US Holtec International has outlined a new "proto-prompt" decommissioning strategy, which could transform a nuclear power plant site to greenfield status within about five-and-a-half years of the plant being shut down.
Holtec said it developed the strategy to address concerns about the risk of accidental pool drainage, with the associated risks of a zirconium fire. It added that this scenario, while "non-credibly improbable, stalks the decision-making process of every nuclear plant owner preparing to draw down its workforce after ceasing operations".
When a reactor is shut down, its used nuclear fuel is usually stored in an at-reactor pool for several years to allow it to cool sufficiently to be transferred to another suitable long-term storage facility or for disposal. Holtec's strategy relies on the use of its friction-stir welded fuel basket made of Metamic HT, an aluminium boron carbide metal matrix composite. The welds do not suffer from distortion typically seen with conventional welding process.
The basket has over ten times the thermal conductivity of conventional stainless steel fuel baskets, which shortens the required cooling period of used fuel, prior to transfer to dry storage, from about seven years to two-and-a-half years. The strategy will eliminate fuel and high-level waste "as the obstacle to demolishing the plant" and allow a site to be restored more quickly.
