05000298/FIN-2017012-02

Finding

Title

Inadequate Testing Activities for Emergency Transformer Bus

Description

The inspectors identified a non- cited violation of Technical Specification 5.4.1.a for the licensees failure to maintain Maintenance Procedure 7.3.41, Examination and High Pot Testing of Non- Segregated Buses and Associated Equipment, Revision 10, to contain adequate instructions for testing of the emergency station service transformer 4160 V bus. Specifically, the inspectors identified a violation of Technical Specification 5.4.1.a for the licensees failure to maintain adequate instructions for performing high potential testing of the emergency transformer bus bars between March 23, 2015, and April 18, 2017. As a result, the licensee did not properly assess corona- related degradation on the emergency transformer bus, which resulted in an emergency transformer bus fault and a loss of the emergency transformer and the supplemental diesel generator on January 17, 2017. Immediate corrective actions to restore compliance included replacement of the faulted portions of the emergency transformer bus, and extent of condition inspection and cleaning of the remainder of the emergency transformer bus bars. Long term corrective actions include replacement of the emergency transformer bus insulation and revision of high potential testing procedure instructions. The licensee entered this issue into the corrective action program as Condition Report CR- CNS -2017- 02164. The licensees failure to maintain Maintenance Procedure 7.3.41 to properly assess degradation of the emergency station service transformer bus, in violation of Technical Specification 5.4.1.a, was a performance deficiency. The performance deficiency was determined to be more than minor, and therefore a finding, because it was associated with the equipment performance attribute of the Initiating Events Cornerstone, and affected the cornerstone objective to limit the likelihood of events that upset plant stability and challenge critical safety functions during shutdown, as well as, power operations. Specifically, the finding resulted in the licensees failure to identify and repair indications of corona -related degradation on the emergency station service transformer bus, which resulted in an emergency station service transformer bus fault, and a loss of the emergency station service transformer and the supplemental diesel generator on January 17, 2017. Using Inspection Manual Chapter 0609, Appendix A, The Significance Determination Process (SDP) for Findings At -Power, dated June 19, 2012, the inspectors determined that the finding required a detailed risk evaluation because it involved the partial loss of a support system that contributes to the likelihood of, or causes, an initiating event (loss -of-offsite power) and the finding affected mitigation equipment (supplemental diesel generator). A senior reactor analyst performed a detailed risk evaluation in accordance with Inspection Manual Chapter 0609, Appendix A, Section 6.0, Detailed Risk Evaluation. The analyst concluded that the finding is of very low safety significance (Green). 4 The performance deficiency had a cross-cutting aspect in the area of human performance, associated with change management , because the licensee failed to use a systematic process for evaluating and implementing a change so that nuclear safety remained the overriding priority. Specifically, on March 23, 2015, the licensee changed the Maintenance Procedure 7.3.41 bus testing method from performance of a megger test to performance of a high potential test, but failed to use a systematic process to evaluate the change to ensure that the new test had instructions that were adequate and consistent with industry Institute of Electrical and Electronics Engineers standards [H.3].

02
Site:	Cooper
Report	IR 05000298/2017012 Section 4OA5
Date counted	Dec 31, 2017 (2017Q4)
Type:	NCV: Green
cornerstone	Initiating Events
Identified by:	NRC identified
Inspection Procedure:
Inspectors (proximate)	P Voss R Deese C Young S Graves C Smith
Violation of:	Technical Specification - Procedures
CCA	H.3, Change Management
INPO aspect	LA.5
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v • d • e

Finding - Cooper - IR 05000298/2017012

1(6)2(4)3(3)4(0)5(0)6(0)7(0)8(0)9(2)10(5)11(1)12(2)301(0)403(0)404(0)501(0)

IR 05000298/2017012: 1 2

Finding List (Cooper) @ 2017Q4

CCA Matrix: 2017Q4

	Q	CCA	Title
05000298/FIN-2017001-01	2017Q1	P.1	Failure to Maintain Alternate Shutdown Emergency Procedure
05000298/FIN-2017001-02	2017Q1	P.2	Failure to Identify a Condition Adverse to Quality Associated with the 250 Vdc Electrical System
05000298/FIN-2017001-03	2017Q1	H.11	Failure to Identify a Condition Adverse to Quality
05000298/FIN-2017001-04	2017Q1	H.6	Failure to Address Nonconforming Pipe Thinning in Accordance with the ASME Code
05000298/FIN-2017001-05	2017Q1	H.5	Loss of Shutdown Cooling due to Relay Maintenance
05000298/FIN-2017001-06	2017Q1	H.7	Failure to Install Correct Mechanical Stop and Verify Proper Operation
05000298/FIN-2017009-01	2017Q2	H.11	Exceeding the Technical Specification A llowed Out of Service Time of the Division I RHR System
05000298/FIN-2017010-04	2017Q2	P.2	Failure to Monitor No. 2 Diesel Generator under 50.65(a)(1) due to Inadequate Maintenance Rule Evaluation
05000298/FIN-2017010-03	2017Q2	P.4	Programmatic Failure to Identify and Correct Adverse Trends
05000298/FIN-2017010-02	2017Q2	H.13	Failure to Perform Timely Operability Determinations
05000298/FIN-2017010-01	2017Q2	P.3	Failure to Assign Corrective Actions to Prevent Recurrence of High Pressure Coolant Injection Failure
05000298/FIN-2017009-02	2017Q2	H.1	Failure to Implement an Adequate Procedure for Equipment Control
05000298/FIN-2017002-03	2017Q2	H.11	Loss of Control Room Ventilation Due to Improper Switch Manipulation
05000298/FIN-2017002-02	2017Q2	H.1	Loss of Control Room Ventilation Due to Ineffective Preventive Maintenance Strategy
05000298/FIN-2017002-01	2017Q2	H.5	Failure to Assess Operability of Technical Specification System Functions during Surveillance Testing
05000298/FIN-2017010-05	2017Q2		Failure to adopt appropriate procedures in accordance with 10 CFR Part 21
05000298/FIN-2017011-01	2017Q3	P.2	Emergency Transformer Bus Failure due to Inadequate Inspection and Testing Activities
05000298/FIN-2017003-01	2017Q3	H.6	Failure to Ensure Suitability of Materials for the Reactor Building Northeast Fan Coil Unit
05000298/FIN-2017003-02	2017Q3	H.7	Failure to Account for Instrument Uncertainty in Safety-Related Ventilation Surveillance Procedures
05000298/FIN-2017003-03	2017Q3	P.2	Loss of Control Room Ventilation Due to Inadequate Post-Maintenance Testing Activities
05000298/FIN-2017012-01	2017Q4	P.2	Inadequate Inspection Activities for Emergency Transformer Bus
05000298/FIN-2017012-02	2017Q4	H.3	Inadequate Testing Activities for Emergency Transformer Bus

Self-Identified List (Cooper)

	Q	Title
05000298/FIN-2017002-04	2017Q2	Licensee-Identified Violation

[Cooper Findings full list]

05000298/FIN-2017012-02

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