US 5,174,946 AGranted

Oscillation power monitoring system and method for nuclear reactors

AssigneeGeneral Electric Company

InventorsGlen A. Watford, Kiran Kumar

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Abstract

To detect core-wide and regional neutron flux oxcillations in a nuclear reactor core induced by thermal-hydraulic instabilities, local power range monitoring (LPRM) strings radially distributed throughout the core and having plural vertically spaced neutron flux detectors are locally assigned to individual oscillation power range monitoring (OPRM) cells radially distributed throughout the core. Groups of OPRM cells are assigned to different OPRM channels based on their geographical positions. Detector signals of the LPRM strings assigned to each OPRM cell are processed pursuant to a unique trip algorithm to detect neutron flux oscillations, and, upon meeting prescribed amplitude and frequency criteria, the assigned OPRM channel is tripped. Suppression of a thermal hydraulic instability is initiated when at least two OPRM channels assigned to geographically adjacent OPRM cells are tripped.

Claims18

Dependent claims

An oscillation power range monitoring system for a nuclear reactor having a core including a plurality of vertically oriented fuel assemblies, said system comprising, in combination:

A. a plurality of power monitoring strings radially distributed throughout said core in contiguous relation with said fuel assemblies, each said monitoring string including a plurality of neutron flux detectors arranged in vertically spaced relation;
B. a plurality of oscillation monitoring cells radially distributed throughout said core, each said monitoring cell receiving detector signals from selected said detectors of those of said monitoring strings situated in the local vicinity thereof and providing a cell output signal representative of a combination of said detector signals received thereby;
C. a plurality of oscillation monitoring channels, each assigned to a selected array of said monitoring cells;
D. means for individually processing said output signals of said monitoring cells in repeating sequence to detect oscillations thereof and operating to trip the assigned ones of said monitoring channels when said oscillations indicate a thermal-hydraulic instability;
and
E. means for issuing an oscillation suppression function signal when at least two of said monitoring channels are tripped.

3 more elements

A method for monitoring thermal-hydraulic instabilities in a nuclear reactor having a core including a plurality of vertically oriented fuel assemblies, said method including the steps of:

A. providing a plurality of power monitoring strings radially distributed throughout said core in contiguous relation with said fuel assemblies, each said monitoring string including a plurality of neutron flux detectors arranged in vertically spaced relation;
B. assigning unique, contiguous geometrical groupings of said monitoring strings respectively to different oscillation monitoring cells;
C. deriving an output signal for each said monitoring cell representative of signals issued by said detectors of said monitoring strings assigned thereto;
D. assigning respective pluralities of said cell output signals to different oscillation monitoring channels;
E. repetitively sampling said cell output signals;
F. tripping a monitoring channel when the cell output signal assigned thereto exhibits an oscillation characteristic of a thermal-hydraulic instability;
and
G. indicating an existing thermal-hydraulic instability when at least two of said monitoring channels assigned to geographically adjacent monitoring cells are tripped.

5 more elements

Dependencies are inferred from the claim text.