ML19343D613
| ML19343D613 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/29/1981 |
| From: | Hovey G METROPOLITAN EDISON CO. |
| To: | Barrett L Office of Nuclear Reactor Regulation |
| References | |
| LL2-81-0109, LL2-81-109, NUDOCS 8105050554 | |
| Download: ML19343D613 (2) | |
Text
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5 Metrooolitan Edison Company N
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MAY 0 41981 > d Wnter's Direct Dial Numtwr g
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April 29, 1981 J
LL2-81-0109 g
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Attn:
Mr. Lake Barrett, Deputy Director
- d U. S. Nisclear Regulatory Commission N
- w c/o Three Mile Island Nuclear Station M
E-Middletown, Pennsylvania 17057 g
Dear Sir:
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N Three Mile Island Nuclear Station, Unit 2 (TMI-2)
Operating License No. DPR-73 Docket No. 50-320 Submerged Demineralizer System During discussions with members of your staff, you requested that we address the potential for inadvertant criticality in spent SDS ion exchange vessels due to the deposition of Uranium and transuranics onto the ion exchange media.
We have performed an analysis of the potential to accumulate a critical mass and have concluded that, because of the small quantitio of fissile material in the Reactor Coolant System and the reactor building containment sump, criticality in the spent SDS liners is not possible.
In August, 1979, we obtained a sample of the water in the sump. Ana'.ysis of that sample revealed that it contained 0.00455 pg/ml of solid uraniin, 0.028 pg/ml dissolved uranium, and 3.3 x 10 pg/ml plutonium. Based on processing 600,000 gallons of sump water, assuming uniform distribution of both radionuclides, the total inventory of uranium in the sump would be approximately 73 grams and the total inventory of plutonium in the sump would be approximately 0.0749 grams.
Assuming that all uranium and plutonium is deposited in one vessel (highly unlikely) during SDS sump water processing, that one vessel would contain 2.96 weight percent uranium. A critical mass of this weight percent uranium would require approximately 2.2 kilograms U-235.
Since only 73 grams of the caterial is present, criticality is not possible.
Further-more, for criticality to occur, 450 grams of plutonium 239 would have to be present concurrently (non-uniform slurry) with 700 grams of uraniu:
235 and 520 grams of uranium 2'43.
Since only 73 grams is available, criticality is not possible.
aerefore, we conclude that criticality
( g from the presence of the radioisotopes alone or mixed is not possible.
51 8 The Reactor Coolant System contains a concentration of 100 ppb uranium and 0.24 ppb plutonium. These concentrations yield a total of i
37 grams of mixed uranium and plutonium. Therefore, based on the previous
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discussiens concerning criticality requirements, criticality is not possible.
k 8165050554 Mero:35 tan Ecison Company is a Member of the General Pubhc Ubbties Systerr
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Mr. Lake Barrett
. LL2-81-0109 1
We believe that this letter adequately addresses your concerns. Should
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you wish to discuss this matter further, please contact Mr. L. J. Lehman, Jr. of my staff.
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d K. Hovey q v Vice-President and Director, TMI-2 GKH:LJL:djb cc:
Dr. B. J. Snyder, Program Director - TMI Office f
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