To improve the accuracy of the calculated reactor internals heating rate in the design of nuclear power plants, this paper studied the contribution of prompt fission γ to the reactor internals heating rate based on the original method of MCNP external neutron source model. The results revealed that the reactor internals heating rate increased by 9% ~38% with prompt fission γ taken into account and the internals nearer to the core had a lager increment. In addition, it is believed after analysis that the contribution of the delayed γ on reactor internals heating rate is similar to the prompt fission γ. Therefore, when calculating reactor internals heating rate, in addition to the neutron source and neutron capture γ, prompt fission γ and delayed γ should also be considered.%为提高核电设计中反应堆堆内构件释热率计算的准确性,本文在原来MCNP外中子源模型计算方法的基础上,计算分析瞬发裂变γ对堆内构件释热率的贡献.计算结果显示,考虑瞬发裂变γ使得堆内构件的释热率增加9％～38％,离堆芯越近的堆内构件的增加值越大.另外,分析认为缓发γ对堆内构件释热率的贡献与瞬发裂变γ相当.因而反应堆堆内构件释热率计算中除了考虑中子及中子俘获所生γ的贡献,还应该考虑瞬发裂变γ和缓发γ的贡献.
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