|Susquehanna Steam Electric Station Unit 2|
|Reporting criterion:||10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications|
|3882017000R00 - NRC Website|
|Person / Time|
Susquehanna, Talen Energy
Document Control Desk, Office of Nuclear Reactor Regulation
|Download: ML18033A039 (4)|
comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 205550001, or by email to used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
f f I FiTael 05000-0388 2017 -010 - 00
CONDITIONS PRIOR TO EVENT
Unit 1 — Mode 1, approximately 100 percent Rated Thermal Power Unit 2 — Mode 1, approximately 100 percent Rated Thermal Power There were no structures, systems, or components that were inoperable at the start of the event that contributed to the event.
Susquehanna Steam Electric Station (SSES) had been utilizing Barton 288A switches in the Reactor Steam Dome Pressure — Low channels that provide the injection permissive for the Core Spray system [EIIS System Identifier: BM] (Technical Specification (TS) Function 1d) and the Low Pressure Coolant Injection system (LPCI) [EIIS System Identifier: BO] (TS Function 2d). In order to address drift issues with the Barton pressure switches, all eight were replaced with GE recommended Cameron 288A pressure switches between September 6, 2017 and November 15, 2017. The switches were bench tested prior to installation and calibration checked at the time of installation. Subsequent calibration checks were performed at intervals less than the quarterly Technical Specification (TS) required calibrations. During these subsequent calibration checks, the Unit 2 "C" (PIS-B21-2N021C) and Unit 2 "D" (PIS-B21-2N021D) pressure switches; were found outside of the Technical Specification (TS) allowable value. A timeline of events is as follows:
On September 20, 2017 ; the obsolete Barton 288A pressure switch for PIS-B21-2N021C was replaced with a GE recommended Cameron 288A pressure switch.
On October 9 2017 the obsolete Barton 288A pressure switch for PIS-B21-2N021D was replaced with a GE recommended Cameron 288A pressure switch.
On October 20, 2017, PIS-B21-2N021C and PIS-B21-2N021D were calibration checked. PIS-B21-2N021C had drifted to 454 pounds per square inch (psi); which was within the TS allowable value (upper allowable value of 454.4 psi). PIS-B21-2N021C was adjusted to a value of 441.4 psi. PIS-B21-2N021D had drifted to 447.8 psi, which was within the TS allowable value (upper allowable value of 455 psi). PIS-B21-2N021D was adjusted to a value of 444.1 psi.
On December 5, 2017. PIS-B21-2N021C and PIS-B21-2N021D were found outside of the TS allowable value during the calibration check. Both drifted outside of the upper allowable value which is intended to ensure that the reactor dome pressure has fallen to a value below the Core Spray and RHR/LPCI maximum design pressures to preclude over-pressurization of the low pressure systems prior to low pressure injection initiation. PIS-B21-2N021C exceeded the TS allowable value by 1.4 psi (455.8 psi versus an upper allowable value of 454.4 psi). PIS-B21-2N021D exceeded the TS allowable value by 2.8 psi (457.8 psi versus an upper allowable value of 455 psi). Both switches were adjusted to within the TS allowable value.
Although drift in the same manner was seen in the other six switches, none of the others were observed to have drifted outside of the TS allowable value during any of the subsequent calibration checks.
Based on the information currently available; Susquehanna believes that the condition existed for longer than allowed by TS 220.127.116.11 and TS 3.5.1. As such, this is a condition prohibited by Technical Specifications and is being reported in accordance with 10 CFR 50.73(a)(2)(i)(B).
Susquehanna Steam Electric Station Unit 2 05000-0388 2017 - 010 - 00 comments regarding burden estimate to the Information Services Branch (T-2 F43), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to NEOB-10202, (31500104), Office of Management and Budget, Washington, DC 20503. If a means used to impose an information collection does not display a currently valid OMB control number, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
CAUSE OF EVENT
The cause is still under investigation. Further information associated with the cause will be provided in a supplement to this LER.
Information concerning safety significance will be provided in a supplement to this LER.
Corrective actions will be determined following completion of the cause analysis and will be provided in a supplement to this LER.
COMPONENT FAILURE INFORMATION
The switches that drifted are Cameron Model 288A pressure switches.
PREVIOUS SIMILAR EVENTS
Pressure Steam Dome-Low Switches", dated February 10, 2016.