WatereoledgraphiteModer-Fedreactor with graphite as a slow neutron reactor with graphite as a chronic agent and water as a cooling agent. In the early days of the development of the nuclear industry, graphite and cold stacks were mainly used to produce nuclear weapons installation -钚, 氖, etc. This heap is generally fuel with natural uranium metal components. Uranium 235 in the natural uranium in the pile absorbs neutron reactor in neutron and releases neutron and energy. These neutron parts are used to maintain chain nuclear fissure reactions, and some are absorbed by the uranium 238 in natural uranium and converted into it to converted into it into. 钚 239 and other 素 isotopes. Structural graphite and cold stacks use nuclear pure graphite masonry as a chronic agent and reflective layer. There are two or three thousand horizontal tunnels (horizontal piles) or vertical tunnels (vertical piles) in the graphite masonry. Inserting graphite sleeves in these holes, aluminum alloy crafts pipes in the sleeve, will cool down to cool down. Water is separated from graphite slow. There are convex ribs on the inner wall of the process tube to maintain the gap between the process tube and the fuel element. The temperature of each part of the graphite masonry is uneven. By changing the gap between the graphite sleeve and the water flow in the process tube, the masonry temperature can be partially adjusted to make the temperature distribution flat. The fuel element is generally made of rods, with a diameter of about 35 to 38mm, and a length of about 100 ~ 200mm. In order to increase the ratio power and make the component's radial consumption uniform, there are also tubular fuel components. In the early days of the development of production stacks, an over -cooled cooling method was adopted. Even if the river water is stacked, the calories are brought out of the river. Due to the large water consumption in this way, high radioactive levels in drainage, and outstanding environmental protection issues, the industry has stopped using it, and a closed cooling method is generally used, that is, cooling water flows from the pile of cores, exports the heat from the heap, and switch through heat exchange through heat exchange. The device gives the thermal conductors to the water on the side of the other circuit, and then returns the core of the main pump to form a main cooling circuit, or a circuit with a closed loop. There are two types of calories that export a circuit of water: one is to guide one circuit of heat through the heat exchanger to the second circuit water through the heat exchanger, and the cooling water tower or river water is cooling to discharge the heat into the environment. Another way is to pass the heat to the residual heat utilization system through the heat exchanger, as the heat source heating or power generation to the outside world. One of the important features of natural uranium graphite cold piles is that the reactionary reaction is very small. The reactivity of early graphite piles increased with its temperature, and the power of the pile also increased (the so -called positive temperature effect), which led to an increase in the reaction. (Control rod, etc.), or cause malignant accidents such as pile of core melting. In 1986, after the Chel Nobeli nuclear accident, the problem of positive temperature effects attracted more attention from all aspects. It must obtain negative temperature effects in the physical design of the heap to ensure that the reactor is crucial to self -stability. The United States has built eight graphite water -cooled army production piles since 1943. One production power generation pile (NPR) is produced, and the latter is 4000mW.