SCM21: practical radiation protection in a large industrial shutdown project

Full text: BHP Olympic Dam recently completed a large shutdown project known as the Smelter Campaign Maintenance 2021 project, or SCM21. This involved shutting down the main production of the site for 4 months to replace the flash furnace, electric furnace and associated infrastructure. During this time, up to 2500 people were working in the smelter complex with multiple simultaneous operations ongoing. During an undertaking of this scale, it can be easy to lose focus on radiation protection due to the sheer scale of simultaneous safety issues. BHP approached this by resourcing a project specific Radiation and Occupational Hygiene (ROH) team. As part of this a Radiation and Occupational Hygiene Management Plan (ROHMP) was submitted to the South Australian EPA in accordance with the requirements of the Mining Code. The first critical aspect of the project was to ensure workers are properly fit tested for personal protective equipment and informed of the risks present at the work site. This was managed in advance of site mobilisation, with additional training as part of site induction. The second part of preparation is task assessment, which began long before site mobilisation but extended throughout the project. This included Construction Risk Assessment Workshops (CRAWs) during the planning phase followed by Task Hazard Assessment (THA) and Confined Space Hazard Assessment (CSHA) at execution. In these, radiation is an important consideration because time, distance, shielding and ventilation are challenging to manage in confined spaces. Next it is necessary to verify the controls identified are in place. This requires both formal verification during sign on, particularly for the first instance of an activity, but also informal walk arounds of the site to identify issues as they arise. Formal work management of tasks by the SCM team allows the ROH team to coordinate the daily activities for maximum effectiveness. Radiation monitoring is a critical part of the plan with monitoring of Long Lived Radioactive Dust (LLRD), gamma surveys and radon decay product measurement undertaken on a planned basis during the project. Logistically, the team also needs to manage isolation of gamma density gauges and Non-Destructive Testing (NDT) radiography issues. Managing radiation perimeters during radiography in the smelter complex is very challenging. A dedicated waste processing area was set up as part of the project. This allowed identification and appropriate cleaning of surface contaminated objects. Following cleaning, the waste can then be directed to the appropriate area, either storage, landfill or recycling. Finally, it is a requirement of the site that all outgoing equipment or other goods are cleared to prevent surface contaminated objects or radioactive substances leaving the site without authorisation. This presented a significant logistical challenge towards the end of the project due to the large number of workers and equipment leaving site on a tight time frame. Review of the project is expected to begin soon, with the aim to understand possible improvements for the next SCM. (author)