Spent nuclear fuel from the two reactors at Exelon’s La Salle County generating station in the US is to be moved from indoor cooling pools to outdoor ‘dry casks’ no later than 2010, according to reports.

The dry casks, already in use at other reactors, appear as small concrete silos lined up on a two-foot thick concrete pad. Within each 180-tonne cask’s reinforced concrete exterior, is an inner steel shell that will contain 68 old but still radioactive fuel assemblies.

The casks are approved by the US Nuclear Regulatory Commission.

As is the case among many industry processes, waste products and by-products are a common occurrence, with this termed as ’spent nuclear fuel’ in the nuclear power process. Spent fuel is nuclear fuel that has been irradiated in a reactor to the point where it is no longer useful in sustaining a nuclear reaction.

This is still high level radioactive waste however, and is naturally potentially hazardous. A number of methods of storage are available, perhaps the most practical and widely preferred of these is dry cask storage (DCS).

The move is necessary at Exelon’s Las Salle County site because the indoor storage area is nearing capacity, and the federal government’s Yucca Mountain nuclear waste repository in Nevada is not completed.

The multi-billion dollar Yucca facility, designed to accept all national radioactive waste, was to have been completed in 1998. It now is anticipated for completion in 2020, according to Bill Stoermer, the station's Government Affairs Director, speaking to the Marseilles City Council.

The dry cask system already has been installed in two other Illinois Exelon plants and will be built soon

“Our intent is not to store any more than the plant has fuel capacity for,” Stoermer is believed to have said.

Exelon Corporation (Exelon) is a registered public utility holding company that, through its subsidiaries, operates in two business segments, Energy Delivery and Generation.

Additional information about dry cask storage is available online from the Nuclear Energy Institute at www.nei.org and the NRC at www.nrc.gov.

A Focus Feature is also available from gasworld, exploring the use of DCS in the nuclear energy sector and the helium involved in this storage technique.