Decommissioning experiences: the case of nuclear medicine facilities and accelerators

Decommissioning of a nuclear medicine department and the relocation of the facilities to a new site present specific challenges. First, the date of cessation of routine patient services must be decided many months in advance, as it must coincide with the date of opening of the new department. The equipment manufacturers’ engineers are typically involved in the dismantling, assembly and commissioning of relocated medical scanners and securing their services.

Figure 1 - Patient treating room for radiation therapy, Wikimedia Commons. Credit: Ikiwaner - GFDL/CC BY-SA 3.0

Figure 2 - Example of PET scan, Wikimedia Commons. Credit: Liz West, PET scan - CC BY 2.0

Figure 3 - Example of radiochemistry laboratory, IAEA Imagebank. Credit: Alejandra Silva/IAEA, Nuclear Medicine in Cuba - CC BY 2.0

Some lessons learned when decommissioning a nuclear medicine department include:

• Where the department is closing and relocating to a new site, ideally there should be a single project manager to oversee both the decommissioning and the commissioning projects to avoid delays and other problems that might arise in communication.
• Any previously lost small sealed sources, e.g. ⁵⁷Co anatomical marker pens or ¹³⁷Cs resin dose calibrator check sources, should not be omitted from the characterisation survey inventory and their disposal must be properly funded, as they are likely to be found once cupboards or benches are removed during decommissioning.
• It is necessary to check whether depleted uranium has been incorporated either as equipment counter-balance weights or as shielding, and ensure the recycling or disposal is properly financed.
• Synchronisation of any regulatory permissions or licence requirements is essential to avoid delays.
• Characterisation should consider any residual contamination in liquid discharge routes or possible ground contamination from broken pipes, or in ventilation systems or at roof level from discharge ventilation points. Failure to do so could result in extra budget for facing such unplanned remedial activities and thus in a project being under-funded.

All particle accelerators, such as linear accelerators (commonly termed linacs), cyclotrons

and synchrotrons, have similar physical characteristics and features that are important for decommissioning. Examples of their decommissioning are available and they highlighted that, in contrast to the generally well characterised waste generated in nuclear reactors, the characterisation of contaminated or activated material in accelerator facilities may suffer from poor records of its past use, including beam times, beam currents and the materials used.

Figure 4 - Examples of particle accelerators: cyclotron, Wikimedia Commons. Credit: Ikiwaner - GFDL/CC BY-SA 3.0

Figure 5 - Examples of particle accelerators: synchrotron, Wikimedia Commons. Credit: Canadian Light Source Inc - CC BY 2.0