Office for Nuclear Regulation

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LC23 compliance inspection of the Highly Active Liquor Evaporation and Storage (HALES) Operating Unit, on Sellafield Ltd.’s nuclear licensed site at Sellafield, Cumbria

Executive summary

Purpose of intervention

This intervention was undertaken on 12 – 15 October 2015 at Sellafield Limited’s Sellafield nuclear licensed site in Cumbria, and comprised a system inspection at the Magnox Reprocessing Separation Plant (MRSP).

The MRSP has an important role within the UK nuclear industry until circa 2020, as it supports a number of UK risk and hazard reduction programmes including the UK Magnox Operating Programme (UK MOP).  If the MRSP is not available to reprocess spent Magnox fuel, there would be significant knock-on effects for a number of other nuclear facilities which would result in safety and security issues.  Continued operation of the MRSP is fundamental to on-going risk and hazard reduction work on the Sellafield site.

In June 2015, the Office for Nuclear Regulation (ONR) served an Improvement Notice (IN) in relation to Licence Condition (LC) 24 ‘Operating instruction’ breaches related to poor conduct of operations within MRSP over the previous 14 months.  Since the IN was served, there have been further conduct of operations events reported at MRSP.

In July 2015 ONR approved a revised regulatory strategy for the MRSP which recognised the strategic importance of the plant, the age (and design) of the plant, and the conduct of operations events that continue to occur.  A key aspect of this strategy is to inspect parts of the MRSP, targeting the areas most important to nuclear safety.

This Intervention Record (IR) reports the first in a series of planned system inspections, currently planned to take place between October 2015 and March 2016, to implement the revised regulatory strategy for MRSP.

Interventions Carried Out by ONR

The intervention comprised undertaking a system inspection of the charge machines and dissolver within MRSP, which was undertaken jointly by ONR’s site inspection and project inspection functions.

The system inspection sought to determine whether the MRSP charge machines and dissolver meet the requirements of the safety case and are adequate.  In accordance with the revised regulatory strategy, the implementation of Sellafield Limited’s (the licensee) arrangements for a number of ‘core’ LCs was tested during the system inspection:

The implementation of the licensee’s arrangements for a number of additional LCs were also examined, but not to the same depth as the ‘core’ LCs.

Explanation of Judgement if Safety System Not Judged to be Adequate

Based on sampling inspection, the MRSP charge machines and dissolver were judged to be adequate.

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

For the MRSP charge machines and dissolver we judged the following IIS ratings to be appropriate:

LC23 – IIS rating 4 (below standard):  We confirmed that the safety case specifies limits and conditions with respect to the operation of the charge machine and dissolver, and that these limits and conditions are clearly specified in appropriate instructions.  The limits and conditions were specified in required Operating Instructions rather than Operating Rules (ORs), and number of the ORs we sampled were worded such that positive compliance could not be demonstrated. This is not consistent with ONR’s guidance on LC23.  However we were satisfied the limits and conditions important to safety were being consistently complied through sampling plant instructions and check sheets.  We judged an IIS rating of 4 (below standard) to be justified against LC23 ‘Operating Rules’ as we identified some procedural weakness with respect to how ORs are defined, we will follow these up with the licensee in subsequent interventions.

LC24 – IIS rating 3 (adequate): We sampled a range of operating instructions, maintenance instructions and alarm response instructions associated with the charge machine and dissolver.  We judged the written instructions sampled to be clear and unambiguous, and related to ensuring compliance with the limits and conditions derived from the safety case.  We judged an IIS rating of 3 (adequate) to be appropriate against LC24 ‘Operating Instructions’.  The licensee has a significant programme of work under way to improve operating instructions, our sample included a number of recently revised instructions which we judged to be of a good standard, giving us confidence the quality of operating instructions in MRSP is improving.

LC27 – IIS rating 3 (adequate): We sampled a number of key Safety Mechanisms (SMs) and Safety Related Equipment (SRE).  Based on our sample, we judged there are suitable and sufficient SMs and SRE for this system, they are being inspected and are in good working order.  The safety case specifies substitution arrangements to be put in place when individual SM are not available – we sampled and were satisfied with the means of enacting substitution arrangements.  We judged an IIS rating of 3 (adequate) to be appropriate against LC27 ‘Safety Mechanisms, Devices and Circuits’

LC28 – IIS rating 3 (adequate): We sampled the Plant Maintenance Schedule (PMS), maintenance instructions and maintenance records for key components of the system.  For our sample, we found all maintenance was being undertaken to an authorised and validated instruction, all maintenance was up to date and in accordance with the PMS, and we confirmed maintenance activities were being undertaken by suitably qualified and experienced individuals.  We therefore judged an IIS rating of 3 (adequate) to be appropriate against LC28 ‘Examination, Inspection, Maintenance and Testing’.

Conclusion of the intervention

We judged that the operation of the MRSP charge machines and dissolver is consistent with safety case requirements, the key equipment that verifies this is available and appropriately maintained and that appropriate written instructions are available.  We did identify some procedural weaknesses which the licensee accepted; these did not have an adverse impact on nuclear safety.

The licensee shared a number of pre-existing issues and associated plans of work related to the dissolver and charge machines with us, we are reassured these are being progressed appropriately.  Through the system inspection we identified a number of areas where ONR can work proactively with the licensee to facilitate removal of barriers which will expedite safe delivery of the UK MOP.  We will progress these via our routine regulatory interactions with the licensee.

Based on the evidence gathered, no significant matters have been identified that are likely to impact on nuclear safety on the Sellafield site at this time.