| 摘要 |
1. Boiling water reactor comprising a fuel core (4) with a plurality of fuel rod assemblies (5) carried by a lower grid plate (6) provided with throttle openings (23, 24) to secure the desired distribution of the flow of cooling water among the fuel rod assemblies (5), the grid plate having receiving devices for connecting the bottom unit (14) of the fuel rod assembly (5) to the lower grid plate (6), said bottom unit (14) being provided with a diffusor (16) for reducing the throttling effect of the throttle opening (23, 24) in the lower grid plate (6) and thereby reducing the pressure drop over the throttle opening (23, 24) and the bottom unit (14), characterized in that the receiving device for the bottom unit (14) of a fuel rod assembly consists of a bore (17) in the lower grid plate (6), at the bottom of which the throttle opening (23, 24) is arranged, and that said bore (17) and said bottom unit (14) of the fuel rod assembly are shaped to form a circular chamber (26) communicating with the opening (27) in said bottom unit (14) through a space (28) between the bottom unit (14) and the bottom (31) of said bore (17) or between said bottom unit (14) and a throttling disc (22) in the lower part of said bore (17). |
