Use of Gravity-assisted Loop Heat Pipes for Passive Cooling of Spent Nuclear Fuel Pools During Station Blackout

Abstract

Decay heat removal in a nuclear power plant’s spent fuel pool during an extended station blackout is a critical function, as demonstrated following the Fukushima Daiichi nuclear disaster in 2011 March. As the water level within these pools is reduced due to evaporation, the risk of fuel sheath melt/rupture and consequent fission product releases increases. The feasibility of removing heat generated through decay power by means of a gravity-assisted loop heat pipe system from a spent fuel pool is being examined at Chalk River Laboratories. Heat pipes offer passive heat removal, low maintenance, and high reliability that can be utilized to maintain spent fuel pools at sub-cooled temperatures to reduce evaporation losses. A small scale test rig was designed and built, with the performance and efficiency of such a system currently being studied. This paper provides a summary of the test rig design, setup and preliminary experimental results.