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The inspectors identified an unresolved is … The inspectors identified an unresolved issue (URI) related to the expected response of the LPCI/RHR system to a postulated LOCA during Mode 3 operation. Specifically, a portion of the LPCI/RHR system, including two RHR pumps, could be isolated while at elevated pressure and temperature. The concern was that realignment of the LPCI/RHR system for injection following a LOCA could result in steam voiding of the piping and/or pumps when the isolation valves were reopened under lower pressure conditions. Technical Specification 3.5.1 required the emergency core cooling systems, including LPCI, to be operable during Mode 3. The TS also stated that the LPCI system may be considered operable during alignment and operation for decay heat removal in Mode 3, if it was capable of being manually realigned and not otherwise inoperable. As part of the scenario review for the postulated LOCA during Mode 3 operation, the inspectors reviewed procedure OI 149, Residual Heat Removal System, and observed a simulator exercise requiring the operators to transfer a portion of the LPCI/RHR system from decay heat removal mode to LPCI injection mode per OI 149, Section 5.2, LPIC Initiation While in Shutdown Cooling. Based on this review, the inspectors noted that this operational sequence would involve isolation of the LPCI/RHR pumps being used for decay heat removal followed by the realignment of the LPCI/RHR system for injection. Based on review of the operating instruction and discussions with operations personnel, the inspectors also determined that this isolation and realignment would be performed whether the subject LPCI/RHR pumps were required for injection or not. The inspectors determined that this portion of the LPCI/RHR system, including two RHR pumps, could be isolated while at elevated pressure and temperature (potentially greater than 100 psig and 300F). The realignment of the LPCI/RHR system for injection following a LOCA could result in steam voiding of the piping and/or pumps when the isolation valves were reopened under lower pressure conditions. Steam voiding could potentially cause damage to the LPCI system suction and discharge piping, as well as the pumps. At the time of the inspection, the potential impact of steam voiding on the system had not been evaluated. The inspectors noted that operating experience with this issue, IN 2010-11, Potential for Steam Voiding Causing Residual Heat Removal System Operability, had recently been issued based on similar concerns at several pressurized water reactors. The licensees review, however, did not result in a detailed evaluation of this potential issue. This was a missed opportunity for the licensee to evaluate this condition. As a result, the inspectors questioned if the LPCI system would actually be operable under these conditions. In response to this concern, the licensee performed preliminary analyses and concluded that the trapped fluid could contain sufficient energy to form steam within the system. However, this analysis did not evaluate the potential impact of steam voiding on system operability. The inspectors concluded that additional evaluation would be required to determine if the potential steam voiding could be damaging and/or impact system operability. The licensee initiated condition report AR01625023 to perform additional evaluations. Since the analysis required to resolve this concern was not completed prior to the end of the inspection, this issue is considered an unresolved item (URI 05000331/2011009-04) pending completion of the analysis by the licensee and review by the inspectors.the licensee and review by the inspectors.
23:59:59, 30 June 2011 +
23:59:59, 30 June 2011 +
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Modification date"Modification date" is a predefined property that corresponds to the date of the last modification of a subject and is provided by <a rel="nofollow" class="external text" href="https://www.semantic-mediawiki.org/wiki/Help:Special_properties">Semantic MediaWiki</a>.
00:44:28, 21 February 2018 +
23:59:59, 30 June 2011 +