05000247/LER-2016-001

LER-2016-001, Technical Specification Prohibited Condition Caused by One Main Steam Safety Valve Outside Its As-Found Lift Set Point Test Acceptance Criteria

Indian Point 2
Event date:	3-4-2016
Report date:	5-2-2016
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
2472016001R00 - NRC Website

LER 16-001-00 for Indian Point 2 RE: Technical Specification Prohibited Condition Caused by One Main Steam Safety Valve Outside Its As-Found Lift Set Point Test Acceptance Criteria

ML16131A636
Person / Time
Site:	Indian Point
Issue date:	05/02/2016
From:	Coyle L Entergy Corp, Indian Point
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NL-16-045 LER 16-001-00
Download: ML16131A636 (6)

Note: The Energy Industry Identification System Codes are identified within the brackets {}

DESCRIPTION OF EVENT

On March 4, 2016 at 1116 hours0.0129 days <br />0.31 hours <br />0.00185 weeks <br />4.24638e-4 months <br />, while at approximately 79 percent power, during surveillance testing of the Main Steam Safety Valves (MSSV) in accordance with procedure 2-PT-R006, MSSV MS-45B on Steam Generator (SG) 22 failed to lift within the-Technical Specification (TS) as-found required range of +/- 3% of the required setpoint pressure. Valve MS-45B lifted at 1125 psig, 29 psig outside its setpoint range of 1034 to 1096 psig and 5.7% above its 1065 psig setpoint. Consequently, MS-45B was declared inoperable and Technical Specification (TS) 3.7.1 (Main Steam Safety Valves) Condition A was entered. Two immediate subsequent tests were performed without any adjustments required and the valve lifted at 1038 psig and 1037 psig. With the valve lifting within the required setpoint range, the valve was restored to operability, allowing exit from the TS 3.7.1 Action Statement at 1126 hours0.013 days <br />0.313 hours <br />0.00186 weeks <br />4.28443e-4 months <br />. During the surveillance test, nine (9) other MSSVs that were tested passed their-as-found test criteria and were left within the +/- 1% set point criteria. The failure of MS-45B was recorded in the Indian Point Energy Center (IPEC) Corrective Action Program (CAP) as Condition Report CR-IP2-2016-01204.

During the performance of the 6-year Internal Inspection Preventive Maintenance (PM) activity on MS-45B completed on Match 31, 2016 during refueling outage 2R22, numerous dimensions, clearances, and tolerances were verified and internal components were inspected for wear/damage. The valve spindle rod was found to have areas of wear along its length arid around the circumference in the form of small steps, which is attributed to system vibration during power operation. All other inspection criteria were satisfactory. - 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 five valves'on each steam line are nominally set to open at 1065, 1080, 1095, 1110, and 1120 psig. The MSSVs are ASME Code relief valves, manufactured by Crosby-Ashton {C710}. Valve MS-45B is a 6-inch by 8-inch Model HA-65W Safety Valve.

CORRECTIVE ACTIONS

A modification was initiated in 2011 to install bronze wear sleeves in the upper and lower spring washers and the adjusting bolt as a solution to valve spring skew and spindle wear for the IPEC MSSVs. This modification was completed for 7 of the 20 Unit 2 MSSVs in the 2014 refueling outage (2R21). Valve MS-45B and the 12 other MSSVs that were not modified in 2R21 were modified in the 2016 refueling outage (2R22). New spindles were also installed in these 13 MSSVs in 2R22. All 20 MSSVs have been modified with the bronze wear sleeves.

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 Table8 3.7.1-1 and 3.7.1-2. The applicable accident/transient analyses require five MSSVs per SG to provide overpressure protection for design basis transients occurring at 10296 reactor thermal power. The MSSVs also provide a heat sink for the Reactor Coolant System if the Main Condenser is unavailable and the ADVs cannot relieve steam line pressure.

Operability of the MSSVs is defined as the ability to open within the setpoint range, relieve SG overpressure, and reseat when pressure has been reduced, and is determined by periodic surveillance testing. TS Surveillance Requirement (SR) 3.7.1.1 requires that each MSSV be verified to lift at its required setpoint per Table 3.7.1-2 in accordance with the Inservice Testing Program (IST). On March 4, 2016, MSSV valve MS-45B was found outside its required setpoint range, therefore, it failed its as- found testing criteria and was declared inoperable. The valve was disassembled and inspected and determined to have conditions preventing proper operation. .The apparent cause determined that failure was due to internal friction caused by spindle rod wear from vibration during the operating cycle. Spindle wear is 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 lifted within its required setpoint range, the valve was concluded to be inoperable for greater than the TS allowed completion time. An evaluation of applicable accident/transient analyses was performed to determine the impact of one MSSV with a higher opening setpoint. The evaluation concluded the condition would not have resulted in a loss of Safety function. Therefore, this condition is not reportable under 10cFR50.73(a)(2)(v) as a safety system functiOnal failure.

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 Chapter 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 setpoint were evaluated and it was concluded that the acceptance criteria for'the transients would have been met with the out of tolerance MSSV.