Currently, Medium Active Concentrate (MAC) - which contains Tc-99 resulting from Magnox reprocessing - is treated to remove radionuclides such as plutonium and americium. The effluent from this process - still containing Tc-99 - is then discharged into the sea. However, from March 2003, BNFL must divert MAC to the high active storage and treatment plants for vitrification.
The UK government pledged to reduce the current emission level of Tc-99of 90TBq a year by at least 80% by 2006, to 10TBq a year.
The environment minister, Michael Meacher, said that a new but currently problematic processing treatment could cause all discharge into the sea to be virtually eliminated within the next four years. In the current treatment process, other radioactive waste elements are removed while Tc-99 is left behind and discharged. Under one alternative, Tc-99 could be redirected and treated in isolation, turning it into glass blocks that are safe for storage.
Another possibility is treating Tc-99 with a chemical called TPP that causes it to solidify, allowing it to be removed from the other waste components. However, it is not yet known whether this can be done safely. "If TPP works, that resolves the situation. There will be no further discharges to sea," Meacher said. "But I cannot guarantee that at this stage."
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