Patent Number: 050248014
Section: claims

1. A method of updating a core model parameter for a system, comprising the steps of: (a) calculating a calculated value which correlates to a parameter of the model;  (b) computing a measured value, which correlates to the parameter, from measured system values;  (c) determining a deviation between the calculated value and the measured value;  (d) compensating the parameter when the deviation exceeds a predetermined value; and  (e) updating the parameter of the model when the parameter is compensated.  (a) calibrating the model periodically;  (b) measuring enthalpy rise and obtaining neutron detector signal readings, power level and rod position;  (c) updating the model using a depletion calculation;  (d) calculating analytical values of axial offset and axial pinch;  (e) calculating measured actual axial offset and axial pinch values from the enthalpy rise, readings, power level, position and axial offset and pinch expansion coefficients;  (f) integrating differences between the measured and analytical values;  (g) comparing an absolute value of the differences with predetermined compensation indication limits;  (h) adjusting second and third buckling coefficients until the calculated values are compensated, if one of the absolute values is greater than the corresponding limit;  (i) updating the parameters when the calculated values are compensated; and  (j) displaying the model including the updated parameters. 2. A method as recited in claim 1, wherein the calculated and measured values comprise calculated and measured axial offset values of a nuclear reactor. 3. A method as recited in claim 1, wherein the calculated and measured values comprises calculated and measured values of axial offset and axial pinch of a nuclear reactor. 4. A method as recited in claim 1, wherein the determined deviation is integrated over time and a time integral deviation is compared to the predetermined value to determine when to compensate. 5. A method of updating analytical model parameters of an analytical model used for prediction of distributions in a nuclear reactor core, comprising the steps of: 6. A method as recited in claim 5, wherein step (e) determines axial offset as EQU axial offset=B.sub.1 (DR.sub.t /Q)+B.sub.2 (DR.sub.b /Q)+B.sub.3 bp 7. A method as recited in claim 6, further comprising updating boron concentration.