Nuclear criticality safety is a field of nuclear engineering dedicated to the prevention of nuclear and radiation accidents resulting from an unintentional event. It involves the implementation of controls, such as physical, mechanical, or administrative measures, to ensure that a nuclear chain reaction does not occur. This article will discuss the principles of nuclear criticality safety, the calculations and analysis used to prevent accidents, and the burn credit system. It will also provide guidance on how to meet relevant requirements to ensure subcriticality when dealing with fissile material and for planning response to major accidents.
The underlying principles of nuclear criticality safety are based on the concept of subcriticality. This means that the fissile material must be kept in a state where it cannot sustain a nuclear chain reaction. To achieve this, the material must be kept at its minimum enrichment level and must not be irradiated. In addition, physical, mechanical, or administrative controls must be implemented to prevent any significant process changes that could lead to a nuclear criticality accident. Calculations and analysis are used to determine the subcriticality of a system.
These calculations involve determining the reactivity of the system, which is the measure of how likely it is to sustain a nuclear chain reaction. The reactivity is determined by analyzing the system's geometry, composition, and other factors. In addition, burn credit calculations are used to determine how much fissile material can be safely stored in a system without exceeding its reactivity limit. The burn credit system is used to track the amount of fissile material stored in a system. This system assigns a credit value to each type of fissile material stored in the system.
The total amount of fissile material stored in the system must not exceed its burn credit limit or else it could become critical. The burn credit system also helps ensure that any changes made to the system do not cause it to exceed its reactivity limit. To ensure subcriticality when dealing with fissile material, regulatory bodies and operating organizations must follow certain guidelines and recommendations. These include implementing inherently safe or fault-tolerant plant designs, as well as administrative controls such as operating procedures and work instructions. In addition, research on static and transient configurations found in the nuclear fuel cycle should be conducted in order to identify potential risks. Nuclear criticality safety is an important field of nuclear engineering that helps prevent nuclear and radiation accidents from occurring.
It involves implementing physical, mechanical, or administrative controls to ensure that a nuclear chain reaction does not occur. Calculations and analysis are used to determine the subcriticality of a system, while the burn credit system is used to track the amount of fissile material stored in a system. Regulatory bodies and operating organizations must follow certain guidelines and recommendations in order to ensure subcriticality when dealing with fissile material.
