Safe storage to allow natural radioactive decay

Opportunity

‘Safstor’ is a nuclear decommissioning strategy that harnesses natural radioactive decay over time to reduce the potential risk to operatives who will ultimately dismantle and remove old nuclear facilities, often many decades from now. At Bradwell, two reactor buildings required weather envelopes capable of covering and protecting both buildings for the next 100 years. Client Magnox wanted a result that would minimise the need for inspection and maintenance activities and reduce onsite personnel requirements over the decades. The capacity of the buildings to withstand environmental loads also had to be assessed, and any required building strengthening designed.

Solution

A 3D laser scan of the buildings was carried out to produce a millimetre-accurate as-built model enabling seamless integration of the new structural works with the old. 3D modelling was used to assess the capacity of the new envelopes to withstand environmental loads such as wind and snow. Our building services engineers also modelled how the internal environment would react to a range of external ambient conditions.

Outcome

Our cocoons will protect the local environment and community from the unpredictable decay of the old structures. The 40m high, 40m deep, 85m long envelopes, made from weathertight aluminium Kalzip cladding, incorporate passive ventilation to reduce corrosion-causing condensation and remove the need for maintenance activities, keeping site operatives safe and workforce needs to a minimum. The buildings will only have to be inspected every five years. Bradwell is now a ‘Safstor’, which means the costs of immediate disassembly and disposal of radioactive waste have been avoided.