05000346/FIN-2016002-01
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Finding | |
|---|---|
| Title | Mispositioned Instrument Air Valves Result in Plant Transient |
| Description | On May 31, 2016, at approximately 10:21 a.m., planned testing of Steam and Feedwater Rupture Control System (SFRCS) Actuation Channel No. 1 was in progress. This was the first performance of this test since the unit returned to operation following RFO 19. Unexpectedly, operators in the control room received several overhead annunciator alarms coincident with a rapid swing in plant power and indications that the SG 12 MFW Regulating Valve (SP6A) had gone closed and then reopened. In accordance with established procedures for responding to such an event, control room operators took manual control of integrated control system (ICS) stations for reactor demand, SG/reactor demand, both MFW regulating valves, both MFW startup valves, and both MFW loop demands. The control room crew was then able to arrest the transient and stabilize plant power at approximately 89 percent. Initial evaluation of the transient by the licensee revealed that two instrument air (IA) valves associated with control air for SP6A (IA1008D, SVSP6A1 Bypass; and IA1008A SVSP6A1 Maintenance Isolation) were out of their normal positions. The mispositioned valves had the effect of placing P6A in a half trip condition, such that when SFRCS Actuation Channel No. 1 was being tested SP6A unintentionally responded to the test signal. The licensee entered this issue into their CAP as CRs 201607282, 201607286, 201607337, and 201608363. Because the licensee had yet to complete their investigation and analysis of the event and the IA valve mispositioning by the end of this inspection period, the issue is being treated as an unresolved item (URI) pending the inspectors review of the licensees completed cause evaluation and proposed corrective actions. (URI 05000346/201600201) |
| Site: | Davis Besse  |
|---|---|
| Report | IR 05000346/2016002 Section 1R11 |
| Date counted | Jun 30, 2016 (2016Q2) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.11 |
| Inspectors (proximate) | A Dahbur D Kimble D Mills J Cassidy J Mancuso J Rutkowski J Seymour M Garza P Smagacz R Walton T Brileyd Kimblej Cameron J Cassidy J Rutkowski N Valos T Bilik T Briley |
| INPO aspect | |
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Finding - Davis Besse - IR 05000346/2016002 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Davis Besse) @ 2016Q2
Self-Identified List (Davis Besse)
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