| 摘要 |
PROBLEM TO BE SOLVED: To prevent a back flow of a coolant in a reactor pressure vessel when inflow of the coolant is lost by a damage of a primary system coolant pipe in a pebble bed type high-temperature gas-cooled reactor. SOLUTION: In this pebble bed type high-temperature gas-cooled reactor, the low-temperature coolant flowing from an outer tube 6 of a cross duct 5 having a duplex tube structure into the reactor pressure vessel 1 is lifted through a passage hole 7 passing a reflector 4 enclosing a core 2 and introduced into a core upper plenum 8, and then the coolant is lowered in the core 2 to heat up to a high temperature, and allowed to flow from the inner tube 10 of the cross duct 5 to the outside of the reactor pressure vessel 1. The reactor is provided with a back flow prevention device 17 on a gas outlet 7a to the core upper plenum 8 of the passage hole 7. The back flow prevention device 17 lowers a float 18 by the self-weight at the inflow losing time of the coolant to block the outlet 7a of the passage hole 7, and thereby the back flow of the coolant from the core 2 to the passage hole 7 is prevented. COPYRIGHT: (C)2005,JPO&NCIPI
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