The US nuclear regulator has informed Mitsubishi Heavy Industries (MHI) that a final ruling on design certification of its Advanced Pressurized Water Reactor (APWR) is now likely to be made in 2015 and not in 2014, as previously expected. The delay follows structural changes made to the design by the vendor.
|A cutaway of the US-APWR design (Image: NRC)
MHI submitted its design certification application for the US-APWR to the Nuclear Regulatory Commission (NRC) in late December 2007 and this was formally accepted in March 2008. However, MHI has since made structural changes to the US-APWR design which required performing a new seismic analysis. The NRC is currently reviewing the new seismic re-analysis technical reports submitted by MHI.
The NRC has now informed MHI that completion of the review has been rescheduled "due to an increased scope of work associated with additional information provided or to be provided in support of the design certification application." Specifically, the regulator said that "the area contributing to the need for this revision ... is the seismic and structural analysis."
MHI lodged a final completion plan for the seismic and structural analyses of the US-APWR design with the NRC in late March. That completion plan included a change to the plant layout, changes to the methodologies for the soil-structure interaction analysis and a new methodology for addressing sliding stability of the nuclear island. Under the plan, MHI will submit five new and revised technical reports between May and August 2012 and to make the supporting calculations and design reports available for audit by February 2013.
The NRC is currently reviewing the technical reports already submitted and designated by MHI as not to be impacted by the reactor design changes. However, it said that it now expects to complete its review of the design certification application and the associated technical reports by November 2013, compared with the previous schedule of January 2013. Meanwhile the safety review of the design is expected to be completed in March 2015, instead of May 2014. The scheduled date for the final ruling on design certification for the US-APWR has slipped from October 2014 to August 2015.
The NRC said that it would periodically review the revised schedule and make necessary adjustments based on the progress made by MHI.
Luminant is proposing the 1700 MWe APWR design for units 3 and 4 at the Comanche Peak nuclear power plant in Texas, while Dominion plans to use the design for the proposed third unit at North Anna plant in Virginia. The NRC informed both utilities in March 2011 that the review of their licence applications to construct the units had been rescheduled by some 18 months after the changes made by MHI to the reactor design.
Researched and written
by World Nuclear News