The current ONR regulatory strategy for Sellafield Ltd (SL) is focussed on stimulating, facilitating and expediting hazard and risk reduction. ONR has a number of planned interventions in place to ensure hazard and risk reduction activities are delivered safely.
Any potential for off-site consequence would attract ONR attention on a proportionate basis. However there are a number of supporting functions at site that play a key role in delivery of hazard and risk reduction, that cannot in themselves lead to an off-site consequence or that the off-site consequence would be low. These would not normally warrant prioritised attention from ONR, nonetheless ONR is keen that such functions have sufficient reliability and resilience such that they do not have the potential to prevent hazard and risk reduction activities at the earliest opportunity.
The intervention reported in this record is one of a series of ‘essential operations inspections’ in accordance with ONR’s Sellafield programme strategy. These interventions are designed to provide ONR with confidence that such supporting functions can adequately facilitate sustained hazard and risk reduction activities.
This intervention focused specifically on the Sellafield Inactive Tank Farm (ITF) that provides a range of non-active chemical reagents to a range of facilities that intrinsically support hazard and risk reduction activities on the Sellafield site. I sought to gain practical confirmation of the availability and reliability of chemical supply including during the periods for maintenance outages
The inspection focused upon the ITF resilience to provide a continuity of supply of non-active chemical reagents to a range of facilities that support hazard and risk reduction activities. As such, discussion and inquiries sampled aspects pertaining to licence conditions LC14 “Safety documentation”, LC25 “Operational Records”, LC28 “Examination, inspection, maintenance and testing” and Safety Assessment Principle EDR.2 “Redundancy, diversity and segregation” as well as general assessment of supply chain resilience.
The inspection was undertaken at the Sellafield site on the 24th January 2017 and comprised of desktop based discussions and a facility inspection.
N/A – This was not a safety system inspection.
At the end of the inspection I provided the following summary of my key inspection observations and regulatory judgements:
SL ITF has a good understanding of its customer demands over the next decade and is using this to inform strategic decisions.
SL ITF have produced a Safety Case Interface Document and signed interface agreements with the facilities that they support. The interface agreements sampled support the SL claim that no facility has placed a nuclear safety claim upon the ITF indicating the supported facilities can shut down safely upon loss of ITF supply.
It was identified that there are a number of alternative distribution sites/ suppliers / manufactures available for the chemicals/gases in the supply chain. Additionally I confirmed onsite stocks were sufficiently in excess of usage rates to be of concern, with reorder points appropriately set. I therefore consider there to be sufficient resilience in the onsite stock holding and supply chain to maintain services should there be disruption to an individual supplier.
There is no redundancy in the distribution pipework between the ITF and the recipient facilities and this represents a vulnerability to the resilience of supply. SLs focus has therefore been on the implementation of an adequate preventative maintenance regime. Although the ITF will be required to support Post Operation Clean Out and decommissioning activities for many years to come, I judge that due to the design costs and implementation timescales foreseen, with the end of all fuel reprocessing by 2020 and the subsequent drop of chemical usage, the viability of a secondary distribution network option is curtailed. However this has not precluded SL considering future options that would improve resilience in this area, taking into account the changing operational state of facilities (e.g. providing more isolation points such that smaller sections of pipework can be more readily replaced reducing down time).
SL has continued to invest in the maintenance of the ITF facility in accordance with their strategy, replacing many systems and with ongoing plans to replace others.
Although confirmed as an improving picture by the SL Internal Regulator (IR), there is a back log of corrective maintenance work. I have therefore discussed this with the SL IR who will monitor the situation to confirm sustained improvement in this area. In addition I have informed the ONR site inspector for the ITF.
SL ITF have a good understanding of their customer demands and I consider there to be sufficient resilience in the onsite stock holding and supply chain to maintain services should there be disruption to an individual supplier.
The single point of vulnerability relates to a lack of alternative distribution pipework between the ITF and the recipient facility. Although the ITF will be required for many years to come, the viability to introduce a secondary system is curtailed by the end of operations of the facilities that the ITF supports. SL has therefore focused attention on providing preventative & corrective maintenance of the distribution pipework. I observed evidence of targeted investment in updating the ITF facility to provide continuity of supply.
I noted that there was a back log of corrective maintenance work, beyond what I would reasonably expect for this facility. SL has stated that recent changes have improved visibility of outstanding work and that the situation is in fact improving. I have therefore confirmed with the SL Internal Regulator that they will monitor the situation to confirm sustained improvement in this area and I have informed the ONR site inspector for the ITF.