Structure mechanics and thermal-hydraulic behaviour of a PWR coolant loop with a postulated crack like leakage

Abstract

Thermal hydraulic calculations, using ATHLET, have been used to evaluate pressures and temperatures in primary and secondary circuits, following a postulated leak in the surge line. These were, then, used as input for the structural mechanics calculations with ADINA. The main results of the analyses may be summarised as follows; global deformations are significantly reduced by the drop in pressure and decrease in temperature (e.g. the vertical displacement of the surge line in the region of the crack is reduced by 50%); the leakage area at the end of the transient is about 30% lower compared with the value at the beginning; the leak rate is slightly increased at the end of the transient in comparison with the initial rate; the consideration of the crack surface pressure is important, as it leads to a significant increase in crack load and leakage area by about 50 and 35%, respectively.