ML17252A769
| ML17252A769 | |
| Person / Time | |
|---|---|
| Site: | Dresden  (DPR-019, DPR-025) |
| Issue date: | 06/13/1975 |
| From: | Stephenson B Commonwealth Edison Co |
| To: | James Keppler NRC/RGN-III |
| References | |
| BBS Ltr. #368-75 50-249/1975-30 | |
| Download: ML17252A769 (3) | |
Text
-*D,., commone11h Edison
. '-'"'. ":) -*
- One First National Plaza, Chicago, Illinois l r:i" Address Reply to: Post Office Box 767
- Chica§o, Illinois 60690 BBS Ltr. #368-75 Dresden Nuclear Power Station R. R. #1 Morris, Illinois June 13, 1975 Mr. JameeG. Keppler, Regional Director Directorate of Regulatory Operation-Region III U. s ~ Nuclear* Regulatory Com'iDission 799 Roosevelt Road Glen Ellyn, Illinois 6o137
SUBJECT:
REPoRT OF ABNORMAL OCCURRENCE PER SEX}TION 6.6.A OF THE TEX:HNICAL SJ?EX:IFICATIONS SBI.C RELIEF VALVE sEil'POINTS LESS THAt('i'Ex::H SPm LiMITs SUBJEX:T: 1r Reg\\iiaior'Y. auiae* 1~16. Rev~* 1 Appendix A
- 2) Notification of Region III of*u. S.* Nuclear Regulatory Commission Telephone:
P. Johnson, 1500-hours on* June 5, 1975 Telegram: J. K~ppler, 1545 ho\\irs'on J~e 5, 1975
- 3) Drawing Number M-364 *
- 4) Letter from H. K. Hoyt to Dr. Peter A. Morris; Report No. 50-237/1970-48 Report Number:
50-249/1975-30 Report Date: June 13, 1975.
Occurrence Date: June 5, 1975 Facility: Dresden Nuclear Power Station, Morris,.Illinois IDENTIFICATION OF OCCURRENCE The Standby.Liquid Control (SBI.C) pump discharge relief valves were found at setpoints lower than the Technical Specification limits.
CONDITIONS PRIOR TO OCCURRENCE umt-;3.was iD:~e* shutdown moae for a refueling outage.
DESCRIPl'ION OF OCCURRENCE On May 24, 1975 a teat was performed, in the maintenance shop, on relief valve
,11~5-A to...__ determine the relief valve setting. The valve was folmd to be set at 1250 ps:i *. '",
Mr. James G. Keppler e **
June 13, 1975 The same test was performed on relief valve 110513 on May 28, 1975. At 1320 psi the*
valve began to.leak.
These events were repo~ed at 1400hours on June!), 1975. Failure to report the incident immediately was a result of a procedural inadequacy which specified that no* ac~ion be taken.
I DF.SCRIPl'IoN OF APPARENT. CAUSE OF OCCURRENCE (Equipment Failure)
Relief valve110SA performed properly in the.test except that the setpoint was low. This 1 incident i~ attributed to setpoint drift.
Relief:valve 1105 B began to leak at 1320 psi, below the required setting
- Disassembly of the valve revealed crystals of sodium pentaborate on the valve
~eat. These cryst8.l.s prevented the valve from seating properly and lowered its relief ~etpoint.
ANALYSIS OF OCCURRENCE Both SBW pumps are 100% capacitY puinps.
When requ;tred, the reactor operator will select one of the systems. Therefore, the operabi~ity of the system is limited to 1256'ipsi. The system is intended as a*backup system for the control rod J
drive system, with the reactor in the. cold.condition, in the event that all rods fail to insert* after a reactor trip. * *
- The SBW system will not: be required to operate with reactor pressure greater than 1250 psi as therenare no expected reactor trans.ients which result in a reactor pressW-e greater than 1250 psi in the period of time which can affect the operation
- of the SBW system. *Therefore, the*health and safety of ~he public were not compromi~~d by this o~curr~ce.
CO~TIVE ACTION Valve 1150-B~*Which started leaking at 1320 psi was cleaned and lapped to remove the crystals around the valve seat. It was then reset to 1448 psi.. and reinstalled on May 30, 1975.
Valve 1105-A wa's cleaned and reset. This event. is consid~red to be an isolated case and does not appear to be an iiiherent problem in the design of the valve.
No further action was deemed ne~cessary.
The procedure for testing the SBW injection lines was revised prior to the most recent valve test. -The valves are now tested with nitrogen in the maint-enance shop. This wili minimize the possibility of sodium pentaborate crystals' forming on the valve seat~ In addition, the relief valve testing procemire will be revised.by.,..J~Y.::.:..:. *' 1975 to ensure that any deviation from Tech Specs limits is reported to-* the *'Shift engineer within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> *of the occurrence.
Mr. J.ames 9. Keppler
.June 13, 1975
~*
,j
..... /
FAILURE DATA A review* of station records indicates that sodium pentaborate.deP9si ts.. on *the valve seat has occurred once before (reported August 25, 1970).
~:)setpoint drift as found on valve 11. 05-A has never occurred before.
BBS:DB:smp File/NRC
- S ephenson *
- Superintendent