A new estimate of atmospheric 14C discharges from sellafield

UNSCEAR has estimated that 14C discharges from the nuclear fuel reprocessing plant at Sellafield are responsible for about a quarter of the total global release of this radiologically important radionuclide. Reported discharges from the site have been based on direct monitoring of the effluent since 1978. Prior to that date, however, discharges have been estimated from the measurement of 14C levels in the annual growth rings of a locally grown tree. In the present study, discharges prior to 1978 have been re-calculated based on new measurements of 14C levels in tree rings. The results indicate that 14C discharges from Sellafield prior to 1978 were significantly lower than previously thought, 124 TBq as opposed to 207 TBq. The total release of 14C to the atmosphere from this site from the start of operations up to 1995 is now estimated to have been 244 TBq.