# US 8,739,621 B2 · Electrical heating element and method of measuring a filling level

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- Number: US 8,739,621 B2
- Document ID: US8739621B2
- Status: Granted
- Kind: B2
- Application number: 12/868,878
- Filed: 2010-08-26
- Published: 2011-02-03
- Granted: 2014-06-03
- Earliest claimed: 2008-02-26
- Assignees: Areva GmbH
- Applicants: Sacha Kaercher; Wolfgang Vogt; Stefan Pfleger; Wilfried Harfst
- Inventors: Sacha Kaercher; Wolfgang Vogt; Stefan Pfleger; Wilfried Harfst
- Web page: https://patentgrep.com/patent/US8739621B2

## CPC

- H05B 3/48: heating conductor embedded in insulating material
- G01F 23/22: by measuring physical variables, other than linear dimensions, pressure or weight, dependent on the level to be measured, e.g. by difference of heat transfer of steam or water (involving the use of floats G01F23/30)
- G21C 17/035: Moderator- or coolant-level detecting devices {(indicating or measuring liquid level in general G01F23/00)}
- G21C 17/112: Measuring temperature
- Y02E 30/30: Nuclear fission reactors
- H05B: ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- G01F: MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G21C: NUCLEAR REACTORS (fusion reactors, hybrid fission-fusion reactors G21B; nuclear explosives G21J)
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION

## Abstract

A pencil-shaped electrical heating element, in particular for application in a device for measuring filling level in a liquid container, in particular in a reactor chamber of a nuclear plant, contains an electrically-conducting sleeve and at least one electric line embedded therein which is in conducting contact with the sleeve. The electrical line has at least two line sections with differing electrical properties and/or thermal conductivities.

## Claims

### Claim 1

An apparatus for measuring a filling level in a liquid container, the apparatus comprising:
a number of thermocouples;
a heating element having an electric line, said electric line having at least one first line portion forming a cold zone and a second line portion forming a heating zone, with said second line portion having a considerably higher resistivity than said first line portion, and with a temperature dependence of resistivity in said first line portion being considerably greater than in said second line portion;
means for measuring a total resistance of said electric line; and
means for determining a temperature in a surrounding area of said first line portion on a basis of a measured total resistance of said electric line.

### Claim 2 (depends on 1)

The apparatus according to claim 1, wherein the resistivity of said first line portion is an approximately linear function of the temperature.

### Claim 3 (depends on 1)

The apparatus according to claim 1, wherein said second line portion is formed from nickel chromium (NiCr).

### Claim 4 (depends on 1)

The apparatus according to claim 1, wherein said first line portion is formed from one of nickel (Ni) and a nickel alloy with a predominant proportion of nickel.

### Claim 5 (depends on 1)

The apparatus according to claim 1, further comprising:
an external cladding; and
an insulator disposed inside said external cladding, said heating element being embedded at least in a portion-wise manner in said insulator.

### Claim 6 (depends on 5)

The apparatus according to claim 5, wherein said insulator is composed of a mineral material.

### Claim 7

A method for operating an apparatus for measuring a filling level in a liquid container, the apparatus having a number of thermocouples and a heating element with an electric line, the electric line having at least one first line portion forming a cold zone and a second line portion forming a heating zone, with the second line portion having a considerably higher resistivity than the first line portion, and with a temperature dependence of a resistivity in the first line portion being considerably greater than in the second line portion, which comprises the steps of:
measuring a total resistance of the electric line; and
ascertaining a temperature in a surrounding area of the first line portion on a basis of a measurement value of the total resistance of the electric line.

### Claim 8 (depends on 7)

The method according to claim 7, which further comprises using the temperature ascertained for a temperature-dependent heating current regulation.