Sellafield nuclear fuel discharges

The seas are a source of aerosol (i.e. small particles), which transfer to the atmosphere. These will subsequently deposit, possibly after chemical modification, either back in the sea (the major part) or on land (the minor part). Marine aerosol comprises largely unfractionated seawater, but may also contain some abnormally enriched components. One example of abnormal enrichment occurs on the eastern coast of the Irish Sea. Liquid effluents from the Sellafield nuclear fuel reprocessing plant in west Cumbria are discharged into the Irish Sea by pipeline. At one time, permitted discharges were appreciable and as a result radioisotopes such as Cs and several isotopes of plutonium have accumulated in the waters and sediments of the Irish Sea. A small fraction of these radioisotopes were carried back inland in marine aerosol and deposited predominantly in the coastal zone. While the abundance of Cs in marine aerosol was refiective only of its abundance in seawater (an enrichment factor - see Chapter 4 - of close to unity), plutonium was abnormally enriched due to selective incorporation of small suspended sediment particles in the aerosol. This has manifested itself in enrichment of plutonium in soils on the west Cumbrian coast,shown as contours of 239+240p deposition (pCi cm ) to soil in Figure 3. 

Figure 1 Temporal variations in the annual quantities of (a) Cs, (b) Am and (c) 239,discharged from the Sellafield nuclear fuel reprocessing plant (data from Gray et al ).

Historically, liquid discharges to the Irish Sea have been dominated by those from the Sellafield nuclear fuel processing plant in Cumbria, UK. There are other sources of artificial radionuclides that could impact the marine environment of Northern Ireland these being comparatively small, including ... 

A major reassessment of historical discharges and doses has been carried out, prompted in large part by civil litigation instigated by a number of local families against British Nuclear Fuels pic, the operators of the Sellafield plant. The reassessment involved the development of the Sellafield Environmental Assessment Model (SEAM), which was used both to calculate doses and to build confidence in the discharge chronology from recorded measurements of environmental concentrations and current assessments of environmental inventories. 

British Nuclear Fuels Sellafield reprocessing plant publishes annual figures of measured discharges and local environmental measurements, in order to conform with environmental legislation (British Nuclear Fuels, 1992). The local environmental burden of anthropogenic radionuclides will be due to discharges from nuclear activities... 

Figure 8.2 Discharges to the Irish Sea from Sellafield (British Nuclear Fuels pic., 1971-1993).

British Nuclear Fuels (Sellafield, Cumbria, UK) have used their Site Ion Exchange Effluent Plant (SIXEP) to treat wastewater from the ponds used to store spent fuels rods, and other effluents, for some 20 years [125]. Clinoptilolite from Mud Hills, near Barstow, California, successfully treats 4700 m3/day, in SIXEP, to remove Cs and Sr radioisotopes prior to direct discharge to the Irish Sea. In this process it has been calculated that, in a typical nuclear effluent, clinoptilolite has the ability to selectively take up 1 mole of Sr and 20 moles of Cs in the presence of 7.5x10s moles of Na, 6.5xl03 moles of Mg and 5xl03 moles of Ca. 

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