Studies of environmental radioactivity in Cumbria. Pt. 13

The main objective of the project was to reconstruct a chronology of past 14C levels in atmospheric CO2 in the vicinity of the Sellafield reprocessing plant by measuring the 14C in individual tree rings from trees felled at a number of sites. The profile obtained from the results reflects the build up of the plant operations and related aerial emissions and a conversion of the tree ring records to past annual aerial discharges of 14C has been attempted. This is compared with values provided from recent estimates of aerial emissions. The effect of dispersion along a coastal transect to a distance of 30km from BNFL Sellafield has also been studied. Comparable, but attenuated profiles to the inland sites are observed although the major peaks are not precisely mirrored along the transect. This is attributed to greater year to year variation due to sea breezes. (author)