05000247/LER-2012-005

LER-2012-005, 450 Broadway, GSB
P.O. Box 249
Buchanan, N.Y. 10511-0249Entergy Tel (914) 254-6668
Patric W. Conroy
Director Nuclear Safety Assurance
NL-12-118
November 19, 2012
U.S. Nuclear Regulatory Commission
Attn: Document Control Desk
Mail Stop 0-P1-17
Washington, D.C. 20555-0001
SUBJECT:M Licensee Event Report # 2012-005-01, "Technical Specification
Prohibited Condition Caused by a Main Steam Safety Valve Outside Its
As-Found Lift Setpoint Test Acceptance Criteria Due to Spring
Skew/Spindle Wear"
Indian Point Unit No. 2
Docket No. 50-247
DPR-26
Reference:M 1. LER-2012-005-00 submitted by letter NL-12-073 dated May 24, 2012
Dear Sir or Madam:
Pursuant to 10 CFR 50.73(a)(1), Entergy Nuclear Operations Inc. (ENO) hereby provides
Licensee Event Report (LER) 2012-005-01. The attached LER is a revision to an LER
submitted on May 24, 2012 (Reference 1), that identified an event where there was a
Technical Specification prohibited condition for an inoperable Main Steam Safety Valve,
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-IP2-2012-01311.
Subsequently, two errors were discovered which were recorded in CR-IP2-2012-4551.
One error concerned reference to a Unit 3 steam generator associated with the inoperable
MSSV and another error concerned a corrective action of the adjustment of the MSSV to
+/- 3% instead of +/- 1'3/0. The safety significance section statement of the design basis of
the MSSVs was clarified to state the MSSVs provide overpressure protection for design
basis transients occurring at 102% reactor thermal power. The changes necessitated the
need to submit a revised LER with corrections.
There are no new commitments identified in this letter. Should you have any questions
regarding this submittal, please contact Mr. Robert Walpole, Manager, Licensing at (914)
254-6710.
Sincerely,
PWC/cbr
cc:M Mr. William Dean, Regional Administrator, NRC Region I
NRC Resident Inspector's Office, Indian Point 2
Mrs. Bridget Frymire, New York State Public Service Commission
LEREvents@INPO.org

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1. FACILITY NAME: INDIAN POINT 2 2. DOCKET NUMBER 1 3. PAGE
0 5 0 0 0 -247 10OF 4
4. TITLE: Technical Specification Prohibited Condition Caused by a Main Steam Safety Valve
Outside its As-Found Lift Setpoint Test Acceptance Criteria Due to Spring Skew/Spindle Wear

Indian Point 2
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v), Loss of Safety Function
2472012005R01 - NRC Website

Note: The Energy Industry Identification System Codes are identified within the brackets II.

DESCRIPTION OF EVENT

On March 2, 2012, while at 100% reactor power, at approximately 10:52 hours, during the performance of surveillance procedure 2-PT-R006A, main steam (MS) {SB} safety valve (MSSV) {RV} MS-46D failed its As-Found lift set point pressure test.

In accordance with the test, MSSVs must lift at +/- 3% of their required setting.

Valve MS-46D lifted at 1136.9 psig, 24.9 psig outside its acceptance range of 1048 to 1112 psig. The other nine MSSVs valves tested passed their As-Found test criteria and were left within +/- 1% of their required setting in accordance with the test procedure. Adjustments were made to MS-46D in accordance with the test procedure and subsequent re-testing was successful in getting the valve to lift within the accepted range. Technical Specification (TS) 3.7.1,(Main Steam Safety Valves), requires the MSSVs to be operable in accordance with TS Tables 3.7.1-1 and 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 Inservice Testing (IST) Program. Operability of the MSSVs is determined by periodic surveillance testing in accordance with the TS and IST program. As valve MS-46D was found outside its acceptable range it failed its As-Found test criteria and was declared inoperable. The condition was recorded in the Indian Point Energy Center (IPEC) Corrective Action Program (CAP) as Condition Report CR-IP2-2012-01311.

There are five code safety valves (MSSVs) and one atmospheric dump valve (ADV) {RV} on each main steam (MS) line outside the Reactor Containment {NH} and upstream of the MS isolation valves {ISV}. The MSSVs consist of four 6-inch by 10-inch and one 6-inch by 8-inch valve per SG on each of four MS lines for a total of 20 valves. The MSSV's provide a heat sink for the reactor coolant system if the Main Condenser is unavailable and the Atmospheric Dump Valves can not relief steam line pressure. The five valves on each steam line are set to open at 1065, 1080, 1095, 1110, and 1120 psig. The operability of the MSSVs is defined as the ability to open within the set point tolerances, relieve SG overpressure, and reset when pressure has been reduced. The accident analysis requires five MSSVs per SG to provide overpressure protection for design basis transients occurring at 102% reactor thermal power. The MSSVs are Code relief valves, manufactured by Crosby-Ashton IC7101. Valve MS-46D is a 6-inch by 10­ inch Crosby-Ashton valve Model # HA-65W.

An extent of condition (EOC) was performed that As-Found tested two additional valves in In-Service Test (IST) Group II for the subject failure (2 additional valves total). Both EOC valves were found satisfactory. All the IST Group II valves (MSSVs) have been tested within the last four years. All MSSVs have been tested in the last four years per the IST program. The condition applies to the remaining 19 MSSVs at Unit 2 and the 20 MSSVs at Unit 3.

Cause of Event

The apparent cause for valve MS-46D lifting at greater than 3% of its nominal set point was due to internal friction caused by spindle wear and spring skew. All springs exhibit some spring skew causing the spindle and internals to not remain perpendicular to the centerline of the valve and creating contact with the guide.

In most cases the spring skew is acceptable but if the spring skew is too great it will push the moving internal parts off to one side and produce frictional forces that will affect the set point. The typical result is the relief valve initially lifts above its setpoint.

Corrective Actions

The following corrective actions have been or will be performed under Entergy's Corrective Action Program to address the cause and prevent recurrence:

• Adjusted valve MS-46D to within the acceptance set point criteria for operability (+/- 3%).

• In accordance with the In-service Test (IST) program two additional valves in IST Group II were tested for the subject failure (2 additional valves). Both extent of condition (EOC) valves tested satisfactorily.

• Performed Preventive Maintenance (PM) on valve MS-46D and returned valve to service after successful testing.

• A modification has been approved to install bronze wear sleeves in the spring washers and adjusting bolts during future PMs on the MSSVs.

Event Analysis

The event is reportable under 10CFR50.73(a)(2)(i)(B). The licensee shall report any operation or condition which was prohibited by the plant TS. TS 3.7.1,"Main Steam Safety Valves," requires the MSSVs to be operable in accordance with TS Tables 3.7.1-1 and 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 Inservice Testing Program. Operability of the MSSVs includes the ability to open within the setpoint tolerances. On March 2, 2012, valve MS-46D was found outside its limit therefore, it failed its As-Found testing criteria. Subsequently, valve MS-46D was disassembled, inspected and an evaluation performed to determine the cause of the condition. On March 25, 2012, the apparent cause was determined to be internal friction caused by spindle wear and spring skew during the operating cycle. Spindle wear and spring skew are not normal drift therefore the valve may have been inoperable during past operation. As it is not possible to determine when the valve would not have met its set point lift pressure range, the valve was concluded to be inoperable for greater than the TS allowed completion time.

� An apparent cause evaluation per CR-1P2-2012-01311 concluded the condition resulted in inoperability of the valve. An evaluation of the accident analysis was performed to determine the impact of one MSSV with a higher opening set point. The analysis concluded the condition would not result in loss of safety function.

Therefore, this condition is not reportable under 10CFR50.73(a)(2)(v) as a safety system functional failure.

Past Similar Events

A review was performed of Licensee Event Reports (LERs) for the past three years for any events reporting TS prohibited conditions due to multiple test valve failures. LER-2010-002 reported two MSSV's failures, one of which was due to valve spring skew and the other was set point drift. The inner diameter of both valves' guide bearings were increased to reduce the potential for spring skew. The work history of the valve reported in LER-2010-002 was determined to have had its guide bearing inner diameters increased to the vendor recommended maximum. A corrective action (CAs) for one valve (MS-48C) reported in LER-2010-002 was to polish out a mark on the spindle where it had been coming in contact with the guide bearing.

The valve spindle was not replaced. After reviewing the collective issues from the past events, the frequency of the PM for the MSSVs was increased from 8 to 6 years.

This event was not prevented by the change in PM frequency as the PM frequency change implementation was still outstanding for this valve.

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 less than or equal to 110% of design pressure for any anticipated operational occurrence or accident considered in the design basis accident (DBA) and transient analysis. The accident analysis requires that five MSSVs per steam generator be operable to provide overpressure protection for design basis transients occurring at 102% reactor thermal power (RTP). The combined MSSVs are sufficient to relieve 108% 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 combined pressure relief capability of the MSSVs and ADVs is approximately 118% of rated steam flow and adequate the 20 MSSVs being out of tolerance. 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 one out of tolerance MSSV.