Decommissioning operators are looking to accelerate the transfer of spent fuel from cooling pools to dry storage to cut costs.

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A recent U.S. licence approval for Orano's NUHOMS dry storage canisters shows how continuing technology advances are accelerating spent fuel transfer and post-shutdown activities. 

The Nuclear Regulatory Commission (NRC) approved the use of Orano canisters to store nuclear fuel with higher decay heat and cooling times as short as two years.

Earlier Orano canister licences limited fuel configurations to minimum three to five-year equivalent cooling periods. The license approval recognizes the canister design and materials can accommodate fuel assembly configurations which include "two-year equivalent" cooled fuel.

Faster spent fuel transfer reduces the large upfront costs associated with decommissioning nuclear plants and allows operators to commence dismantling and decontamination (D&D) activities.

The U.S. is entering a wave of decommissioning projects as operators accelerate closure plans in the face of wholesale price pressures. Some 13 U.S. reactors are set to close between 2018 and 2025 and many of these are set to undergo immediate decommissioning to reduce future cost risks.

       US plants set for closure in 2018-2015

                               (Click image to enlarge)

Source: Energy Information Administration (EIA), September 2018.

Fuel transfer specialists Holtec and NAC International have also reduced spent fuel cooling times. The NRC has already approved a two-year equivalent cool time for Holtec’s MPC-68M multi-purpose canister and a 2.5-year cool time for NAC International's MAGNASTOR system.

Going forward, U.S. fuel transfer times could be further reduced through the licensing of additional technologies, Curtis Roberts, Director of Communications for Orano USA, said.

“Orano has existing technology used in France and elsewhere that could be employed in the U.S. to safely transfer one-year equivalent cooled fuel to dry storage," he said.

Record speed

Growing demand for decommissioning has spawned new joint ventures and business models which aim to speed up the decommissioning process and cut costs.

In the U.S., Holtec and SNC-Lavalin created a joint company, Comprehensive Decommissioning International (CDI) while Orano and U.S. demolition specialist Northstar created Accelerated Decommissioning Partners (ADP). These decommissioning specialists plan to use economies of scale and the latest technology advancements to increase efficiency.

Holtec has moved fast to acquire closing plants. Last month, the company agreed to buy Entergy's 2 GW Indian Point nuclear plant in New York State after it is shut down in 2020-21. Indian point consists of three reactors. Unit 1 is shut down and Units 2 and 3 remain operational.

               Locations of closed or soon-to-close reactors

Source: Energy Information Administration (EIA), September 2018.

The sale would bring Holtec's U.S. commercial decommissioning portfolio to six reactors at four sites. Holtec has already signed agreements to purchase upon closure Entergy's 688 MW Pilgrim plant in Massachusetts, its 811 MW Palisades plant in Michigan, and Exelon’s 636 MW Oyster Creek plant in New Jersey.

Faster spent fuel transfer significantly reduces plant monitoring and labor requirements.

Operations and security costs can fall by $10 to $30 million per year after spent fuel is transferred to dry storage, depending on the size of the plant and staffing levels, Juan Subiry, Vice President, Market and Product Strategy, at NAC International, told Nuclear Energy Insider.

In June 2018, NAC International completed the transfer of 887 fuel assemblies from pool to pad at the 556 MW PWR Kewaunee Power Station (KPS) within five years of shutdown. The fuel transfer was performed in a record time of 23 weeks.

Operational costs at Kewaunee fell by around $13 million per year after defueling was completed, mainly due to lower staffing costs, Subiry said.

Faster dismantling

Going forward, the total time to completion of spent fuel transfer could fall to around 2.8 to 3 years, from first cask in pool to last cask on the pad, Subiry said.

This would involve "mix and matching colder fuel with hot fuel from the last core among a number of casks, and implementing other limiting considerations for doses during storage and eventual transport,” he said.

Wider technology advances will also speed up the reactor dismantling process and allow more work to be completed during spent fuel transfer.

Operators are applying industry learnings and implementing the latest cutting technologies, robotics solutions and 3-D modelling technology to improve dismantling efficiency.

According to Orano, faster fuel transfer combined with optimized dismantling strategies could see D&D of U.S. nuclear plants completed within five years of shutdown.

By Neil Ford