05000456/FIN-2012003-06
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Finding | |
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| Title | MSIV Hydraulic System Design |
| Description | On May 28, 2012, the 1A MSIV active-side hydraulic accumulator pressure was found at 3450 psig, which was below the operability limit of 4800 psig. This prevented manual isolation of the 1A main steam line via the main control room switch, which required the active-side accumulator and is required by Technical Requirements Manual (TRM) 3.3.y Condition D. Each MSIV also has a standby accumulator that could redundantly close the valve if an ESFAS signal was received, but not from the individual isolation control switch. The 1A MSIV standby accumulator pressure was 5400 psig, thus the 1A MSIV could have been closed by an ESFAS signal. The Action Statement for TRM 3.3.y Condition D required restoration of the individual steam line isolation capability within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />. If that was not done, Condition D required the MSIV to be declared inoperable and TS.3.7.2 Condition A.1 to be entered, which required the MSIV to be returned to an operable status within 8 hours9.259259e-5 days <br />0.00222 hours <br />1.322751e-5 weeks <br />3.044e-6 months <br />, or enter Condition B.1, which required the Unit to be in Mode 2 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />. During troubleshooting of the 1A MSIV active-side accumulator pressure issue, the licensee became concerned that they would not find and repair the active-side hydraulic problem prior to the requirement to enter Mode 2. As a result, the licensee elected to remove TRM 3.3.y Condition D from the TRM through the 10 CFR 50.59 evaluation process. As a result, the licensee was not required to declare the 1A MSIV inoperable provided the standby accumulator pressure was within operability limits. The inspectors reviewed the control logic for the MSIV control switches in the main control room and the remote shutdown panel. The inspectors noted that the MSIV control switches on the remote shutdown panels used only the active-side accumulator to reposition the MSIV. When the licensee removed TRM 3.3.y Condition D, they effectively removed any requirement to maintain the ability to close MSIVs from the remote shutdown panel. The inspectors reviewed procedures 0BwOA PRI-5, Control Room Inaccessibility Unit 0; 1BwOA PRI-5, Control Room Inaccessibility Unit 1; and 2BwOA PRI-5, Control Room Inaccessibility Unit 2; and did not identify a requirement to close the MSIVs prior to main control room evacuation. As a result, any MSIV with an active-side accumulator inoperable, which was allowed indefinitely by current site procedures, would not be closed prior to evacuating the main control room and would not be able to be closed from the remote shutdown panel. The licensees position was that there was no reason, purpose, or requirement for the MSIV control switches on the remote shutdown panel and no condition that would require repositioning them from the remote shutdown panel following evacuation of the main control room. The inspectors noted that Step 13.c of procedures 1(2)BwOA PRI-5 directed operators to close all MSIVs if RCS temperature dropped below 557oF. This step would need to be performed from the remote shutdown panel since the main control room was evacuated at Step 9. In addition, the inspectors questioned whether allowing one inoperable accumulator on each MSIV for an unlimited period of time had an effect on the ability of the ESFAS system to perform its safety function. Although only one of the two hydraulic accumulators was necessary to reposition each MSIV, each ESFAS train was assigned to a specific accumulator for each MSIV. For example, the A ESFAS train was assigned to the active-side accumulator on two MSIVs and the standby-side accumulator on the other two MSIVs. The B ESFAS train controlled the MSIVs using the opposite accumulators. As a result, there were certain combinations of accumulators that could be out of service on multiple MSIVs such that an inoperable ESFAS train would fail to close multiple MSIVs. At the end of the inspection period, the inspectors were reviewing whether this allowance satisfied the requirements of TS 3.3.2 and TS 3.7.2. At the conclusion of the inspection period, the inspectors had not completed their review of licensing documents related to this issue. As a result, this URI will remain open pending a review of the stations CLB and requirements associated with the remote shutdown panel and MSIVs. |
| Site: | Braidwood  |
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| Report | IR 05000456/2012003 Section 1R15 |
| Date counted | Jun 30, 2012 (2012Q2) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.15 |
| Inspectors (proximate) | M Perry R Ng R Walton T Go A Garmoe A Shaikh B Metrow E Duncan J Benjamin M Holmbergm Learn M Perry N Feliz_Adorno R Edwards R Ng T Daun T Go V Meghani A Dahbur A Dunlop A Garmoe A Sallman E Duncan J Benjamin J Neurauter J Robbin |
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Finding - Braidwood - IR 05000456/2012003 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Braidwood) @ 2012Q2
Self-Identified List (Braidwood)
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