RACA Journal June 2016 - Page 55

Getting Technical Charles Nicolson Charles Nicolson has a physics and chemistry degree from Natal University which he subsequently put to good use by applying speciality chemicals in mining and industrial processes where water is a major factor. This created an enduring interest in water technology, a passion that expanded to the HVAC industry in 1984 when he joined BHT Water Treatment. Since then, water technology in HVAC water circuits has continued to be an abiding interest. Neighbourhood nuclear heating modules are on their way By Charles Nicolson What are the dangers of nuclear power? And can the potential benefits overcome them? I n December 2015, the Department of Energy (DOE) confirmed that it had been given the go-ahead to issue a request for proposals for a nuclear build programme that will provide an additional 9 600MWe to the South African national electricity grid. At the time of writing, early in April, the request had not yet been issued but is expected within a week or so. Expectations are that there will be two sites, one at Thyspunt, between Oyster Bay and St Francis Bay in the Eastern Cape, and the other at Duynefontein, adjacent to Koeberg in the Western Cape. Each power station is expected have two or three nuclear reactors, therefore reactor sizes will be in the 1 600 to 2 000MWe range which is about the average size of the 450-480 total of currently operating and under-construction nuclear power station reactors. Two aspects of South African nuclear power planning that continually come under question are safety and the capability of South Africans, obviously with the aid of foreign expertise, to build and run new nuclear plants. Regarding South African capability, the example of Koeberg, built and completed by South Africans in 1984 and subsequently successfully operated for over 30 years speaks for itself. So does the Safari reactor within the Pelindaba industrial and research complex, which was commissioned even earlier in 1965 and continues to produce top quality radio isotopes used in nuclear medicine. Koeberg, incidentally, is not only the sole nuclear power station in South Africa but also the only one on the African continent. Safety is an issue that has grown beyond nuclear technology as such, and must now encompass far wider studies of possible external impacts including physical attacks by terrorists and seismic events such as the earthquake/tsunami which flooded the Fukushima nuclear power station in Japan five years ago in 2010. Fukushima became the third nuclear power station after Three www.hvacronline.co.za #GettingTechnical Mile Island and Chernobyl in the US and the former Soviet Union respectively, to experience reactor cooling failure which caused a widely publicised hazardous meltdown situation. Unlike Three Mile Island and Chernobyl, this incident did not arise from any operational technical malfunction but was due to a natural event; an earthquake measuring in excess of 9.1 on the Richter scale which is a large earthquake indeed, even in a geographic area where substantial seismic events are not unexpected. However, according to official investigation reports, it was not the earthquake itself, but the subsequent tsunami produced by the earthquake arriving nearly an hour later which overwhelmed insufficiently high (10m) anti-tsunami walls and flooded out both the external power supply and internal back-up diesel power facilities, disabling emergency cooling water circulation which resulted in reactor meltdowns. The three serious nuclear power station meltdown occurrences caused by cooling failures have been: • 1979: One of the two Three Mile Island nuclear reactors in Pennsylvania, United States. • 1986: Reactor No 4 at the Chernobyl plant near the city of Pripyat in the former USSR. • 2011 Three of the six reactors at Fukushima in Japan. Fatalities caused directly by these meltdowns have been attributed only to Chernobyl at 31. However, both Chernobyl and Fukushima were responsible for subsequent deaths from radiation and longerterm effects such as cancers are still being investigated. Worldwide there are currently about 435 nuclear reactors operating for electricity generation and between 70 and 80 new Continued on page 55 RACA Journal I June 2016 53