Low level waste

LLW disposal in the UK has been ongoing since the 1950s, providing con­siderable perspective on the approaches to, and the strategy development of, LLW disposal. Since 1959, LLW has been disposed of at the UK’s national low level waste repository (LLWR) in Cumbria, in addition to a number of other LLW disposal sites including various Sellafield pits, Hunterston A and Dounreay. LLW strategy development has largely progressed in response to the need to preserve the capacity of the LLWR for as long as possible given future arisings of LLW in the UK.

The LLWR (Fig. 16.4), located on the site of a second World War muni­tions factory, was initially developed as a series of excavated trenches into which wastes were loose tipped between 1959 and 1995 (LLWR, 2011). The trenches were designed with drainage and runoff collection systems and were largely keyed into a low hydraulic conductivity clay layer. Where this was absent, bentonite was rotovated into the trench base.

In 1988, trench disposals were phased out in favour of LLW disposal to engineered vaults. A number of improvements were made to the trench disposal areas after this time. The installation of an interim cap over Trenches 1-6 took place in 1989 to minimise rainfall ingress into the wastes and a bentonite cut-off wall was excavated on the north and east sides of the disposal area in 1988 to reduce the potential for tritium migration in ground­water (LLWR, 2011 ).

Overall, the major components of LLW are building rubble, soil and steel items from the dismantling and demolition of nuclear reactors and other nuclear facilities (Fig. 16.7).

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