ML20135B980

Responds to to I Selin Expressing Concerns Re Current Potassium Iodide Policy

ML20135B980
Person / Time
Issue date:	09/27/1991
From:	Taylor J NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO)
To:	Morris A ANBEX, INC.
Shared Package
ML20135B134	List: ML20135B199 ML20135B203 ML20135B207 ML20135B210 ML20135B215 ML20135B217 ML20135B220 ML20135B229 ML20135B232 ML20135B235 ML20135B243 ML20135B249 ML20135B262 ML20135B897 ML20135B906 ML20135B916 ML20135B935 ML20135B980 ML20135C094 ML20135C248 ML20135C255 ML20135C261 NUREG/CR-1433, Reassigns Differing Professional Opinion Position to RES for Informal Review IAW Mc 4125.Key Issue Raised in Adequacy of cost-benefit Conclusion Originally Made in NUREG/CR-1433 & Adoption/Endorsement by NUREG-1355 & NUREG-1251 Discuss
References
NUDOCS 9703030294
Download: ML20135B980 (3)

Text

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't UNITED STATES 8

i ,i NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20M6 4

1. i

• SEP 2 7 891 Mr. Alan Morris, President Anbex, Inc.

113 Morris Ave.

Denville, NJ 07834 l

Dear Mr. Morris:

This is in response to your July 1,1991 letter to Dr. Selin expressing concerns regarding NRC's current potassium iodide (KI) policy.

I have been apprised of your recent telephone discussions with NRC's Task Manager for this issue, and with an NRC attorney who has been concerned with ,

this issue for several years. I have also been told of the telephone conversations you had with our contractor who is currently reassessing this  ;

issue, and I thank you for the valuable information you made available to him i concerning costs and availability of packaged KI tablets.

1 As you already know from the aforementioned conversations (and as noticed in

! the Federal Reaister on September 28, 1990, cf. 39768), NRC is currently I sponsoring a reassessment of the cost-benefit studies regarding KI use to update the current bases for the Commission's policy on KI (NUREG/CR-1433, March,1980). That current basis used severe accident probabilities and consequences from the Reactor Safety Study (RSS, WASH-1400) along with other i

pertinent data and information that was available in 1980 (for example, the cost and shelf-life of KI and the risks to the thyroid due to internal radiciodine exposure).

The NRC-sponsored reanalysis now underway will reevaluate the quantitative I factors affecting KI use; integrate several qualitative factors into the revision; and reexamine and document the costs and benefits of both predistribution and stockpiling of KI. The quantitative factors that have 1 significantly changed since 1980 and will be updated include: best estimates of the probabilities and consequences of severe accidents (e.g., NUREG-1150);

estimates of thyroid risk as a result of radiciodine exposure; estimates of health risk to the public due to severe allergic reactions if large numbers of I

people take KI without medical supervision; and the cost and best estimate of the shelf-life of KI. The reanalysis will also consider qualitative factors including the intangible benefits of preventing a potentially grave illness.

Furthermore, to the degree practical .the information now becoming available on the experience from the Chernobyl accident (April 1986) where significant bk Okh bk!N PDR

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quantities of KI were administered by Polish and Soviet authorities will be considered.

It is not presently known how the combined effects of these updates will

^

affect the cost-benefit ratio, since there are significant factors that will tend to change the cost-benefit ratio in both directions. For example:

inclusion of the costs to ship, package, and store the KI (not'previously included among the costs of the KI - only the purchase price of the KI tablets was included) will tend to increase the cost-benefit ratio; but consideration

- of the qualitative aspects, including the benefits of avoiding thyroid nodules ,

! as opposed to merely accounting for the charges for their removal once they occur, will tend to decrease the cost-benefit ratio.

! This detailed reanalysis is being coordinated throughout its development with j the members of the Federal Radiological Emergency Preparedness Coordinating Committee (FRPCC) and its chair agency, the Federal Emerger.cy Management Agency (FEMA). As you know, the Commission's reanalysis will result in a ,

l recommendation to the FRPCC whether or not to change the Federal policy '

regarding KI. The FRPCC chair agency (FEMA) will coordinate the review of-this recommendation, and if appropriate will initiate a revision in this '

policy.

I hope this letter is responsive to your concerns.

Sincerely, i

'Cryinal Signed try Hugh LThompson fr.

ames M. Taylor Executive Director for Operations l

• SEE PREVIOUS CONCURRENCE l

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l POLICY ISSUE October 11, 1991 OND@ SECY-91-321 i

) For: The Commissioners i

Ergm: James M. Taylor i

Executive Director for Operations l Subiect: RE-EVALUATION OF POLICY REGARDING USE OF POTASSIUM IODIDE (KI) AFTER A SEVERE ACCIDENT AT 4 A NUCLEAR POWER PLANT l

Purpose:

To inform the Commissioners that a detailed reanalysis

, is now underway, as noticed in the Federal Reoister on i

September 28, 1990, cf. 39768, to update the current

bases for the Commission's policy on KI (NUREG/

l CR-1433, March,1980).

i Backaround: The present federal policy regarding the stockpiling of KI was published in the Federal Register on l July 24, 1985 by the Federal Emergency Management l Agency (FEMA) in its capacity as chair-agency of the -

l Federal Radiological Emergency Preparedness i Coordinating Committee (FRPCC). As a FRPCC member, j the NRC played a key role in development of that j policy through its sponsorship of an analysis j examining the cost-effectiveness of KI use on a j

national basis (NUREG/CR-1433, published in 1980).

I The present (NUREG-1433-based) policy consists of l voluntary federal guidance to the responsible state

] and local health authorities, who must decide among i available options regarding use of KI by the general 4 public during an actual emergency. The voluntary i

i i

Contact:

R. Woods SECY NOTE: TO BE MADE PUBLICLY AVAILABLE IN 492-3908 10 WORKING DAYS FROM THE DATE OF THIS PAPER

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guidance recommends that local authorities consider l stockpiling and distributing KI for emergency workers  :

and institution-alized persons, but does not recomend  !

! predistributing or stockpiling KI.for the general. '

l public. The reason for this guidance.is that in the l event of an accident, protective actions are planned and would be taken for the general public that are capable of reducing whole-body doses, not merely the l

l thyroid gland dose.

i The NRC-sponsored, NUREG-1433 analysis used severe i

accident probabilities and consequences from the i Reactor Safety Study (WASH-1400) along with other j

pertinent data and information that was available in 1980 (for example, the cost and shelf-life of KI i

and the risks to the thyroid due to internal radiciodine exposure).

1 Subsequent to the November 1983 Commission meeting l during which the Commission was briefed by the staff l on NUREG-1433 and the KI policy issue, a staff member from the Office of the General Counsel (OGC) noticed that there were differences between the oral discussion recorded in the transcript of the 4

! Comission meeting and the written materials that had l l

l been provided to the Comission in advance of the l

briefing, and that certain information concerning the '

l l cost of treating cancerous nodules had been omitted from the oral presentation *. This was pointed out to the Comission in a letter from the General Counsel, i and the Commission was later provided with additional i information by the EDO, OGC, and the Office of Policy i Evaluation concerning this point. Thus the Comission _

i l was fully informed before reaching its policy decision  !

! in May, 1985.

4 i

i

• During the oral discussion, the staff stated that the " benefit" associated with preventing a thyroid nodule was $2o,000 per nodule prevented The costs of j-i (the avoided medical charge associated with nodule removal).

stockpiling adequate KI were given in terms of several concentric zones around i

j nuclear power plant sites. Using a population-weig'nted average of those sones, it was calculated that the costs associated eith stockpiling adequate

+

KI for the population out to loo miles from each nuclur plant was $5,100,000-

/ thyroid nodule prevented. Thus the cost / benefitThe ratio presented SECY papers orally provided to

during the meeting was $5,100,000/$20,000 = 255.the commission before the me

[

preventing a thyroid nodule was $100,000 (cancers and fatalities, whic

al).

The costs associated with stockpiling adequate KI were the same in the j

verbal and written material ($5,100,000), so the written material implied a

' cost / benefit ratio of $5,100,000/$100,000 = 51.

)

F ...- 'ssioners 3 However, a Differing Professional Opinion (DPO) was

- subsequently filed raising concerns that the lack of verbal discussion described above could have significantly affected the Commission's perception of the value/ impact ratio (and of the qualitative desirability) for KI stockpiling, and could have influenced state and local agencies in formulating their KI policies. Further, the DP0 disagreed with several of the quantitative-factors that were used in the NUREG/CR-1433 analysis, and raised the concern that " pain and suffering" avoided by preventing.

thyroid-related illness (instead of merely treating those illnesses once they occur) should be taken into account in making policy decisions regarding a national KI policy.

l As part of the NRC's DP0 review process, the DP0 panel L

developed a simplified analysis (see Enclosure 1) of the quantitative bases for KI stockpiling policy, which responded to comments in the DP0 by revising l

l several factors that were used in the NUREG/CR-1433

! analysis. The panel concluded that the results of this analysis did not warrant any change in the Federal Policy. However, in order to take into account all of the issues raised by the DPO, and to ,

(

i incorporate new data currently available for several of the factors used in the analysis, the Office of Research has been directed to perform a detailed update of the Agency's KI policy bases, taking into account both qualitative and quantitative factors.

Issuance of this Commission Paper, and distribution of copies to appropriate state and local agencies through the Office of Governmental and Public Affairs, and by the FRPCC subcommittee on KI through the E-6 Subcommittee of the Conference of Radiation Control Program Directors (CRCPD), is a further response to  ;

the DP0 since it will provide complete information to i affected state and local agencies. l Discussion: The staff has underway a detailed reanalysis of the l Agency's KI policy bases. This analysis will reevaluate the quantitative factors affecting KI use, l integrate several qualitative factors into the revision,-and reexamine and document the costs and benefits of both predistribution and stockpiling i of KI.

The quantitative factors that have changed significantly since 1980 and will be updated include:

best estimates of the probabilities and consequences l of severe accidents (e.g., NUREG-1150); estimates of I

!- The Commissioners 4

1 i~ thyroid risk as a result of radiciodine exposure,  ;

estimates of health risk to the public due to severe i

! allergic reactions if large numbers of people take KI without medical supervision; and the cost and best estimate of the shelf-life of KI. Furthermore, to the i degree practical, the information now becoming ,

i available on the experience from the Chernobyl  !

accident (April 1986) where significant quantities of K! were administered by Polish and Soviet authorities will be reflected in the detailed analysis.

Several qualitative factors will also be considered i including the " pain and suffering" avoided by  !

preventing thyroid-related illnesses instead of merely j treating those illnesses once they occur.

]

.It is not presently known how the combined effects of all the updated and new factors will affect the  !

cost / benefit ratio, since there are significant  !

factors that will tend to change the cost / benefit ratio in both directions. For example: inclusion of the costs to ship, package, and store the KI (not previously included among the costs of the KI - only the purchase price of the KI tablets was included) I will tend to increase the cost / benefit ratio; but l consideration of the qualitative aspects including the benefits of avoiding thyroid nodules as opposed to merely accounting for the charges for their removal l once they occur, will tend to decrease the cost / benefit ratio. l The reanalysis is being coordinated throughout its development with the members of the Federal Radiological Emergency Preparedness Coordinating Committee (FRPCC) and its chair agency, the Federal Emergency Management Agency (FEMA).

The reanalysis started in March, 1991 by commercial l contract. The staff will use the NUREG/CR report from the analysis (scheduled to become available in ,

April 1992) to write a draft Regulatory Analysis -l' describing the options considered, along with the staff's recommendations and decision rationale.

Allowing a-reasonable time period for coordination with FRPCC members and incorporation of their comments  !

into the_ draft recommendations, Commission  !

consideration is projected for Spring, 1993.

Following a Commission decision, the NRC's position will be forwarded to FEMA (in its capacity as the chair agency for the FRPCC) for appropriate action.

Thc Comissioners 5 After that transmittal, FEMA will coordinate final i approval of the NRC-recomended policy by the other members of the FRPCC (which will include review by the various state and local agencies). FEMA will then publish a Federal Register Notice stating FEMA's 4

recomended national KI policy on behalf of the FRPCC, '

and will request public comments on that policy and on the underlying bases for that recomended policy including the NRC contractor's NUREG/CR report and the staff's final Regulatory Analysis.

Summary: The Comission should 3QIf that: a detailed reanalysis is now underway to update the current bases for the Comission's policy on KI and copies of this paper will be distributed to state and local agencies concerned with Ki policy under a staff transmittal 1 letter (Enclosure 2). The staff projects submission l of a draft regulatory analysis, along with recommendations and decision rationale to the Comission for consideration in Spring,1993.  !

/ l N

es M. Ta or ecutive irector for Operations

Enclosures:

1. Simplified Cost-Benefit Analysis Regarding Stockpiling of KI.

2. Cover letter for transmittal of this paper to interested local and state agencies DISTRIBUTION: i Commissioners l OGC CAA IG GPA REGIONS EDO ACRS ACNW ASLBP SECY

Enclosure 1 l-e j Simolified Cost-Benefit Analysis Recardina Stocknilina of KI ,

i The following simplified analysis was prepared in 1989 as part of the review i of a differing professional opinion (DPO) regarding the cost-benefit of '

! stockpiling potassium iodide (KI). This analysis updated many of the '

l significant. quantitative factors involved, taking into account new knowledge

gained since the earlier (1980) analysis. Several different cases were ,

considered, as shown in the Cost / Benefit Summary table. The "best. estimate"  !

! cost was $7,500,000 per year to provide an adequate KI stockpile for the i population out to'100 miles from each nuclear power plant, with benefits-(in

terms of avoided health problems, including nodules, cancers, and fatalities) i ~ of $140,000 per year, yielding a cost / benefit ratio of $7,500,000/ $140,000 -

! 54. . All of the other cases considered involved assumptions believed to be L less realistic and resulted in cost / benefit ratios down to a lowest value

of 6. j

l. 1. Using WASH-1400 (Ref. 1), it is estimated that the probability of a '

i large accidental release is about 10 per reactor-yr.

I 2. Assume 100 reactors in the U. S.

l. 3. Therefore, the probability of a larg'e release per year somewhere in the i U. S. is 10'*/RY x 100 reactors = 10- per year.

l 4. From data in the Strip report (NUREG/CR-2723, Ref. 2) a large release is i calculated to result in a whole body dose of about 10' person-rem, for a l typical U. S. site.

1

} 5. From staff experience with preparation of environmental impact

statements (EIS), the thyroid dose is about an order of magnitude

greater than the whole body dose, for a large release. Therefore, a

+

large release will result in 10' person-rem to the thyroid for a typical

-site.

i

6. The averace thyroid dose is then:

i 10' person-rem / release x 10 release /yr = 10' person-rem \yr.

t 4

-7. The above estimate is based upon the release fractions of WASH-1400, which estimated releases averaging 50% of the core iodine inventory for

! core-melt atmospheric **1 eases (equivalent to core-melt with early

containment failure). NUREG-1150 (Ref. 3) has estimated that such

releases would be lower and would average about 10 to 20%.of the core iodine inventory.

This is about a factor of three lower. Consequently, using the NUREG-1150 release fractions, which are based upon the best available research information to date, the average thyroid dose is j estimated to be:

! 1/3 x 10' = 3.3x10' person-rem /yr.

! 8. WASH-1400 used risk coefficients of 334 thyroid nodules per 10' person-i rem, 200 of which were benign thyroid nodules and 134 of which were i

Y

_ _ __- . - _ . _ . . _ . . ~ . _ . , ._ . . . . _ . , _ ,. -

i 2

thyroid cancers. WASH-1400 also assumed that 10% of the cancers would result in fatalities. The thyroid cancer risk coefficient of WASH-1400 l (134 thyroid cancers per 10' person-rem) is no longer considered valid.

I Instead, the values given in NCRP Report No. 80 (Ref. 4), namely, 74 1 thyroid cancers per 10' person-rem to the thyroid is regarded as the  !

best available data.

! 9. Then, using-risk coefficients of 200 benign thyroid nodules /10' person-

! rem, and 74 thyroid cancers /10' person-rem (with 10% of the cancers resulting in fatalities), the average number of health effects per year becomes:

l l 200 benign nodules /(10' person-rem) x 3.3 x 10' l person-res/yr = 6.6. benign nodules /yr, plus 74 thyroid cancers /(10' person-rem) x 3.3 x 10' l person-rem /yr = 2.44 thyroid cancers /yr, and 10% of the cancers are predicted to result in fatalities (0.25 fatalities per year).

10. In addition to these health effects, hypothyroidism must also be considered. From information taken from NUREG-CR/4214 Ref. 5), the risk coefficient for hypothyroidism is 17 cases per 10'(person-rem to the thyroid, with a threshold dose for occurrence of 1000 rad. .i

11. Since hypothyroidism has a relatively high threshold for occurrence, it -

will occur over a limited area. NUREG-CR/1443 (Ref. 6) presents data showing that the average thyroid dose for a core-melt atmospheric release is equal to or greater than 1000 rem out to about 25 miles from  !

the reactor. Since the analysis in NUREG-CR/1443 made use of WASH-1400 release fractions, the average doses should be reduced by about a factor of three to be in agreement with the results of NUREG-1150. With this correction, thyroid doses equal to or in excess of 1000 rem would be -  ;

confined, on average, to distances of about 10 miles from the reactor.  ;

12. Using demographic data from NUREG-0348 (Ref. 7), the average population within ten miles of a U. S. reactor is 37,000 (1970 census). Adjusting for the 1980 census, this is estimated to be 40,000 persons.

13. The average number of cases of hypothyroidism per year can now be estimated. Given a large release, the average dose in the region from the reactor out to 10 miles is expected to be about 2000 rem to the thyroid (using data from Ref. 6 and adjusting for the reduced release fractions of NUREG-1150, Ref. 3). Although the average population <

within 10 miles is 40,000 persons, only a small fraction would be exposed to the plume of a release. . Generally, estimates are that no more than about 3 sectors, each comprising 22.5 degrees, would be exposed to the plume. Since there are a total of 16 such sectors, the affected population is:  ;

3/16 x 40,000 - 7500 persons, w-- g,5.- -+,e- .--3 - 7 ret 4 -m we w #+ 7 4 mt

3 The total population dose is 7500 persons x 2000 rem = 15x10' person-rem and the number of cases of hypothyroidism, given a large release, is:

17/(10' person-rem) x 15 x 10' person-rem = 255 cases.

Since the probability of a large release is 10-' per yr, the average number per year is:

255 x 10** = 0.26 cases /yr hypothyroidism.

l L [Actually, this is likely an overestimate. If a timely evacuation is carried out, the number of persons exposed would be much lower.

Although this is difficult to estimate with precision, item 16 provides an approximation of the effect of protective measures].

la; Taking values [Ref.8] of $25,000 for the cost of treatment for benign nodules, $50,000 for the cost of. treatment of thyroid cancers (non-l fatal), $50,000 for the cost of treatment for hypothyroidism, and l $1,000,000 for the cost of a cancer fatality, the average costs per year

_ become

6.6 x $25,000 = $165,000 (benign nodules)

2.19 x $50,000 = $109,500 (non-fatal cancers)

! 0.25 x $1,000,000 = $250,000 (cancer fatalities) 0.26 x $50,000 = $13,000 (hypothyroidism)

Total - $537,500 per year.

15. The number of thyroid health effects predicted and the associated costs to society shown above assume that na protective measures are taken to reduce or avoid such exposures. However, a range of protective measures (other than use of KI), including evacuation, sheltering and avoiding the consumption of contaminated food and water, are included in emergency plans and would likely be taken, and would significantly l reduce radiation exposure not only to the thyroid gland but to other body organs as well. Consequently, the thyroid costs shown above are ,

significantly overestimated, probably by a factor of from two to ten. '

Using a factor of two reduction, the total thyroid costs to society i

(assuming other protective measures) are estimated to be approximately 1 1/2 x $537,500/yr = $270,000/Yr. I

[ 16. Timing is critical in the effectiveness of KI as a blocking agent. For  ;

a blocking effectiveness of 50% to be achieved, KI must be given to  :

individuals no later than about 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> after the release of iodine l begins. If KI is not given until 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after intake of radiciodine, i then its effectiveness is sharply reduced to between about 10 and 30% '

blocking. It is difficult to quantify the time delay associated with stockpiling, If KI is available to evacuees at relocation centers and other places within 3 to 4 hours4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> after accident initiation, and if '

t accident releases occur primarily after several hours warning, then this l may be effective. For fast-acting scenarios, this may not be the case.

j Overall, it is estimated that stockpiling will result in a time delay i

r

. I i

i 4

sufficient to reduce the blocking effectiveness to 50% of what it would be if each individual had KI in this possession prior to an accident 1

(predistribution). Using a factor of two reduction, the total costs to sochty of HQI stockpiling KI, i.e., the annual benefits of stocknilina- i KI are esti n ted to be 1/2 x $270,000/Yr = $140.000/vr (approx.).

17. Assume that KI is to be. stockpiled at a number of locations throughout the U. S. and is to be distributed to the affected populace after an i

accident and that the number of locations is sufficient that KI could be i

distributed to the general public within a few hours after an accident.

! 18. Representatives of the American Thyroid Association have stated (Ref. 9) i that clinically significant thyroid disease appears unlikely to result

, from individual thyroid exposures of less than 100 rads. To provide an

!- added measure of protection for children and pregnant women, however the authors of Ref. 9 suggest a radiation dose of 50 rads to the thyroid as j a threshold for iodine blockade for this group.

] 19. Based on thyroid dose vs. distance data presented in Ref. 6 Table 3, i; (and with correction for NUREG-1150 reductions) doses in excess of about 50 rad for a child would be expected at distances up to about 100 miles from a reactor in the event of a large accidental release.

! 20. If KI is to be distributed to children and pregnant women in an i emergency, it is not likely that it could practically be withheld from the general population. It is therefore assumed that KI will be stockpiled in sufficient quantities to be distributed to the general

, population within 100 miles of a nuclear power reactor.

l 21. It is estimated (Ref. 8) that 67 percent of the U. S. population resides i

within 100 miles of a nuclear power plant. Using1980censusdata,KI must therefore be stockpiled for 0.67 x 226 x 10 persons = 151 x 10'

persons.

22. Ref. 10 indicates that in a reactor emergency, KI will be taken for a minimum of several days and for a maximum of ten days. Assuming 4

stockpiling for a minimum of three days, with a usage of one KI tablet i per day, the number of KI tablets to be stockpiled is 151 x 10' x 3 =

453 x 10'.

23. The cost of KI is taken as $0.05 per tablet (Ref. 8). The actual costs are likely to be higher, since this reflects only the cost of KI tablets l in bulk. Not only have warehousing, distribution and inventory control j costs been neglected, but the need for rapid distribution at the time of i an accident would suggest that KI tablets should be pre-packaged in-readily dispensable individual packets containing 3 tablets each. The cost of such packaging has also been neglected.

24. The cost of stockpiling KI then becomes 151 x 10' persons x 3 tablets / person x $.05 / tablet = $2.27x10'.

a

4 i

' 5 Since the tablets should be replaced every 3 years (Ref.10) the annual i cost of stockoilina KI is one-third of this, or $7.5 x 10'/vr. )

25. _ he cost / benefit results are summarized below:

T I

Cost of KI - 575 x 10'/vr (from item 24).

Benefit of K1 - $1.4 x 10'/vr (from item 16, using a best estimate

' blocking value of 50%, and assuming other protective measures).

(Cost of KI)/fBenefit of KI) - 75/1.4 - 11  !

' l 26.

Additional calculations displaying the sensitivity of the benefits of KI to the assumptions used are shown on the following page.

The above

Conclusion:

Stockpiling of KI is not cost beneficial.

assessment indicates that the costs of stockpiling KI are approximately fifty times higher than the benefits.

i i

l l

- . . = - - - - - - - . - _ . - - _ - - . . - - . .-..- --_- - --

6 Cost / Benefit Summary for Stocknilino KI

[ = Cost of KI - $75 x 10*/vr (from Item #24 above) ]

l B - Benefits (given below)*

I 50% Blockina") ((/g] 100% Blockina") ((/S) l i

!- Using NUREG-1150 $1.4 x 10'/yr $2.7 x 10'/yr [28]")

1511")) $4.0 x 10'/yr [19]")

release fractions: $2.0 x 10 /yr [38]"

l Using WASH-1400 $4.1 x 10'/yr (18]"")

$8.0 x 10 5

$12.0 x 10'/yr [9]*

release fractions: $6.0 x 10'/yr [13] ) /yr [6]")

l i

• All benefits shown would be increased by a factor of two if no other l

. protective actions (evacuation, sheltering, fond interdiction) are taken. l

") "50% Blockina" means KI administration is delayed too long after a i severe release to enable maximum I-131 blockage - only half of the l maximum blockage (shown in the "100% Blockino" column) is assumed in the i

"50%" column.

! ") Using the thyroid cancer risk estimates given in NCRP Report No. 80 .

(presently considered the most accurate value). j

") This is'the current best estimate. This- case, with NUREG-1150 release fractions, 50% blocking effectiveness, thyroid cancer risk estimates taken from NCRP Report No. 80, and with other protective actions (evacuation, sheltering, food interdiction) assumed to have been taken, is currently considered to be the most realistic among the several cases presented in this simplified study. A more rigorous NRC-sponsored study to better quantify several uncertainties is now underway.

") Using the thyroid cancer risk estimates of Wash-1400, rather than those given in NCRP Report No. 80. See Note A for further details.

Note A - Risk of Thyroid Cancer Wash-1400 used a risk coefficient of 334 thyroid nodules per 10' person-rem (to the thyroid). WASH-1400 also assumed that 60% of the nodules produced were benign, 40% were cancerous, and that 10% of the cancerous nodules (4% of the total nodules) would result in fatalities. The WASH-1400 risk coefficient for thyroid cancer is therefore 0.4 x_334 or 134 thyroid cancers per 10' person-rem (thyroid).

l This value was re-examined'on light of recent information that was unavailable I to the authors of SECY-83-362. Two sources were used. The first was a Swedish study by Holm, et. al. " Thyroid Cancer after Diagnostic Dose of l Iodine-131: A Retrospective Cohort Study", reported in the Journal of the L

National Cancer Institute, Vol. 80, No.14, September 21, 1988. The second

l

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source was " Introduction of Thyroid Cancer by Ionizing Radiation," National Council on Radiation Protection and Measurements (NCRP), Report No. 80, March 30, 1985. Holm studied 35,074 patients in Swedish hospitals receiving doses of I-131 and included a 20 year follow-up, the average thyroid dose per i patient was stated to be 50 rads. The collective population dose was 35,074 x ,

50 = 1.75 x 10' person-rad. The total number of thyroid cancers observed in this study was therefore 29 thyroid cancers /10' perstn rem, or about a factor

of four less than that used in Wash-1400. '

NCRP Report No. 80 gives an absolute thyroid cancer risk of about 72 to 74 cases per 10' person-rad. This value is stated to be based on population studies of North Americans exposed to external radiotherapy in childhood.

This risk estimate is also considered to be applicable for thyroid doses in i

the range from 6 to 1500 rads. This value is about a factor of two less than i that used in WASH-1400.

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References f i i

1. U. S. Nuclear Regulatory Commission (USNRC), " Reactor Safety Study - An  ;

' Assessment of Accident Risks in U. S. Commercial Nuclear Power Plants,"  ;

WASH-1400 (NUREG/75-014), October 1975.

i 2. D. R. Strip, " Estimates of the Financial Consequences of Nuclear Power 2

Reactor Accidents", Sandia National Laboratories, NUREG/CR-2723, ,

Septembe 1982. l

3. USNRC, " Severe Accident Risks: An Assessment for Five U. S. Nuclear-  !

Power Plants", Second Draft for Peer Review, NUREG-1150, June 1989.  !

4. National Council on Radiation Protection and Measurements (NCRP),"

Induction of Thyroid Cancer by Ionizing Radiation", NCRP Report No. 80, ,

t March 1985.

5. S. Abrahamson, et. a.. " Health Effects Models for Nuclear Power Plant Accident Consequence Analysis", Part II: Scientific Bases for Health  !

Effects Models, Sandia National Laboratories, NUREG/CR-4214, May 1989.

6. D. C. Aldrich, R. M. Blond, " Examination of the use of Potassium Iodide l

' (KI) as an Emergency Protective Measure for Nuclear Reactor Accidents", ,

Sandia National Laboratories, NUREG/CR-1433, March 1980. j t

7. USNRC, " Demographic Statistics Pertaining to Nuclear Power Reactor  ;

l Sites", NUREG-0348, October 1979.  !

8. NRC staff estimate.  ;

D. V. Becker, et. al, "The Use of Iodine as a Thyroidal Blocking Agent 9.

in the Event of a Reactor Accident", Journal of the American Medical 1

Association, Vol 252, No. 5, August 1984.

10. D. V. Becker, " Physiological Basis for the Use of Potassium Iodide as a thyroid Blocking Agent-Logistic Issues in its Distribution", Bulletin of

the New York Academy of Medicine, Second series, Vol. 59, No.10, ,

December 1983. ,

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Enclosure 2 -l i-i TO: State Emergency Preparedness Officials Carlton C. Kamerer, Director FROM:

l State Programs i Office of Governmental and Public Affairs

SUBJECT:

ATTACHED STAFF PAPER TO THE NUCLEAR REGULATORY COMMISSION,

"RE-EVALUATION OF POLICY REGARDING USE OF POTASSIUM IODIDE (KI)

AFTER A SEVERE ACCIDENT AT A NUCLEAR POWER PLANT" l The subject paper is provided to inform you that a reassessment of present policy regarding stockpiling potassium iodide (KI) tablets for use by the

general public during a nuclear power plant emergency is currently underway, i- The present policy consists of voluntary federal guidance to the responsible

!- state and local health authorities, who may then decide among available i options regarding the use of KI during an actual emergency. The voluntary

{ guidance recommends that local authorities consider stockpiling and

distributing KI for emergency workers and institutionalized persons, but does 4 not recommend pre-distributing or stockpiling KI for the general public.

As the paper and its enclosed analysis make clear, new information and analysis results that have become available since 1985 (when the present

, policy was recommended by the NRC and by FEMA) have not indicated the need for i any imediate recommendation to change that policy. l 1 '

i However, if any state or local agency is contemplating or has underway a KI

, policy reassessment, that agency should be aware of the reassessment described j in this paper, because its results may be of use in the development of such

state or local reassessments. ,

i i We will distribute the results of our reassessment as soon as they become j available. The NRC staff will also distribute the results through the E-6 i Subcomittee of the Conference of Radiation Control Program Directors (CRCPD).

I 1

i I Carlton C. Kammerer, Director State Programs Office of Governmental and Public Affairs

Enclosure:

NRC-Staff Memo to The Comissioners, "Re-Evaluation of Policy Regarding Use of Potassium Iodide (KI) After a' Severe Accident at a Nuclear Power Plant".

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