This intervention was undertaken to inspect Sellafield Ltd's compliance with licence condition (LC) 11 - Emergency Arrangements at the Sellafield site, in-line with ONR's approved Sellafield Intervention Strategy.
The intervention comprised a 1.5 day inspection during which ONR witnessed Sellafield Limited's emergency exercise, Starling, a whole site level 1 emergency exercise. The exercise scenario comprised a criticality pulse followed by a sustained criticality.
n/a as this was not a safety system inspection.
Sellafield Limited's general performance during the exercise was adequate, with good performance in some areas. However, Sellafield Limited identified that their performance in the Criticality Assembly Area (CAA) and their time to muster for the affected plant had significant opportunities for improvement. ONR concurred with Sellafield Limited's observation, but in addition highlighted that the visibility/accessibility of Sellafield Limited's radiological decision-making should be improved. A formal regulatory issue has been raised to track the improvements required and ONR will engage with Sellafield Limited to ensure that an appropriate response to the issues raised is provided.
Sellafield Limited's response to the exercise scenario was adequate and in some defined areas was good, thereby potentially deserving an IIS rating the of 3 - Adequate, however, the identified improvements that are required to meet our regulatory expectations with respect to the CAA, mustering and radiological consequence consideration mean that an IIS rating of 4 is appropriate. Noting that the areas for improvement were in relatively narrow, well defined areas ONR considered it would be disproportionate not to consider the whole exercise a successful demonstration of their emergency arrangements. Consequently, ONR will not require Sellafield Limited to carry out a full, formal redemonstration of the site-wide exercise. However, ONR consider that some specific aspects require further work that may require limited additional demonstration to ensure that any improvements identified by Sellafield Limited have been effectively implemented.