05000457/LER-2003-005, Regarding Setpoint Drift Causes Three of Three Pressurizer Safety Valve Lift Tests to Exceed Technical Specification Tolerance
| ML040490661 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 02/09/2004 |
| From: | Joyce T Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| BW040014 LER 03-005-00 | |
| Download: ML040490661 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4572003005R00 - NRC Website | |
text
Exekc n.M Exelon Generation Company, LLC www.exeloncorp.com NucleaT Braidwood Station 35100 South Rt 53, Suite 84 Braceville, IL 60407-9619 Tel. 815-417-2000 February 9, 2004 BWO40014 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Unit 2 Facility Operating License No. NPF-77 NRC Docket No. STN 50-457
Subject:
Submittal of Licensee Event Report Number 2003-005-00, "Unit 2 Setpoint Drift Causes Three of Three Pressurizer Safety Valve Lift Tests to Exceed Technical Specification Tolerance" The enclosed Licensee Event Report (LER) is being submitted in accordance with 10 CFR 50.73, "Licensee event report system", paragraph (a)(2)(i)(b). 10 CFR 50.73(a) requires an LER to be submitted within 60 days after discovery of the event; therefore, this report is being submitted by February 9, 2004.
Should you have any questions concerning this submittal, please contact Ms. Kelly Root, Regulatory Assurance Manager, at (815) 417-2800.
Respectfully, Joyce Site Vice President Braidwood Station
Enclosure:
LER Number 2003-005-00 cc:
Regional Administrator - Region IlIl NRC Braidwood Senior Resident Inspector
Abstract
On December 10, 2003, Braidwood Station discovered that three of three pressurizer safety valves (PSVs) removed during the fall 2003 refueling outage and subsequently tested at an offsite facility, did not meet the Technical Specification (TS) acceptance criteria. TS 3.4.10, "Pressurizer Safety Valves,"
requires three PSVs to be operable with lift settings greater than or equal to 2460 psig and less than or equal to 2510 psig. The surveillance requirement requires each valve to be operable in accordance with the nservice Testing (IST) Program and that following testing the lift setting shall be within
+/-
1 percent of the TS setpoint. Two valves had lift setpoints that were low and one valve had a setpoint that was high.
There are no material condition issues with the PSVs that contributed to the test failures. The PSVs are performing within their design capabilities.
The test failures are mainly due to the close tolerance required by the current plant safety analyses reflected in TS requirements and the inability of the valves to perform within that tolerance. The corrective action to revise the safety analyses to support a relaxation of the one percent TS requirement for the PSV lift setpoint tolerance is being pursued.
An evaluation on the effects of the PSVs lifting outside of the TS tolerance concluded that all acceptance criteria in the Updated Final Safety Analysis Report, Chapter 15, "Accident Analyses," were still met.
This event is being reported pursuant to 10CFR50.73(a)(2)(i)(B).U.S. NUCLEAR REGULATORY COMMISSION (1-2001).
LICENSEE EVENT REPORT (LER)
FACILITY NAME (1)
DOCKET (2)
LER NUMBER (6)
PAGE (3)
YEAR SEQUEN[LAL REVTSION NUMBER NUMBER Braidwood, Unit 2 STN 05000457 I
2 of 3
l1 2003-005-00 A.
Plant Operating Conditions Before The Event
Unit: 2 Event Date: 12/10/2003 Event Time: 08:00 MODE: 1 Reactor Power: 100 Reactor Coolant System (RCS)[AB] Temperature:
580 degrees F, Pressure:
2235 psig B.
Description of Event
There were no systems or components inoperable that contributed to the severity of the condition reported.
As part of the fall 2003 refueling outage activities, the three PSVs (i.e., 2RY8010A, 2RY8010B and 2RY8010C) were removed in accordance with the IST program and replaced with three spare valves which had been previously verified to be within the TS required as-left tolerance of +/- 1 percent.
The three PSVs that were removed were sent to the NWS Technologies facility for as-found lift setpoint testing and refurbishment.
On December 10, 2003, NWS provided the results of the testing to Braidwood Station.
The PSVs acceptance criterion for the as-found lift setpoint is 2485 psig +/- 1 percent, as required by TS 3.4.10.
Three of the three PSVs exceeded this criterion.
One valve lifted at 2453 psig (i.e., 1.3 percent low), the second valve lifted at 2513 psig (i.e., 1.1 percent high) and the third valve lifted at 2427 psig (i.e., 2.3 percent low).
Although outside of the TS required tolerance, the valve as-found lift setpoints were within the American Society of Mechanical Engineers,Section XI, "Rules For Inservice Inspection of Nuclear Power Plant Components," part OM-1 acceptance criteria of +/- 3 percent Since all of the valves that failed the as-found lift setpoint testing had been replaced with operable valves during the fall 2003 refueling outage, no TS action applied at the time the valve test failures were discovered.
However, the condition of multiple PSVs being outside of their required lift setting tolerance band is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B), "Any operation or condition prohibited by the plant's Technical Specifications."
C.
Cause of Event
The safety valves were inspected by the vendor and no material condition issues were found that may have contributed to the out of tolerance condition.
An Electric Power Research Institute (EPRI) evaluation concerning safety and relief valve testing indicates that the PSVs at Braidwood are performing within their design capabilities. The test failures are mainly due to the close tolerance required by the current plant safety analyses and reflected in TS requirements and the inability of the valves to perform within those tolerances.U.S. NUCLEAR REGULATORY COMMISSION (1-2001)
LICENSEE EVENT REPORT (LER)
FACILITY NANIE (I)
DOCKET (2)
LER NUMBER (6)
PAGE (3) lLAR SEQUENIAL REVISION lI NMBER NUMBER Braidwood, Unit 2 STN 05000457 l l 3 of 3 fl 1
2003-005-00 The offsite test facility, NWS Technologies, indicated that based on industry experience, the PSVs performed as expected.
The vendor stated that the number of valves exceeding the one percent tolerance band in the industry is significant.
They also stated that most valves tested do not exceed two percent, and it is rare for valves to exceed three percent.
Based on this information and a review of Braidwood Station's historical data, the Braidwood Station PSV test results are typical of those in the industry.
D.
Safety Consequences
The PSVs in conjunction with the Reactor Protection System, provide overpressure protection for the Reactor Coolant RC)[AB] System.
The safety valves are designed to prevent system pressure from exceeding the RC System safety limit of 2735 psig.
An evaluation on the effects of the PSVs lifting outside of the TS tolerance concluded that all acceptance criteria in the Updated Final Safety Analysis Report Chapter 15 analyses were still met.
The event did not result in a Safety System Functional Failure.
E.
Corrective Actions
Revision of the safety analyses to support relaxation of the TS lift tolerance for PSVs has been completed as the corrective action to prevent future PSV lift test failures.
A request for a license amendment to revise the PSVs lift setpoint was submitted to the NRC on June 27, 2003.
The requested approval date of the license amendment is March 2004.
F.
Previous Occurrences
Test data from the last seven refueling outages at Braidwood Station show that out of 21 valves tested, 11 were found out of tolerance.
Seven of those 11 were out of tolerance low, four were high. Only two of the valves exceeded two percent and none exceeded three percent.
Previously, when valve failures were determined to be outside of the TS limits, station management inappropriately interpreted the TS as being met if the as-found condition of the valve was within three percent, as required by the IST program, and the as-left setpoint was within one percent as required by the TS.
Root cause analysis was performed and the corrective actions discussed in Section E above were developed and implemented.
G.
Component Failure Data
Manufacturer Nomenclature Model Mfg. Part Number Crosby Pressurizer Safety Valve HB-BP-86 N/A
Dee 10 03 07:23a NWS Technalog ies 864 587 9005 P. 2 NWS CEAR#
03-37 technologies g
LJS
\\
Customer Equipment Anomalies Report Customer/Site:
Exelon - Braidwood Station Customer P. 0. 00066489 NWS Traveller :
03-321,03-322, 03-323 ParttDescription:
CrosbyPress'iiizrSaf eWta:V W Part Serial #:
N69640-0021. N56964-090072, N56964-00-0073 NWS Originator c.v. Srn Date: 1218103 NWS Operations:
T.P. Nedero Date: 12t8/03 Description of Condition:
Braidwood as-found acceptance tolerance Is +- 1% of nameplate set-pressure 2485 psig.
Acceptance range Is 2461 to 2509 psIg.
V6IVe;N5696400007 as-found ift-was 2453,psIg-1.3% of nameplate:.
ValveN596440072 ts-found lift was 2513 ffpsgA1i 1% f nameplate.'
Valve N56964-0-0073 as-found lift was 2427psig<2.3%rof narmeplatet OM-1 Code acceptance tolerance Is +I-3%
Recommended Dispostion:
This CEAR is notification of the out-of-tolerance condition only. t requires a Braidwood representatfve to acknowledge this notification by signing below.
Customer Comments Instructions:
Disposition: 5Accept As is I~.[Repair Rew kV'..
Srap M Replace j]l0ther Customer Representative: _
Date: t2-/OQCa Approvals of Disposition NWS Operations:_
Date:
NWS Quaity Assurance:
Date:
ANI Review &Acceptance Required:
EYes No Authorized Nuclear Inspector Date:
This CEAR closed on:;
NWS Quality Assurance:
Date: __-
Forn NWS-QA-F.15-2 Rev. I 0
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