Method and apparatus for protecting a PWR from departure from nucleate boiling and hot leg boiling
AssigneeWestinghouse Electric Corp.
InventorPaul W. Robertson
Life of this patent
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Abstract
A pressurized water reactor (PWR) is protected from departure from nucleate boiling and from hot leg boiling by generating a segmented delta temperature trip function having a first line segment which closely follows the departure from nucleate boiling core limit line and a second segment closely following the hot leg boiling core limit line. Each line segment is a function of the average core temperature and coolant pressure with the departure from nucleate boiling segment further adjusted for axial power distribution. The two set points are continuously compared to actual delta temperature in four independent channels. If either set point is exceeded in at least two channels, the reactor is tripped.
Claims10
A method of protecting a pressurized water nuclear reactor from departure from nucleate boiling and hot leg boiling comprising the steps of
- determining a temperature change in coolant flowing through a reactor vessel (delta temperature);
- determining an average temperature of the coolant flowing through the reactor vessel (average temperature);
- determining a first set point for delta temperature relative to a departure from nucleate boiling core limit;
- determining a second set point for delta temperature relative to a hot leg boiling core limit;
- and
- tripping said reactor when delta temperature reaches or exceeds either said first set point value or said second set point value.
Apparatus for protecting a pressurized water nuclear reactor from departure from nucleate boiling and hot leg boiling, said apparatus comprising:
- temperature sensing means measuring temperature of coolant entering and leaving a reactor vessel;
- means determining from said temperature sensing means a temperature change in the coolant flowing through said reactor vessel (delta temperature) and an average temperature;
- means determining pressure of said coolant;
- means generating from said pressure and said average temperature a first set point value for said delta temperature relative to a departure from nucleate boiling core limit;
- means generating from said pressure and average temperature a second set point value for said delta temperature relative to a hot leg boiling core limit;
- and
- means tripping said reactor when said delta temperature reaches or exceeds said first said set point value or said second set point value.
Dependencies are inferred from the claim text.