Kewaunee dry fuel storage campaign sets records

Tuesday, 11 July 2017

NAC International's completion of a dry fuel storage campaign at the Kewaunee nuclear power plant four years after the unit shut down has set a new benchmark for the transfer of used fuel to dry storage.

Magnastor casks on the ISFSI pad (Image: NAC International)

Dominion Energy's Kewaunee entered retirement in May 2013 after almost 40 years of operation. In December that year, NAC was awarded a contract for the turnkey dry storage project including site engineering, expansion of the plant's Independent Spent Fuel Storage Installation (ISFSI), 24 of NAC's Magnastor dry-cask storage systems, pool-to-pad equipment and loading services.

The project has involved the packaging of 887 assemblies of used fuel remaining at the plant into the Magnastor casks. A licensed loading pattern allowed an accelerated loading schedule, with used fuel cooling times as low as 2.5 years. Pool-to-pad loading services were completed in 23 weeks, with loading durations averaging 2.3 days per cask system.

The 24th and final Magnsator cask was placed on the ISFI on 15 June. Completion of the project four years after the plant closed and 3.5 years after contract execution sets a new benchmark for the complete transfer of all used fuel to dry storage after plant shut-down, NAC said yesterday.

The entire used fuel inventory from nearly four decades of electricity generation at Kewaunee is represented by the 24 Magnastor systems and 14 legacy Nuhoms systems. Nuhoms is a horizontal storage system supplied by Areva.

The contract was a key part of Dominion Energy Kewaunee's strategy to accelerate transition to phase 3 of the US Nuclear Regulatory Commission's (NRC) SAFSTOR decommissioning status. SAFSTOR is one of three decommissioning strategies available to US nuclear power plant licensees. It is a deferred dismantling strategy under which a nuclear facility is maintained and monitored in a condition that allows the radioactivity to decay, usually for a period of 40-60 years, after which the plant is dismantled and the property decontaminated. Defuelling a shut-down nuclear reactor removes about 99% of its radioactivity.

NAC's president and CEO Kent Cole, said: "The safe completion of this project demonstrates the Magnastor system's capabilities to enable prompt defuelling, record-setting loading durations and low operational dose performance, which can be achieved with a strong project team, high standards of performance, and excellent partnership with your customer."

Kewaunee, in Wisconsin, is a single 574 MWe pressurised water reactor. It began operating in 1974 and was sold to Dominion by Wisconsin Public Service and Wisconsin Power & Light in July 2005 for $220 million in cash, including $36.5 million for fuel. At that time, Dominion anticipated establishing a portfolio of nuclear units in the Midwest region but put the unit up for sale in 2011 after a change in strategy. Although the plant had secured a 20-year operating licence to 2033 no buyer was found, and Dominion subsequently decided to close the plant.

According to the NRC, major decommissioning and dismantling activities are scheduled to begin at Kewaunee in 2069, with licence termination set for 2073.

Researched and written
by World Nuclear News