Scholarlink

In nuclear reactors, sustainable fission chain reactions by neutrons are realized without any neutron supply from external sources. In other words, nuclear reactors are systems to generate energy and to utilize radiation rays such as neutrons through properly controlling sustainable fission chain reactions. Based on this consideration, the first step to study nuclear reactors would be to know or understand which conditions in geometry, composition, size, etc. are required to make reactors in a critical state, how reactors can reach a critical state, and how reactors behave during approaching to a critical state. For these objectives, the approach-to-criticality experiment, in which a subcritical reactor is made approaching to a critical state, is carried out. This experiment is fundamental and mandatory, and it is generally carried out prior to other nuclear reactor experiments. In the approach-to-criticality experiment at KUCA, fuel plates made of nuclear materials such as uranium are loaded in a reactor core. Neutron flux level in the core is measured at several different subcritical states, number of fuel plates to be added at the next state is determined according to the measurement results obtained at the present state, and finally the reactor reaches a critical state. This experiment is also carried out as preparation for the subsequent experiments such as the control rod calibration experiment. The critical state in which the effective neutron multiplication factor \(k_{{{\text{eff}}}}\) of the core is unity can be clearly defined in theory or numerical simulation. On the other hand, in actual reactors, it is quite difficult to distinguish the critical state from the slightly subcritical or supercritical state when the reactor power is low. If the reactor power is increased, a deviation from the critical state can be clearly observed in the detector signal on the reactor power. One of the purposes of this experiment is to deepen the understanding of the critical state through the actual use of nuclear reactors.

错误：搜索内容不能为空，请输入英文关键词
错误：关键词超出字数限制，请精简
高级检索

Approach-to-Criticality Experiment

  • 章节

  • 出版模式：

    开放获取

  • 发表日期：

    2025年

查看全文
  • Cheol Ho Pyeon,
  • Go Chiba,
  • Tomohiro Endo,
  • Kenichi Watanabe

摘要

In nuclear reactors, sustainable fission chain reactions by neutrons are realized without any neutron supply from external sources. In other words, nuclear reactors are systems to generate energy and to utilize radiation rays such as neutrons through properly controlling sustainable fission chain reactions. Based on this consideration, the first step to study nuclear reactors would be to know or understand which conditions in geometry, composition, size, etc. are required to make reactors in a critical state, how reactors can reach a critical state, and how reactors behave during approaching to a critical state. For these objectives, the approach-to-criticality experiment, in which a subcritical reactor is made approaching to a critical state, is carried out. This experiment is fundamental and mandatory, and it is generally carried out prior to other nuclear reactor experiments. In the approach-to-criticality experiment at KUCA, fuel plates made of nuclear materials such as uranium are loaded in a reactor core. Neutron flux level in the core is measured at several different subcritical states, number of fuel plates to be added at the next state is determined according to the measurement results obtained at the present state, and finally the reactor reaches a critical state. This experiment is also carried out as preparation for the subsequent experiments such as the control rod calibration experiment. The critical state in which the effective neutron multiplication factor \(k_{{{\text{eff}}}}\) of the core is unity can be clearly defined in theory or numerical simulation. On the other hand, in actual reactors, it is quite difficult to distinguish the critical state from the slightly subcritical or supercritical state when the reactor power is low. If the reactor power is increased, a deviation from the critical state can be clearly observed in the detector signal on the reactor power. One of the purposes of this experiment is to deepen the understanding of the critical state through the actual use of nuclear reactors.