NRC Issues Guidance on FLEX, Vents and Spent Fuel Pool Instrumentation

The following news article originally appeared in NEI’s Nuclear Energy Overview.

The NRC has released Interim Staff Guidance on three post-Fukushima orders the agency issued in March on safety enhancements at the nation’s nuclear energy facilities.

“The NRC guidance issued last week meets the intent of the three orders issued earlier this year,” said Joe Pollock, NEI’s executive director of Fukushima response coordination and strategy. “We look forward to working with the NRC to effectively implement the guidance in the months and years ahead.”

The guidance outlines “acceptable approaches” to implementing changes at U.S. nuclear energy facilities in three areas: implementing the industry’s FLEX strategy for responding to the loss of electric power; ensuring reliable, hardened containment vents; and enhancing spent fuel pool water level instrumentation.

The final guidance will result in many changes at plant sites across the country, including:

• Protecting and making available additional safety equipment to mitigate a loss of offsite electric power and reactor cooling capability, as occurred at Fukushima Daiichi. The NRC endorsed the industry’s FLEX approach to the first order. FLEX will provide additional layers of backup power after an extreme natural event with additional emergency equipment—generators, battery packs, pumps, air compressors and battery chargers—placed in multiple locations. The guidance is available in the NRC’s ADAMS electronic document database under accession number ML12229A174.

• Improving or installing reliable, hardened containment vent systems for Mark I and Mark II boiling water reactors, as described in the guidance for the second order. This guidance is available under accession number ML12229A475.

• Installing enhanced equipment to monitor water levels in spent fuel storage pools, as detailed in the guidance for the third order. The guidance defines standards for equipment mounting, powering and testing, personnel training and other criteria, and is available under accession number ML12221A339.

While the guidance is not mandatory, the NRC said that U.S. plant operators would have to seek NRC approval to pursue a different compliance approach.

The NRC and industry will continue to discuss and refine implementation details as the utilities work to meet the Dec. 31, 2016, deadline for the orders. One area of continuing discussion will be on how licensees can demonstrate the capability of the enhanced spent fuel storage pool level instrumentation to withstand an earthquake.

The industry guidance for pool instrumentation (NEI 12-02, Rev. 1) provides several commercial-based methods that a utility could use to demonstrate seismic capability. The NRC guidance, however, points to sections of IEEE Standard 344-2004, “IEEE Recommended Practice for Seismic Qualification of Class 1E Equipment for Nuclear Power Generating Stations.”