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Reaktor form4/16/2023 ![]() The automatic rods are regulated by feedback from in-core detectors. The main control rods are inserted from the top down and provide automatic, manual, or emergency control. A few short rods, inserted upwards from the bottom of the core, even the distribution of power across the reactor. Control rodsīoron carbide control rods absorb neutrons to control the rate of fission. Heat conduction between the blocks is enhanced by a mixture of helium and nitrogen gas. They act as a moderator to slow down the neutrons released during fission so that a continuous fission chain reaction can be maintained. Graphite moderatorĪ series of graphite blocks surround, and hence separate, the pressure tubes. When fuel channels are isolated, the fuel assemblies can be lifted into and out of the reactor, allowing fuel replenishment while the reactor is in operation. ![]() Each channel is individually cooled by pressurised water which is allowed to boil in the tube and emerges at about 290☌. Within the reactor each fuel assembly is positioned in its own vertical pressure tube or channel about 7 m long. Two of these end on end occupy each pressure tube. A set of 18 fuel rods is arranged cylindrically in a carriage to form a fuel assembly. Pellets of slightly-enriched uranium oxide are enclosed in a zircaloy tube 3.65m long, forming a fuel rod. A number of significant design changes were made after the Chernobyl accident to address these problems. As the Chernobyl accident showed, several of the RBMK's design characteristics – in particular, the control rod design and a positive void coefficient – were unsafe. The combination of graphite moderator and water coolant is found in no other power reactors in the world. (The ADE reactors at Zheleznogorsk and Seversk used for plutonium production are similar to the RBMK but with much lower power density and smaller fuel elements.) Its precursors were an experimental 30 MWt (5 MWe) LWGR at Obninsk which started up in 1954, and two small prototype LWGR (AMB-100 & 200) units – Beloyarsk 1&2, which ran from 19 respectively. It was designed over 1964-66 and is very different from most other power reactors. As with a boiling water reactor (BWR), water boils in the fuel channels (at about 6.9 MPa) and steam is separated above them in a single circuit. It is also known as the light water graphite reactor (LWGR). The Soviet-designed RBMK ( reaktor bolshoy moshchnosty kanalny, high-power channel reactor) is a water-cooled reactor with individual fuel channels and using graphite as its moderator. Major modifications have been made to the RBMK reactors still operating.The design had several shortcomings, and was the design involved in the 1986 Chernobyl disaster.The RBMK is an unusual reactor design, one of two to emerge in the Soviet Union in the 1970s. ![]() ![]() RBMK Reactors – Appendix to Nuclear Power Reactors ![]()
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