ML20207N547
| ML20207N547 | |
| Person / Time | |
|---|---|
| Site: | Vermont Yankee File:NorthStar Vermont Yankee icon.png |
| Issue date: | 10/14/1988 |
| From: | Murphy W VERMONT YANKEE NUCLEAR POWER CORP. |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| FVY-88-86, IEB-88-004, IEB-88-4, NUDOCS 8810190212 | |
| Download: ML20207N547 (4) | |
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VbHMONT YANKEE NUCLEAR POWEll COllPORATION k
FVY 88-86 RD 5 Box 169, Ferry Roac', Brattleboro, VT 05301 ENGINEERING OFFICE y
V 1671 WORCESTER RO AD Fn AMINGHAM. M ASS ACHuSET TS 01701
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retamo renweim October 14, 1988 U.S. Nuclear Regulatory Commission I
Washington, D.C.
20555 Attn Document Control Desk
References:
a)
License No. OPR-28 (Docket No. 50-271) b)
Letter, USNRC to All Licensees for Nuclear Parner Plants Holding an Operating License or a Construction Permit, NVY 88-075, "NRC Bulletin No. 88-04:
Potential Safety-Related Pump Loss," dated 5/5/88 c)
Letter, VYNPC to USNRC, NVY 88-57, "Vermont Yankee's Response to NRC Bulletin No. 88-04:
Potential Safety-Related Pump Loss," dated 7/11/88 i
d)
Letter, BW/IP International to VYNPC, "Vermont Yankee Nuclear Power Purchase Order No. 35468, HPCI Pumo,"
dated 9/8/88 e)
Letter, Bingham Pumps to VYNPC, "RHR, Core Spray, RCIC Pump Minimum Flow," dated 10/6/88
Dear Sir:
Subject:
Results of Vermont Yankee's Long-Term Resolution Action Items: USNRC Bulletin No. 88-04 USNRC Bulletin No. 88-04, dated May 5, 1988 (Reference b)], requested all l
licensees to investigate and correct, as apolicable, two minimum flow design l
concerns.
The first concern involved the potential for the deadheading of one l
or more pumps in safety-related systems that have a minimum flow line common to i
two or more pumps, or other piping configurations that do not preclude pump-to-pump interaction during minimum flow operation. A second concern was whether or l
not the installed minimum flow capacity was adequate for even a single pump in i
operation.
L Vermont Yankee responded to the subject Bulletin on July 'il,1988 (Reference c)}.
This response identified Vermont Yankee's long-term resolution actions to include: obtainir.g updated pump vendor recommenet-tions; reviewing existing procedures and incorporating appropriate vender nui.'areo and completing a flow calculation for Residual Heat Removal (RHP).4inimum flow lines
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to veri 8y that no adverse pump-tn-pump interaction occurr,
.n accordance with 7
I 8810190212 8S1014 If PDR ADOCK 05000271 g
VERMONT YANKEE NUCLEAR POWER CORPORATION U.S. Nuclear Regulatory Commission October 13, 1988 l
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the schedule set forth in Vermont Yankee's July 11, 1988 submittal and discussed 3
with Mr. Vern Rooney (NRR Project Manager for our facility) on October 3, 1968:
j Vermont Yankee herewith submits, as Enclosure 1 to this letter, the results of our long-term r2 solution action items.
1 We trust this letter and enclosure are responsive to Action Item 5 of the subject Bulleting however, should you have any questions or desire additional information, please do not hesitate to contact us.
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Very truly yours, VERMONT YANKEE NUCLEAR POWER CORPORATION I
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j Warren P. Murphy Vice President and Manager of Operations 1
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j cci USNRC Regional Administrator, Region I l
USNRC Resident Inspector, VYNPS
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1 ENCLOSURE 1 RESULTS OF VERMONT YANKEE'S LONG-TERM RESOLUTION ACTION ITEMS - USNRC BULLETIN NO. 88-04
SUMMARY
The Vermont Yankee systems within the scope of Bulletin 88-04 were listed in Table 1 to Vermont Yankee's letter of July 11, 1988 responding to the subject Bulletin. The following describes Vermont Yankee's results for each of the long-term resolution action items identified in Vermont Yankee's response to the i
subject Bulletin.
ITEM 1 Obtain updated pump vendor recommendations and evaluations.
RESULT 1 The pump vendors have provided their current recommendations (References d) and e)) to Vermont Yankee for each of the subject pumps (HPCI, RCIC, RHR and Core Spray). Byron Jackson (Reference d)) has stated that Vermont Yanken's current minimum flow rate for the HPCI pump is adequate. Bingham pumps (Reference e)) has stated that Vermont Yankee's current minimum flow rate for the RCIC pump is adequate.
Bingham also states that the minimum flow ratts for the RHR and Core Spray pumps are adequate for all routine surveillance tetiting.
At this time, Bingham is unable to verify the adequacy of the RHR and Core Spray pumps in the standby mode for a period of up to five hours. This is due to a lack of available data at low flow rates for extended periods of tims. However, the results of the extensive 1987 RHR pump overhaul program at Vermont Yankee, during which all four RHR pumps were completely disassembled and impe11ers replaced, demonstated that the removed impe11ers had no degradation attribunable to cavitation or flow disturbances after 15 years of operation. Vermont Yar kee is currently working with the pump manufacturer to determine if any modifica-tions are necessary to the minimum flow capacity of the RHR and Core Spray pumps.
4 ITEM 2 Review procedures and incorporate vendor guidelines, as appropriate.
RESULT 2 Byron Jackson recommends that Vermont Yankee only use the HPCI pump in
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minimum flow mode for 60 hours6.944444e-4 days <br />0.0167 hours <br />9.920635e-5 weeks <br />2.283e-5 months <br /> per year. Bingham recommends that Vermont Yankee i
only use the RCIC pump in minimum flow mode for pump starts.
For both HPCI and i
RCIC, Vermont Yankee's operating procedures do not use the miniraum flow line and surveillance testing does not involve minimum flow operation.
Therefore, the l
vendor's guidelines are adequately incorporated in Vermont Yankee's existing procedures. Bingham Pump recommends that Vermont Yankee only use the RHR and Core Spray pumps in minimum flow mode for pump starts.
Vermont Yankee's RHR and Core Spray surveillance procedures have cautions in place which minimize opera-l tion in the minimum flow mode.
Therefore, the vendor's guidelines are ade-I quately incorporated in Vermont Yankee's existing surveillance procedures.
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conjunction with the RHR and Core Spray pump effort described in Result 1 above, l
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Page 2 Vermont Yankee is evaluating the existing RHR and Core Spray procedures.o determine if the five-hour standby duration can be reduced to a smaller t'me period. An evaluation is also underway to determine methods of increasing the minimum flow rates of the RHR and Core Spray pumps, should it be necessary.
Within 30 days of the completion of the evaluations, Vermont Yankee will provide the results and notify the NRC of any actions taken.
ITEM 3 Evaluate the RHR minimum flow lines for flow division taking into con-sideration:
a) the actual line and component resistancas for the as-built configuration of the identified systems b) the he'd versus flow characteristics of the installed pumps, incivding actual test data for "strong" weak pump flows: c) the effect of test instrument error and reading errors and d) the worst case allowances for deviation of pump test parameters as allowed by the American Society of MechanicL1 Engineers Boiler and Pressure Vessel Code (ASME Code),Section XI, Paragraph IWP-3100.
RESULT 3 The RHR minimum flow lines were evaluated and formal calculations were per-fctmed for flow division.
This evaluation verified that no adverse pump-to-pump interaction occurs in the RHR system.
The worst case flow is 414 gpm, which is 64 gpm higher than the design minimum flow.
This flow is the lowest possible before the pumps would be declared inoperable by Vermont Yankee In-Service Testing (IST) Program. Vermont Yankee's IST Program's worst case allowances for deviation of pump test parameters were used instead of the ASME Code allowances because Vermont Yankee's allowances are greater than the ASME Codes and are, therefore, more conservative.
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