05000286/LER-2015-002, Regarding Technical Specification Prohibited Condition Caused by Three Main Steam Safety Valves Outside Their As-Found Lift Set Point Test Acceptance Criteria
| ML15125A019 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 04/27/2015 |
| From: | Coyle L Entergy Nuclear Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-15-045 LER 15-002-00 | |
| Download: ML15125A019 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 2862015002R00 - NRC Website | |
text
SEn tergy Indian Point Energy Center 450 Broadway, GSB P.O. Box 249 Buchanan, N.Y. 10511-0249 Tel (914) 254-6700 Lawrence Coyle Site Vice President NL-15-045 April 27, 2015 U.S. Nuclear Regulatory Commission Document Control Desk 11545 Rockville Pike, TWFN-2 F1 Rockville, MD 20852-2738
SUBJECT:
Licensee Event Report # 2015-002-00, "Technical Specification Prohibited Condition Caused by Three Main Steam Safety Valves Outside Their As-Found Lift Set Point Test Acceptance Criteria" Indian Point Unit No. 3 Docket No. 50-286 DPR-64
Dear Sir or Madam:
Pursuant to 10 CFR 50.73(a)(1), Entergy Nuclear Operations Inc. (ENO) hereby provides Licensee Event Report (LER) 2015-002-00. The attached LER identifies an event where there was a Technical Specification prohibited condition for three inoperable Main Steam Safety Valves (MSSVs), which is reportable under 10 CFR 50.73(a)(2)(i)(B). This condition was recorded in the Entergy Corrective Action Program as Condition Report CR-IP3-2015-00898.
There are no new commitments identified in this letter. Should you have any questions regarding this submittal, please contact Mr. Robert Walpole, Manager, Regulatory Assurance at (914) 254-6710.
Sincerely, cc:
Mr. Daniel H. Dorman, Regional Administrator, NRC Region I NRC Resident Inspector's Office, Indian Point 3 Ms. Bridget Frymire, New York State Public Service Commission
Abstract
On February 27, 2015, during the performance of surveillance procedure 3-PT-RO06A, three main steam safety valves (MSSV)
(MS-46-2, MS-45-4 and MS-47-4) failed their As-Found lift set point test.
Per the test, these valves must lift at +/-
3% of their required setting.
Valve MS-46-2 lifted at 1161.3 psig, 41.3 psig outside its acceptance range of 1048 to 1120 psig and 7.5% above its 1080 psig set point.
Valve MS-45-4 lifted at 1120.2 psig 23.2 psig outside its acceptance range of 1034 to 1097 psig and 5.2% above its 1065 psig set point.
Valve 47-4 lifted at 1156.7 psig, 61.7 psig outside its acceptance range of 1063 to 1127 psig and 5.6% above its 1095 psig set point.
During the test, 7 other MSSVs tested passed their As-Found test criteria.
Technical Specification (TS) 3.7.1 (Main Steam Safety Valves) requires the MSSVs to be operable in accordance with TS Table 3.7.1-1 and Table 3.7.1-2.
TS Surveillance Requirement (SR) 3.7.1.1 requires each MSSV be verified to lift per Table 3.7.1-2 in accordance with the In-service Testing Program.
Operability of the MSSVs includes the ability to open within the set point tolerances.
The direct cause of the failure of these valves was severely worn spindle rods.
The apparent cause for the failure of MS-47-4 and MS-46-2 was internal friction due to spindle vibration.
The apparent cause of the failure of MS-45-4 was reuse of a worn spindle.
Corrective actions included testing all 20 MSSVs and adjusting their set point to be within +/-
1% of design set pressure.
Installed new spindles and bronze wear sleeves on valves MS-46-4, MS-46-2, MS-47-4, MS-48-2, MS-49-2, MS-49-I, MS-49-3, and replaced the spindle on valve MS-45-4.
The Unit 3 MSSV test frequency will be changed from 4 years to 2 years until all modifications are implemented in the next outage.
The event had no effect on public health and safety.
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The corrective actions for that event included implementation of a bronze wear sleeve modification.
All the unit 3 MSSVs are scheduled to have the bronze sleeve modification implemented by the next refueling outage.
LER-2011-004 corrective actions included replacement of the valve spindle for valves MS-47-4 and MS-48-4.
Corrective actions for this LER included replacement of the worn spindle for valve MS-45-4 and new spindles installed on valves MS-46-4, MS-46-2, MS-47-4, MS-48-2, MS-49-2, MS-49-1 and MS-49-3 during the bronze wear sleeve installation.
LER-2013-001 cause was foreign material which has not been identified in this LER or previous LER except LER-2013-001.
Corrective actions for LER-2013-001 included replacement of the spindle rod for valve MS-46-3, installation of bronze wear sleeves in valves MS-46-3,MS-48-3, MS-45-4, MS-47-I, MS-47-2, MS-47-3 and MS-49-4, and the increase in the PM frequency from an 8 year cycle to a 6 year cycle.
The increased frequency of testing is expected to identify degraded conditions so that corrective actions can be implemented to prevent valve lift failures.
Safety Significance
This event had no effect on the health and safety of the public. There were no actual safety consequences for the event because there were no accidents or transients requiring the MSSVs.
There was no significant potential safety impact of the condition under reasonable and credible alternate conditions.
Had an accident or transient occurred during the condition of the out of tolerance MSSV, the condition would not have significantly affected accident mitigation capability and the MSSVs overpressure function would have been adequate.
The design basis of the MSSVs is to limit the secondary system pressure to 110% of design pressure when passing 100% of design steam flow.
Each MS line has an ADV capable of releasing steam to the atmosphere.
The ADVs have the capability to relieve approximately 10% of total steam.
The MSSV design basis is sufficient to cope with any anticipated operational occurrence or accident considered in the Design Basis Accident and transient analysis.
The events that challenge the relieving capacity of the MSSVs, and thus Reactor Coolant System pressure, are those characterized as decreased heat removal events, whose evaluations are presented in UFSAR Section 14.
Of these, the full power loss of external electrical load without steam dump is the limiting event.
The limiting UFSAR Chapter 14 transients which do not credit the ADVs and which are impacted by the higher MSSV set point were evaluated and it was concluded that the acceptance criteria for the transients would have been met with the out of tolerance MSSVs.