PWR Outer Nuclear Detection System and Detection Method

Abstract

The invention provides an ex-core nuclear detection system for a pressurized water reactor. The ex-core nuclear detection system is used for zero-power physics testing of reactors, and comprises an intermediate range detector and a reactivity meter, wherein the intermediate range detector is arranged outside a reactor pressure vessel and is used for measuring the nuclear power of the reactor; the reactivity meter calculates the reactivity of the reactor core according to data measured by the intermediate range detector; the reactive data can be used for measuring an isothermal temperature coefficient and a control rod value. Therefore, data measured by the intermediate range detector is transmitted into the reactivity meter, a test with high flux fluctuation can be performed, the gamma noise influence is small, the system can be far away from a Doppler heating point, the measurement result is accurate, low leakage and a low-leakage loading scheme can be implemented, the economic efficiency of fuel utilization is improved, and design of multi-reflection layer can be adopted, so that the economic efficiency and shock resistance of the fuel utilization are further improved, the measurement result is slightly influenced by spatial positions, and the influence of reactor cavity water injection transformation and the like because of RPN outward movement can be effectively reduced.

Description

technical field [0001] The invention relates to the detection field of the outer core of a pressurized water reactor, in particular to the use of a reactivity instrument to measure the temperature coefficient of the reactor core and the value of a control rod during a zero-power physical test of a pressurized water reactor. Background technique [0002] During the zero-power physical test of the PWR, it is necessary to measure the temperature coefficient of the core and the value of the control rods with reactivity instruments. At this time, the working range of the reactivity instrument is generally required to be: the upper limit current is 1 / 5 of the current corresponding to the Doppler heating point (about 0.1% FP), and the lower limit current is greater than the background noise current (generated by the decay of spent fuel assemblies in the core). Gamma results), and the distance between the upper and lower limit currents differs by at least one order of magnitude. In...

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Problems solved by technology

[0004] However, when the core fuel is loaded in a low-leakage arrangement, because the peripheral components use deep burn-up components, the power is low, and more gamma will be generated during decay, which cannot be accurately detected under the influence of gamma noise. It will make it difficult for the reactive instrument current to meet the requirements of zero-power physical tests, and it is necessary to frequently adjust the control rods to control the reactivity of the core

For the core with a heavy reflection layer, because the flux at the detector is too low, limited by the sensitivity, the power range detector will not be able to provide a large current to the reactivity meter, which also makes it difficult to realize zero-power physical tests

In this regard, the existing technology will consider how to increase the sensitivity of the detector or increase the neutron flux, but the first change is costly, and the second change requires rigid design changes to the internal components such as the reflector, which is complicated to operate

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