| 摘要 |
913,655. Controlling reactors. BABCOCK & WILCOX CO. March 16, 1959 [March 14, 1958], No. 8969/59. Class 39 (4). A water moderated reactor is controlled by a combination of absorber rods, burnable poison in the fuel elements, and soluble poison in the moderator. Fig. 1 shows a P.W.R. 10 with rods 11 of B, Hf, stainless steel, or an alloy of cadmium, indium and silver. The moderatorcoolant circuit includes a pressurizer 12, a steam generator 14, and pumps 16. Boric acid solution may be added up to 21 gm./litre from a tank 202, and removed by an anion exchanger 226, or by an evaporator 230 after fission products have been removed in a cation exchanger 228. Each fuel element includes 500 p.p.m. of boron in its Zircaloy 2 sheath 94 or 200 p.p.m. mixed with the fuel; Eu may also be used. The sheaths contain fuel pins 98, comprising highly enriched UO 2 -ThO 2 pellets in stainless steel cladding, mounted in grids; the pins contain heat transfer fluid such as He, Pb, Na. The sheaths fit in support grids with sprung adapters, and their sides are recessed at 94B to leave cruciform spaces for the control rods 128. Fuel elements in the centre of the core contain 5.3% UO 2 , those outside 6.6% UO 2 , the balance being ThO 2 . The pressure vessel is of stainless steel-lined carbon steel surrounded by steel wool and a tank of water, and contains the core supported between grids and enclosed by three steel thermal shields. Specifications 775,151, 775,156, 913,653, 913,654 and U.S.A. Specifications 2,708,653, 2,735,811, 2,756,857 and 2,798,847 are referred to. |
