Light water reactor fuel assembly, light water reactor core and MOX fuel assembly production method

Patent metadata

Field	Value
Publication number	US-12159728-B2
Application number	US-202318219216-A
Country	US
Kind code	B2
Filing date	Jul 7, 2023
Priority date	Sep 26, 2016
Publication date	Dec 3, 2024
Grant date	Dec 3, 2024

Abstract

A method of producing a light water reactor fuel assembly may include: setting conditions at least concerning an operation cycle period and burnup; setting an initial enrichment of enriched uranium; calculating excess reactivity of a light water reactor core where light water reactor fuel assemblies including the enriched uranium are burned until an end stage of a final operation cycle; determining whether a condition where excess reactivity at an end of a first operation cycle in the burnup calculation step is close to a predetermined positive value is true or not; and returning to the setting of the initial enrichment, when it is determined at the determining that the situation is not true, or deciding an enrichment of the enriched uranium when it is determined that the situation is true.

First claim

What is claimed is:

1. A method of producing a light water reactor fuel assembly, comprising:
setting conditions at least concerning an operation cycle period and average discharge burnup;
setting an initial enrichment of enriched uranium to 5% or more;
calculating excess reactivity of a light water reactor core where light water reactor fuel assemblies including the enriched uranium are burned until an end stage of a final operation cycle;
determining whether excess reactivity is positive through the operation cycle and 0.3% Δk at an end of a first operation cycle in the calculating of the excess reactivity;
returning to the setting of the initial enrichment, if the determining determines that the excess reactivity is not positive and 0.3% Δk, or deciding an enrichment of the enriched uranium if the determining determines that the excess reactivity is positive and 0.3% Δk; and
placing the enriched uranium determined in the determining to have the excess reactivity that is positive and 0.3% Δk as fuel pellets into a cladding tube configured to house the enriched uranium pellets, the cladding tube being configured as a LWR fuel rod suitable for in the light water reactor fuel assembly in an array of LWR fuel rods and burnable poison-containing fuel rods.

2. The method of claim 1 , further comprising:
assembling the light water reactor fuel assembly using the enriched uranium,
wherein the light water reactor fuel assembly comprises:
a plurality of the LWR fuel rods, wherein the fuel pellets in each of the LWR fuel rods comprise a first uranium enriched to a first value, and the first uranium in the fuel pellets is present in the form of uranium dioxide, uranium carbide, or uranium nitride; and
a plurality of the burnable poison-containing fuel rods comprising a burnable poison and a second uranium enriched to a second value, wherein the first value is greater than the second value,
wherein the LWR fuel rods extend longitudinally and are arranged parallel to each other,
wherein the burnable poison-containing fuel rods extend longitudinally and are arranged in a lattice pattern together with the LWR fuel rods,
wherein the plurality of fuel assemblies are arranged parallel to each other and in a lattice pattern,
wherein each of the LWR fuel rods has the enriched uranium at the initial enrichment, resulting the excess reactivity of the light water reactor core being positive at the end of a first operation cycle, and
wherein burnable poison in the burnable poison-containing fuel rods at least partially remains at a middle point of a second operation cycle.

3. The method of claim 1 , further comprising:
setting the initial enrichment of the enriched uranium for the fuel assembly higher than a normal-type initial uranium enrichment value in a normal-type uranium fuel assembly comprising burnable poison-containing fuel rods; and
setting the uranium enrichment value in the normal-type uranium fuel assembly in such a way that excess reactivity at an end of an operation cycle comes to zero.

4. The method of claim 1 , wherein a concentration of the burnable poison contained in each of the burnable poison-containing fuel rods in the fuel assemblies is higher than a concentration of the burnable poison contained in each of fuel rods in the normal-type uranium fuel assemblies.

5. The method of claim 1 , further comprising:
arranging a plurality of the LWR fuel rods to extend longitudinally and parallel to each other in an array.

6. The method of claim 5 , further comprising:
arranging a plurality of the burnable poison-containing fuel rods to extend longitudinally and in a lattice pattern together with the LWR fuel rods.

Assignees

• Toshiba Kk

Inventors

• Hiraiwa Kouji
• Kimura Rei
• Sakurai Shungo
• Aizawa Rie
• Yanase Goro
• Kawamura Shinichiro

Classifications

• G21C3/3262

  Enrichment distribution in zones · CPC title

• Y02E30/30

  Nuclear fission reactors · CPC title

• G21C21/02

  Manufacture of fuel elements or breeder elements contained in non-active casings · CPC title

• G21C3/623

  Oxide fuels · CPC title

• G21C3/326 Primary

  comprising fuel elements of different composition; comprising, in addition to the fuel elements, other pin-, rod-, or tube-shaped elements, e.g. control rods, grid support rods, fertile rods, poison rods or dummy rods · CPC title