ML20235F310
| ML20235F310 | |
| Person / Time | |
|---|---|
| Site: | Seabrook  |
| Issue date: | 07/01/1987 |
| From: | George Thomas PUBLIC SERVICE CO. OF NEW HAMPSHIRE |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| NYN-87085, NUDOCS 8707130324 | |
| Download: ML20235F310 (5) | |
Text
, _
George S. Thomas Vice President-Nuclear Production
)
I Putse Service of New Hampshire I
New Hampshire Yankee Division i
July 1, 1987 i
NYN-87085
. United States Nuclear Regulatory Commission Washington, DC 20555 Attention:
Document Control Desk
References:
(a) Facility Operating License NPF-56, Construction Permit CPPR-136, Docket Nos. 50-443 and 50-444 (b) PSNH Letter (NYN-87069), dated May 20, 1987, i
" Residual Heat Removal / Containment Building Spray Systems Interface", T. C. Feigenbaum to the USNRC.
Subject:
Residual Heat Removal / Containment Building Spray Systems Interface Gentlemen:
During discussions with the NRC Staf f regarding Reference (b), New Hampshire Yankee (NHY) committed to provide additional information and clarification to the enclosure of Reference (b). Accordingly, enclosed please find the additional information and clarifications requested.
This information addresses the concerns expressed in our discussions.
NHY therefore requests that the acceptability of the information provided both here and in Reference (b) be reflected in the next supplement to the Seabrook Station SER.
Should you have any questions, please contact the NHY Bethesda Licensing Office (Mr. R. E. Sweeney) at (301) 656-6100.
Very truly yours, hhY O
George S. Tho s 8707130324 B70701 PDR ADDCK 05000443 i
P PDR P.O. Box 300. Seabrook, NH 03874. Telephone (603) 474-9574
r__.___
United States Nuclear Regulatory Commission' NYN-87085 Attention: Document Control Desk Page 2 Enclosure cc:
Mr. Victor Nerses, Acting Director Project Directorate I-3 Division of Projects I/II U. S. Nuclear Regulatory Commission Washington, DC 20555 Mr. William T. Russell Regionni Administrator U. S. Nuclear Regulatory Commission Region 1 631 Park Avenue King of Prussia,-PA 19406 Mr. A. C. Cerne NRC Senior Resident Inspector Seabrook Station Seabrook, NH 03874 l
ENCLOSURE TO NYN-87085 The following provides the additional information and clarifications the NRC Staf f requested as a result of its review and subsequent discussions with NHY regarding the enclosure provided with NYN-87069 [ Reference (b)].
1.
The discussion regarding the opening of the RRR loop isolation valve (Page 5, Third Paragraph) was discussed with Westinghouse.
Westinghouse indicated that it could not identify any regulatory requirements or Seabrook specific licensing commitments that would be compromised by this design during conditions with valves CBS-V2 and CBS-V5 open.
2.
During preparations for the second Hot Functional Test Program, both CBS trains experienced an increase in pressure due to leakage through check valves CBS-V25, -26, -55, and -56.
The source of pressure was via the RHR while lined up to the RCS.
The four (4) subject check valves were dismantled, seats and discs lapped to attain acceptable " blue test" results, and reassembled.
Inspection revealed the check valve (s) leakage was a result of incomplete disc / seat contact and not valve failure.
Subsequent to the repairs, successful seating of the valves was achieved by opening the CBS recirculation valves and venting the CBS side of the check valves back to the RWST.
This method of providing a positive dif ferential pressure across the check valves is provided in Attachment 6 to Reference (b).
3.
The CBS Thermal Monitoring System provides a means of alerting plant operators to a check valve leakage condition during the plant heatup/cooldown mode of operation.
In the event of a 30 gpm leakage condition, sufficient time exists to isolate the associated RHR train from the RCS.
Alarm receipt and limiting time for operator response to a 30 gpm check valve leak is as follows:
Receipt of Check Valve Rate Alarm Operator Response Time CBS-V25,-26 12 min. following 18 min. following rate initiation of alarm valve leakage C BS-V55,-56 4 mi n, following 11 min. following rate initiation of alarm valve leakage The total elapsed time of 30 minutes and 15 minutes for a CBS-V25,-26 and CBS-V55,-56 leak respectively, will assure the CBS analyzed conditions are not exceeded.
4.
The locations of the CBS Thermal Monitoring System thermocouple were selected to ensure a system overstress condition does not l s
l L
f.NCLOSURE TO NYN-87085 l
result following a CBS check valve leakage condition.
Spe cifi c thermocouple locations and alarm setpoints provide for identi-fying leakage paths such that action can be taken to eliminate the migration of high temperature fluid toward critical system components such as the CBS pumps and heat exchangers.
Re ci r cu-lation of a CBS train following receipt of a temperature alarm
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will cooldown and eliminate excessive temperature, thus preven-l ting a potential overstress condition for critical components.
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Interconnecting CBS piping bounded by the source of check valve
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leakage and the CBS recirculation flow path has been evaluated and found acceptable for the high temperature conditions induced by check valve leakage. Therefore, cooldown of these portions of the CBS is not required.
5.
As an additional ef fort, NHY has evaluated the consequences of check valve leakage for those portions of the CBS which could experience conditions of 470 psig/350*F. This hypothetical event would result from check valve f ailure, coincident with the Thermal Monitoring System failure and no operator action.
l The applicable CBS piping, components and supports were eval-l
.uated for a faulted allowable condition of 470 pr;ig/350*F.
The results are as follows:
acceptable with the exception of one (1) CBS piping Train A elbow.
The evaluated stress is 55 ksi as compared to an allowable and ultimate stress of 45 ksi and 65 kai, respectively.
components - acceptable.
supports
- acceptable with the exception of five (5) supports.
Specifically, one (1) hilti bolt / stud associated with each of the five (5) supports would exceed allowable stresses.
However, the evaluation con-cluded that each support, as a composite, would not experience structural f ailure.
)
In summary, for a scenario imposing elevated parameters of 470 psig/350*F, the applicable portions of CBS would retain structural and pressure boundary integrity.
l 6.
A program review was conducted of the Category B valves in the CBS system. The review verified that all active valves i
are in the IST program and tested in accordance with Tech-nical Specification 4.0.5.
7.
Regarding the CBS Train Associated Check Valve Leakage Abnormal Procedure, a revised Attachment 6 is provided herewith clarifying Step 2.a.2.. _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
f.
Enclosure to NYN-87085 PROPOSED OPERATOR ACTIONS (SHORT TERM)
The operator has essentially 3 different methods.of determining check valve leakage:-
'l)
CBS Pump High Pressure Alarm
- 2) High Temperature Alarm
- 3) High Temperature Rate Alarm CBS TRAIN ASSOCIATED CHECK VALVE LEAKAGE ABNORMAL PROCEDURE
- 1) Verify CBS Pump Pressure High
- 2) Monitor thermal elements and primary tanks for evidence of PZR LVL check valve leakage and to determine leak rate.
RCS Press VCT LVL a) Open CBS Recirculation Valves 1
- 1) No temperature increase - check valve seated.
or 2) Temperature increase and leak rate < 25 gpm.
a) Open CBS suction valve.
b) Recire with CBS pump to reduce temperature.
or 3) Temperature increase and leak rate > 25 gpm.
a) Shut down RHR.
b) Close the RHR suction isolation valves.
c) Open CBS suction valve.
d) Recire with CBS pump to reduce temperature.
The above steps will be in place until temperature decreases and the temperature alarm resets at 120*F.
If af ter recire is secured and the temperature continues to increase:
1)
Shut down the af fected RHR train and close the RER suction isolation valves.
Upon receiving the high temperature rate alarm:
I
- 1) Stop RHR pump.
- 2) Close the RHR suction isolation valves.
- 3) Open CBS suction isolation valve.
- 4) Recire with CBS pump to reduce temperature.
- 5) Commence RCS cooldown and depressurization.
ATTACHHENT 6
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