ML19253A856
| ML19253A856 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 07/09/1979 |
| From: | Gossick L NRC OFFICE OF THE EXECUTIVE DIRECTOR FOR OPERATIONS (EDO) |
| To: | Schweiker R SENATE |
| Shared Package | |
| ML19253A857 | List: |
| References | |
| NUDOCS 7909110543 | |
| Download: ML19253A856 (3) | |
Text
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Jllt 9 1979 The Honorable Richard S. Schweiker United States Senate Washington, D.C.
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Dear Senator Schweiker.:
Your constituent inquiry of April 30, 1979, regarding the public whole body scanning program following the Three Mile Island accident (TMI-2) was referred to us for reply by the Department of Er ergy on May 31, 1979.
On April 9, 1979, Mr. Harold Denton, Director of the Office of Nuclear Reactor Regulation, established a whole body counting program, to be conducted by the Nuclear Regulatory Commission.
The details of the program were detennined taking into consider-ation the following factors:
- 1. The only radie
'vity that I:ad been detected in human food chains (milk) as a result of the accident was iodine-131, which has a 7.5 day effective half-life in man (i.e., the activity remaining declines by one-half every 7.5 days after the initial uptake into the body).
- 2. There were no other detectable radionuclides released which would be taken up into the human body through other pathways (e.g., inhalation).
- 3. Sir-the TMI-2 rel~ eases occurred 7 to 10 days earlier, it was necessary to establish the program as quickly as pcssiiale.
- 4. Only one mcbile whole bcdy scanning system was readily available.
- 5. There were too many people living within the evacuation zone (5 miles) to scan within a short time (e.g., within another hal f-life of I-131).
- 6. If no radioactivity was measured in persons living close to the plant and who were exposed to the releases and the uptake of I-131 in milk, it was unlikely that anyone living further away would have measurable I-131.
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- 7. A three mile radius of TMI-2 included about half the population of the nearest community (Middletown) and a total of 10,254 people.
This number implies that about 3,000 families live within 3 miles of TMI. based on available counting equipment, it would have been possible to scan 10 to 20% of those families within one more half-life of I-131.
It was decided that if any radio-activ ty was detected in anyone within 3 miles, we would scan that person's entire family, and if there were measurable amounts of I-131 in persons living in Middletown, we would then extend the radius to five miles and extend the duration of the program.
The program was operating within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> after the assigned staff member arrived at TMI.
The first persons to be counted were dairy fanners who lived near the plant; who were at homc during the major releases of I-131, whose cow's milk showed measurable levels of I-131 and who consumed that milk. Although preliminary calculations indicated there would not be detectable I-131 in t'e farmars, or anyone for that matter, it was essential to look 131 in th c mcst exposed population first to provide further assurance cd guidance an the scanning criteria. When all the results for the farmers were negative, it supported the earlier decision to limit the program to a 3-mile radius.
Subsequently, when whole body scans of the first 50 persons were completed and the results were also negative, it became clear that further scans would not likely reveal any radioactivity originating from TMI-2 releases. However, it was felt that running the program until a r2presentative part of the 3-mile' population had been scanned would provide further reassurance to a large number of people that there was no significant undetected radioactivity in their bodies as a result of the accident.
Since no TMI-? related radioactivity was detectel in the 721 persons scanned (from a total population of about 10,000 persons) and the I-131 released fran the plant essentially disar.peared through radioactive decay, no additional whole body sr.anning was performed.
In closing, based en the people who were counted we beli. eve there is reasocable issurance that no one in the gereral public could have received an internal adiation dose from the TMI accident in excess of a few perccnc of the annual cose from natural radiation.
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The He-We hope this information answers the questions from your constituents.
Sincerely, I
(Signed) T. A Rehm p1/J.ee V. Gdsick Executive D; rector j
for Operations i
Fnclosure:
Incoming Letter from Senator Schweiker e
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