The aim of the project is to demonstrate/investigate the efficiencies of the explosive cutting and microwave techniques developed under preceding CEC programmes, on the full scale biological shield structure of the decommissioned LIDO enriched uranium thermal swimming pool reactor based at Harwell in UK.
The reactor was operated from 1956 to 1972 and was used for shielding and nuclear physics experiments. The reactor core was made up from uranium/aluminium plates clad in aluminium. The core was movable through the water into any position on the centre plane of 3 large aluminium windows or beam holes for heavy shielding experiments to be set up outside. Initial analysis of the LIDO biological shield indicates surface dose rates of up to 10 microSv/hr and contamination levels of up to 50 Bq/g. It is anticipated at this stage, that the main sources of activity are europium-152, cobalt-60 and caesium-137, but further radiological assessment will be carried out during the programme. It is proposed that up to 10 square meters of surface will be removed by the dismantling techniques under consideration.
The present work will concentrate on the use of the 2 dismantling techniques to achieve concrete removal to meet both decontamination and dismantling requirements. This will offer direct comparisons between the techniques and lead to the assessment of their respective economic efficiencies. Effort will be directed at regulatory and safety aspects involved in the large-scale application of the techniques. Practical problems associated with the full-scale use of the techniques will be identified and realistic solutions obtained.
This work programme will be harmonized and carried out in close technical collaboration with work being coordinated by Battelle Institute on the application of explosive techniques for the decommissioning of the biological shield of the HWR KKN at Niederaichbach in Germany and the work being carried out by ENEA-CRE on the application of the microwave technique. A separate programme is also being carried out by KfK, aimed at developing remote manipulator deployment systems for the microwave unit.
To comply with Site Licence conditions an operational control and full safety case for the dismantling trials has been prepared for the decommissioned LIDO enriched uranium thermal swimming pool reactor based at Harwell. Activity assessment on the biological shield walls has been completed. A combination of simple in situ gamma ray detection methods and core sampling were used. A sealed containment has been designed and constructed over the LIDO biological shield to withstand shock and overpressure resulting from explosive blast, to make provision for particulate containment and to provide microwave shielding. A mobile filtration unit (MFU) has been installed. The microwave generator has been refurbished and a wave guide and microwave head have been manufactured and the complete system tested to full power of 25 KW.
1. Preparatory work (AEA, Taywood)
1.1. Establishment of operational control and safety documentation (AEA and Taywood)
1.2. Preparation of documentation for the control of operations on the LIDO structure (AEA)
1.3. Development and construction of a sealed sub-containment on the biological shield including associated ventilation and filtration systems (AEA)
1.4. Pre-test structural assessment (Taywood)
1.5. Activity assessment and coring for material samples (AEA and Taywood)
2. Large-scale technique demonstrations on nonactive zones (AEA, Taywood)
2.1. Implementation of explosive techniques (Taywood)
2.2. Implementation of Microwave technique (AEA)
3. Large-scale technique demonstrations on active zones (AEA, Taywood)
3.1. Implementation of explosive techniques (Taywood)
3.2. Implementation of microwave techniques (AEA)
3.3. Recontamination assessments (AEA, Taywood)
4. Aerosol characterization (AEA)
5. Structural assessment (Taywood)
6. Theoretical assessment (Taywood)
7. Techniques assessment and conclusions (AEA and Taywood)
8. Collaboration with related programmes
9. Generation of specific data
PROGRESS OF WORK AND RESULTS OBTAINED
No significant work was completed in this just starting contract.
Funding SchemeCSC - Cost-sharing contracts
DT2 8DH Dorchester