Publication Abstract

The distribution and inventory of 137Cs in subtidal sediments of the Irish Sea

A.J. Poole, D.C. Denoon and D.S. Woodhead

BNFL Sellafield has been discharging artificial radionuclides into the Irish Sea since 1952. Discharges of 137Cs peaked during the 1970s and have been falling since this time. Extensive surveys of the subtidal sediments ofthe Irish Sea were completed by DFR during 1988 and 1995, when 75 and 83 sites, respectively, were sampled using box corers. Three sub-samples (the top 5 cm, the bottom 5 cm and a bulk sample from the rest of the core) were taken from each core and analysed for 137Cs by gamma (GeLi) spectrometry. Inventory data were then calculated for each core with these data being used to calculate the total inventory of 137Cs in the subtidal sediments ofthe Irish Sea. Approximately 5.0% (- 1532 TBq) ofthe decay-corrected discharges of 137Cs from the BNFL Sellafield plant remained in the subtidal sediments ofthe Irish Sea during 1988; this figure fell to 3.6% (- 959 TBq) by mid-1995. The majority (70 %) of the 137Cs residing in the subtidal sediments ofthe Irish Sea was found in an area of just 7250 km² off the Cumbrian coast in both 1988 and 1995, with much of this being concentrated in the "Sellafield mud patch".

Reference:

A.J. Poole, D.C. Denoon and D.S. Woodhead, 1997. The distribution and inventory of 137Cs in subtidal sediments of the Irish Sea. Radioprotection-Colloques, 32(C2): 263-270