Method for calibrating axial power deviation of out-of-pile nuclear instrument system of nuclear power plant

Abstract

The invention relates to the technical field of a nuclear instrument system of a mega-kilowatt class nuclear power plant and provides a method for calibrating the axial power deviation of an out-of-pile nuclear instrument system of a nuclear power plant. The method comprises in the reactor circulation period, carrying out a xenon oscillation test (for acquiring one-step whole-core fluxgraph data and at least four set of partial fluxgraph data) to acquire power range calibration factors alpha for adjusting reactor core axial power offsets of measurement channels of the out-of-pile nuclear instrument system in the power range, utilizing the factor alpha of the last xenon oscillation test in all the cycles from the current xenon oscillation test to the next xenon oscillation test, and updating the parameters KU and KL of each measurement channel according to the factor alpha. The method reduces the frequency of the partial fluxgraph measurement, reduces the disturbance of the xenon oscillation test on a nuclear power unit and reduces the probability of the shutting-down in advance of the nuclear power unit.

Description

Technical field [0001] The invention relates to the technical field of nuclear instrument systems for mega-kilowatt nuclear power plants, and in particular to a method for calibrating the axial power deviation of nuclear instrument systems outside the reactor of nuclear power plants. Background technique [0002] The power range of the nuclear instrument system outside the nuclear power plant (hereinafter referred to as: RPN) can monitor axial power deviation (hereinafter referred to as: △I) and nuclear power online. Normally, after each refueling and every 90 effective power days, the full-core flux map measurement during the xenon oscillation is performed. Under normal circumstances, the △I indication accuracy of the RPN system can ensure that the deviation from the benchmark △I measured by the offline reactor core measurement system (RIC) is within the allowable range through this periodic test calibration (generally, the axial power deviation range is 3% FP, nuclear The allo...

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Problems solved by technology

However, when the RPN probe is aging, it is necessary to perform frequent xenon oscillation tests to calibrate ΔI (the shortest interval is only 4 days). When the boron concentration is low at the end of the service life, if the traditional monitoring method is used to frequently perform xenon oscillation tests on the core, it will cause damage to the unit. Introducing great disturbance and risk, the unit is difficult to control, and there is a situation that the deviation of ΔI indication cannot be corrected through the normal xenon oscillation test, which leads to the forced shutdown of the unit in advance. On the one hand, the forced shutdown of the nuclear power unit will give multiple Important equipment will bring impact. On the other hand, one shutdown for maintenance will cost at least 30 million yuan and the huge direct economic loss caused by waste disposal

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