Simulation construction method for the measurement of control rod insertion time

Patent metadata

Field	Value
Publication number	US-10192006-B2
Application number	US-201314411361-A
Country	US
Kind code	B2
Filing date	Dec 24, 2013
Priority date	Dec 27, 2012
Publication date	Jan 29, 2019
Grant date	Jan 29, 2019

Abstract

Provided is a method of the simulation construction for measurement of the control rod insertion time including a three-dimensional modeling operation of an inside wall of the nuclear reactor, a control rod, etc; a flow field configuration operation wherein the flow field is differentially configured by a variable grid system comprising variable cells which change the configuration and by an aligned grid system comprising fixed cells which maintains the configuration; a calculation operation of simulation estimated value for the insertion time by analyzing the thermal-hydraulic phenomenon using the three-dimensional CFD; and a cell change operation, wherein an error between the estimated value and the actual value is verified whether the error lies within the reference range, and, when the error exceeds the reference range, the size of the variable cell and/or of the size of the fixed cell is changed.

First claim

The invention claimed is:

1. A method for improving design or operation of a nuclear reactor having at least one control rod that falls by gravity toward a core of the nuclear reactor, the method comprising:
determining an actual insertion time value when the control rod falls by gravity inside the nuclear reactor;
performing a simulation of a control rod falling by gravity toward a core of the nuclear reactor, said performing including:
three-dimensionally modeling an inside wall of the nuclear reactor, the control rod accommodated inside the nuclear reactor, a guide tube guiding the control rod, an impact absorption tube located at the bottom of the guide tube with a diameter smaller than the diameter of the guide tube, a first flow hole located in the inside wall of the guide tube, and a second flow hole located at the bottom of the impact absorption tube;
configuring a flow field by dividing the inside of the nuclear reactor into a plurality of cells, wherein the flow field is configured by a variable grid system comprising a plurality of variable cells having a configuration that changes as the control rod changes location in the path along which the control rod passes, and by an aligned grid system comprising a plurality of fixed cells which maintain their configuration regardless of the location change of the control rod;
calculating a first simulation estimated value for the insertion time until the control rod is inserted into the impact absorption tube, wherein calculating the first simulation estimated value is determined by analyzing a thermal-hydraulic phenomenon using three-dimensional computational fluid dynamics (CFD) codes; and
calculating a second simulation estimated value, wherein the second simulation estimated value is determined by changing a size of one or more of the variable cells and/or a size of one or more of the fixed cells, when the first simulation estimated value is compared with the determined actual insertion time value, and an error between the first simulation estimated value and the actual insertion time value is determined to be out of a reference range; and

using the second simulation estimated value to change the size of the one or more variable cells and/or a size of one or more of the fixed cells, when the second simulation estimated value is compared with the determined actual insertion time value, and an error between the second simulation estimated value and the actual insertion time value is determined to be out of a reference range.

2. The method of claim 1 , further comprising calculating a hydraulic drag of the control rod caused by water filling inside of the nuclear reactor when the control rod falls.

3. The method of claim 1 , wherein said analyzing includes consideration of friction force between water and the control rod and weight of the control rod when the control rod falls.

4. The method of claim 1 , wherein the reference range is set in such a way that the error between the estimated value and the actual value lies within 5% of the reference range.

5. The method of claim 1 , wherein the thermal-hydraulic phenomenon comprises a pressure change, a temperature change, and a density change in the water around the control rod when the control rod falls.

Assignees

• Kepco Eng & Constr Co Inc

Inventors

• Kim Kyoung Ryun
• Lee Cheol Shin

Classifications

• G21C7/08 Primary

  by displacement of solid control elements, e.g. control rods · CPC title

• G06F17/10

  Complex mathematical operations {(function generation by table look-up G06F1/03; evaluation of elementary functions by calculation G06F7/544)} · CPC title

• G21D3/002

  Core design; core simulations; core optimisation · CPC title

• G21C17/00 Primary

  Monitoring; Testing (measuring in general G01); {Maintaining} · CPC title

• B01J2208/00725

  Mathematical modelling · CPC title