requirements of the Ionising Radiations Regulations( IRR17). The article on page 15 discusses the designation of areas in more detail.
Once shielding requirements are established, a shielding assessment determines the required shielding level and type. The choice of shielding material depends on the type and energy of the radiation. Polyethylene is used for thermal neutron shielding, while steel and lead are used for gamma radiation. Concrete is a cost-effective option for both neutron and gamma shielding. The thickness of the shielding must be sufficient to reduce radiation to safe levels, but optimisation is essential to take account of space and cost constraints.
The placement and structure of shielding also play a crucial role in its effectiveness.
Shielding should ideally be close to the source to minimise the required extent, but the design requires optimisation to provide maximum protection while minimising material use and cost. Openings such as windows, gaps and pipe penetrations can allow radiation to stream through unshielded, so design features such as offset shine paths( joggles) may be necessary.
Dose Assessment Once a shielding design is proposed, a dose assessment is conducted to calculate the radiation exposure a person would receive. Legal dose limits are prescribed in the Ionising Radiations Regulations, but most sites work to lower internal limits for added safety. The Shielding Design Process is repeated as needed to ensure the design is optimised and doses are As Low As Reasonably Practicable( ALARP).