build Canada's first nuclear power plant at Rolphton, Ontario, which is upstream from Chalk River. On June 4, 1962, the NPD (Nuclear Power Demonstration) first reactor went critical to demonstrate the CANDU concept, generating about 20 MWe. In 1963, AECL established the Whiteshell Nuclear Research Establishment (now Whiteshell Laboratories) in Pinawa, Manitoba, where an organically moderated and cooled reactor was built. Later work on developing a SLOWPOKE reactor, thorium fuel cycle, and a proposal for safe storage of radioactive waste were carried out at this site. AECL built a larger CANDU prototype (200 MWe) at Douglas Point on Lake Huron, first going critical on November 15, 1966. Douglas Point experienced significant problems with leakage of heavy water, which were eventually solved by much-improved valve design. Other important design refinements worked out at Douglas Point opened the way for upscaling to commercial power CANDU reactors in subsequent years. 1970s In 1971 the first commercial CANDU reactor, Pickering A 1, began commercial operation. By 1973 the other three reactors of the A group at Pickering were online and constituted the most powerful nuclear facility in the world at that time. Each Pickering unit produces about 600 MWe of power. On May 18, 1974, India detonated a nuclear bomb made from plutonium manufactured by the CIRUS research reactor built by AECL in 1956, which was a commercial version of its NRX research reactor. In addition AECL built two power reactors in India based on the Douglas Point design, and many of India's other reactors are domestic variants of this design. The connection between India's nuclear weapons program and its CIRUS research reactor led to a severance of nuclear technological cooperation between Canada and India. In 1977–1978 the Bruce A group went online and began commercial operation. Each Bruce unit produces about 800 MWe of power. In 1978, Whiteshell Labs began research into fuel waste disposal. 1980s Between 1983 and 1986, the Pickering B group went online and also in 1983 the single CANDU reactor at Point Lepreau began operation, as did the Gentilly 2 CANDU reactor. Between 1984 and 1987 the Bruce B group began commercial operation, and also in 1987 the CANDU design was ranked one of Canada's top-10 engineering achievements. Douglas Point was decommissioned in May, 1984. Between 1985 and 1987, a series of design flaws in AECL's Therac-25 medical accelerator caused massive overdoses of radiation on 6 different occasions, resulting