Office for Nuclear Regulation

Inspection of Control of Radiation Exposure CORE and As Low As Reasonably Practicable ALARP

Executive summary

Purpose of intervention

In line with an Office for Nuclear Regulation (ONR) planned intervention, to look at Control of Radiation Exposure (CORE) across a number of licensee sites (under Regulation 8 of the Ionising Radiations Regulations, IRRs 1999), two ONR specialist radiological protection specialists conducted an inspection of control of radiation doses in the context of the Steam Generating Heavy Water Reactor (SGHWR) and Dragon reactor decommissioning projects at Research Sites Restoration Ltd (RSRL) Winfrith.  To ensure consistency with previous ONR CORE inspections, the inspection was conducted using a standard questionnaire and follow up question and answer sessions with the licensee.  In addition, at the request of the ONR site inspector for Winfrith (to inform ONR’s future permissioning strategy on the SGHWR decommissioning project), the inspectors also studied RSRL’s (i.e. the licensee’s) processes for ensuring that radiation doses on the project comply with the As Low As Reasonably Practicable (ALARP) principle.

Interventions Carried Out by ONR

The intervention was conducted at the licensee’s premises at Winfrith and consisted of three distinct components i.e.:

Explanation of Judgement if Safety System Not Judged to be Adequate

No safety systems inspection was undertaken.

Key Findings, Inspector's Opinions and Reasons for Judgements Made

We judged from the SGHWR ALARP meeting that the licensee has an experienced and enthusiastic team working on the project that has a clear focus on dose control/reduction.  The team dynamics in the meeting were good with all members contributing and challenge encouraged and discussed constructively.  There was good evidence of creative thinking at the meeting and of the use of experience from previous work conducted on the project.  ALARP prompt sheets were used and were clearly helpful and there was clear evidence of a focus on conducting tasks semi-remotely in low dose rate fields wherever possible.  Additionally, shielding schemes were considered i.e. to reduce doses where work closer to the radiation source was required.  Documentary evidence provided prior to the meeting evidenced that the licensee has a robust optioneering process in place.

Good use is being made of photographs and drawings from the reactor construction and this information has been used to construct Computer Aided Design (CAD) models of the plant as well as a helpful ‘fly through’ model available to decommissioning operatives on an i-pad.  Health Physics (HP) surveys have also been used to construct dose contour maps which we judge to be a valuable tool for pre-job briefings etc.  There was also good evidence provided of the use of plant mock-ups (constructed in low dose rate areas) and of tasks being practised on low dose rate items to train team operatives prior to conducting actual tasks in more hazardous environments.

Overall, from the evidence presented both from the conduct of the meeting itself and from documentation we sampled prior to the meeting, we judged that the licensee has a strong safety culture and robust processes to conduct its studies against the ALARP principles.

For the CORE inspection itself our key observations from our discussions with key licensee personnel and from documentation we sampled were:

Overall our view is that the licensee is good at controlling and monitoring doses.  The personnel we met gave us confidence in their abilities and understanding of dose management.

Conclusion of Intervention

We considered that the licensee is fully meeting its commitments under Regulation 8 of IRRs and has a strong dose monitoring/reduction culture within its decommissioning projects i.e. there is a commendable focus on reducing risks ALARP.  Accordingly, we recommend to the ONR site inspector that the current hold points in ONR’s permissioning strategy for SGHWR be replaced by a single additional radiological protection inspection (to be conducted in March 2016).  Consequently it is our opinion, from the totality of the evidence we sampled, that a marking of 2 (i.e. “Good Standard”) is merited for this inspection.