Modelling the formation of local blockages at the grids of LMFBR sub-assemblies

Comments are made on a recently developed model for the formation of local blockages at the grids of LMFBR sub-assemblies. The distinction is drawn between formation of a 'fundamental blockage' in a given subchannel and formation in any subchannel. It is shown that for a given set of parameters, for the former, blockage inception times range from a few days to more than a year, whereas, for the latter, the times range from two days to two weeks. Attention is drawn to the importance of these estimates of the debris release rate and examples are given which indicate the large range of possible values for this parameter. The paper concludes that until there is a greater mechanistic understanding of debris release, statistical models are of limited use. (orig.)