ML20045B386
| ML20045B386 | |
| Person / Time | |
|---|---|
| Issue date: | 06/10/1993 |
| From: | Thompson H NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | Rabb J, Wingert V Federal Emergency Management Agency, HEALTH & HUMAN SERVICES, DEPT. OF |
| References | |
| NUDOCS 9306170277 | |
| Download: ML20045B386 (4) | |
Text
_
June 10o 1993 i
Mr. Vernon L. Wingert, Chief Policy Development Branch Federal Emergency Management Agency 500 C Street S.W.
Washington, DC 2P472
-l Dear Mr. Wingert As discussed at ue Federal Radiological Preparedness Coordinating Committee (FRPCC) meeting on March 31, 1993, the enclosed report, "An Analysis of Potassium Iodide (KI) Prophylaxis for the General Public in the Event of a Nuclear Accident," is being provided for your information and that of Co-Chairman James Rabb of the FRPCC's Potassium Iodide Subcommittee.
The staff of the Nuclear Regulatory Commission is considering a revision to agency policy regarding the use of potassium iodide for thyroid blocking in a radiation emergency. One option being considered would support the Federal government stockpiling KI for distribution to local officials in case of a reactor accident. Considerations will include both the quantitaive and qualitative factors, as discussed in the report. Some of these factors have been summarized by the NRC task manager for the project, Dr. Roy Woods, and this summary is also enclosed. Dr. Woods can be reached at (301) 492-3908 for further information.
Sincerely, Originalsignedby &
Hugh LThompson, j
Hugh L. Thompson, Jr.
Deputy Executive Director for Nuclear Materials Safety, Safeguards, and Operations
Enclosures:
As stated DISTRIBUTION i
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Mr. James A. Rabb Senior Emergency Response Coordinator Center for Environmental Health and Injury Control Department of Health and Human Services 1600 Clifton Road, N.E. (E32)
Atlanta, GA 30333 l
Dear Mr. Rabb As discussed at the Federal Radiological Preparedness Coordinating Committee i
(FRPCC) meeting on March 31, 1993, the enclosed report, "An Analysis of Potassium Iodide (KI) Prephylaxis for the General Public in the Event of a Nuclear Accident," is being provided for your information and that of l
Co-Chairman Vernon Wingert of the FRPCC's Potassium Iodide Subcommittee.
The staff of the Nuclear Regulatory Commission is considering a revision to agency policy regarding the use of potassium iodide for thyroid blocking in a radiation emergency. One option being considered would support the Federal i
government stockpiling KI for distribution to local officials in case of a reactor accident.
Considerations will include both.the quantitaive and i'
qualitative factors, as discussed in the report.
Some of these factors have been summarized by the NRC task manager for the project, Dr. Roy Woods, and this summary is also enclosed. Dr. Woods can be reached at (301) 492-3908 for further information.
g d c)p d by pagM.cyson,A Sincerely, Hugh L. Thompson, Jr.
Deputy Executive Director for Nuclear Materials Safety, Safeguards, and Operations Support DISTRIBUTION EDO R/F PDR DEDS (2)
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June 10. 1993 Mr. James A. Rabb Senior Emergency Response Coordinator Center-for Environmental Health and Injury Centrol Department of Health and Human Services i
1600 Clifton Road, N.E. (E32) l Atlanta, GA 30333 Dear Mr. Rabb.
As discussed at the Federal Radiological Preparedness Coordinating Committee ~
l (FRPCC) meeting on March 31, 1993, the enclosed report, "An Analysis of Potassium Iodide (KI) Prophylaxis for the General Public'in the Event of. a Nuclear Accident," is being provided for your information and that of -
Co-Chairman Vernon Wingert of the FRPCC's Potassium Iodide Subcommittee.
i The staff of the Nuclear Regulatory Commission is considering a revision to agency policy regarding the use of potassium iodide for thyroid blocking ~in a radiation emergency. One option being considered would support the Federal government stockpiling KI for distribution to local officials in case of a reactor accident. Considerations will include both the quantitaive and qualitative factors, as discussed-in the report. Some of these. factors have i
been summarized by the NRC task manager for the project, Dr. Roy Woods, and this summary is also enclosed. Dr. Woods can be reached at (301) 492-3908 for-further information.
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Sincerely,
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ut.) L. Thompson Jr 0
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Enclosures:
As stated l
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t June 10 1993 0
Hr. James A. Rabb Senior Emergency Response Coordinator Center for Environmental Health and Injury Control Department of Health and Human Services 1600 Clifton Road, N.E. (E32)
Atlanta, GA 30333
Dear Mr. Rabb:
As discussed at the Federal Radiological Preparedners Coordinating Committee (FRPCC) meetirg on March 31, 1993, the enclosed report, "An Analysis of Potassium Iodide (KI) Prophylaxis for the General Public in the Event of a Nuclear Accident," is being provided for your information and that of Co-Chairman Vernon Wingert of the FRPCC's Potassium Iodide Subcommittee.
The staff of the Nuclear Regulatory Commission is considering a revision to agency policy regarding the use of potassium iodide for thyroid blocking in a radiation emergency. One option being considered would support the Federal government stockpiling KI for distribution to local officials in case of a t
reactor accident. Considerations will include both the quantitaive and qualitative factors, as discussed in the report. Some of these factors have been summarized by the NRC task manager for the project, Dr. Roy Woods, anti this summary is also enclosed.
Dr. Woods can be reached at (301) 492-3908 for further information.
ggggy g}gngj hy Hugh LThompson,Jr.
Sincerely, Hugh L. Thompson, Jr.
Deputy Executive Director for Nuclear Materials Safety, ",afeguards, and Operations Support plSTRIBUTION ED0 R/F PDR DEDS (2) i TMurley JSniezek JTaylor EBeckjord JVoglewede KStablein KSchneider DEDS:TfM DEDS EDO F JVogleffe~de HLThompson JMTs.ylor 6/7/93 6/7 /93 6f g/93
Ench utre 1 AN ANALYSIS OF POTASSIUM IODIDE (KI)
PROPHYLAXIS FOR THE GENERAL PUBIlC IN THE EVENT OF A NUCEAR ACCIDENT Prepared by S. Cohen & Associates, Inc.
1311 Dolley Madison Boulevard McLean, VA 22101 (703) 89M592 under NRC Contract No. NRC-04-90-070 Prepared for U.S. NUCLEAR REGULATORY COhDdISSION Reactor & Plant Safety Issues Branch Division of Safety Issue Resolution OfHee of Nuclear Regulatory Research Washington, DC 20555 H. W. Woods, P.E.
Work Assignment Manager April 1992 AM((Bb4676wy-Bekw I abrwk,Jr dans lM
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Summary of Issues Related to the KI-Stockpiling Re-Evaluation l
A.
Quantitative Factors i
Costs in the attached study were minimized by including only the purchase and periodic renewal price of the KI itself; that is, storage, transportation, and distribution costs were not included. Benefits were maximized by assuming that any prevented (malignant or benign) thyroid nodule causes a $500,000 benefit from avoided psychological _ costs (this is the dominant benefit), and by assuming that stockpiled KI would be immediately available to the entire exposed population during an accident (in reality, such prompt distribution during an evacuation s
would be unlikely).
The analysis took into consideration the latest knowledge and data concerning the following subjects, which are discussed thoroughly and concisely in the report:
exposure pathways, inhalation rates, inhalation dose coefficient, fetal thyroid dose, efficacy of internal radio-nuclides relative to external radiation, risk of thyroid cancer, risk of benign thyroid nodules, risk of hyperthyroidism, risk to the unborn, population distribution around U.S. nuclear power facilities, frequency of severe accidents (releases) at U.S. nuclear power plants, iodine radioisotopes released during severe accidents, effectiveness of KI for thyroid blocking, costs of stockpiling KI for population segments around nuclear plants, direct costs of medical treatment, and indirect costs of economic opportunity lost plus psychological costs.
The key assumptions made by the contractor are stated in boldface type below, followed by a discussion of the assumption. Also given within the discussion are corrections suggested by the NRC staff Task Manager as being appropriate to obtain a more realistic estimate of the cost / benefit ratios from the contractor's results:
(1) The cost effectiveness of K! use can be evaluated independent of other protective actions such as evacuation or sheltering.
Compared to the actual situation during a real emergency, this assumption maximizes the benefits calculated for KI (thus tending to minimize the cost / benefit ratio and make KI stockpiling seem to be more cost effective than it actually would be).
The cost / benefit ratios were derived assuming that the exposed population continued normal activities, i.e., no evacuation or sheltering was assumed beyond normal amounts of time that would be spent indoors. The benefits were calculated as the dollar value of thyroid illness prevented by KI use, which was assumed to have been available to, and promptly taken by, the entire at-risk population before and during exposure to radioiodine.
During a real emergency, KI would have to be distributed during an evacuation or sheltering operation. Since KI is effective only in reducing exposure of the thyroid to radioiodine isotopes (KI is not effective in reducing any other type of radiation damage to any part of the body, such as that due to noble gases, or strontium, or cesium radioisotopes), evacuation or sheltering would be essential in addition
to KI use.
Evacuation or sheltering would significantly reduce the fraction of the population that would be able to effectively (i.e.,
quickly) obtain and use KI (going somewhere to obtain stockpiled KI is r
not compatible with promptly taking shelter or evacuating the area).
This incompatibility would reduce the number of people who would obtain and effectively use KI.
This would reduce the total KI benefits and increase the cost / benefit ratio of KI stockpiling (that is, make its stockpiling even less justifiable on a cost / benefit ratio basis). The fractional reduction in benefits cannot be calculated in any known rigorous manner. But if one wishes to move toward more realistic cost benefit ratios from the cost / benefit ratios given in the contractor's report, then for the purpose of illustration it is postulated that at least a factor of three reduction in benefits (i.e., a factor of three increase in the cost / benefit ratio) may be assumed. This would cause the more realistic cost / benefit ratios to increase by a factor of three (due to this cause alone) above those given in the contractor's report, which were calculated using assumptions that give XI stockpiling "a reasonable chance of being cost effective".
Additionally, with KI available, its benefits would be further reduced because some fraction of the at-risk population would fail to evacuate or take shelter in the mistaken belief that "I don't need to evacuate or take shelter - I've taken KI, and I'm protected".
It's considered unlikely that this factor will ever be quantified; it wouldn't be possible to collect reliable data concerning this personal, private matter even after an actual event.
But this factor should be noted, even though this summary will not attempt its quantification (this factor would increase the cost / benefit ratios by some unknown amount).
Increased public education regarding the limited benefits of KI (KI protects the thyroid gland from exposure to radiciodine, but XI provides no other protection for other sources of_ radiation exposure to the thyroid gland or to other parts of the body) would minimize the increase on the cost / benefit ratios from this cause, but would not eliminate it completely.
(2) The plume center-line exposure calculations made by the MACCS computer code are the appropriate representation of expected population expsure to be used in deriving the cost / benefit ratios for KI stockpiling.
The meteorological model used in the current " state-of-the-art" MACCS code maintains a straight-line plume over extended periods of time following a release (i.e., the plume does not meander).
This projects unrealistically high center-line doses for populations located at significant distances from the release. Any recommended stockpiling of KI would likely be in the form of a recommendation that it be stockpiled for "that population whose exposure is predicted to exceed (some stated limit)". Thus, use of unadjusted MACCS code results from our cost / benefit analysis would result in stockpiling KI for an unnecessarily large population, thus unnecessarily increasing the costs of such stockpiling.
The benefits of stockpiling would not be significantly affected by assuming results based on the non-meandering plume in the MACCS code as opposed to the more realistic meandering plume. Due to the linear dose
I-model assumed (health effects are directly proportional to the level of exposure), the total benefits would remain the same.
It would not matter whether the same total avoided dose were spread among many people each-receiving a small dose assuming a meandering plume, or among a smaller number of people each receiving a larger dose, assuming a steady plume -
due to the linear dose model, the total health effects avoided by KI use would remain the same in the two cases.
But the costs of stockpiling KI would be significantly affected by assuming results based on the non-meandering plume in the MACCS code as opposed to the more realistic meandering plume.
It is estimated (verbal estimate on July 29, 1992 by telephone from the contractor's principal technical investigator to the NRC staff's task manager) that the maximum radius at which an individual's thyroid exposure might exceed 100 rads or 50 rads (the levels most often mentioned as candidate limits) would be a factor of three lower in the realistic (meandering plume) case compared to the MACCS results (steady plume). This comparison is for the most likely case of a release extending over some hours as opposed to a single, brief but massive release.
Assuming a uniform population density and noting that area is proportional to the square of the radius, this implies that if one wishes to move toward more realistic cost benefit ratios from the cost / benefit ratios given in the contractor's report, then for the purpose of illustration it is postulated that a factor of nine reduction in costs may be assumed. This would cause the more realistic cost / benefit ratios to decrease by a factor of nine (due to this cause alone) below those given above which were calculated by the contractor using assumptions that "give KI stockpiling a reasonable chance of being cost effective".
(3) No redundancy in stockpile quantities is needed.
The contractor's report assumed that it was only necessary to stockpile the exact amount of KI needed for the population predicted to exceed the specified maximum allowable thyroid exposure.
This is an unrealistic assumption.
For efficient distribution, a stockpile is needed containing at least twice the quantity of KI that would be distributed in the event of an accident.
This implies that if one wishes to move toward more realistic cost benefit ratios from the cost / benefit ratios given in the contractor's report, then for the purpose of illustration it is postulated that a-factor of two increase in costs may be assumed. This would cause the more realistic cost / benefit ratios to increase by a factor of two (due to this cause alone) from the report's results which were calculated using assumptions that "give KI stockpiling a reasonable chance of being cost effective".
(4) The only cost of KI stockpiling is the purchase and periodic replacement cost of the KI itself.
Other costs of KI stockpiling (transportation, inventory, storage space, providing instructions / informational / educational material) might not be charged directly to the KI program.
For example, the Veterans Administration might volunteer to store KI " free" in its hospitals.
i 4
Nevertheless, in some less direct way these other costs would be borne by society, and so an increase in the cost {and thus the cost / benefit ratios) by a factor of at least.t.wa for these other costs appears to be a reasonable assumption, if one wishes to move toward more realistic cost benefit ratios from the cost / benefit ratios given in the contractor's report.
(5) It is appropriate to include avoided psychological costs among the i
benefits attributed to KI use. The amount assumed for this benefit is
$500,000 for each thyroid problem of any kind (fatal and non-fatal cancer, benign nodule, or hyper-thyroidism).
This assumption is a departure from previous practice, where the benefits due to avoided psychological costs have not been included in the cost / benefit ratio determination.
Using the contractor's results without the $500,000 avoided psychological costs, it is found that the cost / benefit ratios are increased by a factor of 9.2 when this benefit is deleted.
Combining all of the above factors and applying them to the contractor's cost / benefit ratios yields the following:
KI Cost / Benefit Ratios. Showina Results of Assumptions that Give A More Realistic Result Population Zone C/B Ratio More Realistic C/B Ratio (mi. from plant) from contractor's with and without report with all costs psychological costs j
<5 2.2 2.9 27 5 - 10 7.6 10 93 10 - 25 50 67 610 25 - 50 250 330 3100 50 - 100 1000 1300 12000 100 - 150 2300 3100 28000 150 - 200 4200 5600 52000 200 - 350 11000 15000 130000 350 - 500 10000 13000 120000 (6) The "best estimate" or "mean" severe accident and release frequencies are appropriate for use in this new analysis.
All of the cost / benefit ratios given above are based on the mean frequencies calculated for significant releases in NUREG-1150.
However, it is recognized that estimates regarding accident frequencies and other parameters have a wide uncertainty band.
Since the benefits of KI stockpiling are directly proportional to the frequency of using the KI l
(i.e., to the significant release frequency), if one were to perform a sensitivity study, the cost-benefit ratios would change accordingly. For example, if the sensitivity study indicated that the frequency could be higher by a factor of ten, then the cost-benefit ratio for various segments of the population surrounding a nuclear plant would be reduced j
l by the same factor, i.e. by a factor of ten, as shown in the following table-KI Cost / Benefit Ratio Sensitivity Study ShoWinQ Result of a Factor of Ten Increase in the Severe Release FreouenCY Population Zone More Realistic C/B Ratio Sensitivity Study C/B Ratio I
(mi. from plant) from item (e) above with psychological costs with psychological costs i
<5 2.9 0.29 5 - 10 10 1.0 10 - 25 67 6.7 25 - 50 330 33 50 - 100 1300 130 100 - 150 3100 310 i
150 - 200 5600 560 200 - 350 15000 1500 350 - 500 13000 1300 B.
Qualitative Factors (1) Present State and Foreign Government KI Programs.
At present, only the states of Tennessee and Alabama have plans to provide KI to limited portions of the general population.
Following the THI experience, in late 1981 Tennessee State Health officials conducted a program to pre-distribute KI tablets to all 7
households within 5 miles of TVA's Sequoyah Nuclear Power Plant. The initial distribution succeeded in providing the tablets to 66% of the households within that area. However, after three years, when the distributed tablets were considered to have become out-of-date and to be in need of replacement, only 32% of the households so advised responded i
by picking up their free replacement tablets at the local health department. Thus, a few years after the initial distribution, coverage was less than half complete due to expired tablets that had not been replaced, and due to new residents that had moved into the area.
The Alabama plan does not include predistribution like the Tennessee pl an.
Rather, the Alabama plan calls for KI to be distributed at reception centers, after evacuation, should the State Health Officer decide on its use.
The (former) Soviet Union emergency preparedness plans included procedures for stockpiling and distribution of KI tablets. This i
stockpile provided tablets for 135,000 persons following the Chernobyl 1
accident.
Following the Chernobyl accident, in Poland KI was distributed in all kindergartens, schools, public health centers, and pharmacies.
It was initially recommended for use by children and teenagers, but not for adults, and the government was neutral with respect to a recommendation for pregnant women. As the radiological conditions worsened later during l
the event, the governmental recommendations regarding use of KI became,
- 6 considerably less restrictive.
It is estimated that 10,000 pregnant women used KI during the event along with 10.5 million children and teenagers.
An ordinance to activate a plan to distribute KI tablets to 6.9 million i
inhabitants of Switzerland became active August 1,1992. The initial
^
distribution over the first several months will be to 50,000 residents within 4 km of Swiss nuclear plants. The entire plan is expected to require 100 million tablets, with distribution to be completed in 1994.
The Federal government is responsible for production, distribution, storage, and provision of informational materials about use of the tablets. The initial cost of the tablets is estimated at the equivalent of more than U. S. $4 million at current rates with 55% for tablets, 40%
for informational material, and 5% for administration.
In Canada, the policy regarding use of KI rests with each province. The three provinces that have nuclear power reactors (New Brunswick, Quebec, and Ontario) each maintain a stockpile of KI for the general public within the " primary zone", which is the area within ten kilometers (6.2 miles) of each plant.
In New Brunswick, due to the sparse population density, KI has been predistributed to families within the primary zone of that province's single plant.
In Quebec, KI is stockpiled at a single location to be distributed door-to-door by local municipal personnel within the primary zone of that province's single plant.
In Ontario, there are 20 nuclear power units which are located at 3 sites, each of which has its own stockpile of KI which would be distributed to residents in the primary zone.
(2) Consideration of opinions ani expectations of the general public in setting national KI stockpiling poli:y.
The federal government might wish to sponsor a reserve KI stockpile which could be quickly provided to state or local authorities upon their request during a nuclear emergency.
Provision of such a stockpile would not require any change in national policy.
It would require only acquisition of the stockpile and communication to state and local agencies that such a stockpile exists and would be available to them upon their request during a nuclear emergency.
Qualitative reasons for such a stockpile include:
(a) KI was requested during the TMI event and could not be provided in the time frame during which it was thought to be needed (although thankfully it was not needed); and (b) the Chernobyl event resulted in the actual need for (and use of) tens of thousands of KI doses; and (c) the occurrence of those events (and other potential precursor events) might be an indication that the need for KI could be more frequent than predicted based on the NUREG-Il50 results.
Roy Woods, KI Study Task Manager, April 13, 1993 (301) 492-3908 !