Loading patent…
AssigneeWestinghouse Electric Corp.
InventorMichael D. Heibel
Estimating the term…
Excore detector measurements are used to generate on-line absolute reactor power in a pressurized water reactor (PWR) by calibrating detector current measurements to the reactor thermal power calculation made at a base time early in reactor cycle while the thermal reactor power measurement is still accurate. Measurements are also made at the base time of the three-dimensional core power distribution and the core inlet temperature. Present core power measurements are then made by measuring the present excore detector current, the most recent three-dimensional core power distribution and the present core inlet temperature. The present core power is then calculated as the ratio of the present detector current to the detector current at the base time multiplied by the reactor thermal power measurement at the base time. The product is then corrected for changes in three-dimensional power distribution as a function of the difference between the three-dimensional core power distribution at the base time and a most recent three-dimensional core power distribution. The product is also corrected for changes in core inlet temperature by a correction factor which is an exponential term in which the difference between the present core inlet temperature and the core inlet temperature at the base time is multiplied by a constant. This constant is empirically determined at two different temperatures, preferably during start-up.
A method for determining the power output of a pressurized water reactor having an excore detector system, said method comprising the steps of:
A system for determining the power output of a pressurized water reactor system having a reactor with a reactor core with a core inlet through which reactor coolant enters for circulation through said reactor core, a steam generator through which reactor coolant circulated through said reactor core passes before it returns to said core inlet and feedwater means supplying feedwater to said steam generator and providing a feedwater flow measurement from which thermal power generated by said reactor is calculated;
Dependencies are inferred from the claim text.
Drawings are temporarily unavailable. Open the PDF at USPTO
No related US applications are recorded in the indexed filing history.
Monitoring
Regulation of any parameters in the plant: by a combination of a variable derived from neutron flux with other controlling variables, e.g. derived…
Energy generation of nuclear origin
Energy generation of nuclear origin: nuclear fission reactors
Term ended 21 Jul 2014 (estimated)
USPTO file history isn’t available for this patent, so only indexed dates are shown.
1. Field of the Invention
This invention is directed to a method and apparatus for determining on-line core wide power output of a pressurized water reactor (PWR) using the excore detector system, and to correction of the same for changes in three-dimensional power distribution in the core and in coolant density.
2. Background of Information
A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which:
FIG. 1 is a schematic diagram of a PWR incorporating the invention.
FIG. 2 is a plot of total detector current versus weighted assembly power for a PWR shown in FIG. 1.
FIG. 1 illustrates a nuclear electric power generating plant 1 in which a nuclear steam supply system (NSSS) 3 supplies steam for driving a turbine-generator 5 to produce electric power. The NSSS 3 has a pressurized water reactor (PWR) 7 which includes a reactor core 9 housed within a reactor vessel 11. Fission reactions within the core 9 generate heat which is absorbed by a reactor coolant, light water, which is passed through the core. The heated coolant is circulated through a hot leg 13 to a steam generator 15. Reactor coolant is returned to the reactor 3 from the steam generator by a reactor coolant pump (RCP) 17 through a cold leg 19. Typically, a PWR has at least 2 and often 3 or 4 steam generators 15 each supplied with heated coolant through a hot leg 13 forming with a cold leg and an RCP 17 a primary loop, and each supplying steam to the turbine-generator 5. For clarity, only one loop has been shown.
Coolant returned to the reactor flows downward through an annular downcormer 18 and then upward through the core 9 in the direction indicated by the arrows in FIG. 1. The reactivity of the core 9, and therefore the power output of the reactor, is controlled on a short term basis by control rods 20 which may be selectively inserted into the core 9. Long term reactivity is regulated through control of the concentration of a neutron moderator such as boron dissolved in the coolant. Regulation of the boron concentration affects reactivity uniformly throughout the core as the coolant circulates through the entire core. On the other hand, the control rods 20 affect local reactivity and therefore, result in an asymmetry of axial and radial power distribution within the core 9.
Conditions within the core 9 are monitored by several different sensor systems. These include the excore detector system 21 which measures neutron flux escaping from the reactor vessel. The excore system 21 includes source range detectors (not shown) used when the reactor is shut-down, intermediate range detectors (also not shown) used during start-up and shut-down, and power range detectors used when the reactor is above about 5% power. The power range excore detectors comprise top and bottom equal length un-compensated ion chambers 21.sub.t and 21.sub.b stacked on top of each other to form a power range excore detector channel. There are four power range detector channels (only 2 shown in FIG. 1) symmetrically located, radially and axially, just outside the reactor vessel 11.