- Site: Sellafield
- IR number: 21-081
- Date: September 2021
- LC numbers: 22
Executive summary
Purpose of Intervention
Sellafield Ltd has requested ONR agreement to commence active commissioning of the waste retrievals plant installed on Pile Fuel Cladding Silo (PFCS) compartment 5. The commencement of active commissioning and subsequent waste retrievals is a significant step towards securing hazard and risk reduction at PFCS. However, it also represents a step change from the current care and surveillance operations.
The purpose of the inspection was to inspect Sellafield Ltd’s implementation of the waste retrieval operations safety case which has been made under Licence Condition (LC) 22 arrangements. The intention was to gain assurance that the safety case is understood by the licensee and that the people, plant, and processes will be in place prior to commencing active commissioning and subsequent waste retrievals. The findings of the inspection will be used to inform the decision in response to Sellafield Ltd’s request for ONR agreement to commence active commissioning of the waste retrievals equipment installed on Pile Fuel Cladding Silo (PFCS) compartment 5.
Interventions Carried Out by ONR
Licence Condition 22 requires the licensee to make and implement adequate arrangements to control any modification or experiment carried out on any part of existing plant or process which may affect safety. This inspection focussed on the arrangements to prepare the people, plant, procedures, and to assess the licensee’s readiness to safely commence active commissioning and subsequent waste retrieval operations.
The inspection was undertaken against LC22 in accordance with ONR Technical Inspection Guide NS-INSP-GD-022, LC22 Modification or experiment to existing plant, revision 6, January 2021.
Explanation of Judgement if Safety System Not Judged to be Adequate
This was not a system-based inspection, and therefore it is not applicable.
Key Findings, Inspector's Opinions and Reasons for Judgements Made
During the inspection, Sellafield Ltd provided an overview of the status of the inactive safety commissioning activities. Based on the evidence sampled, we did not identify any areas of concern in relation to the inactive commissioning completed to date. However, at the time of the inspection there were some emerging issues associated with the box bolting robot, which has delayed the completion of the inactive safety commissioning activities. Sellafield Ltd will need to complete the final inactive safety commissioning activities once the emerging issues associated with the box bolting robot have been resolved. Prior to issue of the Licence Instrument (LI) for commencing active commissioning of the waste retrievals plant, ONR will seek confirmation that Sellafield Ltd has completed all inactive safety commissioning and that actions identified in response to issues identified with the box bolting robot are adequately addressed.
We inspected a sample of the key operations to confirm the operators clearly understood the required Operator Instructions (rOI), Operator Assumptions (OA) and that they supported reliable human performance. The sample selected covered the three main fault sequence groups (management of silo atmosphere, waste retrievals operations and personnel access). Overall, based on the discussions with the operations team members during this inspection, we gained confidence that the staff understood their tasks and the contribution to safety that they make.
In relation to the management of the silo atmosphere, we targeted the monitoring and control of oxygen levels within the silo which is the subject of a regulatory issue. As part of the inspection, we visited the PFCS Control Room located within a separate building to PFCS. The operators talked through the hourly readings/checks that are completed, including the oxygen concentration levels. We were satisfied that the operators understood the action levels and that the operating procedures supported the approach. The evidence sampled during the inspection has enabled the outstanding action associated with the regulatory issue to be closed.
The project has identified several credible off-normal events, which are referred to as outliers and have been documented in an Outlier Guidance document. Through a further regulatory issue there was a requirement for Sellafield Ltd to provide evidence of links from instructions to the outlier flowcharts, and that training had been provided to the operations team on the transition between normal and off-normal, prior to active commissioning commencing. Based on the evidence sampled and discussions with the operators during the inspection, we were satisfied that this action has been adequately addressed.
During the inspection, we sampled several individual training profiles/records to ensure that they aligned with the PFCS Training Profile Description. The Retrievals Training Lead also attends the Plant Operations Committee (POC), which we consider positive as it will provide an on-going focus on training and increases the likelihood that operational staff training will be current. The strategy and plan to demonstrate how the competence of new and returning staff will be ensured and integrated into the existing PFCS operations team was also discussed. Based on the evidence sampled and discussions with the licensee we were satisfied with the training arrangements that have been implemented.
We sampled operator aids and discussed how waste characterisation activities are integrated into the waste retrievals operations and the interaction between the technical team and operations team. Sellafield Ltd has established a learning steering committee consisting of a multi-disciplined group tasked with collecting and analysing any associated learning from waste retrievals. Based on the evidence sampled and discussions with personnel, we were satisfied that the Retrievals Operators had access to, and were familiar with, the waste examples operator aid and arrangements were in place for learning from retrievals.
An outstanding aspect related to the management of video footage associated with waste retrievals; whilst we were generally satisfied with the proposed strategy, at the time of the inspection this was not yet captured in the supporting instructions and arrangements. Following the inspection, Sellafield Ltd has provided more information on the proposed identification and retention of video footage enabling this regulatory issue to be closed.
Conclusion of Intervention
From the evidence sampled during this inspection, we consider that the Sellafield Ltd is approaching a state of readiness for the commencement of active commissioning of the waste retrievals plant and equipment. Based on discussions with Sellafield Ltd staff and evidence provided at the time of the inspection, the inspection identified no significant concerns that would prevent ONR granting agreement to the start active commissioning of the waste retrievals.
Prior to issue of the ONR Licence Instrument (LI) for commencing active commissioning of the waste retrievals plant installed on Pile Fuel Cladding Silo (PFCS) compartment 5, ONR will seek final confirmation that Sellafield Ltd has completed all inactive commissioning. In addition, ONR will also confirm with Sellafield Ltd that actions identified in response to the emerging issues associated with the box bolting robot are adequately addressed.
It is my opinion that an inspection rating of GREEN (no formal action required) is appropriate.