05000456/FIN-2013002-06
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Finding | |
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| Description | The inspectors identified an URI regarding the licensees interpretation of their CLB requirements pertaining to the RCS Pressure Control Safety Function during a postulated seismic event and assumed 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> period in hot standby. Specifically, the inspectors identified three issues of concern that questioned the licensees ability to maintain RCS pressure control without the reliance of the primary safety valves and in a manner that could accomplish an RCS cooldown within a timeframe required by RSB BTP 5-1. Description: The licensees CLB utilized the standards in NRC BTP RSB 5-1, Design Requirements of the Residual Heat Removal System, Revision 2, dated July 1981, to meet aspects of 10 CFR Part 50, Appendix A, General Design Criteria (GDC) 19 and GDC 34. In summary, the station was licensed to demonstrate the capability to reach a cold shutdown condition assuming a design basis earthquake resulting in a LOOP and the failure of all non-safety, non-seismically qualified equipment. Design functions necessary to maintain hot standby and cold shutdown conditions include inventory control, reactivity management, decay heat removal, and RCS pressure control. The three issues of concern discussed in this URI are related to the RCS pressure control function during the assumed 2 hour2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> hot standby period. The licensees Analysis of Record (AOR) assumed the following: 1) the time spent in hot standby will be limited to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />, 2) the safety-related PZR PORV and associated instrument air accumulators could maintain RCS pressure in hot standby without the reliance on the RCS code safety valves, and 3) every attempt would be made to open key CVCS valves needed for auxiliary spray in the case that the PZR PORVs were not available. Since instrument air was considered nonsafety-related, instrument air was assumed to be unavailable during this postulated seismic event. The licensees UFSAR stated, however, that every attempt would be made to either restore the instrument air compressors (in the case of a LOOP) or to utilize nitrogen bottles to open the necessary air valves to restore the nonsafety-related auxiliary spray system if the PZR PORVs were not available. Issue of Concern 1: Inadvertent Removal of the Design Basis Requirement to Commence a Cooldown within 2 Hours Following the Establishment of Natural Circulation Conditions and Loss of Instrument Air to Containment...... Issue of Concern 2: Failure to Account for Allowable PZR PORV Accumulator Air Leakage During 2 Hour Hot Standby Period. .....Issue of Concern 3: No Procedures for Crediting the Use Auxiliary Spray Utilizing Portable Nitrogen Bottles. ....Based d on the above, the inspectors questioned whether the licensee had appropriately addressed the issues both individually and collectively to the standards required by NRC regulations. At the conclusion of the inspection period, the inspectors were reviewing the licensees CLB. This URI will remain open pending additional review. (URI 05000456/2013002-06, 05000457/2013002-06, Current Licensing Basis Requirements for RCS Pressure Control Function During a Postulated Seismic Event in Reference to NRC RSB BTP 5-1) |
| Site: | Braidwood  |
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| Report | IR 05000456/2013002 Section 1R15 |
| Date counted | Mar 31, 2013 (2013Q1) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.15 |
| Inspectors (proximate) | A Garmoe E Duncan J Benjamin M Holmberg M Perry R Jickling R Ng T Daunm Learnm 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 Robbins |
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Finding - Braidwood - IR 05000456/2013002 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Braidwood) @ 2013Q1
Self-Identified List (Braidwood)
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