the future, modified versions of the AGR were selected over SGHWR as no further development effort was needed. The Winfrith Reactor reactor remained operational and was used for a wide variety of purposes until it ceased operation in October 1990 after 23 years of operations. it is in the process of being decommissioned by Magnox Ltd on behalf of the Nuclear Decommissioning Authority. In 2022 over 1000 drums of radioactive waste will be transported by 11 trains to the Low Level Waste Repository. The material was once intermediate-level waste but had decayed down to low-level waste while being stored at Winfrith. Design SGHWR is similar to the Canadian CANDU reactor designs in that it uses a low-pressure reactor vessel containing the moderator and high-pressure piping for the coolant. This both reduces the total amount of expensive heavy water required, as well as reducing the complexity of the reactor vessel, which in turn reduces construction costs and complexity. It differs in that it uses ordinary "light" water as a coolant, whereas CANDU uses heavy water here as well. Light water reduces the neutron economy to the point where natural uranium can no longer be used as fuel. The ability to run on natural uranium was considered a major benefit in the 1960s as it appeared the demand for enrichment would outstrip the supply. By the 1970s it was clear that fuel supplies were not going to be a problem, and the use of unenriched fuel was no longer a major design goal. Using slight enrichment leads to higher burnup and more economical fuel cycles, offsetting the now-low costs of enrichment. The idea of using heavy water for the moderator and light water for the coolant was explored by a number of designs during this period. The Gentilly-1 Nuclear Generating Station in Quebec used the same solution, but this was not successful and shut down after a short lifetime. The Fugen Advanced Test Reactor in Japan suffered a similar fate. The Italian CIRENE design, hosted at Latina Nuclear Power Plant, was built but never commissioned. The last attempt to use this basic design was the modern Advanced CANDU Reactor of the early 2000s, but development ended without an example being built. References RSRL Winfrith Site Operations Steam Generating Heavy Water Reactor – SGHWR – The final chapter, Magnox, 2015 Heavy Water Reactors: Status and Projected Development, IAEA, 2002 Sghwr Sghwr Nuclear technology