uniform population density of 100 persens/
category was
' mile2 . .Only-the Core Melt Atmospheric accident .
addressed. However, as shewn earlier, this'has a negligible effect on the predicted results. The cost-benefit ratics in Tables 9~and 10 are no't significantly dif ferent for the intervals close to the reacter. This is because the doses within those intervals are sufficiently high to result in thyroid nodules
~for essentially all exposed individuals, regardless of the coefficient assumed.
At larger distances, the cost-benefit ratio in Tacle 10 is a factor of 2 lower, as expected.
l 1
assumed by Beyea
- nis .s also very close to ;he risk coefficient for adults (see Secticn 4).4 54
- - ' ~
-_.-a- _ _ _ _ _ _ _ _ . _ _ _ _ _ . . _ _ _ _ _ _ _ _ _ _ _ _ , _ _ , _ , _ _ _ _ _ _ , _ , _ ,_ __ ,
'f ' iI f: I !i g 5
- o. r o i n 5 0
6 0
6 0
7 0
7 0
8 0
0 0 ,.
t r 1 1 1 1 1 1 1 c e x x x x .
a t x x 'x l
- n. .
f l e 9 4 7 2 4 5 7 a t
s h 4 1 3 ai 3 f rx s S 7 1 1 e a . . .
n e sss v e bs eee i
v e iii ll ttt t l a t iii c1 id lll e3 f1
' won aaa ttt
- f - y s aaa e eI ee fff re pr er t l r rrr a so i
v d ua eee 5 6 6 7 7 8 e of i 5 0 0 0 0 0 o% ccc l s ue d t c
0 1
0 1 1 1 1 1 1 n9 nnn aaa 1
di 1 A x x x x d ccc ot x x x i ,
ni l
0 l a 6 7 9 2 2 6 0 os rd ddd iil ri eb h
t m
r 5 7 1 6 2 7 1 yi ooo yrt pa ho ryy b
i W b I
t r y hhh i
$o eh ttt
( r ht .
I p t d
eees r t re KS f e aaai G ot t fI a %%1i o r %l 1 24l a
o g 4b e . t n 5 5 6 6 7 7 7 y a iiit vvv a sd c 0 0 0 0 0 0 0 r r r Ue n a i
r 1 1 1 1 1 1 l e aaaf rt u e 1
er s s s, r os f
t x x x x x x x t a a eeee f s s~ l 2 7 3 9 6 ms lll c a s e 0 6 i e oolin s e h
. l i os n e
S 4 5 1 3 1 3 0 xs.iida oa rc) vV y F t r n oc t v p 7 d aI i pe eeel t
I K t A gerrro c al aaat y e
te iv fi f1 t3
.mb sdT906t aa1 %%h L et e1 d 258 nc - i dm,,,e ee e1 oio r if l
- f s
or t y '
rorsssa yrfddd t e do f i b C d e f E f h y(l il %
s v 5 5 0
5 0
6 0
6 0
7 0
7 0 th ooo4 o1 1 i 0 1 1 1 1 t sr r t C9 t 1 1 1 d cyyyl 0 c v 9
A x x x x x x x edihhhi d t ett tt a e) . t u 2 2 3 0 2 0 2 aci ta i o
l a l ulddds ad met e h m 3 4 7 2 6 2 4 bdaeeee aet t ttl s r it i t > raaaat i t
t ns i i fl l l v e bbbo r
ses W M r Eva ahraaon t e s ceeee
. ef nr r r r 9 l i
oaaaaa c
e h % %%%%
l l a x0d0006 w
b 8l 741 9 a vr t o
T hyt yyyy e tl yl l ll t) ns 0 0 0 n ttteh ttt e e e e '
I e I a aaaa ei l
5 0
1 5
2 5 0 0 1
5 1
0 2 smemmmm eiriiii
, cm - - - -
0 0
0 d xaxxx x n(
a 0 5 0 1
5 2 5 0 5 uo l t % r r r r oooo 1
t 1 c )q1 >>>p q q1 s nt t g t l i
i A AAAA D ah Cd"I
=
, j
' i-
- i Il1i f!lI lfll
t h
t e Na ne r
8 o 6C tv 5 ie 0 5
0 5
0 6
0 6
0 6
0 7
0 6 f r 1 e p 1 1 1 1 1 1
. = 1 n e x x x x x x x 3 e l t1 D u 2 7 3 1 2 5 1 n- t d eI o 3 3 5 1 3 9 2 i . s n cr o/
i o P S
. ff -
(
f -
er oo
- ct C c )
k a r sf y i - /
rs s
- s e e'. l -
- ns u 3 3 2 2 2 2 2 see d - - - - - - -
nvi o 0 0 0 0 0 0 0 .
oit n 1 1 1 1 1 1 1 )
iti ( ^
3 t cl x x x x x x x pci n n mEb o 5 5 0 3 6 1 6 o uf a i i sob t 2 6 3 5 7 4 2 t s o c c A er u e sp d S o e
.dt i l e n n e e s re 1. d *
( ,
d0i 2 l c C S e ioc n G l o
GnaS i t
1 m
i A
n y a, G c o s bidI u r m
d f d
I o ,
te r K r y i 9 0 0 0 0 0 0 s r yl 7 6 5 0 6 3 3 t e fh n l 1 4 1 1
1 4 9 i l
n p ot o a 2 3 5 2 l e i i 0 eoy t cs0 lst r n id1 I
mg o e fi t f of ree b er o oy ort I f - a ch y nc k t t i
s >e rt sd s i
srn yee y i
rt e en l pd l tt ad a i aiK dl n' c I'n mv 1 7 1 6 7 0 1 nb n A '0 c e rt % 9 5 6 3
1 3
t 6 3 2
5 aao 1 a l ot9 1 4 1 i t iC Nc9 t sdt irc d) A rna f ei bna oal epr t t u n e e csp i
esh ep dm i( y, aeo fl p ll s o l t u t i > r ai 0 5 0 0 0 0 0 ed m mv i
sl m y 7 2 1 9 3 7 0 sor ool h ri 2 6 5 1 9 1 9 ono CnA 'l ot 2 4 5 3 1 d f Nc hi A et n
. gou 0 ab 1 a ss e el _ ees ca) ddnu e l 5 0 0 0 0 b nvs 0 2 5 0 5 0 m
a ar e 5 1 - - 1 1 2 i l T t el - - 0 5 - - - ccu sti 0 5 1 2 0 0 0 nns inm 5 0 5 I 1 A DI j 1 1 " b" oo l
- -w -
s y
.- ' k .'
Finally, Table 11 summarizes an identical analysis performed , .
for children using the APS upper bound risk coefficient.of 6500 {- t a
^2 In this case, thyroid nodules per 10 person-rem to the thyroid.
6 ..
s the estimated cost-benefit ratios range from 4.9 x 10 5 S/ nodule 6 S/ nodule prevented within preve'nted within 0-5 miles to 2.2 x 10 .
150-200' miles. Note that th,e ratio for the 0-5 mile. interval , .
is actually higher than in Tables 9 and 10.* .
i The cost-cenefit ratios given in each of the preceding. .
. tables were calculated for selected distance intervals from a sincle ' reactor. fdowever, if there were two reactors at a parti-cular site, the probability of an accident at that site would be twice as high and 'tne cost-cenefi: ratic.for each distance ,
Similarly, in many areas interval would be a fa'etor of 2 lower.
of the U.S.,
several reactors at different sites may contribcte to an individual's risk of thyroid damage. The extent :: which ratio for .I< depends on a-tnis'would reduce the cost-tenefit number of factors, including the specific' location with respect reac c: power to neighboring plants, wind direction frequencies, levels, etc. For example, there are approximately 13 reac cts" Using currently operating winnin 200 miles of ;4ew York Ci y.
l the thyroid dose is still
- For rnis assumed risk ccefficien:,nemeers of thyroid nedules, nigh enough to cause significant even with 99% effective KI.
1 .,
- P.eactors (power level > 200 M;ie) within 25-50 mile interval:
Oyster Cree < , daddas :4e ck, b Indian Point 2 and 3; 50-100 miles: Salem, Vermont Yankee,' Peach l~ - Millstone 1 and 2; 100-150 miles:Tnree dile Island 1 and 2, Bottom 2 and 3; 150-20 0 ; nile s :
(- Filerim.
1 l
- t
l l
' e ,
~
4 b :
id o) t e
- 1. S
.Rn at tv e
5 5 5 5 5 6 6 i .
k0Gs I ie f r 0
1 0
1 0
' 1 0
1 0
1 0
1 0
1 io,~ ep :
rn y n x x x x x x x .
ee
,ln Dl 9 9 6 5 3 1 2 do i
t-s ul x 4 3 3 4 6 1 2 .
oy ow .
ryo - rr C $/r ehg (
pt e s, p t t
a oa '
t c O) a
. Emt r I
Are en
/y '
ni oc d s e n M
l ssc u 3 3 2 1 l 1 1 nra d - - - ~ ~ - ~
oe o 0 0 0 0 0 0 0 l pe t i (
n 1 1 1 1 1 1 1
_ g0e r n
x x x x x x x s
i 1 h p i o 6 1 4 3 0 7 5 srs t 1 6 4 1 3 3 2 Aeo pm u c
t d
- .sA e ne el t f
l ri l d h e l xM x 2 l i d e Gdr e n i
- l o i yoC i
o i t
br c /m y , s n
. i Lh1 h<
Kt3 e o t
2 s
l i 4 0 0 0 0 0 r f0 -
o0I 1 3 6 0 0 0 0 e p
5 l
a 1 4 1 3
1 9 1, 1, 0, e6 r i 7 6 7 0 s o t 2 2 1 s0 l
t ft n d1 r _o r t e i of ono f et . b ro I y r cs hy sd ae tt il fi i si t yh s i l cul _ltl y _ .dsen a
nrnb ei "
s aiK
-ri%mv 2 6 0 0 0 0 0 ]
0.
5l adte Aoea e 6 1 1 3 0 3 2 7 0 bn f vb l bt9 2 5 4 5 5 3 4 1f ao t i o u y ol t j t c9 2 3 4 2 1 i itt r we A f ncp
& . t rr ax eee t n eoal nift a i t u ecf n Biee d-e i
t ccsp oaeo
- f tf ei d o<
r l t y Sfl l i sesc y ai 4 0 0 0 0 0 0 t
n oooc Ccda h mv 7 2 9 0 0 0 0 la se1>vir l
' ri 3 0 5 6, 6, 4, 3, cot o bt
- c 1 5 2 1 l f 9 i
s d
hi f
1
. A 1 3 2 1 yet n hjou 1 t ab e a .
nss l
b cal el 0 0 0 aees o citwwe T
nvs 0 5 0 0 5 0 i ar e 5 1 2 5 1 1 2 ril im t i t
t el stl 0 5
0 5
0 0
0
- eccs mnns i
nn DI p 1 2 5 0 5 AI iA 1 1 "l > Cd
' t' li{l llllllf (: l [
_nw .
. , . i l
the data provided in Table'9 ,above, and ignoring wind' direction i. . j M
frequencies and differences'in reactor power-level and design, E n.
the cost-benefit ratio specific to New York City can be estimated I
to be approximately a factor of 4 lower than if only the nearest
. reactor (Indian Point.1. or 2) was considered alone.* Similarly,.
for the city of Chicago (which has more than 10 operating plants
. within 200 miles), ,the cost-benefit' ratio is approximately five times lower than the ratio if only a single reactor was considered. -
- 7. Risk-Senefit Analysis As discussed in Section 2, the risk posed by the use of KI as an emergency protective measure for reactor accidents was . judged- by the NCP.P to be minimal. Nevertheless,.a brief analysis is presented here to determine under what conditions, if any, the risk posed by the drug might outweigh its potential benefits. .
Assuming a risk of adverse reaction of 10-6 per 130 =g 1 taclet of KI (see Section 2) and that a total of 10 tablets -
would be administered to each person following an accident, the e risk posed to that persen by the drug equals 10-5 To estimate the thyroid dose for which the potential benefit (reduced risk "From Tacle 9, for normal activity and no 0.1 I-131 dose effectiveness factor, NYC cost-benefit ratio for a single Indian Point reactor = 2.0 x 10 5/;hyroid nodule. Including all 13
-- reactors: -
.' 2 .+ 4 .* * -
5.2x10' 2.0x10' 4 .
4.2x10' cost-cenef;; ratio 2.0x10" and cost-benefit ratio = 5.2 x 10 5 5/ hyroid nedule.
- 59
o . .
4
- 3. .
t.
L 'of nodule occurrence).and risk:of KI are equivalent, the follow-
- e ' '
p
~
ing additional assumptions are made: risk coefficient for -
g4 .
t individual = 3.34 x 10-4/ rem, no-0.1 dose. effectiveness factor j
- for I-131, and 99 percent effective
- use of KI reduces total ~ .
I thyroid dose. by 90 percent.** Then 10-5 , o,9 x (3,34 x lo-4/ red)-
x (equivalent dose), and the equivplent dose =-3 x 10-2 rem.
p 3
What if other assumptions are.made?. Higher ~ risk coefficients,.
L such as those for children (see Se'etion 3),'would result in lower r
credicted
- equivalent. doses. The administration of KI to_everyone within 360* of a site, rather than only to exposed persons, would increase the equivalent dose. Fcr example, if the radioactive plume was 15 wide, the equivalent dose would be a factor of 24 (i.e., 360/15) higher *** (='O.5 rem). Assuming only 50 percent effective Ki (rather than 99%), as well as 360* admi.nistration, the equivalent dose would become 2 rem. Jinally, if a 0.1 dose effectiveness factor for -131 is also assumed, the equivalent dose is increased to approximately 5 rem.****
"99 percent reduction in dose from inhaled radioicdines.
"' Actual percentage reduction depends on the composition of the release. For the accident categories addressed in this study, rouc.hi.v 90 .cercent of the thyroid dose is due to inhaled radiciodines (see Table 5).
- 24 times as man.y individuals would new take the drue.. The adverse reaction risk would therefore be 24 times higner.
- I-131 contributes approximately 75 percent of the dose from inhaled iodines (see Table 5). With a 0.1 dose effectiveness-factor, the effective dose from inhaled iodines is reduced by a factor of (0.75)(0.1) - (0.25) = 0.33. The potential benefit of 50 percent effective K: = 0.3 (0.33)(0,5)(3,34 x 10 ')(equivalent dose). Setting this equal to 24 .'10- ;, the equivalent dose = 5 rem. '
60 i
m ,a -
l
- ]
\
..a l
s.
f.
The range of equivalent doses calculated above for various a.
T. . .!
assumptions are all below the level recommended by the NCRP ."
. a.-
for use of K! (10 rem, see Section 2). Therefore, at the recom- 2.'
4 I.
mended level, the risk posed by the drug does appear to be small ..
f However, several recent compared to its potential benefits.* >.
4 reports sucgest that the risk assopiated with the druc may- be t. ,9
' l"
[
significantly higher than 10-6 per dose for certain segments of .
the population.23,24 If this is confirmed, the risk-benefit .
conclusion for KI would have to be reassessed.
- 8. Summary, Conclusions and Recommendations This study was undertaken to provide guidance to ecliev.- .
makers concerninc the use of pctassium iodide (KI) as an emerc.encv.
protective measure for reactor accidents. Although the effective use of KI could significantly reduce the number of thyroid nodules res ultinc. frem a serious accident, it would have no, or enly .
minor, impact en other accident consequences; including immediate deaths er injuries, delayed cancer deaths, and long-term land contamination. Therefere, the availability of K! would provide oniv.. a sur. e. l emental stratecv. :o he censicered alone. with other cessible protective measures.
The study was performed using the Reac cr Safety Study ('4A5E-1400) consequence model, IRAC. Four categories cf accidents were L
addressed: gap activity release accidents (CAP), OAP withcut
=
rather than 10-C per 1
l *If the adverse reaction riskrisk was 10~'by K! would be minimal posed dcse (see Secticn 2), the compared to its pctential benefits.
Al 1
l i
l u-----____--______-_______ _
1 containment isolation (GAP w/o Isolation), core melt with a -
?
melt-through release (Cere Melt Melt-Through) and core melt .. f t . .- . .
w:.tg an atmospheric release (Core Melt Atmospheric).
. A series 5) -
of thv.roid dose calculations showed that the GAP categor.v does a s
not pese a significant health hacarf to the public at any dis- f tance from the reactor. Fcr the GAP w/o !solaticn and Core Melt Melt-Through categories, doses in excess of recommended protec-tive action guidance levels (PAGS)(5-25 rem) are confined to areas \
within ac. c. roximatelv. 10 and 15 miles of the reactor, re so. e ct ivel.v . ,.
For the Core Melt Atmospheric catecorv., however, thvroid doses - . c, are likelv. to exceed PAGs cut to 100's of miles.
A cest-cenefit analysis for the use cf K: was also performed,
- , ,u ,. ,, .,. .._ u. ,...e. .
- ..
c u..e , ,. s ,d , . c.a .. w. : ., u. .; . .u.
a . , c..... ... , . . ,c.
.. . - .=. . . . . . .. ..
ratios (S per th.yroid nodule crevented) are presented for selected .
- 0
~. ".e . o, . o . e. . .' " a ..a = .e. " . a. s a . =.
.di.s ance 4. 7.a .v a ' s , .= s e ".u' *..".. = . . ~. ~s
..c. . .
- t . .. . . . . u.. e . s. e.. ... .-.
,e
- a. ". .=. . " a *. #. ~. . . t.*. 4 .e. ". a. .' . a. . ..' -. e
. n ... e"~. a - ."-d
. .- *. =. d..
- a. _e -. : e e.. , e .e. ,. ..; :. _=e ...:.
u , : -
. 2 . ./_,..,_ .
, . a s .:,
. .a .. n .. . . . ~. -= u. . a. 1 a..c ..
tion has the potential to be 100%, effective in reducing all dese .
- h
$ I- , g '* . d tg
. f.*J m.) ,Q M c. 4. $. *. C. w.* .
$ .8 g .d".A*".".-)
. . y . .E .C u. . @. .E. u g .O v.* O. { .* **...[31..%
-- 4.".N. A. **
A . .
3 -voy.Ag 4 g . .z e. . m.,..e. m: -. . m. w A o w. 4. ,e..
.J. . .g . - ggg .e..e o....g A 4 .3 .wi . .. 5 g a..g .7 v 3 .4 e. ,
f e
4 .7
. * '.v.
. o .d d .d e .= e . "..".e . e .". . a. , 4. . . *c..". c=ses,
. " a.
~
.." v. . ^w- .4 - # 'c w: . =. " ". - .
'd .'" *** o " .' #,. ",e '." a.. d'J a. d , E .**. *
> 4 .m, g g .E J. w- w. .J o. A
",V ' .h. e e ' ' *r ,,m. ' a. "...e .*. *. * . ' * =., e . ^w #. ,
.c. #.w^ s
- . *-".'a.
.cs .' .' o* C_' #
- a. '"^..*..e-os
.. u.. e 'n . .- ^, s *. -*
- e . . e .. ##*
~ .. ,
- f . e e e ". . a. d ponding'.y increased. ,
. k e c. . c e . *. a d.
. . . . ' a. s
. d. .a. .ha e e . .'.... a . a. d
.,s. "e.e'.. ..=.4-e.
o . . v. .= . a. * =
j
".ra,
.v * .e C ..*y *. #.. . . .e,
~~ 5 w
- .-8 d. . . .#. e . #. v .4 . .': . ". a.. . .*. *. .' c .e ." *. .*
V e '.:' .? .*. *.* *
- a. .
.- kp. .". 3. 5"
' :. ' . * . .' k. a.
A. .,,. g e ~.w. ~ . . e. g v. ~ ...s
- 4 .y a. ..* y. z e .c. oo g 4 --
.wm e. .p A .a . ~. .s . . .
66
^
)
9 -
e '.
) d dd l
b d s e en
~
a e e m r ma
'T t
, ss ur o u n so t s ,
t n e -
- a sf c ss o ov .
p A . a ar r ie s f o f
(
ytr t ap
- d u
t
. s s
. tc ht i R o ro s ia b, v e l ac e wer itl c e n y
a tit t 5556677 yo . e s cfd 0000000 e ns v l e i Aeo 1111111 r r e i rl ap s nn .
o e ,s t y l e xxxxxxx o f p.n c ei l aBd ~
e e. ep e nt a mi 3472624 b n .f il n rt o oixst l u A osr Noy g
u s
r ,eee l y m
t Ch r eI ei1 l ,
i t d pK v m . et f / -
i 0 t u e S e rf t0 ao n ( k . eoa0 o mc e an p r2 n i t e et ( x ,
B
- k 0 cun os t sa 1ili s re s nt . rnht pi o o . 0 pi t n pt C sesS mie ai rre edwi l I eai=sa p
c ei K t a )i lb simhdi f t aa r l el acnWf cb o l rirraP e so f aubgu o r saopgt c dp e ,abr nW n l .eopeiMs at .
b hr t ns a l e. m pI r t o0 c eet T a .
1 e K t0 e gd n v ( vt yi 2 f rie acl y r infl n3f r e I t eono( e . l ce a t Kcd om -)
e at m n) eit ree f m I s 000 et css ,
osn r ,f u e 050050 s vocoent oo ase S el 512511 2 n iracd ocdd so ci nm a(
0505000 12505 i
t o t p c 0dl t e01 er0 ecur03 uia l
yec n es 2 t 11 p f e4t nb 4 1 1 s m th1 aiiI 1 - tGn tc i u et - m r - 1 it e e )
I s oi itt yi l l acf l s % St ssl b r t; ef b A 9oAsoinA o rf e s a 9NWicdOWf l ef ~
T y cec K
e
. . . . . . ln I os l
a 1 234 56 b Kd
~~
c i
w+
m 1 ..
d
,,g.
. , e. .
.c .
i:
i ; effective-(i.e., all persons take the' drug before the cloud .
.a .
n ..
'-passes). Realistic. effectiveness values could be significantly .
- t. Q.f r2 :
smaller. WASII-1400 accident' probabilities were assumed. ' Prob- -.* P i- .
c' ability uncertainties have been estimated to be at least an order , ,
^
'cf= magnitude (see.Section 6). . Estimated costs for a KI program .
were conservatively based on only the' purchase price of the drug .
s and did not include costs for distribution, monitoring, and -
! administrative expenses. The ratics presented in Table 12 are appropriate if there is only a single reacter within 200 miles. '
Many actual sites would be influenced by several reactors, and. .
cost-benefit ratics could be reduced by facters of 2 to 5 (see section 5) . uncertainties in dose and health effects parameters are also large and cocid result in either higher or lower cest- .
benefit ratics. ,
To-seme' extent, the large uncertainties in the abcve assump-tiens hinder cur ability to provide definitive guidance. Never-theless, for the assumptions made, the calculated cest-benefit ratics are nic.h; and even including uncertainties r KI ac.c. ears to be caly mar inally cost-effective, at test.*
Finallv. , us ine. statistics .crevifed bv. the NCRP4, a simc.ie risk-'ce ne f it analysis shewed the risk of adverse reaction pesed by KI at the recccmended acticn levels and desages to be small ecmpared c its potential benefits. Ecwever, several recen:
- A1:nou=n :ne :::a1 ces: associated with a case cf thyroid nodules was not s p e e d " ~ = , , y a c. .cressec, an approximate uppertcune or. .
.517,000 can be inferred frem the information presented in refer- )
ence 25 assuming 1) average hospi:11 care ces s cf 52,300,
- 2) that-hospital ecs:s are 60% cf all direct costs, and 3) that indirect ces:s (ecenemic icsses due to mortality and mercidity) are 4 times higher than direct ecs:s.
64
3 .:, v . , .
j: : - *-
q.
y c,*;. - ..
z.
4.
' ~
[
a_
reports suggest that there-is a significantly higher risk-
. ?..
m u p. associated.with use of the., drug among certain segments.of.the' E;-
t t
! ) ' .'.
population.23_,24 If this is. confirmed,'the risk-benefit.'conclu-
[ 'i j y;.
].,
sion for KI would have to be reassessed.
'e. ..;
i a: Based on the abcve analysis, the following'acditional N- recommendations and commentseare made:. .
'k' 7 . The risk of thyroid nodules was shown to be dominated i~
by the large releases associated with core. melt e
.' accidents in which the containment f ails directly to
- the at
- osphere. Therefore, if design = codifications, i such as filtered containment venting systems, are-implemented to reduce the likelihood of those releases,
. the potential benefit of KI could.be substantially-reduced.
. Before any KI program is implemented, specific alterna-tive strategies for stockpiling and-distributing the drug should be examined to reduce costs and assure effectiveness.
. The use of ccmmen household items (e.g., handkerchiefs and tevels) as res.ciratory filters mav . . erovide siTni-ficant additienal protection against dose due to inhaled radionuclides and shocid be considered further in the development of protective strategies.
4 If a KI .cro.::am is
. =plemented, resocnsicle c.overnmen: .
-[ agenciesshouldgiveprioritytoestablishingguida.[ce (PAGs) concerning when, or ender what conditions, :ne drug should be used.
9 65 l
.,s t
, , I
. . ,i I
, .n
. Finally, whether cr.not a public KI program is imple- . J-o
~
as m. '
mented, it might be wise to have sufficient quantities t. ' ~
of the drug available at or near reactor sites for use -j Oy 1) site personnel, 2) of fsite emergency respense .
personnel, and 3) controlled populations in offsite institutions (e.g., hospitals ,' 'p ris ons ) where -immediate evacuation would be difficult er infeasible.
e 6
m e
66 m___________________.________..______ _ _ _ _ _ _ _ _ _ _ _ _ . _ _ _ . . _ _ _ _ _ _ _ _ _ _ _ . . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
~.
u- -
-g s
s 4
_i. References a.
. ~
4 Calculation of Reac'; -
Reactor Safety Study Accendix VI: (NUREG 7 5/014 ) , U.S.
. t- ~
1.
Accident Consequences, WASH-1400 Ifuclear Regulatory Commission, October 1975.
C. Rasmussen, Examina-Aldrich, D.' C., P. E. McGrath and N. i Measures --
- 2. tion of Offsite Radiological Emergency Protect ve SAND 76-for Nuclear Reactor Accidents Involving Core(1978). Melt, 0454, Sanc:.a Laboratories', Albuquerque, NM '
i-Jan Bev.ea, Some Lonc-Term to theConsequences Atmospnere frcaof Hvoothetical Ma o
/
- 3. _
n.
Tnree Mila l Releases of Radioactivityto the President's Council on Environment
~
Island, Craft Repcrt
~
Qualley, Center for Fnergy and Environmental Studies, .
Princeton University, September 1979.
of Releases of
- 4. Protection of theNCRP Thyroid Gland in the EventNational Council on Radia-Report No. 55,
'Radiciodine, 1977.
tion Protection and Measurements, August G. N. Kelly, United National Radio-Kingdom.
- 5. Personal communication with Dr.
logical Protection 30ard, Harwell Didect, l
- 6. "FeefsAccidental and Potassium Radioactive Iodide as a Contamination Thyroid-3 locking Agentof of Human in Health, Educ and Cepartment Federal Register, a Radiaticn Welfare, Emergency , Food and
- c. art v!!, Drug Administration,p. 58790.
Fridav., December 21, 1978, i0ns Manual of Pr0tective:en-:.0/1 Acticni:-v01,Guifes and Pr0tective septencer .:.
.0, Act--
- 7. - .
- or Nuc_ ear -ncicents,
'U . S .
Environmental Protecti0n Agency.
al., " Risk Assessment Review " Group Report NUREG-CR-0400,
- 5. H. W. Lewis, et to the U.S. Nuclear Regulatory Commission, Septemoer 1973.
9 on Lighr-Water Reactor Sadety," Review of M 47, 1975.
McGrath, E. W.
S. Yaniv, R. M. Elend, P. E.
Wall, I. B., S. Wayland, Overview 10.
Church, and J. R. NuclearofRegulatory the Reactor Saf ety Ccmmiss1:n, Study Consequence Model_, U.S.
o fiUREG-03 40 (1977). l o
and I. 3. Wall, "The Rear: 0r M. Ericson,
- 11. P. E. McGrath, D. and Its Implications for Radic-J Safety Study (WASE-1400) International Svm csium Resconse Planninc,"
I
-- _ :ecreary 1::<.,
~ . -
logical Emer:ency . . - es n, ec:. cents ,
ne danc1:.ng 0:. Rac. iatien on Vienna,~ Austria, IAEA-SM-215/23.
67
- - - ' ' - - - - - - - - _-_m____ _ _ _ _ _ _ _
4
~ D. Johnson, Public' -
12.
D. C. Aldrich, D. M. Ericson, Jr., and J. - d ts:
Protection Strategies for Potential Nuclear Reactor Acci enPuclic and" .1Private .
Sheltering Concepts with ExistingSandia Laboratories, (1977).
Albuquerque, NM
.e SAND 77-1725, .5 f' of State of and Light Local Water Govern--
Nuclear _
- 13. Plannine Basis for the Develcoment
-ment Im2rgency
-~_
Response Plans in Support Nuclear Regulatory Ccamission and Environ- ' -
I'd $fe r P l a n t s_ , U.S. EPA 520/1-73-016, 1978.
inintal Protection Agency , NUREG-039 6, Jcnes, A Model of_
Aldrich, D. C.,
R. M. Blond, and R. B.
14.
Public Evacuation for Atmoscheri'c Radiological Releases,
~
June 1978.
S AND7 S-0092, biddia Laboratories, A1:uquerque, NM ,
L. T. Ritchie, and J. L. Sprung, Effect of ident Con,
- 15. Aldrich, D. C., NM, Revised Evacuation SAND 75-0095, Mocel en Reactor Safety Study AccSandia Laborator secuences, February 1979.
R. 3. Jones, P. E. McGrath GEU Aldrich, D. C., D. M. 2ricson, Jr.,of Offsite Emergency ?rotec- %'f.
- 16. "Examinatice l Meeting en 2 and N. C. Rasmussen, i S-10, h"$%
tive Measures for Core Melt 7.0cidents," ANS Tcp caPro 1973, Newport Beach, CA.
Ericson, Jr., Public ProtectionMulti-Aldrich, D. C., and D.
M. ~
17.
Strategies in the Event of a Nuclear Reactor SAND Acc dent:
77-1555, compartment ventilation Model for Shelters _, January 1976.
Sancia Laboratories, Albuquerque, SM, s Cohen, D. C.
Aldrich (ed.), Infiltrating
- 13. A. F. Cohen, S. L. Sancia of Particulate Matter into Buildings, 5AND79-2079, NM, Ncvemoer 1979.
Lacora: Ories, Albuquerque, Auten, " Emergency Res- j
- 19. E. G. Guy:On, E. M. De c.<e r and G. T. 2-d Biological piratory ProtecnicnArch.'Ind. agains t Health Radiolog' 20_,-=' 91-95 (1959).
Aerosols, A.M.A. I Industrial Hygiene Industrial
- 20. Respira: cry Protective Devices Manual, Am.Associa::en, A Ev. c. ienis ts , 19 6 3.
C. Frdmann, "Cemparison of the EPRI F. L. Leverenc and R. Or Saf ety 5tudy ,"
- 21. Science and ~ewis Cenmittee deview cf the Reac c.repared fcr Electric Power Research Institute by Inc., EPRI Recorr N?-ll30, J uiv. 1979.
Ae.olications,
. ^
cf Nuclear Pcwer Plants ," Nuclear News , Vol. 22,
- 22. "World ist __
No. 10, August 1979. ~
al. , "?o assium Iodide Sensitivity inf Tour
- 23. Curd, John G., et Patients with EypccOmplementemic Decencer, 1979, Vol. Vasculitis,"
91, No. Annals O6, pp 353-557.
Internal Medicine, !
t 68 i
. , a
. e ,. ; .
( 24. Rosenstein, 3eryl J., et al., " Iodide-Induced Hypothyroidism l Without a Goiter in an Infant with Cystic Fibrosis," Journal .
! i- of Pedriatrics, August, 1978, Vol. 93, No. 2, pp 261-262. [.
~ .
,,
- 25. Scotto, Joseph and Leonard Chiazze, " Cancer Prevalence and
.s Hospital Payments," J. Natl. Cancer Inst., Vol. 59, No. 2, August, 1977, pp 345-3498. -
e 4
M 4
O e
A 4
9 O
e o e A
W l
DISTRIBUTION: _
- 3 l . Roger.31ond (50) .
5
- t l- Probabilistic Analysis Staff ,-
Office of Nuclear Regulatory Research i '* *'
USNuclear Regulatory Commission
. Washington, DC 20555 A. Bayer INR-Kernforschungszentrum Karlsruhe 75 Karlsruhe 1 'e Postfach 3640 '
West Germany Douglas Cooper Department of Environmental Health Physics Harvard School of Public Health 663 Huntington Avenue Boston, MA 02215 Keith Woodward Picard & Lcwe Associates -
1200 18th Street T4 Washington, DC 20036 Joseph Logsdon US Environmental Protection Agency nn.,.,,o,...L 401 M Street NW Washington, DC 20024 r#
S. Chakrahorty Abteilung fur die Sicherheit der Kernanlagen Eidgenossisches Amt fur Energiewirtscnaf:
CH-5303 Wurenlingen Switzerland N. Rasmussen .
Nuclear Engineering Department Massachusetts Institute of Technology Cambridge, MA 02139 Dr. Ulf Tveten Institutt for Atomenergi PO Box 40 2007 Kieller .
Norway-m.
Dr. Seppo Vuori
. Valtion Teknillinen Tutkimuskeskus Statens Tekniska Forskningscentral helsinki Finland 71
u ,
H-- .,
c
- y
, , v, - -
, .=
I 'D'r. Rosalyn S.fYalow 4' >
.Montefiore Hosoital and Medical Center. ~
- ~~
F .
111 East 210th Street.1 .c- e
. Bronx, NY. 10467 - .s
- . . .' J
^
Dr.' Frank.' von Hippel -
Center for Environmental Studies-Princeton University. * .)
-Princeton, NJ 08544 Dr. Thomas Fearon -,
National. Councail on Radiation - '
Protection'and Measurements
- .7910 Woodmont Avenue, Suite 1016' -
L Washngton, DC: 20014 -
\:
l Prof. Richard Wilson .
. Department of Physics
-Harvard University "
Cambridge, MA- 02138 _
H. Arnold.
Secretary of Health -
" Commonwealth of-Pennsylvania
, 802. Health and Welfare Eldg. .
Harrisburg, PA 17120 Dr. H. L. Gjorup Health Physics capartment .
Riso National Lacoratory DK-4000 Roskilde Cenmark Prof. Niel Wald .
Graduate School'of Public Health '
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Of fice of Nuclear Reactor Regulatory
.US Nuclear Regulator-y Ccamission 545 Phillips Washington, DC 20555 J. Schut:-Larsen Arvebiologisk Institut Tagensverj 14 e KD-2200 Copenhagen N ._ ,
Denmark .
. 72
___m._.--..- __ a _ _ _ _ . _ _ . - _ _ . _ ___--.__--a_m____._______._.__m_.__m---__ __.__ _ _ _ _ _ _ _ _ _ _ . ____
! 1 1
l j
Bernard Conen l University of Pittsburgh -1
- a. Faculity of Arts and Sciences ;
Department of Physics (
Pittsburgh, PA 15260 -
- s. .
,, s -
I Pfo. Dade Moeller (3) -
j Department of Environmental Health Physics I Harvard School of Public Health 663 Huntington Avenue >
Boston, MA 02215 ,
o Dr. Bernard Shleien (5)
Bureau of Radiological Health HFX-460
. 5600 Fishers Lane ~
Rockville, MD 20857 Dr. Eugene L. Saenger Eugene L. Saenger Radioisotope Laboratory Cincinnati General Hospital 234 Goodman Street Cincinnati, OH 45267 Dr. F. HorsCa Projekt Nukleare Sicherheit Kernforschungszentrum Karlsruhe GmbH Postf ach 3640 0-7500 Karlsruhe 1 West Germany Mr. T. Iijima Division of Reactor Safety Evaluation -
Tokai Research Establishment Japan Atomic Energy Research Institute Tokai-mura Ibaraki-ken 911 13 Japan Jim Martin Probabilistic Analysis Staff US Nuclear Regulatory Commission Washington, DC 20555 Dr. G. N. Kelly (3)
National Radiological Protection Board
.: Harwell, Didcot l3 Oxfordshire OX 11 CRC "ngland ..
e4 We Yo
1 a
. . )
I
. . .. i J
-l
.Mr..C. Deville rs Chef du Service d' Etudes de Surete - < J l Radiologique et des Sites - ' #
l Contfe d' Etudes nucleaires 'i SP Wo. 6 -
r 1
1 F-92260 Fontenay-aux-Roses 1 France . i E. C. Watson ,
Battelle Pacific Northwest Laboratories '
Battelle. Boulevard .
Richland, WA 99352 Dr. Ian Wall Nuclear Safety and Analysis Department Electric Power Research Institute 3412 Hillview Avenue Po dox 10412 Palo Alto, CA 94303 Pfo. Yasushi Nishiwaki Jagdschicssgasse 91 A-1130 Vienna Austria Dr. Jan Beyea
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~
Harcid'C0111ns (100) office of State Programs US Nuclear Regulatory Ccamission 7713 M.N33 -
dashingten, DC 20555 Dr. G. D. l'a is e r United Kingdom ATctac Energy Authority Safety and Reliability Directorate Wigshaw Lane Dulcheth Warrington WA 3 4NE -
Cheshirt England e
- g 74
_ _ _ . _ _ _ _ __. __-_________--_-_.mm__-_____.---- - - . __----_---_------------_ . - -
a
. 1233 J. M. Taylor ,
l 4000 A. Hara:n
!;. 4400 A. W. Snyder - ;
!. 4410 D. J. McCloskey i
!*- Attn: J. W. Hickman
* G. B. Varnado L. D. Chapman 4413 N. R. Ortiz 4413 D. C. Aldrich (100) 4413 N. C. Finley 4413 J. D. Johnson ,
4413 L. T. Ritchie '
4414 D. M. Ericson, Jr.
3141 T. L. Werner (5) 3151 W. L. Garner (3) for DOC / TIC (Unlimited Release) 3154-3 R. P. Campbell (25) for URO Distribution to NTIS 6266 S. A. Aas I:
o, 0
O 9
4
^ ~ ~ ~ ~ ' ~'
~ _ ~ . _ _-_______--_-_---_ _ -_= _ -- _
9 9
- 9 mm I
4 8
9 d
ENCLOSURE D
tj UNITED STATES ndosum 1
- gj' ,., ( NUCLEAR REGULATORY COMMISSION
, 3 \[Ijnj- ADVISORY COMMITTEE ON REACTOR SAFEGUARDS
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WASHINGTON. D. C,20555
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May 17, 1983 Mr. William J. Dircks '
Executive Director for Operations i U.S. Nuclear Regulatory Commission Washington, D. C. 20555 ,
Dear Mr. Dircks:
SUBJECT:
ACRS SUBCOMMITTEE REPORT ON THE USE OF POTASSIUM IODIDE (KI)
AS A THYROID BLOCKING AGENT On April 28, 1983 the ACRS Subcommittee on Reactor Radiological Effects met with the NRC Staff for discussions on the issh,e of stockpiling and redistribution of potassium iodide (KI) for potential nuclear power plant accidents. This issue had previously been discussed during the ACRS joint Subcommittee meeting on Class 9 Accidents and Reactor Radiological Effects, February 22, 1983. Representatives from the Food and Drug Admin -
istration (FDA) and the National Council on Radiation Protection and Measurements (NCRP) also participated in the Subcommittee meeting on April 28.
On the basis of these discussions, the Subcommittee has summarized its comments and.a copy is enclosed for your information. Also appended for your information, are copies of the written comments on this subject sub-mitted to the Subcommittee by Dr. Eugene Saenger, representing the NCRP, and Dr. Bernard Shleien, representing the FDA. We trust these comments will be helpful to the NRC Staff.
Sincerely yours.
f>C $ =
Jesse C. Ebersole Acting Chairman
Enclosures:
- 1. " Comments on the Use of Potassium Iodide (KI)
As a Thyroid Blocking Agent," by ACRS Subcom-mittee on Reactor Radiological Effects - 4/30/83
- 2. " Comments on the NRC Document: Radiation Protection -
Thyroid Blocking - Draft" by Eugene L. Saenger, 4/28/83
- 3. " Recommendations on the Use of Potassium Iodide as a -
Thyroid-Blocking Agent in Radiation Accidents - An FDA Update," by Bernard Shleien odzia
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COMMENTS ON THE USE OF POTASSIUM IODIDE (KI)
AS A THYROID BLOCKING AGENT Prepared by
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Subcommittee on Reactor Radiological Effects
. Advisory Comittee on Reactor Safeguards April 30,1983 The ACRS Subcommittee on Reactor Radiological Effects met on April 28, 1983, with representatives of' the NRC Staff; the Food and Drug Administration (FDA), and the' National Council on Radiation Protection and Measurements (NCRP) to discuss the evaluation being conducted by the NRC Staff relative to the use of' potassium iodide (KI) as a thyroid blocking agent during reactor accidents. On the basis of this meeting, the Subcommittee prepared the following comments:
- 1. Estimates presented to the Subcommittee by the NRC Staff indicate that, for accidents covering a wide range, the greatest projected health impact (cancer fatalities) on the population as a result of passage of the plume would be due to whole body exposures as contrasted to expos-ures to the thyroid., If this is true, it raises questions as to the basis for the use of thyroid blocking as a primary emergency protective action. This matter should be reevaluated before proceeding f urther with the development of an agency position on this issue. Of parti cu-lar importance in this reevaluation is the consideration of the newer source term information which should result from current NRC research.
- 2. The risk / benefit analyses conducted by the NRC Staff on this subject do not appear to be cornpatible with (or comparable to) approaches used in evaluating other aspects of nuclear emergency planning. For example, if the same evaluations were made, would there be justification for the' conduct of eme rgen cy drills or the installation of warning sirens?
Simila rly, the question could be raised as to whether there would be justifi cation for population evacuations.
- 3. The NRC should also be encouraged to join with the Federal Emergency ,
Management Agency (FEMA) in developing definitive guidance for state '
and local agencies on these matters. Provision of KI to onsite nuclear power plant workers and to potential emergency rescue teams appears to be justified. Mechanisms for the distribution and instructions on the use of KI by the general public, however, should be left to the judgment of state and local public health and/or emergency planning officials.
Stockpiling or redistribution of KI to the public should not be made an NRC licensing requirement.
- 4. Review of this subject by the Subcommittee indicated that several ad-ditional technical questions remain to be answered. These include determinations relative to:
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- a. ' The shelf life of KI and possible methods for' extending it.
.b. The question of the potentially greater carcinogenic effects of-thyroid exposures from external sources as contrasted to those !
from internally deposited radiciodine.
- c. The sensitivity of the cost / benefit calculations, assuming a uniform . population. density, versus more realistic' population distributions.
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Comments on the NRC Document:
RA.DIATION PROTECTION - THYROID BLOCKING -' DRAFT L Eugene L. Saenger, M.D.
- April 28, 1983 .
- In 1972 the NCRP formed an ad hoc committee on Thyroid Blocking resulting in the issuance of NCRP Report 55. In
,' addition to'three thyroidologists, a nuclear engineer and a public health physician, aid was received from a number of staff members of NRC. The final report was reviewed'by the NCRP membership numbering about 65 scien'tists and physicians. The report recommended a blocking dose of 130 mg of KI (100 mg of I) per day _upon advice of public health authorities if the radiation
' dose t o the thyroid approaches 10 rad. This daily dose is to be continued under guidance of public health authorities.
Sheltering, evacuation and milk surveillance were also discussed as were possibic complications of KI therapy. No specific recommendations for stockpiling and distribution were made.
The FDA reviewed, expanded and finalized these recommendations between 1977 and the present.
In March and April 1979'at Three Mi3e Island there was
-escape outside of the containment vessel of so small an amount of.
radioactive iodine that it did not constitute a threat to the population either within the plume or ingestion zones. Since then there has been speculation (at least from this physician's viewpoint) as the possible occurrence of a deficit in release of radioiodines.
Meanwhile the potential use of KI has been criticized in several ways. Aldrich and Blond of the NRC in_several '
publications have indicated that XI is not cost effective in preventing either thyroid nodules or thyroid cancer. Yalow (Yalow RS. Potassium iodide: Effectiveness after nuclear accidents. Science 218: 742, 1982) regards the use of KI as dangerous pointing out that the number of serious iodine effects wi31 exceed the number of thyroid tumors which may be prevented.
The American Thyroid Association although agreeing that chemical blocking of the thyroid gland is a reasonable protective measure if administered under appropriate circumstances recommends that the decision point should be a potential thyroid dose of 100 rad.
An opposite viewpoint has been expressed on a number of occasions by Von Hippel (Von Hippel F. Potassium iodide policy.
Science 218: 6, 1982) who believes that KI should be distributed -
over a radius of 100 -200 miles. His yaygument focuses on his interpretation of equal efficacy of I as compared to external x-irradiation in the production of thyroid abnormalities and certain other calculations regarding the dissemination of radiciodines which differ from those of the Reactor Safety Study (RSS).
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The RSSchas been critically reviewed on several occasions and was criticized in part as being not sufficiently conservative (NUREG/CR-04 00 [see p. A-2 of NRC draft)). Rasmussen, however, pointed out that the RSS prediction was conservative in its productions in comparison with the actual experience at TMI (Hubner K, Fry S: The Medical Basis for Radiation Accident Preparedness. . Elsevier/ North Holland, New York, 1980). .More recentlyil,9wis has indicated that the RSS is-conservatively ~
biased (Scientific American, March 1980). More recent studies (NUREG 2239) suggest that the major, areas of contamination may well involve sectors within a 2-5 mile radius, i.e. that more planning and drills will be useful close to the fence line. A probability is assigned to the ingestion zone of about 1-2 orders of' magnitude less than in the plume zone.
The current NRC draft is based on some assumptions that require further discussion and clarification. It is quite unclear why the entire U.S. population needs to be supplied with KI. In addition to the lowered probability of release of radiciodines from the containment vessel (NUREG 2239) it seems likely frem the extensive meteorological studies that only a few sectors. downwind would be involved. Also it does not seem reasonable that Governmental agencies, either local or Federal, should be required to stockpile and distribute e blocking agent.
The governments] agencies do not necessarily plan to furnish transportation for evacuation although they have certainly cooperated well with the private sector and service agencies such as the Red Cross in many crises in the recent and distant past.
These points will be analyzed further below but the present draft seems unrealistic in these two important parameters based on relatively recent NRC documents.
Currently we are attempting to purchase the 130 mg KI tab 3ets as OTC preparations in the Cincinnati area. This effort has been unsuccessful. Certainly there are many reasons for this difficulty. At the very low cost and presumably low price, it wi]1 be necessary to generate a large volume of sales in order to provide the participating drug companies with a cost effective product. These concerns should not be penalized for their apparent lack of willingness to participate in this effort. It is important to provide some marketing opportunities. For example over the past deccde it became necessary for DOE to subsidize the production of pharmaceutical grade DTPA compounds in amounts suitable for therapy of transuranic element contamination because the FDA would not accept the manufacturer's claim of. efficacy for other purposes. A similar ro3e for KI hardly seems justifiable although this possibility may require consideration. -
In order to make some further estimates.of the need for'KI. _.._ .
based on a given dose, say 20-100 rem to the thyroid, the total population in the vicinity of 36 power reactors was summed from NUREG 3856 as shown in Table 1. Using many of the assumptions in the NRC draft dccument except for the need to supply the total E.L. Saenger, M.D.
ma m - . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ . . _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
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L LU.S. population each with one tablet some further calculations I follow.-
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POPULATIONS AROUND POWER REACTORS E From NUREG 1856* July 1981 Radius Permanent' Transient Row Totals 2 mile '99523 18313 117836 5 mile. . 490601 88479 579080 110 mile _
2136016 301854 2437870 Column Totals '2726140 408646 3134786
- Fifty tso reactor sites are listed but only 36 supplied
. population date As an example derived from tge NRC draft document, with a
- U.S. population of about 200 x 10 persons, the number within a 10 mile radius of 36 repetor sites is 3/200 = 1.5% of U.S.
population. .'It'would seem w.ithin reason to estimate that no more thanthisfractionwouldrecyj{eKIprotectionbasedonthelow prohnbility of a :n3 ease of I. To carry these projections.
further.with a probability of a reactor accident of 10 /yr for.
36 reactors listgd in the above report, one.can calculate the
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cost as'36 x 10 x 0.015 x $200 x 10 = 1080/yr = $1080.00 at IOc per tablet for a 10 day supply.
131 It is true that I can possibly involve a portion of the ingestion zone but probably not within a period of 24-48 hours which would give sufficient tine for sheltering, evacuation, distribution of KI and redistribution of existing milksheds.
Estinate of thyroid nodules: BEIR III (p.301) estimates 12 cases per 10' PY per rad. Usigg the above population within the 10 mile zone, about 3 x 10 , and without correctiog for ageg race, sex or latency, an estimate would be 3 x 10 x 32 x 10 per rad per year or 36 cases / rad in a given year. Again without corrections about 12 cases / rad /yr might be malignant, about 1-2 cases / rad / year would be fatal.
At a cost of S1080 the cost benefit ratio would be 1080/36 =
'530.00 per nodule per rad per year. If one were to multiply these values by an average lifetime of 50 years after exposure, the excess cases prevented wou3d be 36 x 50 years or 1800 and the cost' benefit ratio would become 1080/1800 = 60c/ case assuming 100% effectiveness of KI and blocking at I rad or less. If 30 rad is used as a threshold cost becomes 20/ case.
If one were to include the ingestion zone based on Tables 1 and 2 there is a change in the above calculation of a factor of E.L. Scenger, M.D.
April 28, 1983 . _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - _ _ -
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. ' .i ,30-300 that would increase the cost benefit ratio to S6.00-560.0,0.
In a period when there are enormous investments in nuclear "
power p.lants many of which are not completed for various reasons and great concern by citizens concerning safety, it does not seem useful to engage in debates concerning the protection of the thyroid gland between agencies of the Government. Several steps are recommended to aid in the' resolution of this problem:
- 1. A more thorough study of the e'ffects of policies of other governments, principally those in. Europe, should be made preferably by an international conference held here or by individual visits.
2.- There shculd be further-studies on stability under different conditions of packaging, climate, storage and other factors of various iodine preparatio,ns.
- 3. In the drills as required in UUREG 0654 study of methods of distribution of. iodine compounds as compared to sheltering and evacuation shculd be carried out.
Particular attention should be paid to the recommendations of masks, filters, wet towels and other home remedies to filter out airborne iodine compounds in whatever physico-chemical states they exist. These casual proposals, however simple and inexpensive they may seen,' offer serious threats to large classes of persons including infants and young children, patients with chronic cardiac and pulmonary diseases, the elderly and persons who are or may easily become emotionally disturbed.
- 4. A trial of distribution by local authorities as compared with over the counter sales should be carried out in two comparable areas to determine the efficiency and costs to the public of these two different methods.
- 5. It is essential to define far more precisely than has been donc before the population which may be at risk for thyroid exposures above 25 rad at each reactor site.
1 E.L. Saenger, M.D.
April _2Bo_1983_ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
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Reco==endations en the use cf Potessium Icdida s.,
cs a Thyroid-Biceking Agent in Radiation Accidents An TDA Update
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Bernard Sh1eien, Pharm.D.
Certified Health Physicist, ABEP National Center for Devices and Radiological Health Jerone A. Ealperin, M.P.E.
James M.,Bilstad, M.D.
Paula Botstein, M.D. i Edwin V. Dutra, Jr., J.D.
National Center for Drugs and Biologics Food and Drug Administration The Tood and Drug Ad= ministration (TDA) published a notice in the Federal R2gister on Decenber 15, 1978 entitled " Potassium Iodide as a Thyroid Blocking Agent in a Radiation E=ergency." In this notice TDA invited manufacturers to sub=1t New Drug Applications (NDA) for potassium iodide products and announced the availability of labeling guidelines. The notice had no i==ediate effect, however, en public discourse (1). It was only ofter the accident at Three Mile Island that TDA received any NDAs.
Approval of NDAs opened further debate about the use of potassium iodide.
Tha past 3 years have produced vigorous, often heated discussion about the role of the drug as a thyroid-blocking agent, with many opinions expressed about the population in when the drug should be used, the thyroid dose at
.which it should be used, and the =ethods for =aking it available. The controversy did not reach its heights until TDA issued its final reco==en-dations on the use of potassium iodide as a thyroid-blocking agent in a radiation e=ergency (2). This is not surprising because the agency had to make sene decisions with which there was no unanimit,y. These decisions involved the weighing the benefits of using potassiu= iodide with the -
radiation risk tosche thyroid gland fre= iodine-131. There are, in addition, other controversial matters concerning the stockpiling and distribution of 1
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L ';.':porcssium iodid2 on which th3 FDA properly did not.take a positica. This is ecause these matters do not fall within the jurisdiction of the FDA. !
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- j. At this juncture it is appropriate to review TDA's recommendations to \
J understand the agency's positions and the likely implications for the use cf potassium iodide. At the same time, it is also appropriate to review the ralated issues upon which TDA did not take a p(sition. I J
Safety and Effectiveness In its initial notice on potassium iodide the FDA stated that potassium iodide is safe and effective for use as a thyroid-blocking agent in,a ,
radiation energency in which radiciodines are accidently released into the environment (1). This finding is based on TDA's review of the infor=ation en the ability of stable iodine to saturate the thyroid gland and on
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psssible side effects of the drug in the published literature dating back to the 1800's, including reports in the FDA's Voluntary Reporting Syster on cdverse drug reactions.
There is general agreement that the drug can achieve almost co=plete (greater than 90 percent) blocking of radioactive iodine uptake by the thyroid gland. This effect can be obtained by the oral ad= ministration of 130 milligra=s (=g) of potassiu= iodide (65 =g for infants under one year of age) just before or at the ti=e of exposure to iodine-131. A substantial b2nefit (i.e., a block of 50 percent) is attainable if administered up to three to four hours af ter acute exposure.
On the issue of potassium iodide's safety, however, there is less agreement. -
For exa=ple, Dr. Xalow raised significant questions concerning the risk of
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.w w porcss'ium. icdide in har ' comments en a dref t of FDA's recommendations (3)
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cod more recently in a summary of testimony at a Congressional hearing cheired by Mr. Markey of Massachusetts held on March 5, 1982 (4). Dr.
Yolov suggested that based on arperience by Curd and the incidence of ,
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hypocomplementemia vasculitis in rheumatoid' arthritis that there might be 6in'10,000 acute,severereactionsfrorthemedicallyunsurperdised i administration of potassium iodide. Dr. Yalow's reference to Curd was to a report in the Annals of Internal Medicine of December 1979, by John C.
. Curd, M.D.,' et al. titled, " Potassium Iodide Sens'itivity in Four Patients with Hypocomplementemia Vasculitis *(5)., Metabolic studies of. radio-labeled proteins were conducted in 126 patients of which four (3 percent of the patients in the study group) were suspected of being sensitive to potassium.
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' iodide because they had repeatedly developed urticaria and other allergic w 'nptoms af ter multiple administrations. The potassium iodide was administered in 0.5 gram doces on multiple occasions in serial fashion to block thyroid uptake of iodine for purposes of the study. ' Two of the four patients were selected to evaluate the possible association of potassium iodide sensitivity with urticaria, hypoce=plemente=1a and vasculitis. The patients were given .
1 gram of potassium iodide initially and then potassium iodide was administered
-twice a day until sensitivity reactions occurred or for 2 days. Challenge with 1.0 gm of potassium iodide in the two sensitive patients precipitated on allergic type reaction of moderate severity in one patient, and a prolonged severe systemic illness in the other. The authors believed both reactions vare caused by the potassium iodide. Ten control patients did not present tha sa=e reaction, tending to confirm the impression of potassium iodide sensitivity in the two patients.
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- 1. Th'dy,. Curd's study confirm 2d potassium iodide sensitivity in two patients !
i Isha had had repeated, multiple, large (0.5 gram) administrations of the d'ru g .*
Th2 incidence cf hypocomplementemia vasculitis is a rare condition.
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At the
- I University of Cincinnati Medical Center, a referral institution, with over
'2,000 patient beds.and hundreds of thousands of outpatient visits per year, j t
caly 12 individuals are seen per year with this condition (6). Based on Curd's study (in which 3 percent of the patients had a severe reaction) and tha incidence cited above, the figure of 6 per 10,000 appears to be greatly cvar estimated. ,
Potassium iodide in large doses (200-1200 mg daily for adults and 100 mg or more for children) has been vi'dely used for years in the long-term catage=ent of brecchial asthma and other pu1=onary disorders. Individual reports of complications frem iodide ad= ministration in the medical literature for the '
cost part do not identify the size of the patient population taking iodides from which the cases have been drawn. While cases are undoubtedly under-reported, the nu=ber of reports of adverse reactions from potassiu= iodide ' .
received by the FDA has been low. yhe incidence of significant adverse reactions from short-term ad= ministration of potassiu= iodide to hu=ans in daily doses of 65 or 130 mg is unknown but is expected to be low (2). (It is important to distinguish the much more com=en reports of reactions to organic bound iodine ec= pounds). ,
The known potential for potassiu= iodide to cause serious side effects in a small sensitive population is not sufficient grou=ds from which to conclude,
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a cr :reca pastulete, a significant end quantificble proportion of sarious
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recetions (or deaths) in patient populations which would be exposed to much czaller doses of the drug over a limited time and which would not be expected to include patients of this category. (Most are under a physician's care). -
Th2 adverse reactions to potassium iodide can be grouped into thyroid and ntn-thyroid effects. For example, the thyroid reactions include: (1) o Iodide gotter with or without_ hypothyroidism (especially neonatal goiter);
(2) Hyperthyroidism (Jedbasedow syndrone); and (3) Hypothyroidism. The nonthyroid reactions include: (1) Dermatologic and zucous me=brane reactions;
_ (2) " Iodide Mu=ps" and miscellaneous reactions; and (3) Serum sickness type hypersensitivity and vascular reactions. The occurrence of most side offects and toxicities appears' to be proportional to dose and duration of treccuent, and except for anaphylassis most are not expected under the phar =aceutical dose regines rece== ended for thyroid-blocking. ,
In view of the benefit to be derived from the use of the drug to block the thyroid in a radiation accident, the FDA concluded that the benefit / risk ratio favors the use of the drug for that purpose when the projected' radiation dose to the thyroid gland from radiciodines released into the environment is equal or greater than 25 re=. This conclusion is discussed
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further under Thyroid Radiation Risks.
Thyroid Radiation Risks There is a paucity of human data relevant to the induction of radiation effects from iodine-131, particularly in children. Two epide=iological ,
studies are availahle which atte=pt to quantify the risk of thyroid cancer
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[ .fhaiodins-131irrodiatien. Data froa Rallista et s1. (7) and Holm (8) . ,
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didnot show any increase of thyroid cancer in their irradiated popcia-
- tions with- estimated mean thyroid doses of 18 to 160 rem,' respectively, from nuclear weapon' fallout or iodine-131 diagnostic procedures when -
compared to the spontaneous thyroid cancer incidence. Holm's study popu-
) iction was mostly adult at the time of irradiation (8). 1a adult thyroid cells do not normally undergo cell division, their radiogenic thyroid cancer risk would not be expected to be the same as those in infants and children.
Furthermore, about a third of the Holm's irraddated population received thyroid hormone therapy, surgery, or both following irradiation, which may also have contributed to the lov observed thyroid cancer incidence.
In the Rallison et al. study,an esti=4ted average thyroid dose of 18 re=
from fallout from atmospheric nuclear weapons tests was believed to have
, been received by his study population (7). The actual thyroid doses have not been adequately der.er=ined in this populatien. This is evidenced by the continuing controversy surrounding radiation effects around the Nevada test site fre= veapon testing in the 1950's and 60's. Moreover, the i
follow-up. period of 14 years in his irradiated population may not be '
adequate for full radiogenic thyroid'eancer expression.
In an earlier case study of Marshall Islanders exposed to nuclear weapon fallout, Conar'd et al. found that within 22 years af ter exposure 24 of 68 persons exposed on Rongelap had developed thyroid nodules and four of these ware thyroid cancer (9). Thyroid doses for the Rongelap people were estimated to be from 220 to 450 rads for an adult and 700 to 1400 rads for
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o child (9). Thes, doses include those from radiciodines (including short-lived radiciodice isotopes) and an estimated external gat =a dose of
, 175 rad'.
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fha.riskfof'thyroidcancarinman=fromexternal-x-rayhosbeen. demonstrated-
' '1in' numerous : epidemiologies studies (10,11,12). 'For young adults treated a- ,
_ with x-rays, the rdsk of thyroid cancer is-esti=ated at 1.6 to 9.3 excess casesfof thyroid cancer per 106 yy. rem (13).~(PY is a person year of 4 follow-up). . Ron~ and Modan reported an increased incidence of thyroid cancer it a mean thyroid dose of about 9 rads in about 11,000 children irradiated for tinea capitis and followed up for 12 to 23 years (10).
The irpression that iodine-131 is not' as effective as x-rays in thyroid ,
cancer induction was' based mainly on the observations of Donisch in rats and Maxon et al. :bs man (14,15). Doniach's conclusion that x-ray was 10 times more effective than iodine-131 in thyroid cancer induction was-based on the results of three rat studies in which an estimated thyroid dose of approx 1=4tely 10,000 rem frem iodine-131 was thought to be equivalent to that'of 1000 rem from external x-rays. In these studies, a surviving proportion of less that 28 percent of the ani=41s was left after a 15 month or a 2 year study. Such lov survival and s=all su=ber of ani=als per dose group can lead to serious biasesJOs the esti=4 tion of cancer incidence.
The effect of cell killing at the high radiation doses due to the iodine-131 versus the lower dose used for external x-rays was not accounted for by the Donisch study (14). Similar117 , the relative thyroid cancer susceptibility of 70:1 between x-ray and iodine-131 as reported by Maxon et al. in children could also be due to difference in cell killing at the higher iodine-131 j doses used in the comparison. (The x-ray dose ranged from 0-1500 rem, 1
- l. whereas the iodize-131 doses were approximately 9000 rem).
Thus the risk ofs thyroid cancer following external x irradiation' of the
.g thyroid has been well established, but the risks fron internal exposure to
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tydin;-131creest. Until n:v the i=prossion was that lodin2-131 was cuch
'.', lass , effective than external x-rays _ in thyroid cancer induction. The
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-ritionale usually given for this difference is a low dose rate and an un:ven dose distribution in the thyroid gland from internal exposure to l
icdine-131.- However, data from a recent animal study by Lee et al. (16) i demonstrated that the dese-response functicus in thyroid cancer induction i
in rats from both iodine-131 and external x-rays are similar within the dose range of 0-1000 rea.
Tha paucity of human data relevant to the induction of radiation effects froa iodine-131, particularly in children, has convinced the FDA that it is prudent to e= ploy risk estimates from external irradiation studies in reoching the conclusions upon which its recoc=endations are based.
Fro 3 this evidence, the TDA concluded that the risks of radiciodine-induced thyroid nodules or cancer at a projected radiation dose of 25 rem or greater to the thyroid gland from radiciodines released into the environ =ent outveigh tha risks from the short-ter= use of relatively lev doses of potassium iodide for thyroid blocking in a , radiation e=ergency. The TDA reco== ends that potassfu= iodide in doses of 130 mg per day for adults and children 1 yaar and above, and 65 ng per day for children below 1 year of age, be considered in those persons likely to receive a projected radiation dose of 25 rem or greater to the thyroid gland from radiciodines released to the environ =ent (2). A projected dose of this magnitude is equal nu=erically to the Environmental Protection Agency's upper Protective Action Guidance.l./
1/ EPA Protective Action Guides call for sheltering, evacuation and -
controlledaccest(hsprotectiveactionswhenthetotalaccu=ulatedthyroid doses are projected at 5 to 25 re= for the general population (17). The Iowar level is used if there are no =ajor constraints. If local constraints exist, the higher value is e= ployed. However, the EPA guides do not specifically note the use of potassium iodide as an appropriate protective cetion for the general population.
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"Prettetic1 Bstrd's uppar icval proptscd for pstcasf.am iodida use (18).
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These Agencies expect some protective action to 'ae taken at a projected 1 r:diation dose of 25 rem or greater to the thyroid from radiofodines raleased into the environment.
In its comments on a draft of DA's final recom=endations, the American Thyroid Association wrote, " Based upon avai,lable data, it vould seem unlikely that. clinically significant thyroid disease would result from '
individual thryoid exposure of less than 100 rads. To provide an add'ed eacsure of pro'tection for children and pregnant women, a radiation dose of 50 rads to the thyroid is suggested as a theshold for lodine blockade for this group (19)." This ce=nent made before the publication of the results of the ani=al studies of Lee et al., and is thus based on the earlier studies of comparative iodine-131 and external r-ray thyroid risks a1 ready ,
.n2ntioned. In any case, given that the most sensitive segments of the population should be' protected the opinion of the American Thyroid Associa-tion and the conclusions of the DA are not very far apart.
Ovar-the-Counter Starus FIA approved potassium iodide for use in radiation e=ergencies as a non- .
prescription drug because the agency was able to conclude that adequate directions for its use by the public could be written.(1) A second reason for the decision was to provide the necessary flexibility to state and locci officials considering distribution of potassium iodide as part of their energency response planning.
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t p *, ' khanco,potcssiumiodidaforthyroidbiceking10-unlikeotharnonprescrip-
'sticd, drugs: Its cafe end offcetive us2 dap2nds en a determination by 1ccal public health authorities that a radiation emergency has occurred or is itkely and that projected release levels.of radiciodines vould be such as to make the benefits of using of the drug outweigh its risks. For that
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rcosen, special labeling for the consumer must secompany the drug. This icheling states, among other things, that it should be taken only when public health authorities so direct.
To date there are three manufacturers holding approved new drig applications for this product. The three are Carter-Wallace, Roxane Laboratories, and
'Ambex, Inc. of New York City. In November 1982, Anbex Inc. began ,rusning anvspaper advertisements in tb.e Earrisburg, Pa., area, the site of the Three Mile Island plant, offering to sell potassium iodide tablets for rad'istion protection directly to the public. In press reports by the Associated Press and Earrisburg area newspapers," Anbex said it also planned to promote the tablets soon in Peoria, Ill.--a city not near a nuclear powar plant--to compare public response with that of the Harrisburg area.
If interest was strong, a nationwide marketing campaign by Anbex vss plcnned.
While the ether PDA-approved manufacturers of potassium iodide for thyroid ,
blocking (Carter-Wallece and Roxane Laboratories) voluntarily agreed at the ti=2 of approval to limit distribution to state and local officials and nuclear power plant cperators, Anbex did not agree to follow such restrictions.
Because of Anbex's ca=paign, TDA* notified th'ese other manufacturers that it un longer expects them to abide by their voluntary agreenents.
't 10
Alt ugh'porcssium iodida is alma availabla cs en ingrcdicnt in proscription 3 Jrugs f,tr trosting cothr.a cnd cth2r lung disord2rs, th2s2 prescription products provide yuch higher doses than are necessary for. thyroid blocking .
in a radiation energen:y. Also, the enteric coated form of many of these dalays absorption through the digestive tract, possibly impeding the drug's effoetiveness in a radiation e=ergency. Furthermore, prescription products cre cot' labeled properly for this specific us,e.
Distribution, Stockpiling, and Cost Effectiveness Perhcps the most heated aspects of the controversy surrounding the use of potassium iodide are stockpiling and distribution, and cost effectiveness.
Th2 Department of Eealth and Eu=an Services (and hence the TDA) is charged
.vith provid'ing guidance to State and local gover==ents on the use of potcosiu= iodide, including the radiation dose at which its use should be considered, but the Depart =ent's role is not to define whether or not potassiu= iodide should be, stockpiled or distributed. These responsibilities preparly reside with the States. Tederal guidance in these matters however, is to be provided by the Tederal E=ergency Manage ent Agency and the Nuclear R2gulatory Cc==ission; not the FDA (20).
On these matters TDA's final reco==endations state: *Each State has the l responsibility for formulating guidance to define if and when the public should be given potassium iodide and instructed to use it. In preparing guidance and making rules, State or local officials should inform citizens of the nature of the radiation hazard and of the potential benefits and advarse effects of potassium iodide. In those instances where State or .
.y local officials a2=inister or direct the ad= ministration of the drug to 11
,. *r
.cijizensthesa=ekindsofissu2sastoliabilitymayarisacshavacristn
'#'io phblic i== uni:stion programs (21, 22). Citizens should be provided Adth, and encouraged to read, the infernation lesfiet, which accompanies the drug. Notice of the availability of guidelines on the information leaflet has been published in the Federal Register (1,23)." Also, the Depart =ent and the FDA recently approved a draf t of the Federal Radiological Preparedness Coordinating Co==ittee's (chaired by TEMA) national policy statement that reiterated this stand (24).
Once it is deter =ined to include potassiu= iodide in emergency plans, the two issues regarding supply are: 1) stockpile or don't stockpile and if the decission is =sde to stockpile, then: 2) redistribute or don't pre-distribute. The advocates of stockpiling say that proper preparedness planning requires that an adequate amount of potassium iodide tablets or solution be available within the State or, where there is = ore than one nuclear power plant, at several sites within the State. Tre= these sites, in the event of an energency, it can be rapidly distributed to persons who cre living in areas where they may be a risk of receiving doses to the thyroid of"25 re= or greater. The non-stockpile advoc'ates point out that stockpiling is expensive. It requires the initial purchase of the drug plus warehouse expenses. Since drug products have finite lifetines, replacement of stockpile stocks when the drug product reaches its expiration date, requiri=g additional investnent is also needed. Non-stockpile advocates argue that in the event of an energency, the drug can be procured quickly from the manufacturer or, conversely, the drug should be stockpiled, but by the Federal govern =ent or the utility, and not by the State.
.c 12
fIh5casaforpre-distributionisbas2duponthapre=1sathatifcedwh2n 3 -
- ..tha drug is naadad, it would taka too long for it to reach the sffected
..~
population from large stockpile locations and, to be sure that people vill h ve it when they need it, each person, family, or househcid should have its own supply readily available. Such pre-distribution to L..e household Icvel would solve one Icgistics problem, but as those who oppose pre-diatri-i bution argue, it vould just substitute a di'ferent set of proble=s. They point out that if the drug was pre-distributed to households it would likely get lost or be forgotten when the e=ergency was at hand or it could b2 out of date.
According to inf roution from the Conference of Rec'iation Control Program Directors, State emergency plana have addressed these supply issues in the following u neer (25):
Stockpile for use by e=ergency workers: 31 States Stockpile for public use, but do not pre-distribute: 6 States Pre-distribute to public i=nediately residing around a nuclear power l P l ant: 1 State Adopted a position not to use for anyone: 4 States Adopted a position not to use for the general public only: 5 States l Tha survey covers 37 States which have an Energency Planning Zone within j their jurisdiction.
Overseas, the United Kingdo= bas stockpiled but not pre-distributed the l
l drug for public use. Sweden has nade the drug available and pre-distributed l
l ~
ft to populations,around reactor sites.
's 13
- -- - - q Andthar-crgu=2nt made cgoinst th2 pre-distribution of the drug is thct 4- . i
','tha probability for o reactor accident which would release radiciodine to
th2 environment is very low and that, in any case,-previous estimates of tha a=ount of radiciodice released in an accident are too high. -
The probability issue is beyond the context of this discussion. Concerning the source ter= (a=ount of radiciodice released), it is reasonable to conclude that if less radiciodine than previously~esginated is released in a reactor cccident, that the zone in which potassium iodide vould be useful vould be greatly. reduced, but it would n,et disappear altogether.
The cost effectiveness of stockpiling potassium iodide has also been raised os a significant iss.ue for concern. An NRC study indicates that the use of potascium iodide as a thyroid-blocking aEent en a large scale may not be cost-effective (26). This study deter =ined cost effectiveness fre= the cost of the drug, the nu=ber of thyroid nodules that could be avoided by its use, and the probability of occurrence of a catastrophic nuclear power plant accident. The conclusion of the study is that if the probability of a nuclear power plant accident of the type that releases consequential quantitites of radiciodine.is one in about 1,400 years with the present nu=ber of operatinE nuclear power reactors, the larEe sesle stockpiling and distributi~en of potassium iodide would not be cost effective. Of course, the cost-effectiveness of other e=ergency measures'(for exa=ple, alerting and warning syste=s) should also be considered for a fair comparison. The probability of occurrence of an accident influences the cost-effectiveness
- of all energency planning neasures including the use of potassiu= iodide.*
If the probability of a serious reactor accident were greater, then the w
14
g, __
.'ccat 2 0ffectiv ness of stockpiling potassium iodida vnuld b3 more favorchie.
Although production, distribution, and stockpiling costs on a' national
. basis may be sig~nificant, the procurement of potassium f odide tablets has be:n estimated to cost about 40 to 75 cents per person dose package.
- Potessium iodide solution in 1 ounce bottles, containing enough drug for an cntire family may cost less on a per person basis.
Conclusion In viev ';f-the current state of kncwledge on radiation risks to the thyroid cod the benefits and risks of potassium iodide.as a thyroid-blocking agent, th2ra is no new compelling evidence that suggests a need to modify the
~
current FDA reco==endations on the use of potassium iodide as a thyroid-blocking egnet . - The Depart =ent of Eealth and Hu=an Servicer and the TDA concur with o-draft statement of Federal-policy. that incorporates the principle that individual States are responsible for for=ulating policies concerning the stockpiling and distribution, as well as if and when to use this drug in radiction accidents that release radioiodines to the environment.
l
.P 15
Ruforancas 4
~1. Tood and Drug Administration (EIV), Accidental Radioactive Contamination i
of Euman Tdods and Animal Teeds and Potassium Iodide as a Thyroid-Blocking Agent in a Radiation Emergency. 43 FR 58798, December 15, 1978. *
?;. U.S. Tood and Drug Administration. Potassius Iodide as a Thyroid-Blocking AE ent in a Radiation Emergency: Final , Recommendations on Use. Federal Register, Vol. 47, No-125, pp. 2B158-28159 (June 29, 1982).
- 3. Talov, R.S. Potassium Iodide: Good or Evil after Nuclear Accidents.
Presented before the Endocrine Society Symposium, June 18, 1980 4 Talov, Rosalyn S. , Potassfu= Iodide's Role in Energency Planning f or a Nuclear Accident, Eealth Physics Society Nevaletter I:7 (May 1982).
- 3. Curd, J.G.,, H. Milgram, D.D. S tevenson, et al., Potassium Iodide Sensitivity in Pour Patients with Eypocenplemente=de Vasculitis, Ann.
Intern. Med. 91:853-857 (1979).
- 6. Maxon, E. R. When should Potassiu= Iodide be used as a Thyroid-Blocking Agent for Protection of the General Poptiation from Potentially Earmful Effects of Radiciodine? Prom proceeding of the Electric Power Research ,
Institute (EPRI) Workshop on Energency Pl.anning, Washington, D.D., January 1982.
- 7. Rallison, M.L. , B. Dobyns , R. Keating, et al., Thyroid Disease in Children - A Survey of Subjects Potentially Exposed to Fallout Radiation, Aner. J. Med. 56:457-463, (April 1974). .
- s
'k 4
4
j a
' Humans Af ter Erposure to Diagnostic . Doses of Iodin 2-131.. II. Estimation ef'
" Thyroid Ciced 5123 Thyroid Radiction Dosa, cud Pradicted Versus Observed
. 1 Number of Ralignant Thyroid Tumors. J. Nat. Cancer Inst. 65:1221 (1980). )
l
- 9. Conard, R.A., Su= mary of Thyroid Findings in Marshallese 22 years after l
Exposure i to Radioactive Fallout, in Radiation Associated Thyroid Carcinoma (DeGroot, 1. , ~e t al. Eds.) Acade=de Prgss, N.Y. (1977).
4
- 10. Ron, E. and B. Medan, Benign and Mailgnant Thyroid Neoplasms af ter Childhood Irradiation for Titea Capitis, J. NCI, 65:7-11, (July 1980).
- 11. Albert, R.E. and 1.R. O=ran, Fo11cw-Up Study of Patients Treated by I-Ray Epilation for TineaCapitis, Arch. Environn. Health, 17:899-918, (1968).
- 12. Shore , R.E. , E.D. Woodward, B.S. Pas ternack, and L.H. He:pelmann et al. ,
Radiation and Host Factors in Ha=an Thyroid Tu= ors Tellowing Thy =us Irradiation, Health Physics 38: 451-466, (April 1980).
- 13. National Academy of Sciences, National Research Council, The Effects on Population's of Exposure to Low Levels of Ionizing Radiation, Report of the Advisory Co==1ttee on the Biological Effects of Ionizing Radiation, 1980, Washington, D.C.
- 14. Denisch, I. Effects Including Carcinogen 1 sis of 1311 and I-Ray on the Thyroid of Experd= ental Animals: A Review. Health Physics, 9:1357-1362 (1963).
.s
- \
./ ' 9e
, )5.,H.R. Max:n,S.R.Th: mas..E.L.Scenger,etcl.,IonizingIrradictionand-che Induction.of Clinically Significant Disease in the Human Thytoid Gland, Am. J. Med.,' 63:967-978, (December 1977).
-16. Lee,: W. , Chiacchierini, R.P. , Shleien, 3. and Telles , N.C. Thyroid Tumors Following 131 1 or Localized I Irradiation. to *.he Thyreid and i-Pituitary Glands in Rats. Radiation Research 92:307-319 (1982).
4
- 17. U.S. Environmental Protection Agency, Manual of Protective Action Guides and Protective Actions for Nuclear Incidents, EPA-250/1-75-001
. (September 1975 - Revised June 1980).
- 18. National Radiological Protection Board, E=ergency Reference Levels:
Criteria for Limiting Doses to the Public in the Event of Accidental Irposure to Radiation, ERL 2 (July 1981).
- 19. Becker, D.V. State =ent of the Environmental Earards Com=1ttee of the American Thyroid Association, October 5, 1981.
- 20. General Services Administration, Tederal Preparedness Agency. Radio-logical Incident EmerEency Response Planning; Tixed Tacilities and Transportation, Federal Register (40 TR 5941) December 24, 2975).
Federal E=erEency Manage =ent Agency. National Radiological E=ergency Preparedness / Response Plan for Cc==ercial Nuclear Power Plant Accidents (Master Plan). Tederal Register (45 TR 84910) (December 23, 1980).
Federal E=ergency Management Agency. Radiological E=ergency Planning and Preparedness; Final Regulations (47 TR 10758) (March 11,1982).
- 21. Reyes v. Wyeth Laboratories, 498 T. 2d 1264 (5th Cir.) cert den.419 w
U.S. 1096 (l't74).
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ENCLOSURE E
- m. meo 9, J. X. ational Audubon Society 950 THIRD AVENUE, NEW YORK, N.Y.10022 (212) M21200 CABLE: NATAUDUBON m., .4~
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W May 31, 1983 Mr. William J. Dircks Executive Director for Operations U. S. Nuclear Regulatory Commission Mail Stop MMBB 6209 Washington, D. C. 20555
Dear Mr. Dircks:
I would like to clarify a point in connection with your draft memo to the Commissioners on RADIATION PROTECTION--THYROID BLOCKING. On page A-3, the thyroid dose effects coefficients that were used in your analysis were compared with coefficients that I useo in one of my studies:
"The summary table from NUREG/CR-1433 assumed 334 thyroid nodules permillionperson-remtothethgroid--with60percentbenign, and 40 percent cancerous. Beyea has assumed these values as lower bounds, with an upper bound of a factor of 2 higher for the general population and a factor of 20 higher for children."
This is not quite correct. Let me indic te what I have done: I have j assumed an upper bound coefficient for adults (not the general population), that '
is twice the NUREG/CR-1433 value per million adult rem for children. I have assumed a value four times higher per million child rem than the values assumed l in NUREG/CR-1433, not twenty times higher. (The factor of two difference between the adult and child coefficient is based on Marshallese data.) However, since ;
children have a much smaller thyroid than do adults, the thyroid dose to the i child is considerably higher than for an adult when both are exposed to the same ,
airborne concentration of radiciodine (even when differences in breathing rates I are taken into account.) I take this factor to be five. (As I recall, NRC Reg. guides suggest a value of about 2.7.) Thus, the factor of 20 quoted above is a product of a dose / effects coefficient factor and a dose increase factor.
(4 X 5 = 20.) As a result, thyroid nodules in children in my calculations account for about two-thirds of the total, even though they are assumed to represent only 15 percent of the population. ;
l The bottom line is that my upper limit predicts 4.5 times as many thyroid nodules in the entire population as would be predicted using NUREG/CR-1433 1 assumptions. I also state a lower limit for thyroid nodule incidence in the entire population that is 1.65 times lower than the value that would be predicted l
using the NUREG/CR-1433 approach. This lower limit arises for delayed releases l (when the short-lived Iodine 133 component has lost significance). ]
l- 0013Q 1
A MLHICANS COMMITTILD TO CONS 1 IWAl lON ;
-:, : l.
Mr. Willima J. Dircks 1'
. May 31, 1983 Page 2 -
I hope my remarks will help clarify this matter.
cereiy, I,8w L -
an Beyea Senior Energy Scientist JB:db cc Roger Blond Frank von Hippel Y'
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