The team was concerned that the licensee had not taken action to confirm that the thermal performance of
RHR Heat Exchanger B remained adequate to remove worst case design basis heat loads. The projected fouling rate was based on limited data, some of which may not have been sufficiently accurate to rely on over a long period. Also, the licensees historical data was not sufficient to provide high confidence that the fouling created a linear or predictable impact on heat transfer. Therefore, an unresolved item is being issued to further assess the capability of
RHR Heat Exchanger B and determine whether a performance deficiency exists. In response to this concern, the licensee stated their intent to clean and/or conduct a thermal performance test of this heat exchanger prior to the onset of warm weather to ensure that the this component remained capable of removing the design basis heat load. The inspectors will review the results of the testing and/or cleaning when it is completed. Additional information was needed to determine whether there were any violations of NRC requirements associated with this issue. This issue will be tracked as an unresolved item to verify that the fouling did not involve a loss of function:
URI 05000416/2007008-02, Verify continued operability of
RHR Heat Exchanger B due to fouling.
