05000250/FIN-2017008-02
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Finding | |
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| Title | Potential Failure to Complete an Adequate Risk Assessmen |
| Description | Inspection Scope The team reviewed the licensees Maintenance Rule 10 CFR 50.65 (a)(4 ) risk management program actions associated with the emergent issue on the Unit 4 leak on the recirculation line of the high head safety injection (HHSI) pumps. The team reviewed the Unit 3 and Unit 4 risk management actions following the failure of the Unit 3 3A 4kV switchgear bus. The team also interviewed the control room shift manager, and the Unit 3 and Unit 4 control room unit supervisors that had the shift responsibilities the day of the Unit 3 4kV switchgear failure to assess their understanding of the risk management actions associated with declaring the 4A and 4B HHSI pump s available to perform their safety function. The team reviewed the software program used by the licensee to assess on -line risk and used the program to run several independent specific scenarios to obtain the core damage frequency (CDF) on- line risk for those scenarios. The team reviewed the clearance tag out that was used to place the 4A and 4B HHSI pumps out of service for making the repairs to the pump recirculation line. The team reviewed the emergency operating procedures for the operator actions the licensee credited for starting the HHSI pumps, versus an automatic start , and assessed whether the actions were adequate to maintain the HHSI pumps available in the on- line risk monitor (OLRM) . The team reviewed the training provided to licensed operators with respect to crediting operator actions to maintain safety systems as available in the OLRM . The team reviewed the licensees procedures that described guarding and protection of safety - related equipment during periods when other systems were undergoing maintenance or being tested. b. Findings and Observations Overall, the team identified several weaknesses with the licensees Risk Management Program actions, both prior to, and after the event. Specifically, 10 CFR 50.65(a)(4) actions associated with the emergent issue for the Unit 4 HHSI system were based on the incorrect assumption that the 4A and 4B HHSI pumps were available. This led to risk management actions that did not include the protection of the 3A and 3B 4kV switchgear which allowed work in the 3A switchgear room to proceed . The team s review of the licensees procedures and practices for accounting for risk on the opposite unit with equipment removed from service identified issues for further follow -up by the regional senior risk analyst and, therefore , an URI was opened, as documented below . URI 05 000250, 251/2017008- 02, Potential Failure to Complete an Adequate Risk Assessment Introduction: The team identified an URI associated with the licensees assessment and management of risk under 10 CFR 50.65(a)(4) prior to and following the event, including their conclusions regarding availability of the Unit 4 HHSI pumps . Description : On Friday March 17, 2017, Unit 3 was operating at 100 percent rated thermal power (RTP) and the operational core damage frequency ( CDF ) of the OLRM was in the low end of the Green band , indicating power operations in the low risk band. Unit 4 was operating at 100 percent RTP and the CDF was also Green in the OLRM . A down- power on Unit 3 was planned to start the next day in preparation for entering a refueling outage. A work crew was inside the 3A 4kV safety -related switchgear room 16 installing Thermo-Lag insulation on cable trays. The licensee needed to complete this insulation work by the end of the Unit 3 outage in order to meet NFPA 805 commitments. The Thermo-Lag work had been ongoing for several months. In the afternoon of March 17, 2017, Engineering identified a leak on a 34 -inch diameter test line pipe down- stream of the common line that joins the 4A and 4B HHSI pump recirculation lines. Based on the identified leakage and engineering inspection, the licensees immediate operability assessment concluded that Unit 4 HHSI system was operable and Operations requested a two- day prompt operability determination. The tag- out clearance to repair the test line required isolating the pump recirculation line to complete a welding code repair, resulting in the Unit 4 HHSI pumps becoming TS Inoperable and also unavailable to perform their safety function. It was estimated the work would take approximately 18 hours2.083333e-4 days <br />0.005 hours <br />2.97619e-5 weeks <br />6.849e-6 months <br />. On Saturday, March 18, 2017, the licensee took the 4A and 4B pumps out of service to start the repair. At 6 :24 a.m. EDT, both Units entered TS 3.5.2.a Action d, and started a 72- hour LCO for two of the four HHSI pumps TS Inoperable. During the day -shift turnover, the shift manager, both u nit control room supervisors, and the reactor board operators were updated and informed of the plan to repair the HHSI test line. The crews reviewed the Unit 4 HHSI pumps status of pull -to-lock and the risk assessment that was completed which required operator actions to maintain the HHSI pumps available. None of the SROs challenged the licensees decision to use the EOP network to credit operator action or timeliness to start the pumps to declare the pumps available on the OLRM. The 4A and 4B HHSI return line was isolated at approximately 7: 36 a.m. EDT , which prevented HHSI pump recirculation flow. The 4A and 4B HHSI pump breakers remained available and were not tagged out, and both pump control switches had been placed in pull -to-lock which prevented the pumps from automatically starting on either a Unit 3 or a Unit 4 safety injection (SI) actuation signal . The licensee did not enter the 4A and 4B HHSI pumps into the OLRM as unavailable, instead the pumps were declared available to perform their safety function based on crediting operator action to start the pumps . The licensee protected the 3A and 3B pump rooms, as well as the 3A and 3B pump supply breaker cubicles on their associated 4kV switchgear; however, with the 4A and 4B pumps considered available, the licensee did not protect the 3A and 3B 4kV switchgear, and the Thermo-Lag work continued in the 3A 4kV switchgear. Both u nits OLRM remained in the Green band, based , in part , on having four available HHSI pumps as determined by the licensees risk assessment actions and OLRM results . The Turkey Point Unit 3 and Unit 4 HHSI systems are shared systems. Although each unit has two HHSI pumps, the OLRM credits four available HHSI pumps for Unit 3 and Unit 4. If either unit receives an SI actuation signal, all four pumps receive a start signal and inject into a common HHSI header. The Unit 3 and Unit 4 control rooms are co- located in one large room. There are four HHSI pump control switches in each control room, (i.e., each control room has switches for the 3A, 3B, 4A and 4B pumps ). Each control room has the capability to start or stop any pump. However, if any pump switch is in the pull -to-lock position in either control room, then that pump will not automatically start , nor will it have manual start capability . The licensees risk assessment, credit ed control room operator action to start the 4A and 4B HHSI pumps, in place of an automatic start on a SI actuation, and did not enter the pumps as unavailable into the OLRM. Specifically, operator action was credited by the control room operator taking steps to manually start the HHSI pumps when entering the EOP network during a SI actuation. After entering EOP -E-0, Reactor Trip OR Safety Injection, step 4 had the operator check if SI was actuated, SI Annunciators ANY ON, OR, Safeguards 17 equipment AUTO STARTED. In the response not obtained column of the EOP , if SI was required , the procedure had operators manually actuate SI and proceed to step 5. That step required operators to complete Attachment 3 of EOP -E-0, Prompt Action Verifications, which required verification of pump operation of At least two High- Head SI pumps RUNNING. The response not obtained column requested the operator to manually start High- Head Pump(s). It was determined that it would take approximately 8.5 minutes to advance to that point in EOPs for the control room operator to manually start the tagged out Unit 4 HHSI pumps, in place of the immediate automatic pump start on an SI actuation. Additionally, the team found that on the Unit 3 control room switches , the 4A and 4B HHSI pumps had also been tagged and placed in pull -to-lock. Additional time and coordination would have been needed between the two unit control room supervisors to take the 4A and 4B HHSI pumps out of pull to lock on the Unit 3 side, and this was not addressed in the EOP. During the interview s of the control room supervisors, they did not recall if this sequence of removing the pull -to-lock on both unit control rooms switches had been discussed and the licensee had not provided any written instructions or procedures to the board operators to address this portion of the switch sequencing for taking credit for operator action to start the 4A and 4B HHSI pumps. The team found the licensee did not have a validated timeline to show that all operator action steps would be completed to make the HHSI pumps available prior to the time the HHSI pump safety functions were required. Specifically, the licensee had not validated that any accident scenario required a HHSI pump to start in less than 8.5 minutes . Additionally , it was identified during the inspection that during a specific type of small break LOCA, the HHSI pumps could be started and left dead headed for more than 3 minutes. In this scenario , because the HHSI pump recirculation lines were tagged out, the pumps would have overheated and been damaged , causing the control room operator s to have to address additional issues during accident mitigation, (i.e., loss of refueling water storage tank inventory due to potential leakage from pump s) . In determining the risk assessment of the HHSI pump for availability, the licensee had not addressed this issue and no procedures were provided to control room operators to prevent running the pumps dead headed for longer than 3 minutes. At 11 :07 a.m. EDT , the Unit 3, 3A 4kV switchgear failed and the unit automatically tripped. The licensee determined the 3A HHSI pump was inoperable and at 11 :13 a.m. EDT both units entered T.S. 3.0.3 due to having three of four HHSI pumps inoperable on two units. The repair work on the Unit 4 HHSI test line had not progressed to the point of cutting the pipe and the licensee took actions to restore the 4A and 4B HHSI pumps. At 1 :36 p.m. EDT , the Unit 4 recirculation return line was restored and the HHSI pumps were returned to available and operable status. The team found that the licensee had not assessed the OLRM after the failure of the 3A 4kV switchgear and Unit 4 remained in Mode 1 at 100 percent RTP without an updated risk assessment. During the inspection, the team obtained Unit 3 and Unit 4 OLRM print outs for the equipment that was unavailable prior to, and after, the Unit 3 4kV switchgear failure. The results showed that with two HHSI pumps unavailable, (4A and 4B ), Units 3 and 4 remained in the Green risk band. After the Unit 3 A 4kV switchgear failure, with three HHSI pumps unavailable, Unit 3 increased to the Red band and Unit 4 risk increased to the upper limit of the Green band. 18 The team questioned the adequacy of the licensees decision to credit operator actions to maintain the Unit 4 HHSI pumps available while : (1) performing the code repair on the Unit 4 common HHSI pump test line, (2) potential existed for the HHSI pumps being operated without a recirculation flow line , and (3) the adequacy of instructions or procedures to control room operators when starting the HHSI pumps in certain accident scenarios which would cause pumps to run dead headed. Additionally, the team questioned the licensees risk manage men decisions which included allowing work to continue in the 3A 4kV switchgear room, and, after the failed Unit 3A 4kV switchgear and Unit 3 reactor trip, failure to complete a risk assessment to account for additional unavailable safety -related equipment. The NRC required additional inspect ion to determine whether a performance deficiency exist . Specifically , further review is needed to: (1) determine the adequacy of risk management actions taken to protect Unit 3 equipment while the 4A and 4B HHSI pumps were removed from service, (2) review the OLRM tool to determine whether the CDF results are consistent with the unavailability of the HHSI pumps and the 3A 4kV switchgear, and (3) review the licensees procedures to determine why instructions were provided to start the HHSI pumps while the recirculation lines were tagged out, without evaluating the potential consequences for damaging the pumps during a small break LOCA . (URI 05000250, 251/2017008- 02, Potential Failure to Complete an Adequate Risk Assessment |
| Site: | Turkey Point  |
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| Report | IR 05000250/2017008 Section 4OA5 |
| Date counted | Mar 31, 2017 (2017Q1) |
| Type: | URI: |
| cornerstone | No Cornerstone |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 2201/004 |
| Inspectors (proximate) | E Stamm G Crespo J Patel J Reyes L Suggs N Melly |
| INPO aspect | |
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Finding - Turkey Point - IR 05000250/2017008 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Turkey Point) @ 2017Q1
Self-Identified List (Turkey Point)
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