# US 4,394,346 A · Water level gauge for a nuclear reactor

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- Number: US 4,394,346 A
- Document ID: US4394346A
- Status: Granted
- Kind: A
- Application number: 06/215,655
- Filed: 1980-12-12
- Granted: 1983-07-19
- Earliest claimed: 1979-12-20
- Assignees: Tokyo Shibaura Denki Kabushiki Kaisha
- Inventors: Shinichi Morooka
- Web page: https://patentgrep.com/patent/US4394346A

## CPC

- G01F 23/14: by measurement of pressure
- G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME

## Abstract

A water level gauge for a nuclear reactor includes heat conduction means for absorbing and conducting heat to the outside of the drywell, the heat being supplied to reference water head water inside a reference water head tube defining a reference water level inside a reference water level container, and to water inside a lower part pressure pipe connecting a nuclear reactor pressure vessel with a differential pressure detector. The water level gauge further includes heat exchanger for removing the heat. With this device, the water level of the nuclear reactor may be correctly detected even in the case of leakage accident of the coolant of the nuclear reactor.

## Claims

### Claim 1

A water level gauge for a nuclear reactor having a reference water level container communicating with a fluid in the upper part of a nuclear reactor pressure vessel through an upper part pressure tube, a differential pressure detector with two inlets for detecting a differential pressure between the reference water level in the reference water level container and the water level inside the nuclear reactor pressure vessel, a reference water head tube connecting one of said two inlets of the differential pressure detector with the reference water level container, and a lower part pressure tube connecting the other inlet of the differential pressure detector with a predetermined measuring point of part of the nuclear reactor pressure vessel, characterized by further comprising heat conduction means for absorbing heat from the reference water head water inside said reference water head tube and from the water inside said lower part pressure tube and for conducting the heat to the outside of a housing of the nuclear reactor pressure vessel, and a heat exchanger for removing the heat conducted to the outside of the housing by said heat conduction means.

### Claim 2 (depends on 1)

A water level gauge according to claim 1, wherein said heat conduction means are covered with a heat insulating material.

### Claim 3 (depends on 1, 2)

A water level gauge according to claim 1 or 2, wherein said heat conduction means are heat pipes wound around said reference water head tube and said lower part pressure tube, said heat pipes comprising metal pipes, a porous material laminated on the inner walls of said matal pipes and a heat conducting material impregnated in said porous material.

### Claim 4 (depends on 1, 2)

A water level gauge according to claim 1 or 2, wherein said heat conduction means comprise sealed heat transfer pipes which are coaxially arranged around said reference water head tube and said lower part pressure tube and in which a working fluid is sealed, and slanted tubes which open from the upper parts of said thermosiphon tubes and reach said heat exchangers at an upward slant.

### Claim 5 (depends on 1, 2)

A water level gauge according to claim 1 or 2, wherein said heat conduction means comprise casings covering said reference water head tube and said lower part pressure tube, and cooling water forcibly circulated within said casings.