Behaviour of a fibre-type thermal insulation for high temperature reactors under rapid depressurization; theory and measurement

The depressurization behaviour of a fibre-type thermal insulation has been investigated both by measurements with air and helium and with numerical models. A simple lumped parameter model has been used to reproduce the measured transients for air as well as for helium. All the experimental data have been obtained with reasonable accuracy by fitting two empirical parameters, the effective surfaces of the flow through the venting holes and the flow through the perforated tube. It is remarkable that the same parameters reproduce the experimental data for such different gases as air and helium. The dependence of the depressurization behaviour on the different parameters has been treated by a dimensional analysis. (Auth.)