Abstract: The mathematics model in which radioactive nuclides are released from(nuclear) fuel to the environment during accident conditions in China Advanced Research(Reactor)(CARR) is eatablished.The source terms in the following accidents are analyzed,including small loss of coolant accident,heat exchanger plate break,heavy water loop break,fuel handling accident,coolant channel blocking accident,and three fuel(assemblies) meltdown.The quantities of radioactive(nuclides) released to the environment through different paths during accidents are given to prevent undue radiological hazard to the public during accident conditions.