ML19249D331
| ML19249D331 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/24/1979 |
| From: | Jay Collins NRC - TMI-2 OPERATIONS/SUPPORT TASK FORCE |
| To: | Herbein J METROPOLITAN EDISON CO. |
| References | |
| NUDOCS 7909240131 | |
| Download: ML19249D331 (2) | |
Text
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August 24, 1979 Docket No. 50-320-
.Str. John C. Herb'nin, Vice President Uuclear Operation Metropclitan-Edison Company
- 1 railer Number 120 Middletown, Pennsylvania 17057
Dear Mr. Herbein:
SUBJr:CT: NRC COMMENTS TO THE CPU LEITER ON RCS PRESSURE INDICATION DURING UNIT 2 SAMPLE LINE TIE-IN, DATED AUGUST 15, 1979 e have reviewed GPU's evaluation of alternate reactor coolant system pressure indication during the tie-in of the new Unit 2 Sample Syctem. Our general comment is that we concur with GPU's recommendation of delaying the sample sink tie-in.
'la prefer to wait until a direct decay heat removal system would be in operation (e.g., the mini-DHR system).
Please note that with the mini-DHR system in service, RCS pressure indication would be available and additional sampling capability would exist.
RCS samples withdrawn from this system would be more representative than the samples obtained from the pressurizer.
Secondly, if the sample sink tie-in were to be made, sole reliance on the standby pressure control system for RCS pressure indication would not be a satisfsetory pr: ctice. Further comments are as follows:
1.
If the semple sink modification is required as soon as possibic, we fwould prefer to use the RC pump seal cavity pressure indication for RCS pressure indication as it is more reliable.
The standby pressure con:rol (SPC) system is not a proven system and still has a number of problems associated with its operation.
Phase II (control from the Unit 2 control room) for the SPC is not yet complete. Using the SPC for RCS pressure indiert. ion will mean turning off the RC makeup system (to prevent a possible overpressure transient which the SPC could not handle) and thus there will be no RC pump seal cavity pressure indicatiot.
Also, we question the reliability of reading level changes in the SPC surge tank (SPC-T3) for monitoring RCS pressure transients.
- Further, the pressurizer heaters must be surveyed to assure their inadvertent actuation and a possible overpressure trcnsient.
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I'.r. John G. Herbein August 24, 1979 2.
Consideration should be given to using the existing pressure gauge on the Dl!R drop line where an additional Heise gauge and DVM are located, just inside the Fuel Handling Building.
It is our understanding that this new Heise gauge and DVM have been installed.
RCS pressure can be obtafned by slightly opening DH-V1 or DH-V171.
Since DH-V3 serves as isolation, reactor coolant would go out as far as DH-V3, and all neces-sary shielding and HP precautions can be taken.
There may be some drawbacks to this method such as potential opening of the relief valve in the event of overpressurization of the RCS.
However, to our uader-standing, the sample sink modification will require only 16 hours1.851852e-4 days <br />0.00444 hours <br />2.645503e-5 weeks <br />6.088e-6 months <br /> so the time during which DH-V1 or DH-V171 is open is minimal.
Sincerely,
. k!.u.)
[JohnT. Collins,DeputyDirector TMI-2 Support I
cc:
R. Vollmer M. Greenberg S. Newberry J. Wermiel A.
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