ML19308B339
| ML19308B339 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 11/23/1979 |
| From: | Jay Collins NRC - TMI-2 OPERATIONS/SUPPORT TASK FORCE |
| To: | Wilson R METROPOLITAN EDISON CO. |
| References | |
| NUDOCS 7912280444 | |
| Download: ML19308B339 (1) | |
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DISTRIBUTION:
SEP r/f PSB r/f TMI r/f NRR r/f CENTRAL FILE i M
i NRC PDR November 23, 1979 Local PDR l
JTCollins Docket No.: 50-320 Mr. R. Wilson, Director i
DfI Unit 2
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, _ __, ') I O f f Metropolitan Edison Company
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P. O. Box 480 j
[Q Middlatown, PA 17057 Dear Mr. Wilsons t
i At your last Monthly Technical Meeting, you requested GPU/B&W Engineering to evaluate the consequences of depressurizing the reactor coolant system given the hydrogen gas volume that currently exists in the CRDM region of the reactor vessel. Parallel with this effort, I also requested that my staff make an independent evaluation. Attached for your infor-l mation is a copy of our evaluation. We conclude from this evaluation that there should be no detrimental effects with regard to gas expansion when lowering the RCS pressure down to 100 psig providing that the sample
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analysis data represents true cdaditions in the ACS.
Should you or your staff have any questions concerning our evaluation, please don't hesitate to contact me.
Sincerely, John T. Collins i
Deputy Director TMI Support
Attachment:
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Docket No. 50-320
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. T.W MEMORANDuti FOR:
J. T. Collins Deputy Director, TMI-2 Support Task Force i..J i
FROM-A. J. Ignatonis, Tri!-2 Support Task Force
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SUBJECT:
b EVALUATION OF GAS EXPANSION IN RCS FOLLOWING DEPRESSURIZATION 1
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- al-9 During the November 7,1979 meeting you have requested the staff to evaluate
{j the consequences of depressurizing the reactor coola..t system (RCS) given
. Qg, that a hydrogen gas volume of 68 cubic feet currently exists in the CRDi4
" ? c.i region of the reactor vessel.
Enclosed is my evaluation of the gas d,'f?
expansion in the RCS following pressure reduction of 274 psig (current
. }',. A state) to 100 psig.
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T In summary, the highlights of the study are as follows:
4 i en:
(1) The sensitive parameter that contributes to gas expansion in the RCS IE ;
is the concentration of hydrogen in water.
Based on sample analysis i s.'
data, the hydrogen released from the water to the existing gas space
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y.
f during depressurization accounts for more than half of total gas
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expansion.
The gas volume at 100 psig is estimated to increase
. y p to approximately 368 cubic feet.
This is based on ideal gas law
~ l-relationship and hydrogen release from water.
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(2) The gas is expected to expand to 252 cubic feet in the upper head of
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.h.1 the reactor vessel.
(Based on upper limit of H concentration in
- ), D water of sample analysis.) Since the upper heab volume of the reactor vessel is 508 cubic feet, the reactor vessel inlet and outlet nozzles
.,fY would not uncover.
The candy cane portion of the hot legs may be
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partially uncovered. However, this uncovery is not likely to impeds natural circulation because 85 cubic feet needs to be uncovered to stop circulation.
I estimate 30 cubic feet uncovery.
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-l of (3) Use/ Henry's constant in determining the solubility of H in water and 1:5 hence gas release to +5e RCS results in a much larger g,as expansion p.y m.y than determined by use of sample analysis data.
The volumetric gas
..gl expansion is by a factor of five to eight. To my understanding use of Henry's constant assumes maximum saturation of gas concentration in water Thus, the results would be very const rvative.
If we were to use
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