Patent Number: 
Section: claims

1. A plant abnormality prediction detection system for detectably monitoring an abnormality prediction in a nuclear power plant, comprising:a data storage unit configured to store plant operation data including an instrument parameter measured in the nuclear power plant and an alarm threshold for a warning of abnormality in the nuclear power plant; anda monitoring control unit configured to detect an abnormality prediction in the nuclear power plant on the basis of the plant operation data,wherein the nuclear power plant performs a base-load operation so that the instrument parameter has a predefined target value, andwherein the monitoring control unit is further configured to set a region having a value which is equal to or smaller than the alarm threshold as a normality determination range in which the instrument parameter is normal and a region having a value greater than the alarm threshold as an abnormality determination range in which the instrument parameter is abnormal, and set, in the normality determination range, a normal range which is a range for a transition of the instrument parameter in an operation cycle from operation starting to operation stopping of the nuclear power plant based on the past plant operation data to store the normal range in the data storage unit in advance, and configured to detect an abnormality prediction in a case where the instrument parameter at the current time exceeds the set normal range. 2. The plant abnormality prediction detection system according to claim 1,wherein an alarm threshold for a warning of abnormality in the nuclear power plant is set in advance,wherein the alarm threshold is a threshold value for dividing a region of the instrument parameter into a normality determination range in which the instrument parameter is normal and an abnormality determination range in which the instrument parameter is abnormal, andwherein the normal range is set in the normality determination range. 3. The plant abnormality prediction detection system according to claim 1,wherein a plurality of operation modes corresponding to operation situations of the nuclear power plant are prepared in advance,wherein the normal range is prepared in a plurality on the basis of the plant operation data in the past operation situations corresponding to the plurality of operation modes, andwherein, if the operation mode corresponding to the present operation situation of the nuclear power plant is set, the monitoring control unit is further configured to set the normal range corresponding to the operation mode. 4. The plant abnormality prediction detection system according to claim 1,wherein the monitoring control unit is further configured to change a width of the set normal range.