Method for determining at least one threshold value of at least one operating parameter of a nuclear reactor, and associated computer program and electronic system

Patent metadata

Field	Value
Publication number	US-11488735-B2
Application number	US-201816772787-A
Country	US
Kind code	B2
Filing date	Dec 18, 2018
Priority date	Dec 18, 2017
Publication date	Nov 1, 2022
Grant date	Nov 1, 2022

Abstract

A method for determining at least one threshold value of at least one operating parameter of a nuclear reactor is implemented by an electronic determination system and includes the steps of determining a first threshold value of a respective operating parameter for an operation of the reactor at a first power; and determining a second threshold value of said parameter for an operation of the reactor at a second power. The operation at the lower power of the first and second powers is an operation continued for a duration of at least 8 hours over a 24-hour sliding window. The method also includes determining a third threshold value of said parameter for an operation of the reactor at a third power between the first power and the second power.

First claim

What is claimed is:

1. A method for determining at least one threshold value of at least one operating parameter of a nuclear reactor comprising a core in which fuel assemblies are loaded, the fuel assemblies comprising fuel rods each including nuclear fuel pellets and a cladding surrounding the pellets, the method being implemented by an electronic determination system and comprising:
determining a first threshold value of a respective operating parameter for an operation of the nuclear reactor at a first power;
determining a second threshold value of a respective operating parameter for an operation of the nuclear reactor at a second power,
the operation at the lower power of the first and second powers being an operation continued for a duration of at least 8 hours over a 24-hour sliding window; and
determining a third threshold value of the respective operating parameter for an operation of the nuclear reactor at a third power, the third power being between the first power and the second power,
the nuclear reactor being in a thermomechanical deconditioning mode of the fuel rods, the first power being greater than the second power, the nuclear reactor being intended to operate successively at the first power, the third power and the second power during the thermomechanical deconditioning mode of the fuel rods, the third power corresponding to a power level in the thermomechanical deconditioning mode.

2. The method according to claim 1 , wherein the first power preferably being substantially equal to the rated power of the nuclear reactor.

3. The method according to claim 1 , wherein the second power is substantially equal to a target power for a sustained operation at intermediate power of the nuclear reactor.

4. The method according to claim 1 , wherein the respective operating parameter is selected from the following group: a temperature deviation in the core, a linear power in the fuel rods and a neutron flux variation in the core.

5. The method according to claim 1 , wherein the method further comprises:
operating the nuclear reactor while verifying that the value of the operating parameter is below the respective threshold value of the operating parameter among the first, second and third threshold values for the operation of the nuclear reactor at the corresponding power among the first, second and third powers.

6. A non-transitory computer readable medium comprising a computer program comprising software instructions which, when executed by a computer, carry out the method according to claim 1 .

7. The method according to claim 1 , wherein the power level corresponds to an operating duration of the nuclear reactor at said power greater than one hour.

8. The method according to claim 7 , wherein the first power is substantially equal to a target power for a sustained operation at intermediate power of the nuclear reactor.

9. The method according to claim 7 , wherein the second power is substantially equal to the rated power of the nuclear reactor.

10. The method according to claim 1 , wherein each threshold value of the respective operating parameter is determined via a calculation of a PCI margin.

11. The method according to claim 10 , wherein the calculation of the PCI margin comprises:
ii) simulating at least one operating transition of the nuclear reactor,
iii) calculating a value reached by at least one physical property during the operating transition in at least part of a cladding of a fuel rod, and
iv) determining, as the PCI margin, a deviation between a maximum value reached by the value, calculated at ii), during the operating transition and a technological limit of the fuel rod.

12. The method according to claim 11 , wherein the transition simulated at ii) is a transition chosen from among the group consisting of:
an excessive load increase,
an uncontrolled withdrawal of at least one group of control clusters,
a fall of one of the control clusters, and
an uncontrolled boric acid dilution.

13. The method according to claim 11 , wherein the physical property is chosen from among the group consisting of:
a constraint or a constraint function in the cladding; and
a deformation energy density in the cladding.

14. An electronic system for determining at least one threshold value of at least one operating parameter of a nuclear reactor comprising a core in which fuel assemblies are loaded, the fuel assemblies comprising fuel rods each including nuclear fuel pellets and a cladding surrounding the pellets, the electronic system comprising:
a first determination module configured to determine a first threshold value of a respective operating parameter for an operation of the nuclear reactor at a first power;
a second determination module configured to determine a second threshold value of a respective operating parameter for an operation of the nuclear reactor at a second power,
the operation at the lower power of the first and second powers being an operation continued for a duration of at least 8 hours over a 24-hour sliding window; and
a third determination module configured to determine a third threshold value of the respective operating parameter for an operation of the nuclear reactor at a third power, the third power being between the first power and the second power,
the nuclear reactor being in a thermomechanical deconditioning mode of the fuel rods, the first power being greater than the second power, the nuclear reactor being intended to operate successively at the first power, the third power and the second power during the thermomechanical deconditioning mode of the fuel rods, the third power corresponding to a power level in the thermomechanical deconditioning mode.

15. A method for determining at least one threshold value of at least one operating parameter of a nuclear reactor comprising a core in which fuel assemblies are loaded, the fuel assemblies comprising fuel rods each including nuclear fuel pellets and a cladding surrounding the pellets, the method being implemented by an electronic determination system and comprising:
determining a first threshold value of a respective operating parameter for an operation of the nuclear reactor at a first power;
determining a second threshold value of the respective operating parameter for an operation of the nuclear reactor at a second power,
the operation at the lower power of the first and second powers being an operation continued for a duration of at least 8 hours over a 24-hour sliding window; and
determining a third threshold value of the respective operating parameter for an operation of the nuclear reactor at a third power, the third power being between the first power and the second power,
the nuclear reactor being in a thermomechanical reconditioning mode of the fuel rods, and the first power is less than the second power, the nuclear reactor being intended to operate successively at the first power, the third power and the second power during the thermomechanical reconditioning mode of the fuel rods, the third power corresponding to a power level in the thermomechanical reconditioning mode.

16. The method according to claim 15 , wherein the power level corresponds to an operating duration of the nuclear reactor at said power greater than one hour.

17. A method for determining at least one threshold value of at least one operating parameter of a nuclear reactor comprising a core in which fuel assemblies are loaded, the fuel assemblies comprising fuel rods each including nuclear fuel pellets and a cladding surrounding the pellets, the method being implemented by an electron

Assignees

• Framatome Sa

Inventors

• Andre Poyaud Gilles

Classifications

• G21D3/04

  Safety arrangements (emergency protection of reactor G21C9/00) · CPC title

• G21C7/36

  Control circuits · CPC title

• G21D3/001 Primary

  Computer implemented control · CPC title

• G21C17/112

  Measuring temperature · CPC title

• G21D3/10

  by a combination of a variable derived from neutron flux with other controlling variables, e.g. derived from temperature, cooling flow, pressure · CPC title