Method for controlling a pressurized water nuclear reactor during stretchout

Patent metadata

Field	Value
Publication number	US-2016372222-A1
Application number	US-201414902299-A
Country	US
Kind code	A1
Filing date	Jul 4, 2014
Priority date	Jul 4, 2013
Publication date	Dec 22, 2016
Grant date	—

Abstract

A method for controlling a pressurized water nuclear reactor is provided, including core producing thermal power, sensors for acquiring the mean temperature of the primary coolant and for calculating the thermal power, actuators for controlling the axial distribution of power, the control method including:
a first control phase for controlling the reactor during normal operation by controlling the mean temperature of the primary coolant so as to make it correspond to a reference temperature profile (P ref ) dependent on the thermal power of the reactor; and a second control phase, referred to as stretchout, that occurs after normal operation of the reactor in order to control the reactor in stretchout by controlling the axial distribution of power, the mean temperature varying freely in a temperature range delimited by an upper limit and a lower limit.

First claim

1 . A method for controlling a pressurized water nuclear reactor comprising:
a core producing thermal power; sensors for acquiring the mean temperature of the primary coolant and for calculating the thermal power; actuators for controlling the temperature of the primary coolant; actuators for controlling the axial distribution of power; the control method comprising: a first control phase for controlling the reactor during normal operation by controlling the mean temperature of the primary coolant so as to make it correspond to a reference temperature profile (P ref ) dependent on the thermal power of the reactor; and a second control phase, referred to as stretchout, that occurs after normal operation of the reactor in order to control the reactor in stretchout by controlling the axial distribution of power, the mean temperature varying freely in a temperature range delimited by an upper limit and a lower limit.

2 . The method for controlling a pressurized water nuclear reactor according to claim 1 , characterized in that the upper limit of the temperature range corresponds to the reference temperature profile (P ref ) during normal operation of the reactor.

3 . The method for controlling a pressurized water nuclear reactor according to claim 1 , characterized in that the lower limit of the temperature range corresponds to the reference temperature profile (P ref ) during normal operation of the reactor with a shift of −Y° C., Y being comprised between 5 and 50, and preferentially between 5 and 30.

4 . The method for controlling a pressurized water nuclear reactor according to claim 1 , characterized in that the lower limit corresponds to a fixed temperature equal to the reference temperature at 100% of nominal power with a shift of −Z° C., Z being comprised between 10 and 50, and preferentially between 20 and 30.

5 . The method for controlling a pressurized water nuclear reactor according to claim 1 , characterized in that in stretchout phase the control of the axial distribution of power is brought about by movements of rod clusters in the core.

6 . The method for controlling a pressurized water nuclear reactor according to claim 5 , characterized in that in stretchout phase the control of axial distribution is brought about by movements of a group of rod clusters situated above mid-height of the core such that the lower ends move between the upper part and the mid-height of the core.

7 . The method for controlling a pressurized water nuclear reactor according to claim 6 , characterized in that during normal operating phase the control of the mean temperature of the primary coolant and the axial distribution of power are brought about by movements of rod clusters in the core with or without modification of the boron concentration of the primary liquid.

8 . The method for controlling a pressurized water nuclear reactor according to claim 1 , characterized in that in stretchout phase the control of the axial distribution of power is automated.

9 . The method for controlling a pressurized water nuclear reactor according to claim 1 , characterized in that in stretchout phase the control of the axial distribution of power is carried out to within a dead band around the set point axial distribution of power.

10 . The method for controlling a pressurized water nuclear reactor according to claim 1 , characterized in that in stretchout phase, the temperature range in which the mean temperature of the primary coolant can vary freely, is limited by the maximum power which can be supplied to the turbine dependent on the temperature of the primary coolant, called turbine limit

11 . The method for controlling a pressurized water nuclear reactor according to claim 2 , characterized in that the lower limit of the temperature range corresponds to the reference temperature profile (P ref ) during normal operation of the reactor with a shift of −Y° C., Y being comprised between 5 and 50, and preferentially between 5 and 30.

12 . The method for controlling a pressurized water nuclear reactor according to claim 2 , characterized in that the lower limit corresponds to a fixed temperature equal to the reference temperature at 100% of nominal power with a shift of −Z° C., Z being comprised between 10 and 50, and preferentially between 20 and 30.

Assignees

• Areva Np

Inventors

• Grossetete Alain

Classifications

• G21D3/08 Primary

  Regulation of any parameters in the plant · CPC title

• G21Y2002/203

  Physics · mapped topic

• G21C17/022

  for monitoring liquid coolants or moderators · CPC title

• G21Y2004/401

  Physics · mapped topic

• G21C7/117

  Clusters of control rods; Spider construction · CPC title