ML19093B063
| ML19093B063 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 12/23/1977 |
| From: | Stallings C Virginia Electric & Power Co (VEPCO) |
| To: | Case E, Reid R Office of Nuclear Reactor Regulation |
| References | |
| Seri al No. 382B/092477 | |
| Download: ML19093B063 (3) | |
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if VIRGINIA ELECTRIC AND POWER Cok1PAll{t[/f't1:. ;\\~
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December 23, 1977
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Mr~ Edson G. *Case, Act=i:ng Director Nuclear.Reactor.Regulation*
- U. S ~ -Nuclear.Regulatory. Commission Washington; D. C. ; 20555 ATTN :
l1r ~. Ro her t W. Reid; Chief Operating.Reactors Branch 4
Dear *Mr~ -Case:
Seri
- o. 382B/092477
- PO&M/ALH:wbh
-. Docket Nos~* :50...:280
- 50...:2s1 License Nos. *DPR-,32
-DPR..,:37
.The purpose of this.letter is to provide information.requested by
}:lr. *David.Shi.tin of -your. staff. to.support. his.review of -our* proposed*.modifica-tions to the low head*safetyinjectionand.recirculationspray pumps at Surry.
The* information.requested is provided in the attachment to this.letter.
.Attachment cc: - Mr; James P. 0 'Reilly
. Very truly yours,
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- C. J'f *. Stallings Vice President - Power Supply and Production Operations
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e Attaclunent
,l NRC REQUEST FOR INFORMATION.
REGA..~ING PROPOSED RS/LHSI MODIFICATIONS NRC Question Is it possible to provide the Westinghouse calculated mass and energy release rates and energy distribution for a PSDER at Surry?
Response
As part of our contract for-steam generator replacement, Westinghouse is connnitted to provide calculated mass and energy release rates _and energy distributions for a PSDER at Surry.
We are.currently reviewing necessary system data so that the analysis can be dmducted.
A firm schedule for com-pletion has not been agreed upon, but we are making~every effort to get this information as soon as possible.
NRC Question What is the IRS pump operating point for the temporary modification dis-cussed in the September 12, 19~7 submittal?
Response
The operating point for the IRS pump is 3500 GPM whenever the calculated available NPSH is greater than or equal to 11.0 FT-H20, The flow rate is conservatively assumed to decrease to 3000 GPM when tlie calculated available NPSH falls below 11. 0 FT-H2o.
The actual pump flow will gradually decrease as available NPSH decreases.
This relationship of flow and NPSH ~s shown on figure 3 of the September 12~ 1977 submittal.
NRC Question What is the friction head loss versus time for the IRS, ORS and LHSI pumps for the proposed temporary and permanent fixes?
Response
The following Table presents data from which the friction loss, for any flow rate of IRS, ORS, LHSI pumps, may be calculated:
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e Height of Containment Sump Floor Above Centerline of 1st Stage Impeller-FT IRS Friction Loss-FT ORS Friction Loss-FT 1 Pump Operation 2 Pump Operation LHSI Friction Loss-FT 1 Pump at 3500GPM 2 Pumps at 2600GPM ea.
IRS-3500GPM 7.9 0.8 e
Attachment ORS-2250GPM 9.1 2.7 3.5 LHSI 8.6 7.2 4.0 During the recirculation phase of LOCA, the ORS and LHSI pump friction losses will remain constant with time since the flow rates of these pumps will remain constant.
The IRS pmnp flow rate.will vary with available NPSH which has already been discussed.
Using the transient curves provided in the September 12 and November 22, 1977 submittals, the variation of IRS NPSH and thus flow and friction loss with time can be calculated NRC Question Why doesn't the LOCTIC computer code used for NPSH analyses use the ASME steam tables that can be used below 53oF?.
Response
The notes at the bottom of table 6 in both the September 12, 1977 and November 22, 1977 submittals which gave rise to this question need clarifica-tion.
An examination of the figures showing NPSH versus time in each of our submittals shows that the limiting case for LHSI NPSH is a PSDER with minimum ESF for all values of service water temperature.
Therefore it is not really necessary to calculate the available NPSH for other conditions.
Regardless of this fact, we have discussed the possibility of using the ASME steam tables in the LOCTIC Code with our Architect Engineer.
Their staff has informed us that it can be done, but the time and expense required to do so are extensive.
Furthermore, the A-E staff feels that this effort is unwarranted since the LOCTIC Code as it now exists adequately calculates the limiting LHSI NPSH case; namely a PSDER with minimum ESF.
We concur with the feeling of the A-E staff and do not believe that the expense required to insert ASME steam tables into LOCTIC can be justified.
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