05000348/FIN-2014007-10
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Finding | |
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Title | Potential Misapplication of Void Transport Empirical Correlations |
Description | The team identified a URI regarding the potential misapplication of void transport empirical correlations. Specifically, the licensee developed suction void acceptance criteria using questionable empirical correlations. On January 11, 2008, the NRC requested each addressee of GL 2008-01 to evaluate its ECCS, DHR, and CS systems licensing basis, design, testing, and corrective actions to ensure that gas accumulation is maintained less than the amount that would challenge the operability of these systems, and take appropriate actions when conditions adverse to quality were identified. Part of the licensees actions to address these requests was to develop acceptance criteria for void volumes that are identified during periodic monitoring. The team noted the acceptance criteria methodology used for assessing suction voids found at suction piping potentially misapplied empirical correlations for void transport. Specifically, these empirical correlations were developed from a test known as Purdue test and were a set of correlations that preceded the ones reviewed by NEI 09-10, Guidelines for Effective Prevention and Management of System Gas Accumulation. The NRC endorsed this industry guidance in RIS 2013-09. Section 3.16 of NEI 09-10 discussed the Purdue test report and stated Empirical correlation predictions are limited to estimating uncertainties. It also discussed test data weaknesses and states, The NRC staff concludes that the modeling of two-phase two-component transient flow must be conducted with allowance for these data weaknesses. The associated NRC safety evaluation (SE) (i.e., ML12342A368) included the same statements. In addition, it states The NRC staff finds the methodologies and correlations described in the references have not always been sufficiently compared to experimental data to establish that they are acceptable for determining operability under all conditions. It also states Licensee use of the references must address the weaknesses that are addressed in this SE. Based on this information, the team questioned the technical adequacy of the empirical correlations used by the licensee when developing suction void acceptance criteria. In addition, since these empirical correlations were the predecessors of the correlations reviewed by NEI and NRC, the team questioned if additional weaknesses existed. The licensee captured the team questions in their CAP as CR 834115. The team, in consultation with NRR staff, determined this issue is unresolved pending further NRR review of the acceptability of the licensees methodology for determining suction void acceptance criteria and determination of further NRC actions to resolve the issue to determine if a performance deficiency exists. (URI 05000348, 364/2014007-10, Potential Misapplication of Void Transport Empirical Correlations) |
Site: | Farley |
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Report | IR 05000348/2014007 Section 1R21 |
Date counted | Jun 30, 2014 (2014Q2) |
Type: | URI: |
cornerstone | Mitigating Systems |
Identified by: | NRC identified |
Inspection Procedure: | IP 71111.21 |
Inspectors (proximate) | D Mas E Stamm G Macdonald M Yeminy N Feliz _Adorno R Nease S Kobylarz T Light |
INPO aspect | |
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Finding - Farley - IR 05000348/2014007 | |||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
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Finding List (Farley) @ 2014Q2
Self-Identified List (Farley)
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