05000298/LER-1917-002, Regarding Valve Test Failures Result in Condition Prohibited by Technical Specifications and a Loss of Safety Function
| ML17139D350 | |
| Person / Time | |
|---|---|
| Site: | Cooper  (DPR-046) |
| Issue date: | 04/27/2017 |
| From: | Higginbotham K Nebraska Public Power District (NPPD) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NLS2017046 LER 17-002-00 | |
| Download: ML17139D350 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2981917002R00 - NRC Website | |
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H Nebraska Public Power District Always there when you need us NLS2017046
. April 27, 2017 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001
Subject:
Licensee Event Report No. 2017-002-00 Cooper Nuclear Station, Docket No. 50-298, DPR-46
Dear Sir or Madam:
The purpose of this correspondence is to forward Licensee Event Report 2017-002-00.
There are no new commitments contained in this letter.
Sincerely, Kenneth Riggi Vice President Nuclear-Chief Nuclear Officer
/jo Attachment: Licensee Event Report 2017-002-00 cc:
Regional Administrator w/attachment USNRC - Region IV Cooper Project Manager w/attachment USNRC - NRR Plant Licensing Branch IV Senior Resident Inspector w/attachment USNRC-CNS SRAB Administrator w/attachment COOPER NUCLEAR STATION NPG Distribution w/attachment INPO Records Center w/attachment via ICES entry SORC Chairman w/attachment CNS Records w/attachment P.O. Box 98 /Brownville, NE 68321-0098 Telephone: (402) 825-3811 /Fax: (402) 825-5211 www.nppd.com
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BYOMB: NO. 3150-0104 EXPIRES: 0313112020 (04-2017)
Estimated burden per response to comply with this mandatory collection request: 80
/UfJ/;j(
hours. Reported lessons learned are incorporated into the licensing process and fed back to ii
- Ji..
LICENSEE EVENT REPORT (LER) industry. Send comments regarding burden estimate to the Information Services Branch
~
(T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or bye-
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(See Page 2 for required number of digits/characters for each block) mail to lnfocollects.Resource@nrc.gov, and to the Desk Officer, Office of Information and (See NUREG-1022, R 3 for instruction and guidance for completing this form Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMS control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 3. PAGE Cooper Nuclear Station 05000298 1of4
- 4. TITLE Valve Test Failures Result in Condition Prohibited by Technical Specifications and a Loss of Safety Function
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED YEAR ISEQUENTIALI REV FACILITY NAME DOCKET MONTH DAY YEAR NO.
MONTH DAY YEAR 05000 NUMBER FACILITY NAME DOCKET 02 28 17 2017 -
002 -
00 04 27 2017 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply)
D 20.2201(b)
D 20.2203(a)(3)(i) 0 50. 73(a)(2)(ii)(A)
D 50.73(a)(2)(viii)(A) 1 D 20.2201(d)
D 20.2203(a)(3)(ii) 0 50.73(a)(2)(ii)(B)
D 50.73(a)(2)(viii)(B)
D 20.2203(a)(1)
D 20.2203(a)(4)
D 50. 73(a)(2)(ii)
D 50.73(a)(2)(ix)(A)
D 20.2203(a)(2)(i) 0 50.36(c)(1)(i)(A) 0 50.73(a)(2)(iv)(A)
D 50. 73(a)(2)(x)
D 20.2203(a)(2)(ii) 0 50.36(c)(1 )(ii)(A) 0 50.73(a)(2)(v)(A)
D 73.71(a)(4)
- 10. POWER LEVEL D 20.2203(a)(2)(iii)
D 50.36(c)(2) 0 50. 73(a)(2)(v)(B)
D 73.71(a)(5) 0 20.2203(a)(2)(iv)
D 50.46(a)(3)(ii) 0 50. 73(a)(2)(v)(C)
D 73.77(a)(1) 100 0 20.2203(a)(2)(v) 0 50.73(a)(2)(i)(A)
!8:1 50.73(a)(2)(v)(D)
D 73.77(a)(2)(i) 0 20.2203(a)(2)(vi)
[8J 50. 73(a)(2)(i)(B) 0 50.73(a)(2)(vii)
D 73.77(a)(2)(ii) 0 50.73(a)(2)(i)(C) 0 OTHER Specify in Abstract below or in SEQUENTIAL NUMBER
- - 002 REV NO.
- - 00 SRV pilot assembly serial number 382 was inadvertently disassembled by Target Rock technicians prior to the performance of the as-found lift test, thus due to the absence of as-found test data, the results were conservatively considered a failure of the +/-3% setpoint criteria.
BASIS FOR REPORT CNS is reporting this event as an operation or condition prohibited by plant TS per 10 CFR 50.73(a)(2)(i)(B), and also as a condition that could have prevented the fulfillment of the safety function of structures or systems as defined under 10 CFR 50.73(a)(2)(v).
An engineering analysis demonstrated that the reactor vessel would not be challenged during an overpressure event. In addition, an analysis determined that the existing Minimum Critical Power Ratio (MCPR) operating limit would have protected the MCPR safety limit in the event of an anticipated operational occurrence. As such, this event will not be counted as a Safety System Functional Failure to the Nuclear Regulatory Commission performance indicator since no loss of safety function occurred.
SAFETY SIGNIFICANCE
Although the TS SR related to the set point lift pressures of the SRV pilot valve assemblies was exceeded, an analysis of this event indicates that the design basis pressures to ensure safety of the reactor vessel and its pressure related appurtenances were not challenged. Public safety was not at risk. Safety to plant personnel and plant equipment was not at risk.
CAUSE
Corrosion bonding was determined to be the cause of SRV pilot serial number 377 failing its lift test.
The lack of a barrier to prevent inadvertent disassembly of SRV pilot serial number 382 prior to the as found testing resulted in the conservative failure of the +/-3% setpoint criteria. The conservative failure of serial number 382 eliminated margin for the remaining SRV pilots.
CORRECTIVE ACTIONS
As reported in LER 2015-001-01, presuming that no technical reason is discovered to prevent the following, submit a TS change to the Nuclear Regulatory Commission requesting setpoint changes as noted in EE 10-053; NEDC-33 543P, Revision 0, Class Ill, ORF 0000-0103-4647, dated February 2010; GE-H NEDC-33620P, Revision 0, May 2011; and GE-H, report 002N5242.RO, entitled, Cooper Cycle 28 SRV Set Point Study. This action has not been completed.
In addition, CNS will ensure that Target Rock's procurement documentation includes a mechanism to prevent the inadvertent disassembly of a CNS SRV pilot valve prior to performance of the as.,.found setpoint testing.
PREVIOUS EVENTS SEQUENTIAL NUMBER
- - 002 REV NO.
- - 00 Licensee Event Report (LER) 2015-001 On January 26 and February 11, 2015, five of eight Target Rock SRV pilot valves assemblies failed to lift within TS lift setpoint requirements. National Technical Systems, formerly Wyle Laboratories, performed this testing. The pressure setpoint for SRV pilot assembly serial number 385 was 1090 +/-3%; it lifted at 1124 psig. The pressure setpoint for SRV pilot assembly serial number 386 was 1100 +/-3%; it lifted at 1192 psig. The pressure setpoint for SRV pilot assembly serial number 1242 was 1090 +/- 3%; it lifted at 1267.7 psig. The pressure setpoint for SRV pilot assembly serial number 1243 was 1100 +/- 3%; it lifted at 1139 psig. The pressure setpoint for SRV pilot assembly serial number 1241 was 1090 psig +/-3%; it lifted at 1138 psig. Subsequent informational lifts were performed for all of the failed assemblies and were within TS pressure setpoint tolerances. The direct cause of the failures was corrosion bonding.
LER 2011-005 On June 22, 2011, one of eight Target Rock SRV pilot valve assemblies failed to lift within TS lift setpoint requirements. Wyle Laboratories performed.this testing. The pressure setpoint of the failed pilot assembly was 1090 +/- 32. 7 psig; it lifted at 1199 psig. Two subsequent informational lifts were performed for the SRV pilot assembly and were within the TS pressure setpoint tolerances. The mechanistic cause was the same as reported in previous LERs, pilot disc-to-seat corrosion bonding.
LER 2010-001 On January 12, 2010, two of eight Target Rock SRV pilot valve assemblies failed to lift within TS.lift setpoint requirements. Wyle Laboratories performed this testing. The pressure setpoint for the first pilot assembly is 1100 +/- 33.0 psig; the SRV pilot assembly lifted at 1166 psig. The pressure setpoint for the second pilot assembly is 1090 +/- 32. 7 psig; it lifted at 1139 psig. Two subsequent informational lifts were performed for both SRV pilot assemblies and were within the TS pressure setpoint tolerances. The mechanistic cause was the same as reported in previous LERs, pilot disc-to-seat corrosion bounding.
LER 2008-002 On July 7 through July 9, 2008, the results of Target Rock SRV test data performed at Wyle Laboratories identified that one of eight SRV pilot assemblies failed as-found pressure setpoint testing. The SRV pilot assembly lifted at 1165 psig, outside its TS setpoint tolerance of 1100 +/- 33.0 psig. The mechanistic cause was pilot disc-to-seat corrosion bounding between the Stellite 21 pilot disc and Stellite 68 pilot body seat to cause the SRV pilot assembly to lift outside its TS setpoint tolerance.
LER 2007-002 On February 28 through March 2, 2007, the results of Target Rock SRV tests performed at Wyle Laboratories identified that one of eight SRV pilot valve assemblies failed to lift within its TS lift setpoint of 1090 +/- 32. 7 psig. The failure was a result of sufficient corrosion bonding between the SRV pilot valve assembly Stellite 21 disc and the pilot valve Stellite 68 body seat to cause the SRV pilot valve to lift outside its TS setpoint tolerance. Page 4of 4