That's due to the heat that remains in the nuclear core, both from the recently-disabled but still-hot fuel rods and from the various byproducts of the fission process.

燃料棒虽然停止工作，但仍然非常炙热，而且裂变反应生成的多种副产物也会产生很多热量，这些热量一直维持在反应堆的核心。

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So the impact of fuel assemblies burn-up on core fission neutron source parameters shall be considered in the neutron transportation calculation.

因此，在中子输运计算中，必须考虑组件燃耗对堆芯的裂变中子源参数的影响。

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