05000461/FIN-2017012-03

Finding

Title

Evaluation of RCE 04082490, Reactor Scram from Trip of 1AP07EJ)

Description

Inspection Scope The inspectors held discussions with licensee personnel, reviewed the response of equipment and operations personnel, and reviewed historical corrective action program and maintenance related documents to evaluate whether a higher level of NRC response was needed to review this event. b. Discussion The inspectors did not identify any circumstances of the event that warranted escalation of the inspection to an Augmented Inspection Team. The event itself followed the anticipated sequence according to accident analysis and with a few non-consequential exceptions, plant equipment functioned as designed. While performing the preliminary risk analysis for the MD 8.3 Evaluation to determine the risk criteria, the Senior Reactor Analyst modeled the transient as a Loss of Condenser Heat Sink initiating event due to the manual reactor scram and closure of the inboard MSIVs. Direction to use the steam line drains to maintain the condenser as a heat sink when the MSIVs are closed was contained in site procedures. Procedure CPS [Clinton Power Station] EOP1; RPV Control, listed MSL drains as one of the systems to be used to control RPV pressure and cooldown rate. Procedure CPS 4100.01; Reactor Scram, directed the operator to use an appropriate cooldown method listed in CPS 9000.06, Unit Shutdown. In CPS 9000.06 Section 8.8, Cooldown With Main Condenser, MSL drain valves were one method listed and included a statement that it was OK to shut MSIVs when using this method. In this scenario, the control room supervisor stated that he considered using RCIC for pressure control, but determined that he did not need to because the 13 main condenser remained available and he was able to control the pressure/cooldown rate using the MSL drains to the main condenser. When the final MSIV closed and pressure started to rise, the crew started RCIC in the pressure control mode. The operating crew then continued to cooldown the reactor to Mode 4. The inspectors identified a concern that evaluation of the generic implications of the transformer failure could only be completed when the root cause of the transformer failure was known. Determination of the actual cause of the transformer failure to ground required an inspection of the damaged transformer at the ABB facility. The dry type transformer was built in 1980 and the design worst-case loading was 40 percent of the transformer rating. This type transformer was used in 29 480 VAC substations in the plant (only 5 of the 29 are safety-related). The safety-related transformers are inspected and megger tested at an 8 year frequency aligned with the safety-related bus outage schedule. The non-safety dry type transformers are inspected and megger tested at an 8 year frequency (some have been extended to 16 years based on performance). No degraded condition was found during the past preventative maintenance activities on the dry type transformers. However, operators at Clinton identified noises coming from one of the non-safety related dry type transformers in 2015. The transformer was removed from service and replaced. The transformer vendors evaluation identified degraded insulating material as the cause for the noise. Pending additional information from the inspection of the December 2017 transformer failure and the associated root cause investigation, the extent of condition and related activities were determined to be acceptable. c. Findings No findings were identified. During the review of the reactor scram and transformer failure that occurred on December 9, 2017, inspectors concluded that sufficient information was not available to identify generic implications or potential performance deficiencies with the design, manufacture or maintenance of the dry-type transformers pending completion of the licensees root cause analysis to be documented in RCE 04082490, Reactor Scram from Trip of 1AP07EJ. This issue is an unresolved item (URI) pending NRC evaluation of the additional information being developed by the licensee. (URI 05000461/201701203: Evaluation of RCE 04082490, Reactor Scram from Trip of 1AP07EJ)

03
Site:	Clinton
Report	IR 05000461/2017012 Section 4OA3
Date counted	Dec 31, 2017 (2017Q4)
Type:	URI:
cornerstone	Mitigating Systems
Identified by:	NRC identified
Inspection Procedure:	IP 71153
Inspectors (proximate)	J Mcghee C Phillips
INPO aspect
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v • d • e

Finding - Clinton - IR 05000461/2017012

1(4)2(7)3(5)4(4)5(0)6(0)7(1)8(1)9(1)10(0)11(1)12(3)201(1)301(0)403(0)404(0)405(0)502(0)

IR 05000461/2017012: 1 2 3

Finding List (Clinton) @ 2017Q4

CCA Matrix: 2017Q4

	Q	CCA	Title
05000461/FIN-2017001-01	2017Q1	H.14	Plant Barrier Control Program Failed to Compensate for an Impacted Flood Barrier (
05000461/FIN-2017001-02	2017Q1	H.14	Failed to Verify an Appropriate Alternate Method of Decay Heat Removal
05000461/FIN-2017001-03	2017Q1	H.12	Failure to Develop and Review a Worker Tag Out
05000461/FIN-2017001-04	2017Q1	H.1	Failure to Perform Maintenance on Residual Heat Removal Pump C Breaker in Accordance with Procedures
05000461/FIN-2017002-01	2017Q2		Failure of Operators to Meet Time Critical Operator Actions
05000461/FIN-2017002-02	2017Q2	P.3	Failure to Perform Adequate Evaluation of Crane Rail Clips
05000461/FIN-2017002-03	2017Q2	H.12	Unexpected Start of the Division 3 Emergency Diesel Generato
05000461/FIN-2017002-04	2017Q2	H.6	Failure to Provide Sufficient Work Instructions for Performing Maintenance on the Control Room Ventilation System Charcoal Filte
05000461/FIN-2017002-05	2017Q2	H.11	Failure to Properly Classify a Shipment per DOT Regulations
05000461/FIN-2017002-06	2017Q2		Failure to Perform Preventive Maintenance on a Safety - Related Breaker Cubicl
05000461/FIN-2017002-07	2017Q2	H.1	Root Cause Evaluation Failed to Identify Corrective Action to Preclude Repetition
05000461/FIN-2017008-01	2017Q2	H.5	Failure to Perform Required S urveillances on Multiple Fire Dampers
05000461/FIN-2017007-01	2017Q3	H.1	Failure to Evaluate Defeating Reactor Core Isolation Cooling System Interlocks and Trips before Adding Them to an Emergency Operating Support Procedure
05000461/FIN-2017003-05	2017Q3	H.9	Failure to Establish Secondary Containment Prior to Entering MODE 2
05000461/FIN-2017003-04	2017Q3	H.14	Flow Control Valves Not Locked Out Results in Reactor Recirculation Pump Runback
05000461/FIN-2017003-03	2017Q3	H.13	Failure to Perform Engineering Evaluation to Determine the Cause of Failure of Snubbers
05000461/FIN-2017003-02	2017Q3	H.1	Failure to Adequately Control Access in Locked High Radiation Area
05000461/FIN-2017003-01	2017Q3	H.6	MSIV TS Leakage Limits Exceeded Due to Condition Based Maintenance Approach
05000461/FIN-2017009-01	2017Q3	H.11	Failure to Evaluate Replacement Relay Dropout Voltage
05000461/FIN-2017201-01	2017Q3	H.5	Security
05000461/FIN-2017012-01	2017Q4	H.5	Failure to Perform a Corrective Action to Prevent Recurrence
05000461/FIN-2017012-02	2017Q4	H.13	Failure to Properly Classify Non-Safety Related Auxiliary Transformers as Operationally Critical Components
05000461/FIN-2017012-03	2017Q4		Evaluation of RCE 04082490, Reactor Scram from Trip of 1AP07EJ)
05000461/FIN-2017011-01	2017Q4	P.2	Failure to Correct an Identified Degraded Condition on the Division 3 Shutdown Service Water Pump
05000461/FIN-2017004-01	2017Q4	H.5	Reactor Down Power due to Reactor Recirculation Pump Motor Lower Bearing Oil Leak
05000461/FIN-2017004-02	2017Q4	H.5	Failure to Assess and Manage Risk Associated with the Performance of Control Rod Time Testing
05000461/FIN-2017004-03	2017Q4	H.8	Failure to Identify the Extent of Condition for an Inadequate 10 CFR 50.59 Evaluation
05000461/FIN-2017004-04	2017Q4		Failure to Perform an Evaluation in Accordance with 10 CFR 72.48 for Changes Made to the Time-to-Boil Calculation

Self-Identified List (Clinton)

[Clinton Findings full list]

05000461/FIN-2017012-03

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