ASSESSMENT OF HTGR ACCIDENT CONSEQUENCES

Assessments were made of the consequences of the higher risk accident conditions postulated to occur in a reference 1975 General Atomic 3000-MWRt: high-temperature gas-cooled reactor. The most representative accident conditions are R1: core heatup caused by a loss of off-site power or by a large earthquake, leading to a loss of forced circulation, R2: reheater tube failure, R3: depressurization of the primary coolant, and R4: steam-generator main bundle tube failure. The results indicate that the high-temperature gas-cooled reactor has excellent safety characteristics, which are inherent in the concept and are primarily associated with the choice of coolant and core design. Over a wide range of accident frequencies (from one accident per reactor-year to one accident in 10 million reactor-years), no accidents considered in the study are predicted to cause early or delayed fatalities or illnesses.