Monday, July 17, 2017

Junk Plant Browns Ferry Junk Safety Relief Valves

A host of precious metal coating on seats and ending in two delaminated with platinum and some spring is sprung. I is bad when two component are broken.    
July 7, 2017
Browns Ferry Nuclear Plant, Unit 2 Renewed Facility Operating License No. DPR-52 NRC Docket No. 50-260
Subject: Licensee Event Report 50-260/2017-004-00
On May 8, 2017, the Tennessee Valley Authority was presented with as-found testing results indicating that four of th hirteen Main Steam Relief Valves (MSRV5) from Browns Ferry Nuclear Plant, Unit 2, were outside the +/- 3 percent setpoint band required for their operability. Troubleshooting determined that three MSRVs exceeded their setpoints when their valve discs failed by corrosion bonding to their valve seats. The valve discs were previously platinum coated to prevent this, but the valve seat's rough Stellite surface caused the coating to delaminate. This was the first Unit 2 MSRV service interval to implement the improved surface treatment since a resolution to the delamination issue was identified in 2015. The valve which failed below its setpoint band was determined to have a faulty pilot spring.
Ihese four MSRVs were found to have been inoperable for an indeterminate period of time between April 9, 2015, and February 25, 2017, and longer than permitted by Technical Specifications. The affected valves remained capable of maintaining reactor pressure within American Society of Mechanical Engineers code limits. Additionally, the valves' ability to open under remote-manual operation, activation through the Automatic Depressurization System, or MSRV \utomatic Actuation Logics were not affected. The valves remained capable of performing their required safety unction…

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