Incore and Thermocouples - New Incore

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Incore System:

The Incore system is responsible for providing information about neutron flux distribution in nuclear power plants.

This information is supplied using mobile detectors.

Neutron flux detectors have the ability to cover all the fuel to generate a three dimensional map of neutron flux and provide data that enable determination of power distribution of the reactor at any time and to check calibration, linear power density, fuel burned and fuel inventories. These data also provide basic operating condition trends, enabling corrective actions to be taken before a problem becomes critical.

Thimbles are the guides through which nuclear detectors are inserted to make a map of the core. These tubes are subject to friction of the detectors moving inside and can lose thickness. For this reason, in every refuelling operation, 50 thimbles are inspected by induced currents to measure wear and to identify possible fragile areas, and if necessary, they are replaced.

The main difficulty in this work is extracting, cutting and storing old thimbles because they are radioactive by being inserted into the fuel elements. Extraction is performed with the cavity full and work is done using the fuel crane with the help of the polar crane. Thimbles are retracted before the fuel is unloaded and the operation of extraction and cutting is performed when there is no nuclear fuel present. The operation takes some 12 hours. Subsequently, the level of water in the cavity is lowered to the level of the flange and new thimbles are inserted by hand, they are cut to measure and the connections prepared.

New Incore is a specialised and highly qualified company that performs preventative, predictive and corrective maintenance of the Incore system from the control room to the reactor. We have highly trained staff and specific equipment to perform this work, consisting of high technology machinery and equipment developed and manufactured by the company.

New Incore carries out maintenance on the nuclear system, both in normal operation and at the time of refuelling, consisting of:

1. Thermal imaging of the electronic cabin.
2. Reflectometry.
3. Detector monitoring to prevent any anomalies.
4. Recording of data from electro-mechanical devices.
5. Reporting the work performed.

Breakdown of specific work performed by New Incore:
a) Maintenance
1. Replacement of thimbles.
2. Cleaning of thimbles.
3. Extraction and insertion of thimbles.
4. Replacement of the high pressure seal.
5. Revision of the 5- and 10-way transfer device.
6. Revision of the impulsion unit.
7. Replacement of nuclear detectors.
8. Cleaning of Teleflex cables.
9. Lubrication of Teleflex cables.
10. Revision of the electronics booth.

b) Upgrade, replacement and installation of old and obsolete equipment with new equipment:
1. Replacement of impulse unit cabling.
2. Replacement of control unit and power drive unit.
3. Replacement of encoder cabling.
4. Replacement of overhead connector and cabling of the 5- and 10-way transfer channels.
5. Internal replacement of cabling and micro-switches in 5- and 10-way transfer channels.
Thermocouple system:
Thermocouple system
The thermocouple system provides the temperature of the fuel elements. The thermocouples are mounted on the top of the core, with a specific distribution for good data recording of the fuel assembly.

New Incore is a highly specialised and qualified company for performing maintenance of the thermocouple system. We have highly trained staff and specific equipment to perform this work, consisting of high technology machinery and equipment developed and manufactured by the company.

New Incore carries out preventative maintenance on the thermocouple system, both in normal operation and at the time of refuelling, consisting of:

  1. Thermal imaging of the control train.
  2. Data recording from the control train, both hot and cold.
  3. Reflectometry.
  4. Tele-visual inspections of the thermocouple guide tubes.
  5. Reporting work performed.

Breakdown of specific work performed by New Incore:
  1. Replacement of thermocouples.
  2. Replacement of lower and upper Whitaker.
  3. Modification of thermocouple conducting tubes.
  4. Replacement of ERD connectors.
  5. Control and adjustment of thermocouple mechanical elements.
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