Detection of coolant void in lead-cooled fast reactors

摘要

Previous work (Wolniewicz et al., 2013) has indicated that using fission chambers coated with Pu-242 and U-235, respectively, can provide the means of detecting changes in the neutron flux that are connected to coolant density changes in a small lead-cooled fast reactor. Such density changes may be due to leakages of gas into the coolant, which, over time, may coalesce to large bubbles implying a high risk of causing severe damage of the core. By using the ratio of the information provided by the two types of detectors a quantity is obtained that is sensitive to these density changes and, to the first order approximation, independent of the power level of the reactor.