Assembly and method for detecting and measuring the fouling rateof flow holes in a secondary circuit of a pressurized water nuclear reactor

Patent metadata

Field	Value
Publication number	US-9360207-B2
Application number	US-201113110695-A
Country	US
Kind code	B2
Filing date	May 18, 2011
Priority date	May 19, 2010
Publication date	Jun 7, 2016
Grant date	Jun 7, 2016

Abstract

An assembly for detecting and measuring the fouling rate by deposits containing at least one ferromagnetic material, including a probe which can be continuously moved inside a tube and which has a body carrying on its outer surface at least one magnetized source for self-orientation of the body of the probe, at least three magnetic field emitters and at least three magnetic field detectors each positioned between two contiguous emitters.

First claim

What is claimed is:

1. An assembly for detecting and measuring a rate of fouling, by deposits containing at least one ferromagnetic material, of flow holes in tube support plates of a secondary circuit of a steam generator of a pressurized water nuclear reactor, the generator comprising a bundle of primary water circulation tubes, vertical branches of the tubes being held in the flow holes of the tube support plates, each flow hole having at least three alveoli separated by solid portions in contact with one of the tubes of the bundle, the assembly comprising:
a probe which can be moved inside and along one of the tubes of the bundle of primary water circulation tubes, the probe comprising a body of cylindrical elongate shape with a central longitudinal axis, the body carrying on its outer surface at least three magnetic field emitters for emitting a magnetic field, the body of the probe containing at least three magnetic field detectors for detecting the magnetic field, each magnetic field detector being positioned between two angularly consecutive magnetic field emitters,
the body carrying on its outer surface at least one magnetized source for angular self-orientation of the body of the probe relative to the solid portions of the flow holes, arranged such that the at least three magnetic field emitters are each automatically angularly positioned opposite one of the solid portions and the at least three magnetic field detectors are each automatically angularly positioned opposite one of the alveoli when the probe inside the tube is moved to each flow hole,
an assembly of the magnetic field detectors being connected by a connector to a system for amplifying and displaying signals transmitted by the magnetic field detectors when the probe moving in the tube arrives at each flow hole to be inspected in the tube support plates,
the at least one magnetized source being a permanent magnet or an electro-magnet, the magnetized source having a North-South magnetic axis extending radially from the central longitudinal axis of the body of the probe.

2. The assembly according to claim 1 wherein the magnetic field emitters and the magnetic field detectors are arranged on a same plane perpendicular to the central axis.

3. The assembly according to claim 1 wherein the at least one magnetized source is in front of a circumference formed by the magnetic field emitters and the magnetic field detectors relative to a direction of travel of the probe in the tube.

4. The assembly according to claim 1 wherein the at least one magnetized source is behind the circumference formed by the emitters and the detectors relative to a direction of travel of the probe in the tube.

5. The assembly according to claim 1 wherein the at least one magnetized source comprises at least one first magnetized source and at least one second magnetized source arranged on either side of the circumference formed by the emitters and the detectors.

6. The assembly according to claim 2 wherein the body has three magnetic field emitters distributed at 120° from one another around the central axis, the body having three magnetic field detectors distributed at 120° from one another around the central axis and angularly shifted from 60° around the central axis with regard to the magnetic field emitters.

7. The assembly according to claim 2 wherein the body has four emitters and detectors distributed at 90° over the circumference.

8. The assembly according to claim 1 wherein each magnetic field emitter is a permanent magnet or an electro-magnet having one pole directed radially towards an outside of the body of the probe.

9. The assembly according to claim 1 wherein the at least one magnetized source and at least one of the magnetic field emitters are arranged on a line substantially parallel to the central axis of the body.

10. The assembly according to claim 1 wherein each magnetic field emitter is an emitting coil.

11. The assembly according to claim 10 wherein each emitting coil is arranged on a line substantially parallel to the central axis of the body and substantially median between the magnetized source and a second magnetized source.

12. The assembly according to claim 1 wherein each magnetic field detector is a magnetometer.

13. A method for detecting and measuring a rate of fouling, by deposits containing at least one ferromagnetic material, of flow holes in tube support plates of a secondary circuit of a steam generator of a pressurized water nuclear reactor, using a detecting and measuring assembly according to claim 1 , the method comprising the following steps:
inserting at least one freely rotating probe into at least one tube of a bundle of tubes of the steam generator,
moving the at least one probe at a determined rate inside the at least one tube, automatically orienting a body of the probe by at least one magnetized source to position each magnetic field emitter opposite a solid portion of the flow hole and each magnetic field detector opposite an alveolus of the flow hole, and
transmitting the variations in the signals transmitted by the detectors when the at least one probe moving in the at least one tube arrives at each flow hole to be inspected in the tube support plates are amplified and visualized.

14. The method according to claim 13 wherein the variations in the signals transmitted by the detectors includes mapping the distribution of the deposits in each alveolus for at least one flow hole of the at least one tube support plate of the steam generator.

15. The assembly according to claim 1 wherein the body of the probe is freely rotatable in the tube.

16. The assembly according to claim 1 wherein the at least one magnetized source is arranged on the outer surface of the body such that the at least one magnetized source is magnetically attracted by one of the solid portions of the flow hole when the probe inside the tube is moved to each flow hole and the probe aligns itself in a given angular position with respect to the flow hole.

17. The assembly according to claim 1 wherein the at least three magnetic field emitters are angularly spaced from one another around the body of the probe.

Assignees

• Debroise Mikael
• Kernin Yann
• Piriou Marc
• Sartre Bernard
• Areva Np

Inventors

• Debroise Mikael
• Kernin Yann
• Piriou Marc
• Sartre Bernard

Classifications

• G01N17/008

  Monitoring fouling · CPC title

• F22B37/003 Primary

  Maintenance, repairing or inspecting equipment positioned in or via the headers · CPC title

• G01N27/87

  using probes · CPC title

• Y02E30/30

  Nuclear fission reactors · CPC title

• G21C17/017 Primary

  Inspection or maintenance of pipe-lines or tubes in nuclear installations · CPC title