BNFL has today begun the trial of a chemical removal process that may significantly reduce the discharges of the radionuclide Tc-99 from the Sellafield nuclear reprocessing plant in Cumbria, England.
Laboratory trials have indicated that the addition of the chemical tetraphenylphosphoniumbromide (TPP) to Sellafield discharges could enable Tc-99 to be removed from the discharge stream.
In June 2003 British Secretary of State for Environment, Food and Rural Affairs Beckett requested a nine-month halt to all Tc-99 discharges into the Irish Sea in order for new technologies to be developed that could combat the problem.
Although the trial will result in some discharges of Tc-99, the objective of the trial is to determine how effective TPP is in reducing Tc-99 from discharges. TPP may not prove to be effective on a plant scale, but a trial is the only way to determine this said BNFL in a statement.
Tc-99 discharges arise when medium active concentrate (MAC) from Magnox reprocessing is treated in the Enhanced Actinide Removal Plant (EARP). This plant removes the most significant radioactive substances but is unable to remove Tc-99 from the discharge stream.
The trial will entail the processing through EARP of 240m3 of MAC in separate batches of 27m3. TPP will be added to each batch and the resultant Tc-99 retaining solid will be contained in cement and stored in stainless steel drums at Sellafield.
Effectiveness of the trial will not be fully known until early in 2004, following a review of the results by BNFL, the Health and Safety Executive (Nuclear Installations Inspectorate), the Environment Agency and Nirex.
‘This trial is the culmination of a lengthy period of intense research and development into Tc-99 discharge abatement,’ said BNFL Sellafield’s Head of Environment, Health & Safety, John Clarke. ‘The current discharge limit for Tc-99 discharge is 90TBq per year and this limit could be reduced to 10 TBq per year from about 2006.’