Radiocaesium and plutonium in intertidal sediments from southern Scotland

Abstract

The dispersion of radionuclides discharged to the Irish Sea from the works of British Nuclear Fuels Ltd at Sellafield (Windscale) is a topic of major importance, attracting considerable interest in recent years. Annual surveys by the Ministry of Agriculture, Fisheries and Food (MAFF) of marine radioactivity^1,2 supplemented by other work^3–17 have defined the major features of this dispersion during the 30 yr of the plant's operation. Two species of radiological concern are radiocaesium isotopes (¹³⁷Cs, β, γ, t_½ = 30.25 yr; ¹³⁴Cs, β, γ, t_½ = 2.05 yr) which constitute the main effluent radioactivity and plutonium isotopes (²³⁸Pu, α, t_½ = 86 yr; ²³⁹Pu, α, t_½ = 2.44 × 10⁴ yr; ²⁴⁰Pu, α, t_½ = 6.58 × 10³ yr) with high radio-toxicities. We present here plutonium and radiocaesium profiles for intertidal sediment cores collected from four sites in southern Scotland (Fig. 1) during October 1979 and discuss the present and longer-term significance of the interaction of Sellafield effluent with such sediments.