Executive summary
Date(s) of inspection:
- March 2023
Aim of inspection
To seek assurance on the adequacy of the implementation of the safety case at THORP in relation to the Medium Active Salt Free Evaporator (MASFE) and the associated Pipe Bridge.
Subject(s) of inspection
- LC 10 - Training - Rating: Green
- LC 23 - Operating rules - Rating: Green
- LC 24 - Operating instructions - Rating: Amber
- LC 27 - Safety mechanisms, devices and circuits - Rating: Green
- LC 28 - Examination, inspection, maintenance and testing - Rating: Amber
- LC 34 - Leakage and escape of radioactive material and radioactive waste - Rating: Green
Key findings, inspector's opinions and reasons for judgement made
I undertook a system based inspection (SBI) of the Medium Active Salt Free Evaporator (MASFE) and associated pipe bridge at the Thermal Oxide Reprocessing Plant (THORP) at the Sellafield Site. I was supported by specialist inspectors, and we undertook a plant walkdown and sampled evidence to support compliance with the safety case for the six licence conditions associated with SBIs. For four of the licence conditions (LCs) (LC10 (Training), LC23 (Operating rules), LC27 (Safety devices, mechanisms and circuits) and LC34 (Leakage and escape of radioactive material and radioactive waste) I was satisfied that Sellafield Ltd is compliant with the LCs and has implemented its safety case. However, for two of the LCs (LC24 (Operating instructions) and LC28 (Examination, inspection, maintenance and testing (EIMT)) I was not satisfied that THORP was compliant with the expectations of the licence conditions. For LC24 I found that written instructions had been withdrawn without adequate control, meaning written instructions to implement operating rules were not available. I was satisfied that in this instance safety was not affected but will seek improvement to ensure that the withdrawal of written instructions as THORP progresses its safety case through post operational clean out is controlled. For LC28 I found that although THORP has overall implemented the EIMT requirements required by the safety case, improvement is required. For the civil structure (pipe bridge) I found that recommendations from inspections had not been acted upon. For the main MASFE plant, THORP was unable to demonstrate that it has an adequate inspection regime for pipework carrying radioactive material within the pipe bridge. Overall, I am satisfied that THORP has implemented its safety case but will seek improvement to address the shortfalls identified through appropriate enforcement and Regulatory Issues.
Conclusion
Having reviewed the evidence provided by THORP, I am satisfied that for LC10, LC23, LC27 and LC34 a Green (no formal action) rating is appropriate. However for LC24, I am of the opinion that THORP has withdrawn written instructions required to implement conditions and limits of safe operation, and furthermore this withdrawal is not limited to isolated cases. For the conditions and limits of safe operation sampled, I am satisfied that THORP remains safe, however I plan to seek improvement over the method in which THORP is withdrawing its written instructions as it progresses through its safety case change points. As a result of my inspection, I am of the opinion that an Amber (seek improvement) rating for LC24 is appropriate. For LC28, I found that for safety related equipment, THORP was able to demonstrate that it had been maintained. However, for the inspection regime on the civil structure, THORP was unable to (1) demonstrate that it had sentenced or actioned a significant number of recommendations from the principal civil inspection report; and (2) was unable to evidence that it had adequately completed the two-yearly inspection. Furthermore, for the pipework and liner, THORP was unable to demonstrate that it had an adequate inspection programme in place. I therefore rate the LC28 element of this inspection as Amber (seek improvement).
Overall, I am satisfied that THORP has implemented its safety case but will seek improvement to address the shortfalls identified through appropriate enforcement and Regulatory Issues.