Another contender

I am surprised that Stuart Nathan (

, 2 July) blithely ignores the most innovative of the four reactor technologies that have met the Government's eligibility criteria for the opening phase of the planned generic design assessment, Atomic Energy of Canada's Generation III+ ACR-1000 Advanced CANDU Reactor.

Combining the best features of light- and heavy-water PWRs, the ACR-1000 retains CANDU's unique reactor core layout of small diameter pressure tubes immersed in several hundred tonnes of cool moderator and shielding light water as opposed to the large, thick-walled pressure vessels of the light-water PWR.

The ACR-1000's massive and passive heat sinks are complemented by two technically diverse and physically separated, passively driven fast shutdown systems, additional to the normal reactor regulation systems and operate entirely within the low pressure and temperature moderator. These contrast with the PWR's single fast shutdown rods operating in a high temperature and pressure environment.

The ACR-1000 has been dramatically simplified from its predecessor, the CANDU 6 reactor, of which 10 units operating on four continents have achieved lifetime capacity factors averaging more than 88 per cent.

Moving to moderately enriched (2.4 per cent U-235) fuel and light water coolant has allowed a 50 per cent reduction in heavy-water inventory and an increase in electrical output of over 60 per cent, all in a smaller plant footprint and with greatly reduced numbers of systems and components. The resulting highly competitive economic performance makes this technology one to watch.

AECL's last new-build reactor project, the Qinshan Phase three twin CANDU six plant in Zhejiang, China, came in 10.6 per cent under budget and four months ahead of schedule. Since starting operation in 2002/2003 these units have joined their four fellow CANDU six units at Wolsong, Korea at the head of both Korean and Chinese reactor performance charts.

You owe your readers the opportunity to learn more about this technology, the only contender with a strong British streak in its pedigree.