The pond is designed as a water-retaining structure and as a means to provide shielding against the ionising radiation from stored fuel elements. These considera­tions necessitate typical pond external wall thicknesses of 1.0 m of concrete although walls of up to 1.7 m thickness are required where there are working areas immediately adjacent to the external walls.

The ponds are designed to comply with the relevant Code of Practice for water retaining structures [37]. The pond walls and floor are painted with a phenolic resin paint. Water bars are incorporated in all con­struction joints and each joint in the pond base is provided with drainage channels leading to leakage tell-tale sumps. Facilities are provided for pumping out any seepage into the sumps. By these means, accidental loss of radioactivity to the environment is guarded against, and the operators provided with early information on any defects in the pond structure.

In order to avoid undesirable structural stresses it is recommended that the rate of change of pond temperature is kept to a minimum.