Internal storage is used in fast reactors as it allows burnt fissile assemblies to cool down before being removed from the reactor. These assemblies are usually stored in the neutron shielding zone far from the core to avoid additional induced fissions. The BALZAC-SI experiment performed in the MASURCA Reactor was dedicated to study internal storage characteristics of a SFR-type MOX core. Fission rate distributions throughout the geometry are calculated with both the TRIPOLI-4® Monte-Carlo and the new APOLLO3® deterministic code. Results show that discrepancies up to 20% are obtained on fission rates with the TRIPOLI-4® code, the APOLLO3® code giving similar results to TRIPOLI-4®. Sensitivity and uncertainty calculations of the different responses to nuclear data are performed in order to explain these biases. We show that uncertainties due to nuclear data may explain a large part of the obtained biases, but further investigations are required to explain remaining discrepancies.

内部存储用于快速反应堆中，因为它可使燃烧后的易裂变组件冷却下来，然后再从反应堆中取出。这些组件通常存储在远离堆芯的中子屏蔽区中，以避免额外的诱发裂变。在MASURCA反应堆中进行的BALZAC-SI实验专用于研究SFR型MOX堆芯的内部存储特性。使用TRIPOLI-4®Monte-Carlo和新的APOLLO3®确定性代码都可以计算出整个几何体的裂变率分布。结果表明，使用TRIPOLI-4®代码可获得高达20％的裂变率，APOLLO3®代码给出的结果与TRIPOLI-4®类似。为了解释这些偏见，进行了对核数据的不同反应的敏感性和不确定性计算。