Haleema Hann is a Criticality Safety Consultant at Cerberus Nuclear and is a member of the SRP ' s Rising Generations Group.
Fissile material is material that can undergo nuclear fission when nuclei capture a low energy neutron. A selfsustaining chain reaction can only be achieved with fissile material.
Criticality safety considerations are required for the management of any waste containing fissile material; mostly meaning the isotopes Uranium-235 or Plutonium-239.
Criticality safety Criticality can be controlled by parameters that influence the factors of neutron production, absorption and leakage. These parameters are universally known by the acronym ' MAGIC MERV ' to ensure all nine are considered.
Criticality is a state of self-sustained, but not increasing, nuclear fission chain reaction.
Subcriticality is a state where the chain reaction is not self-sustained.
Supercriticality is a state where the chain reaction is self-sustained and growing.
Criticality safety assessments present the case for managing the criticality hazard appropriately and ensuring a system remains subcritical. The assessment contains analysis of hazards and appropriate controls based on the MAGIC MERV parameters.
Criticality safety considerations are made for waste containing any amount of fissile material. Assessment ensures that fissile material cannot assemble into a critical configuration and that controls proportionate to risk can be implemented. This approach allows for safe activities involving these waste streams and protects against the potential consequences of an inadvertent nuclear chain reaction, primarily through prevention.
Regulatory Requirements UK regulations governing criticality safety( in common with other aspects of nuclear safety) come from the interpretation of international publications from organisations such as the International Atomic Energy Agency( IAEA) or the Nuclear Energy Agency( NEA). Legislation is then interpreted by bodies such as the Office for Nuclear
24 Radiation Protection Today www. srp-rpt. uk