Hitachi, Ltd.

Hitachi Engineering Co., Ltd.

Satoshi Miura

Shozo Yamanari

Hiroshi Goto

Kenji Tominaga

Koji Hashimoto

Yoshiyuki Kataoka

Kotaro Inoue

Isao Sumida

Tetsuo Horiuchi

Michio Murase

Hiroaki Suzuki

Masaki Matsumoto

A natural circulation reactor includes a reactor pressure vessel, a cylindrical shroud disposed within the reactor pressure vessel to surround a reactor core and to extend to a position above the reactor core, and a coolant descending passage defined between the reactor pressure vessel and the shroud for allowing the coolant discharged from the top of the reactor core to be again supplied to the bottom of the reactor core. In such a natural circulation reactor, a liquid level of coolant in the coolant descending passage is adjusted on the basis of a reactor power request signal at a position below a liquid level of coolant in the shroud, and thus reactor power is controlled so that it may reach a predetermined reactor power by adjusting the liquid level of coolant in the coolant descending passage.

Method of and apparatus for controlling power of natural circulation

Two systems of low-pressure core spray appratuses have coolers, and are adapted to supply cooling water to a core spray header provided in a core-surrounding cylindrical shroud in a reactor pressure vessel. Two systems of high-pressure core flooding apparatuses and one system of high-pressure coolant injection apparatus are adapted to supply the cooling water to a region formed between the shroud and reactor pressure vessel. The elevation of the openings, which are in the reactor pressure vessel, of the high-pressure core flooding apparatuses and high-pressure coolant injection apparatus are higher than that of the core spray header. A pipe for returning the cooling water in the reactor pressure vessel to the above-mentioned coolers is connected to either the portion of the interior of the reactor pressure vesssel which is below the core or the portion of the interior of the reactor pressure vessel which is between the walls of the shroud and reactor pressure vessel. The above-mentioned pipe is provided therein with a valve which is adapted to be closed when the nuclear reactor stops being operated in an emergency in which the breakage of a pipe occurs, and to be opened when the nuclear reactor is stopped under normal conditions.

Emergency core cooling apparatus

Growing community of inventors

Hitachi, Japan

Satoshi Miura