Hitachi, Ltd.

Hiroshi Kodama

Yuichiro Yoshimoto

Mikio Sakurai

A nuclear reactor power monitoring system for monitoring the power level of a reactor and preventing an excessive rise thereof attributable to a transient increase in the core coolant flow rate before the reactor is scrammed. The system include an operating region monitor (ORM) for blocking the increase in the core coolant flow rate or running-back the flow rate when the power level exceeds a predetermined coolant block threshold power level which is a function of the core coolant flow rate.

Nuclear reactor power monitoring system

A nuclear reactor having a vertical annular space defined between a shroud enclosing a reactor core and a pressure vessel surrounding the shroud, and a plurality of internal circulation pumps disposed in a lower portion of the space for forcing a coolant in the space to flow into below the reactor core so that the coolant flows through the core in forced circulation. A tubular guide member is disposed adjacent to a suction port of each internal pump for vertically guiding a flow of the coolant being sucked into the pump to increase the effective inertia of the flow of the coolant, thereby to enhance the stability of the flow conditions of the coolant flowing through the reactor core.

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Hitachi, Japan

Hiroshi Kodama