Plant Dismantling challenge overview
During dismantling we need to be able to use the characterisation data discussed in the ‘Characterisation Game Changer’ to efficiently plan and execute work to:
- Gain access and egress from the cell
- Locate the work-face in the cell and move dismantling equipment into position
- Use the dismantling equipment to cut, unscrew etc. the piece of plant
- Lower waste to floor level
- Move the waste to the disposal package
- Possibly size-reduce at ground level (possibly in a new or repurposed sort and segregation cell)
- Export the waste package
A combination of people and machines are involved in these steps.
Innovative dismantling tools and techniques will seek to complement the existing ‘baseline methodologies’ to perform better dismantling and associated Waste Management activities. Decommissioning operations have numerous challenges including:
- Difficult deployment in areas of restricted access:
- Access may only be possible via small holes (approx. 100mm diameter)
- Access sometimes located at height and through several meters of concrete, lead shielding or water
- High radiation, loose and fixed contamination
- Complex and highly congested environment due to numerous pipes, vessels, vents and cables in close proximity that criss-cross large closed spaces
- Standard set of high integrity and heavy containers, up to 3m3 which constrain the size of items which can be disposed of, without the use of size reduction operations
- A range of different pH environments (pH<0 to greater than 11) in different plants
- Heterogeneity of materials being measured
- Speed of deployment; currently weeks
- The duration and expense of data assessment and reporting, desire for real time and cheaper techniques
- Lack of efficient and secure data transmission in large robust buildings across the Sellafield site
- Requirement to collaborate widely without sophisticated or costly IT packages, data that can be exported to standard Microsoft office packages
- Requirement for equipment deployed to be either cheap enough to be disposable or robust and designed for easy maintenance and decontamination.
- Desire for operation by non-specialists without the need for complex commissioning or recalibration
PLANT DISMANTLING AND DECOMMISSIONING VISION
Imagine if with minimum, or no, intervention into hazardous environments we could dismantle plant, segregate waste and pack it efficiently into a form fit for disposal, leaving the remaining building able to be repurposed or in safe, low cost state for the long term.
- Could we follow a trajectory like the automotive industry, which has moved from bespoke one-off operations, through production line hand build to being fully robotized?
- Could a similar trajectory be applied to decommissioning?
- Could we use a standard set of out-sourced components, modular facilities and common architecture to reduce the perceived high cost of remote decommissioning?
To do this, technology development will have to address the scale of facilities and unstructured environments on Sellafield site which are unlike a factory.
At the moment, our decommissioning activities adopt to a human scale; what if we used smaller scale, collaborative robots or larger scale to move glove boxes and vessels without breaking containment? To support this we would need a range of flexible fit for purpose decommissioning waste packages.
The current approaches tend to cut up plant and equipment and lower it to the cell floor to be possibly further size reduced and packaged; how can we adopt processes that have fewer steps?
We are looking for technology that allows buildings to be placed into a care and maintenance regime that monitors them whilst they are in a long term quiescent state; we need to prevent degradation of the building, prevent migration of contamination and provide assurance efficiently for perhaps 70 years whilst the rest of the program continues.
To reduce cost and risk during the period it would be ideal if they did not require any external services.
At the moment, the level of manual work is such that we tend to decommission during the 5 day working week, as we move to autonomous working we will be able to mount work continuously which could have a significant impact on the duration of projects and the associated costs.