VALIDATION OF CATHENA AGAINST THE CS28-1 HIGH-TEMPERATURE EXPERIMENT UNDER AN IMPAIRED COOLING CONDITION

The loss of cooling flow to the fuel channel in CANDU reactor can resu lt in high fuel temperatures and low steam flowrates over extended per iods of time. Under these conditions, high temperatures can increase t he quantity of fission products released from the fuel, and the produc tion of large quantities of hydrogen gas, and eventually may cause fai lure of pressure tube, The CHAN-IIA code has been designed to simulate the behaviour of the CANDU fuel channel under these extreme condition s and validated against the CS28-1 experiments. however, the code over -estimates fuel temperature transient and hydrogen production. It is o bserved that subchannel model and simple radiation model ill fuel ring s would contribute to under-estimation of heat removal in fuel channel . The CATHENA code, which has bean developed for the analysis of two-p hase flow and heat transfer in piping network and fuel channel, shows tile good agreement with the CS28-1 experimental data.