An improved method for modelling coolant radiolysis in ITER

Predicting the effects of coolant water radiolysis induced by neutron and gamma radiation in the International Thermonuclear Experimental Reactor (ITER) is important, as oxidizing species like O2 and H2O2 will corrode structural materials, increasing maintenance costs and potentially compromising safety. In this work, a new model has been developed, by modifying existing models, to evaluate the water radiolysis behaviors in different Primary Heat Transfer Systems (PHTSs) in ITER. The new model takes the circulation of coolant, and the combined gamma and 14 MeV neutron radiation into consideration. We recommend injection of about 5 cc H2 under standard temperature and pressure (STP) per kilogram of H2O into the First Wall/Blanket (FW/BLKT) PHTS to both efficiently suppress water radiolysis and avoid problems caused by addition of excessive H2.