Argument A1.2.2.1.7.3.1 A mitigation strategy exists for Hazard 1 Collision

• Supports Claim: C1.2.2.1.7.3 The identified hazards have a tolerable and ALARP mitigation strategy for each

Child nodes:

• Has evidence Evidence: E1.2.2.1.2.1 Hazard identification, security and analysis report
• Has evidence Evidence: E1.2.2.1.6 Hazard Log

Collision

• Consequence: damage to the pond lining, resulting in a leak of liquor from up to 5 cm below the surface of the liquor

• The likelihood of this consequence has been reduced to tolerable and ALARP by the presence of a safety instrumented function SIF.

• As the occurrence has been reduced to tolerable and ALARP no protection barrier is necessary, however, as recognised good practice (RGP) and for defence in depth the following provides a protection barrier
• The pond is bunded and can easily contain the maximum volume of liquor that could leak
• Radiologically and water proof PPE for all workers within 10 m of the edge of the pond.

• As the occurrence has been reduced to tolerable and ALARP no mitigation barrier is necessary

An operational condition is necessary: The operation shall only be conducted when the pond liquor level is at its highest operation level.

• It is estimated that the max quantity of liquor will not exceed <x> L and it will not exceed <x> mSv.
• The pond liquor level will be immediately drained to 5 cm below its highest operational level. This retains enough head of liquor to prevent any radiological leak or the consequences of a ‘dry’ pond
• A method has been established to repair the pond that is tolerable and ALARP.
• A method has been established for remediation of the contaminated liquid and the bund which is tolerable and ALARP. The liquor will be returned to the pond
• It can and will be carried out by a suitably qualified and experienced person (SQEP) with appropriate PPE and suitable tools.
• The tools can and will be decontaminated following use