Case Studies.To focus the work and provide suitable scenarios to evaluate the capabilities of the developed characterisation technologies, five specific case studies, representative of generic nuclear environments, and materials held within those environments, will be used. The case studies represent a range of extreme environments, possessing physical access restrictions and a range of potentially hazardous materials. Below is more information about each case study.
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Sellafield legacy storage ponds and silos
These facilities, constructed in the 1950s and 1960s to support the UK’s nuclear programme, have degraded over time and are described by the Nuclear Decommissioning Authority as ‘intolerable risks’ that are in urgent need of decommissioning. One pond alone, FGMSP contains 14,000 m3 of contaminated water, 500 tonnes of solid nuclear fuel, sludge from corrosion of fuel cladding, fuel fragments, other organic and non-organic debris, is subject to algae blooms, reducing visibility and is dosed with caustic (pH is 11.5). The lack of a precise inventory in the ponds and silos means that a highly conservative decommissioning plan, extending to beyond 2050 is in place.
Accurate characterisation of the materials present in the legacy ponds will:
Accurate characterisation of the materials present in the legacy ponds will:
- Increase productivity as improved understanding of materials present will result in more efficient planning and processing, accelerating decommissioning.
- Reduce the risk of criticality events as material is moved around the facility and reduce cost as materials can be accurately identified as low-level waste (LLW) or intermediate level waste (ILW) to lower storage costs.
Sellafield hot cells and storage facilities
There are numerous small-scale plants at Sellafield (>170 such facilities) and elsewhere that contain a range of materials that need characterising. These facilities, many of which are termed “hot cells” are typically high radioactivity environments (alpha, beta and gamma) containing a mix of radioactive and non-radioactive materials. Human access to these facilities is often restricted or even forbidden, and restrictions in transporting hazardous samples out of such facilities mean there is often little scope for sample collection and analysis. In-situ characterisation of these environments is essential if decommissioning is to be accelerated and costs are to be reduced (through reduced lab-based sample analysis).
Fukushima core access
The Fukushima Daiichi nuclear power plant, having areas of extreme radiation and limited accessibility, has created the need for fundamental engineering advances. The radiation field comprises gamma and neutron radiation levels of up to 1000 Sv/hr in certain areas, the characterisation of which will accelerate the decommissioning of the power plant. In this trajectory, we aim to develop a tailored characterisation scheme, which we will demonstrate to an invited audience at the Naraha Remote Technology Research Centre.
H-Canyon at Savannah River Site
Constructed in the 1950s, H-Canyon is a chemical separation facility at the Savannah River Site nuclear reservation operated by the US Department of Energy. The facility is used to produce uranium fuel for nuclear reactors. Concrete ventilation tunnels allow for exhaust of air from where the materials are reprocessed, eventually into a sand filter, after a distance of 300 m. Operators of H-canyon wish to inspect along the ventilation tunnels to assess concrete integrity, and any possible radioactive contamination.
The exhaust air is hot, humidity, and acidic, with winds of 10-30 mph in the tunnel, and so human access is prohibited due to this extreme environment. Robots have been used in the tunnel previously, equipped with video cameras. The TORONE project would deploy a robot equipped with radiation monitoring sensors, as well as scientific instruments to assess the quality of the concrete and steels in tunnel, checking for signs of fatigue such as corrosion.
The exhaust air is hot, humidity, and acidic, with winds of 10-30 mph in the tunnel, and so human access is prohibited due to this extreme environment. Robots have been used in the tunnel previously, equipped with video cameras. The TORONE project would deploy a robot equipped with radiation monitoring sensors, as well as scientific instruments to assess the quality of the concrete and steels in tunnel, checking for signs of fatigue such as corrosion.
Fusion Environments
Fusion environments are accompanied by high and variable neutron count rates, high gamma background and magnetic fields. Accurate monitoring will allow for more efficient control of tokamaks . While the latter is of interest to this project, it is also an opportunity is to ‘’stress test’’ the developed tools in such environments, including the MAST and JET tokamaks at Culham Centre for Fusion Energy.
