Office for Nuclear Regulation

Radiological Protection inspection in Main Production Facility, AWE Aldermaston

Executive summary

Purpose of Intervention

Office for Nuclear Regulation - ONR assessors are currently assessing AWE’s submission (under Licence Condition 15 – “Periodic Review”) of its second Periodic Review of Safety, PRS2, for its Main Production Facility on the Aldermaston site.  As a part of this assessment I have been sampling the submission in the technical area of radiological protection, RP.

Following my review of the submitted documentation, I had a number of outstanding questions relating to dose control in the Main Production Facility, dose trending and dose control performance.  This was discussed with AWE in January 2019 and ONR has now conducted a reactive RP focused inspection (under the Ionising Radiations Regulations – IRR 2017).  This report presents the findings of this intervention.

Interventions Carried Out by ONR

Supported by ONR’s Project Inspector for the Main Production Facility’s PRS2 and joined by a member of the licensee’s own Internal Regulation, IR, team, I conducted an inspection under IRR 2017 on 28/3/2019 in the Main Production Facility at AWE Aldermaston.  Henceforth in this report I have referred to ‘we’ to signify this inspection team.

Explanation of Judgement if Safety System Not Judged to be Adequate

Not applicable, as no System Based Inspection (SBI) was conducted.

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

During our plant walk-down, we identified that the control of higher dose rate areas on the plant could be significantly improved e.g. by limiting personnel access to such areas and where possible via the use of local shielding schemes.  In addition, the quality of signage on the plant, advising of higher dose rate areas and for personnel to keep away from such areas, was generally not of the standard expected. 

We also observed that metal tables, in one of the plant cells, continue to block access to emergency pull cords, this was an adverse finding from a previous ONR inspection.  We also again observed out of date historical signage on the plant, which could potentially be misleading to plant personnel, again this is a matter that has been brought to the attention of facility managers by ONR on previous occasions, but which does not seem to have been satisfactorily resolved. 

Accumulations of excess, i.e. not directly required for production purposes, material in a significant number of gloveboxes continues to exist and this condition, which is driving elevated dose rate fields on the plant, has been tolerated for some time now.  The licensee’s recently established programme to address this position will be likely to take some time to deliver. 

The above adverse findings resulted in an ‘Amber’ inspection rating and the findings will be recorded as ‘Recommendations’ in ONR’s Assessment Report on RP aspects of PRS2.  The sum total of all these ‘Recommendations’ will in turn be recorded within an ONR Regulatory Issue and appropriate actions and timescales will be agreed with the licensee to address each ‘Recommendation’.

In addition, one expectation of a PRS is that it will look forward over the next 10 year period, as well as back over the previous 10 years.  From the evidence provided by the licensee, it was our opinion that the licensee’s forward look is of an inadequate quality e.g. ongoing plant ageing and potential shifts in worker dose accrual have not been adequately addressed.  Again a ‘Recommendation’ will be recorded in the ONR Assessment Report designed to seek work from the licensee to address this shortfall.

However, in contrast to the above findings, the licensee was also able to provide robust evidence of its dose trending on the plant, that it does endeavour to maintain doses As Low As Reasonably Practicable, ALARP, although noting the areas for improvement in paragraph 5 and that its day to day operational dose control on the plant broadly meets ONR expectations, with some areas of good practice evidenced e.g. the licensee’s dose rate ‘heat maps’ and the general level of engagement between the licensee’s RP professionals and the plant workforce.

Conclusion of Intervention

From the totality of the evidence sampled, the inspection met its objectives, in adequately filling in the gaps in the documentation originally submitted by the licensee to support its PRS2 documentation. 

The inspection also revealed a number of deficiencies that resulted in an ‘Amber’ inspection rating i.e. against ONR’s inspection guidance and which will result in a number of additional ‘Recommendations’ in the ONR Assessment Report for RP aspects of PRS2.  All ‘Recommendations’ from the PRS2 RP assessment will be ‘rolled up’ under an ONR RP related Regulatory Issue and actions and timescales will be agreed with the licensee to close off the shortfalls described in the ‘Recommendations’.