ML20215E502
| ML20215E502 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 10/03/1986 |
| From: | Leitch G PECO ENERGY CO., (FORMERLY PHILADELPHIA ELECTRIC |
| To: | NRC OFFICE OF ADMINISTRATION (ADM) |
| References | |
| CON-#486-1097 OL, NUDOCS 8610150340 | |
| Download: ML20215E502 (6) | |
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O PHILADELPHIA ELECTRIC COMPANY 23O1 M ARKET STREET P.O. BOX 8699 PHILADELPHIA PA.19101 (215)8414000 October 3, 1986 Docket No. 50-352 Document Control Desk U.S. Nuclear Regulatory Commission Washington, D.C.
20555
SUBJECT:
Limerick Generating Station Unit 1 Safety Relief Valve Setpoint Drift The purpose of this letter is to provide information to the Nuclear Regulatory Commission on the results of recertification setpoint tests performed on the Limerick Unit 1 Reactor Safety Relief Valves (SRVs) during the May, 1986 outage.
This subject was previously addressed in Inspection Report 50-352/86-09 dated June 27, 1986.
In accordance with Technical Specification l
surveillance requirement 4.4.2.2, which states "At least 1/2 of the safety relief valves shall be removed, set pressure tested l
cnd reinstalled or replaced with spares... at least once per 18 months...", eight SRVs were removed for testing during the week of May 5, 1986.
The SRVs were sent to Wyle Laboratories where the set pressure was tested.
The testing on these eight valves resulted in six of the eight valves exceeding the + 1% variance of the nominal lift setpoint allowed by the Technical Specifications.
Once these test results were known, the balance (six) of the SRVs were sent to Wyle Laboratories for testing.
The complete test results are as follows:
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4 Mr. Robsrt Barnaro Octobsr 3, 1986 Page 2 Serial No.
Date of Nameplate As Found Lift (S/N)
Test Setting (psig)
Pressure (psig)
Variance First Group of Valves 517 (A) 5/12 1150 1154
+0.4 525 (C) 5/13 1150 1198
+4.2 513 (G) 5/12 1150 1184
+3.0 515 (K) 5/13 1140 1188 (Note c)
+4.2 522 (M) 5/13 1140 1220 (Note a)
+7.0 (Note c) 528 (S) 5/12 1140 1140 (Note c) 523 (H) 5/12 1130 1165 (Note c)
+3.1 518 (J) 5/13 1130 1160
+2.7 Remainder of Valves 516 (N) 5/27 1130 1153
+2.0 521 (L) 5/27 1130 1159
+2.6 519 (F) 5/28 1150 1153
+0.3 527 (E) 5/28 1140 1187
+4.1 526 (D) 5/27 1140 1129
-0.97 520 (B) 5/29 1150 1178 (Note c)
+2.4 Serial Nominal As-Found Subsequent Lifts Number Set Pressure Lift / Reseat (psig)
(S/N)
(psig)
(psig) 2nd 3rd 4th 517 1150 1154/812 1155 1148 1145 525 1150 1198/783 1149 1140 1140 513 1150 1184/797 1153 1142 1140 515 1140 1188/923 1127 1137 1138 522 1140 1220/976 1145 1136 1135 528 1140 1140/786 1139 11-33 1127 523 1140 1165/790 1145 1138 1125 518 1130 1160/806 1125 1125 1122 516 1130 1153/785 1146 1136 1141 521 1130 1159/833 1155 1145 1143 519 1150 1153/783 1147 1147 1141 527 1140 1187/796 1136 (Note b) (Note b) 526 1140 1129/867 1145 1136 1128 520 1150 1178/817 1165 1160 1157 NOTES a
As-found first set pressure greater than 1190 psig, full scale instrumentation limited to 1200, extrapolated to 1220 psig for SRV S/N 522 b
Testing suspended for investigation into delayed main disc movement.
c Automatic Depressurization System Valve l
's l
Mr. Robart Barnero October 3, 1986 Page 3 Operating History Previously, all 14 valves tested had been refurbished by the Target Rock Corporation during 1984 in accordance with General Electric Service Information Letter (SIL) #196 dated September 30, 1976 including inspection in the labyrinth seal area,and the enhanced valve internals maintenance program.
The tested valves were also manually cycled open for 10 seconds during the startup test program at Limerick, once during the heatup phase at 358 psig (427 degrees F) and 4.8% power on January 6, 1985, and again during Test Condition 2 at rated pressure of 956 psig (510 degrees F) and 25.5% power on January 6, 1985.
During the testing performed during the May outage, ten of the fourteen valves failed to lift ("as found" first lift) within + 1% of the nominal lift setpoint as required by the Technical Specification.
Five of these valves exceeded the 103%
ASME Code limit.
The maximum setpoint variance was + 7.0%.
The mean value of setpoint name plate variance was + 2.6% for the "as found" first lift and - 0.7% for subsequent lifts.
Due to the non-conservative results of the testing performed on the 14 SRVs removed from Unit 1, replacement valve Serial Number 507 was selected from storage and sent to Wyle Laboratories for the identical "as-found test".
Valve #507 which has a nameplate setpoint of 1150 psi lifted at 1148 psi during the "as-found" test.
This value is 0.2% less than the nameplate 4
setp:n it and is within the + 1% Technical Specification limits.
Following the results of the tests on the SRVs by'Wyle Laboratories, an analysis to assess the impact of SRV setpoint drift was performed by General Electric (GE).
The report is titled "SRV Setpoint Drift Assessment for Limerick Unit 1" dated j
May 28, 1986.
The GE assessment determined that a conservative + 10%
variance in setpoint drift would not have a detrimental effect on any of the following items:
4 1.
the pressure margin to the ASME Code limit of 1375 psig 2.
the operating thermal margin (MCPR) 3.
the ECCS/LOCA performance 4.
the plant equipment performance capability, and 5.
the containment response The valves removed for testing were replaced by seven SRVs from the PECo warehouse (Unit 1 spares) and seven SRVs from the Bechtel Warehouse (Unit 2 spares).
's Mr. Robart Barnero October 3, 1986 Page 4 Test results on these replacement valves were also obtained from a January 11, 1985 test performed by the Target Rock Corporation which included a setpoint check and leakage test using nitrogen.
This test was followed by a steam test, the results of the steam test are as follows:
Serial No.
Nominal Lift. Pressure (S/N)
Set Pressure (psig)
(psig) 501 1130 1125 504 1130 1126 505 1140 1136 507 1150 1151 508 1140 1132 510 1150 1154 511 1150 1142 512 1130 1123 514 1140 1138 529 1140 1142 530 1140 1136 531 1130 1120 532 1130 1123 533 1130 1137 534 1150 1150 535 1150 1152 502 1130 1133 509 1140 1138 During these tests, all of the valves lifted within their design setpoint band (nominal setpoint pressure i 1%)
indicating that, under the proper storage conditions (which were verified) in conjunction with the random lift test of SRV Serial
- 507, a high degree of confidence can be placed in the replacement valves installed in Limerick Unit 1.
The investigation into the cause of the 10 of 14 valves lifting above their Technical Specification Limits is being investigated as part of work being performed by the BWR Owner Group (BWROG).
Philadelphia Electric Company is closely monitoring the investigation and will take appropriate action in accordance with the results.
This test data, along with other equipment data gathered during the May outage is being evaluated and will be reported to the Nuclear Plant Reliability Data System (NPRDS) as appropriate.
e Mr. Rob 2rt Bsrnaro October 3, 1986 Page 5 If there are any further questions, do not hesitate to contact us.
Ve y trul
- yours, d)
. M.
eitch Superintendent Nuclear Generation Division cc:
Dr. Thomas E. Murley, Administrator, Region I, US/NRC E. M.
Kelly, Senior Resident, Site Inspector E.
L. Jordan (NRC)
Service List l
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