Kabushiki Kaisha Toshiba

Yutaka Takeuchi

Yukio Takigawa

Kazuki Yano

Hiroshi Ono

Kazumasa Hirayama

Mikihide Nakamaru

Shigeru Kanemoto

Mitsuhiro Enomoto

Nobuaki Abe

Shiho Miyamoto

Hitoshi Uematsu

Hiroyuki Takeuchi

Masao Kobayashi

Provide a nuclear reactor power monitoring technology for enhancing the monitoring accuracy and reliability in nuclear thermal hydraulic stability. A power monitorincludes a first calculation unitconfigured to calculate a first stability index based on time series data indicating power oscillation in nuclear instrumentation signals outputted from a plurality of nuclear instrumentation detectors; a first determination unitconfigured to compare the first stability index and a first reference value and determine whether nuclear thermal hydraulic stability of the reactor core is stable or deteriorated; a second calculation unitconfigured to calculate a second stability index of the reactor core based on the time series data when the deteriorated state is determined in the first determination unit; and a second determination unitconfigured to compare the second stability index and a second reference value and determine whether to perform suppressing operation of the power oscillation.

Nuclear reactor power monitor

An apparatus for monitoring nuclear thermal hydraulic stability of a nuclear reactor, contains: a calculation unit configured to calculate a stability index of a nuclear thermal hydraulic phenomenon based on nuclear instrumentation signals, the signals being outputted by a plurality of nuclear instrumentation detectors placed at regular intervals in a reactor core; a simulation unit configured to simulate the nuclear thermal hydraulic phenomenon based on a physical model by using information on an operating state of the nuclear reactor as an input condition; a limit value updating unit configured to update a limit value of the nuclear thermal hydraulic phenomenon based on a result of the simulation; and a determination unit configured to determine, based on the stability index and the limit value, whether or not to activate a power oscillation suppressing device.

Apparatus, method and program for monitoring nuclear thermal hydraulic stability of nuclear reactor

A natural-circulation type boiling water reactor includes a plurality of divided chimneys provided above a reactor core and a number of fuel assemblies are charged in the reactor core. The natural-circulation type boiling water reactor is provided with a pressure equalization structure arranged on rectangular-columnar lattice plates of the divided chimneys for equalizing pressures in divided chimney portions so as to equalize the pressures of the divided chimneys with the pressure equalization structure.

Natural circulation type boiling water reactor

A shadow mask for use in a cathode ray tube comprises a mask body having a mask effective section where a number of electron beam passage apertures are formed and a skirt portion provided at a peripheral edge of the mask effective section, and a mask frame arranged to be layered outside the skirt portion. The mask frame and the skirt portion are resistance-welded to each other at a plurality of portions. At each welding portion, a plurality of concave and/or convex portions each having a smaller area than an area of a contact surface of an electrode for resistance-welding are formed at an inner surface portion of the skirt portion which the electrode contacts.

Shadow mask, cathode ray tube, method and apparatus for manufacturing shadow mask

In a system for monitoring power of a nuclear reactor, a plurality of neutron flux measuring devices are arranged in a reactor core of the nuclear reactor for measuring neutron flux so as to generate neutron flux signals on the basis of the measured neutron flux. The neutron flux signals are filtered through a first weighting coefficient and a second weighting coefficient previously held in a monitoring signal calculating unit so as to generate stability monitoring signals. The first weighting coefficient corresponds to a fundamental mode of a neutron flux distribution in the reactor core and tire second weighting coefficient corresponds to a higher mode of the neutron flux distribution therein. The stability monitoring signal filtered through the first and second weighting coefficients are transmitted to a stability monitoring unit the stability monitoring unit monitors the stability of the core according to the transmitted stability monitoring signals.

System for monitoring power of nuclear reactor

A system for monitoring power, particularly a power distribution, of a nuclear reactor includes a plurality of neutron flux measuring units disposed in a core of the nuclear reactor for measuring neutron flux in the core and generating neutron flux signals. A unit, generally constructed by a process computer, for calculating a neutron flux distribution in the core in response to the neutron flux detection signals from the neutron flux measuring units, is provided. A unit for calculating a higher mode of the neutron flux distribution in accordance with results of calculations performed by the neutron flux distribution calculating unit, is provided. A filter calculating unit is provided for obtaining a filter for extracting characteristics of change of the neutron flux detection signal in response to the neutron flux detection signal and an input/output unit for transmitting the neutron flux detection signal filtered by the filter obtained by the filter calculating unit.

Growing community of inventors

Tochigi, Japan

Yutaka Takeuchi