§ Mr. Austin Mitchellasked the Secretary of State for the Environment what research he has commissioned on sulphate attack on concrete and concrete cancer; what is the life expectancy of concrete linings in near-surface nuclear waste dumps; and how long metal drums containing solid low-level nuclear waste take to decay.
§ Mr. WaldegraveMy Department supports a long-term research programme at the Building Research Establishment on sulphate attack on concrete. Results of the first five years' exposure of concrete specimens are summarised in
Harrison and Peychenne. Sulphate resistance of buried concrete: second interim report on long term investigations at Northwick Park. BRE, HMSO, 1981.Work is now being done on concrete specimens which have been exposed for 15 years, and further work will be carried out in due course on specimens after 25 years' exposure.
BRE's current recommendations for producing concrete resistant to sulphate attack are given in BRE Digest 250 "Concrete in sulphate bearing soils and groundwaters" (revised 1984) and are incorporated in the recent British Standard on structural concrete BS8110, 1985, part I, table 6.1.
The life expectancy of concrete linings in nuclear waste repositories would depend on many factors including the composition of both concrete and groundwater, and the 292W method of placement. The subject is discussed in Harwell report No. 11465 "An assessment of long-term durability of concrete in radioactive waste repositories".
My Department and NIREX are jointly funding work on the specification of a waste drum with a life expectancy of 300–500 years. Results so far available suggest that this life expectancy should be achieved with thin-walled stainless steel or thick-walled carbon steel drums.