05000456/FIN-2014003-01
From kanterella
Jump to navigation
Jump to search
Finding | |
|---|---|
| Title | Issues That Could Adversely Affect the UHS |
| Description | Unresolved Item: Issues That Could Adversely Affect the Ultimate Heat Sink Introduction: The inspectors identified four potential issues of concern after the licensee discovered that station procedures to address a failure of the Braidwood cooling lake dike did not include steps to secure nonsafety-related pumps, although the UFSAR stated and design calculations assumed that all circulating water pumps and nonsafety-related service water pumps would be secured.15. Description: Issue 1: TS 3.7.9, Ultimate Heat Sink, Limiting Condition for Operation Applicability After Identifying that a Non-Conforming Condition Could Challenge and/or Exceed the Associated Ultimate Heat Sink 30 Day Mission Time. The Braidwood cooling lake dike allows the ultimate heat sink (UHS) level to be maintained greater than the TS minimum level of 590. A failure of this nonsafety-related dike would cause a loss of level in the UHS to the 590 TS minimum level. During the inspection period, the licensee discovered that station procedures to address a failure of the Braidwood cooling lake dike did not include steps to secure nonsafety-related pumps, including circulating water pumps and service water pumps, that take a suction from the UHS and discharge to a location outside the UHS. As a result, and because the UFSAR stated and design calculations assumed that all nonsafety-related pumps, including circulating water pumps and service water pumps, would be secured to conserve UHS inventory following a dike failure, a non-conforming condition was identified. The licensee concluded that this non-conforming condition did not render the UHS inoperable as discussed in IR 1675291, Unanalyzed Condition Identified During IR 1674557, and IR 1676076, Discrepancy in the UFSAR Ultimate Heat Sink Description (Section 2.4.11.6), based upon the following: The issue was process-related and only concerned future planned actions for increasing the maximum UHS temperature; All TS 3.7.9, Ultimate Heat Sink, surveillance requirements were met; The Braidwood cooling lake did not actually reach the minimum TS level of 590; A cooling lake dike failure did not actually occur; and A statement in the UFSAR concerning the ability of the UHS to handle an assumed loss-of-coolant-accident coincident with a design basis seismic event that the licensee believed was erroneous. Specifically UFSAR Section 2.4.11.6, Ultimate Heat Sink Design Requirements included the following statement: ...The essential service water cooling pond (ESCP) is an excavated area located within the cooling pond designed to provide a sufficient volume to permit plant operation for a minimum 30-day period without requiring makeup water in accordance with Regulatory Guide 1.27. The ESCP has been reviewed to determine its ability to handle the total heat dissipation requirement of the station assuming a loss of coolant accident (LOCA) coincident with a loss of offsite power on one unit and a concurrent orderly shutdown and cooldown from maximum power to cold shutdown of the other unit using normal shutdown operating procedures, a single active failure, a coincident design basis seismic event... The inspectors noted that IR 1674557, Question on Ultimate Heat Sink License Amendment Request Impact on Pumps, documented that the licensee had preliminarily determined that operation of a single nonsafety-related service water pump at full flow would deplete the UHS in about 3.6 days and, as a result, the UHS would not be able to satisfy the 30-day post-accident volume requirements required by the plants design basis. The licensee concluded that even though procedural guidance did not 16 explicitly direct that nonsafety-related pumps be secured following a design basis accident, operators would recognize the problem and take actions to ensure that the UHS would still be able to perform its safety function and meet all design basis requirements. At the end of the inspection period, the licensee planned to more formally document the bases for UHS TS operability consistent with the definition of operability in the site-specific TSs and the licensees Operability Determination procedure. The licensee subsequently corrected this non-conforming condition by revising procedures to secure nonsafety-related pumps upon reaching a low lake level condition consistent with plant design calculations. Therefore, the inspectors did not have a current operability concern. Issue 1 will remain open pending the completion of the inspectors review of the licensees past operability determination. Issue 2: Timeliness of Actions to Inform the Shift Manager and/or Unit Supervisor of an Issue that May Affect Ultimate Heat Sink Operability On June 25, 2014, the inspectors reviewed IR 1674557, which documented that AOP BwOA ENV3, Braidwood Cooling Lake Low Level, did not direct nonsafety-related pumps that take a suction from the UHS and discharge outside of the UHS to be secured following a dike failure. In particular, although the Operability section of IR 1674557 was left blank, the Reviewed section concluded the following: There were no equipment deficiencies identified. This is a process issue regarding future planned actionsthere are no TS/Technical Requirements Manual/Offsite Dose Calculation Manual/GOCAR [General Operation Corrective Action Requirement] actions applicable; reportability criterion affected; or any SSC [structure, system and component] availability or functionality concerns raised by this issue. The inspectors determined that although the context of IR 1674557 suggested that this issue only impacted future planned actions that, in fact, the issue could affect the current operability of the UHS. Therefore, the inspectors promptly discussed this issue with the Operations Shift Manager who was not aware of any operability concerns associated with the issue or station actions to address the issue. Later that shift, the Shift Manager determined that the issue was reportable under 10 CFR 50.72(b)(3)(ii)(B), Unanalyzed Condition. At the end of the inspection period, it was not clear if the station had adhered to OPAA108115, Operability Determinations to inform the Shift Manager and/or Unit Supervisor of this issue in a timely manner. Issue 2 will remain open pending the licensees completion of a timeline of events and an inspector review of the station standards and implementation of those standards for this issue. Issue 3: Implementation of Operations Standing Order Upon Reaching a Low Lake Level Condition Without Performing a 10 CFR 50.59 and/or Generic Letter 8610 Review17. Upon discovery of the non-conforming and unanalyzed condition of the UHS, the licensee implemented an operations standing order that directed the nonsafety-related service water system, fire protection water system, and circulating water system to be secured following a cooling lake dike failure and low lake level of 590. This operations standing order augmented AOP BwOA ENV3, which did not direct any of these actions. In developing the subject standing order, the licensee did not perform a 10 CFR 50.59 evaluation and/or an associated review in accordance with Generic Letter 8610, Implementation of Fire Protection Requirements. At the end of the inspection period it was not clear if the licensees standing order process, or any other process, permitted this type of change without performing a 10 CFR 50.59 and/or associated Generic Letter 8610 evaluation. Additionally, it was not clear if the licensees temporary change was adequate (i.e. tripping both units, securing all circulating water and non-essential service water system pumps, and securing all running Fire Protection pumps just prior to reaching a low lake level of 590). Issue 3 will remain open pending the licensees completion of a timeline of events and additional inspector review. Issue 4: Safety Category II Structure, Systems and Component Interaction with the Ultimate Heat Sink The turbine building and a number of systems and components within the turbine building are designated as Safety Category II SSCs. The licensee defined Safety Category II SSCs as SSCs that were not designed to Safety Category I Standards. Specifically, Braidwood UFSAR Section 3.2.1.2 defined Safety Category II as follows: Those SSCs which are not designated as Safety Category I are designated as Safety Category II. This category has no public health or safety implication. Safety Category II structures, systems, and components are not specifically designed to remain functional in the event of the safe shutdown earthquake or other design-basis events (including tornado, probable maximum flood, operating basis earthquake, missile impact, or an accident internal to the plant). A reasonable margin of safety is, however, considered in the design as dictated by local requirements. Many Safety Category II items in Category I buildings are supported with seismically designed supports. These items and their supports are not Safety Category I or Seismic Category I as defined by Regulatory Guide 1.29. Structures and major components not listed in Table 3.2-1 as Safety Category I are Safety Category II. Safety Category II systems or portions of systems and components do not follow the requirements of Appendix B to 10 CFR 50. The quality assurance standards for these systems and components follow normal industrial standards and any other requirements deemed necessary by the Licensee. The licensee determined that a circulating water system line break and/or main condenser expansion joint rupture was not credible based on a review of postulated safe shutdown earthquake loads, and therefore a failure of this system following a design basis event such as a safe shutdown earthquake was not within the current licensing basis. The inspectors identified that a failure of the Safety Category II circulating water system could impact safety. For example the Braidwood cooling lake dike was also a Safety Category II structure. A failure of the cooling lake dike and establishment of the UHS18 level of 590 followed by a circulating water line break/expansion joint failure in the turbine building would result in a condition not currently evaluated (i.e., less useable UHS volume due to the displacement of a fraction of the UHS volume into the turbine building). At the end of the inspection period it was not clear how a Safety Category II SSC such as the circulating water system could be credited in a manner to not fail during a safe shutdown earthquake or other associated design basis event since, by definition, Safety Category II SSCs are not specifically designed to remain functional during these events. Additionally, the inspectors planned to review the Safety Category II Lake Screen House structure design to ensure that it could not adversely affect the intake in a manner that would prevent the UHS from performing its intended safety function. Issue 4 will remain open pending NRC review to ensure that the licensee is in compliance with their current licensing basis. (URI 05000456/201400301; 05000457/201400301, Issues That Could Adversely Affect the UHS) |
| Site: | Braidwood  |
|---|---|
| Report | IR 05000456/2014003 Section 1R15 |
| Date counted | Jun 30, 2014 (2014Q2) |
| Type: | URI: |
| cornerstone | Mitigating Systems |
| Identified by: | NRC identified |
| Inspection Procedure: | IP 71111.15 |
| Inspectors (proximate) | B Bostn C Hunt D Betancourt D Mcneil D Reeser G Edwards J Benjamin J Bozga J Jandovitz M Garza T Bilik T Gob Bostond Betancourt E Duncan J Benjamin J Laughlin L Rodriguez M Learn M Perry R Edwards R Jickling T God Betancourte Duncan F Ramirez J Benjamin M Perry T Bilik T Go |
| INPO aspect | |
| ' | |
Finding - Braidwood - IR 05000456/2014003 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Finding List (Braidwood) @ 2014Q2
Self-Identified List (Braidwood)
| |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||