CN113871040A - Reactivity instrument and system with background current correction - Google Patents

Reactivity instrument and system with background current correction Download PDF

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Publication number
CN113871040A
CN113871040A CN202111147553.6A CN202111147553A CN113871040A CN 113871040 A CN113871040 A CN 113871040A CN 202111147553 A CN202111147553 A CN 202111147553A CN 113871040 A CN113871040 A CN 113871040A
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reactivity
current
background current
meter
background
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林昭涛
何子帅
胡驰华
樊武
吕标剑
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Cai Yueqing
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Fuzhou Qizhenggu Technology Co ltd
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    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21C—NUCLEAR REACTORS
    • G21C17/00—Monitoring; Testing ; Maintaining
    • G21C17/10—Structural combination of fuel element, control rod, reactor core, or moderator structure with sensitive instruments, e.g. for measuring radioactivity, strain
    • G21C17/104—Measuring reactivity
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin
    • Y02E30/30—Nuclear fission reactors

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  • Plasma & Fusion (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Measurement Of Radiation (AREA)
  • Monitoring And Testing Of Nuclear Reactors (AREA)

Abstract

The invention relates to the technical field of reactivity instruments, in particular to a reactivity instrument with background current correction and a system. A reactivity meter with background current correction, the reactivity meter for: when the reactor is not critical, the current measured by the detector when it is just switched into the reactivity meter can be set as the background current. After the background current is obtained, the current caused by the neutrons with the background current removed can be used in subsequent reactivity calculation, so that the lower limit of the power level measurement of the reactivity meter is further reduced, and the reactivity measurement precision is ensured while the power level measurement range of the reactivity meter is enlarged.

Description

Reactivity instrument and system with background current correction
Technical Field
The invention relates to the technical field of reactivity instruments, in particular to a reactivity instrument with background current correction and a system.
Background
The reactivity is the relative deviation of the effective multiplication coefficient Keff of the reactor to a critical value, and is an important parameter reflecting the operation condition of the reactor when the reactor is physically started. The accurate measurement of the reactor is of great significance to the safe operation of the reactor and the exertion of the economic benefit of the reactor. The reactivity meter is a device for directly measuring the reactivity of the reactor and is also a key device for starting a physical test of the reactor of the nuclear power plant.
In the existing refueling reactor, a power range non-gamma compensation ionization chamber detector generally has higher gamma current, namely background current. The existing reactivity meter directly substitutes the measured signal data into a point reactor equation to carry out inverse dynamic solution of reactivity, and therefore the reactivity measurement of the existing reactivity meter needs to require that the reactor power level is at a high enough level to ignore the influence of background current (mainly gamma current) and ensure the accuracy of the reactivity measurement. This makes the reactor power level measurement range of the reactivity meter limited, which affects greater use of the reactivity meter. And if the reactor power level measurement range of the reactivity meter is exceeded, it may result in inaccurate reactivity measurements.
Disclosure of Invention
Therefore, it is necessary to provide a reactivity meter with background current correction to solve the technical problems of inaccurate reactivity measurement caused by the background current, limited reactor power level measurement range of the reactivity meter, and the like. The specific technical scheme is as follows:
a reactivity meter with background current correction, the reactivity meter for: when the reactor is not critical, the background current measured by the detector when the detector is just connected to the reactivity meter is received.
Further, the reactivity meter is configured with a display;
a system setting interface of the reactivity instrument is provided with a background current setting interface;
the background current setting interface is displayed on the display.
Further, the reactivity meter is further configured to: and calculating current caused by neutrons according to the background current, and calculating reactivity according to the current caused by the neutrons.
In order to solve the technical problem, a system with background current correction is also provided, and the specific technical scheme is as follows:
a system with background current correction, comprising: a reactivity meter and detector;
the detector is used for: measuring to obtain background current when the reactor is not critical and is just connected into a reactivity instrument, and sending the background current to the reactivity instrument;
the reactivity meter is used for: the background current is received.
Further, the reactivity meter is configured with a display;
a system setting interface of the reactivity instrument is provided with a background current setting interface;
the background current setting interface is displayed on the display.
Further, the reactivity meter is further configured to: and calculating current caused by neutrons according to the background current, and calculating reactivity according to the current caused by the neutrons.
The invention has the beneficial effects that: a reactivity meter with background current correction, the reactivity meter for: when the reactor is not critical, the current measured by the detector when it is just switched into the reactivity meter can be set as the background current. After the background current is obtained, the current caused by the neutrons with the background current removed can be used in subsequent reactivity calculation, so that the lower limit of the power level measurement of the reactivity meter is further reduced, and the reactivity measurement precision is ensured while the power level measurement range of the reactivity meter is enlarged.
Drawings
FIG. 1 is a schematic diagram of a current curve and a reactivity curve for unreduced background current and a current curve and a reactivity curve for subtracted background current according to one embodiment;
FIG. 2 is a schematic diagram of a background current setting interface according to an embodiment;
FIG. 3 is a block diagram of a system with background current correction according to an embodiment.
Description of reference numerals:
300. a system with background current correction is provided,
301. the reactivity instrument is used for measuring the reactivity of the sample,
302. and a detector.
Detailed Description
To explain technical contents, structural features, and objects and effects of the technical solutions in detail, the following detailed description is given with reference to the accompanying drawings in conjunction with the embodiments.
Referring to fig. 1-2, in this embodiment, an embodiment of a reactivity meter with background current correction is as follows:
a reactivity meter with background current correction, the reactivity meter for: when the reactor is not critical, the background current measured by the detector when the detector is just connected to the reactivity meter is received.
Further, the reactivity meter is further configured to: and calculating current caused by neutrons according to the background current, and calculating reactivity according to the current caused by the neutrons.
The following specific description is provided for the specific implementation process:
the signal detected by the detector actually contains two parts, one is the neutron-induced current (signal, for convenience of expression, current is taken as an example here), the other is the gamma-induced current, and the other is the system measurement noise, i.e. the system measurement noise
Im＝In+Iγ+Inoise (1)
In the formula ImIs the current measured by the detector; i isnIs a current due to neutrons; i isγIs a gamma induced current; i isnoiseIs the measured noise current of the system.
For convenience, the gamma-induced current and the measured noise current of the system are collectively referred to as the background current, i.e.
Ibg＝Iγ+Inoise (2)
The formula (1) becomes
Im＝In+Ibg (3)
The core of the first furnace is clean and has no contribution of gamma current. If the measurement system does well and the system noise is negligible, then
Im≈In
After refueling or core operation, the gamma current in the detectors is not negligible. Although the pulse neutron detector and the gamma compensation neutron ionization chamber can theoretically eliminate the influence of gamma, in practice, the working voltage of the pulse neutron detector and the gamma compensation neutron ionization chamber must be set properly to reduce the influence of gamma to be small enough; rather than a compensated neutron ionization chamber, the measured signal, as the name implies, has a gamma contribution in addition to the neutron contribution.
The conventional reactivity meter applies this signal ImThe method is characterized in that a point reactor kinetic equation is directly substituted into the point reactor kinetic equation to be used as n for solving the reactivity, so that the calculation accuracy of the reactivity is influenced, the influence of the gamma current can be ignored only when the power level is high enough, and the measurement accuracy of the reactivity is ensured.
The reactivity meter of the present application can subtract background current, i.e.
In＝Im-Ibg (4)
Neutron current InSubstituting into the point reactor kinetic equation (i.e. as n), thereby further reducing the lower limit of the power level measurement of the reactivity meter (above the source influence area), increasing the power level measurement range of the reactivity meter and ensuring the reactivity measurement precision.
Figure BDA0003285996050000041
Referring to FIG. 1, I1 and ρ 1 are the current curve and reactivity curve of the un-subtracted background current, and I2 and ρ 2 are the current curve and reactivity curve of the subtracted background current, respectively. The reactivity calculated with the current without background current subtracted is significantly affected by the background current, and when the current drops to 5e-8A when the control rod is inserted, the reactivity begins to deviate from the constant, which is inconsistent with expectations. I2 is the current with background current subtracted, and the reactivity calculated by it can maintain constant for a longer time, corresponding to the control rod insertion, and the calculation of reactivity is more accurate before the current drops to 2 e-9A. In this example, the lower current limit that ensures the accuracy of the reactivity calculation drops by a factor of about 25 after background current subtraction. In addition, after subsequent rodding, the reactivity ρ 2 shows normal, while the reactivity ρ 1 shows incorrect.
After the background current is obtained, the current caused by the neutrons with the background current removed can be used in subsequent reactivity calculation, so that the lower limit of the power level measurement of the reactivity meter is further reduced, and the reactivity measurement precision is ensured while the power level measurement range of the reactivity meter is enlarged.
Further, the reactivity meter is configured with a display; a system setting interface of the reactivity instrument is provided with a background current setting interface; the background current setting interface is displayed on the display. Therefore, the reactivity meter can operate on the background current setting interface at any time to deduct the background current, so that the reactivity measurement precision is ensured, the power level range during the zero-power physical test is enlarged, and the measurement error of the reactivity during the test is reduced. As shown in fig. 2.
Referring to fig. 2 to 3, in this embodiment, an embodiment of a system 300 with background current correction is as follows:
a system 300 with background current correction, comprising: a reactivity meter 301 and a detector 302;
the detector 302 is configured to: when the reactor is not critical, measuring to obtain a background current just after accessing the reactivity instrument 301, and sending the background current to the reactivity instrument 301, wherein it is required to be noted that the detector 302 sends a current signal to the reactivity instrument 301 through a cable;
the reactivity meter 301 is used to: the background current is received.
Further, the reactivity meter 301 is also configured to: and calculating current caused by neutrons according to the background current, and calculating reactivity according to the current caused by the neutrons.
The following specific description is provided for the specific implementation process:
the signal detected by the detector 302 actually contains two components, one is the neutron-induced current (signal, current is taken as an example here for convenience of expression), the other is the gamma-induced current, and the other is the system measurement noise, i.e., the system measurement noise
Im＝In+Iγ+Inoise (1)
In the formula ImIs the current measured by the probe 302; i isnIs a current due to neutrons; i isγIs a gamma induced current; i isnoiseIs the measured noise current of the system.
For convenience, the gamma-induced current and the measured noise current of the system are collectively referred to as the background current, i.e.
Ibg＝Iγ+Inoise (2)
The formula (1) becomes
Im＝In+Ibg (3)
The core of the first furnace is clean and has no contribution of gamma current. If the measurement system does well and the system noise is negligible, then
Im≈In
After refueling or core operation, the gamma current in the probe 302 is non-negligible. Although the pulsed neutron detector 302 and the gamma-compensated neutron ionization chamber can theoretically eliminate the gamma influence, in practice, the working voltage of the pulsed neutron detector 302 and the gamma-compensated neutron ionization chamber must be set to be proper to reduce the gamma influence to be small enough; rather than a compensated neutron ionization chamber, the measured signal, as the name implies, has a gamma contribution in addition to the neutron contribution.
The conventional reactivity meter 301 applies this signal ImThe method is characterized in that a point reactor kinetic equation is directly substituted into the point reactor kinetic equation to be used as n for solving the reactivity, so that the calculation accuracy of the reactivity is influenced, the influence of the gamma current can be ignored only when the power level is high enough, and the measurement accuracy of the reactivity is ensured.
The reactivity meter 301 of the present application can subtract background current, i.e.
In＝Im-Ibg (4)
Neutron current InSubstituting into the point reactor kinetics equation (i.e., as n) further lowers the lower limit of the power level measurement of the reactivity meter 301 (above the source influence region), increases the power level measurement range of the reactivity meter 301, and ensures the reactivity measurement accuracy.
Figure BDA0003285996050000061
Referring to FIG. 1, I1 and ρ 1 are the current curve and reactivity curve of the un-subtracted background current, and I2 and ρ 2 are the current curve and reactivity curve of the subtracted background current, respectively. The reactivity calculated with the current without background current subtracted is significantly affected by the background current, and when the current drops to 5e-8A when the control rod is inserted, the reactivity begins to deviate from the constant, which is inconsistent with expectations. I2 is the current with background current subtracted, and the reactivity calculated by it can maintain constant for a longer time, corresponding to the control rod insertion, and the calculation of reactivity is more accurate before the current drops to 2 e-9A. In this example, the lower current limit that ensures the accuracy of the reactivity calculation drops by a factor of about 25 after background current subtraction. In addition, after subsequent rodding, the reactivity ρ 2 shows normal, while the reactivity ρ 1 shows incorrect.
After the background current is obtained, the current caused by the neutrons with the background current removed can be used in the subsequent reactivity calculation, so that the lower limit of the power level measurement of the reactivity meter 301 is further reduced, and the reactivity measurement precision is ensured while the power level measurement range of the reactivity meter 301 is enlarged.
Further, the reactivity meter 301 is configured with a display;
a background current setting interface is arranged on a system setting interface of the reactivity instrument 301;
the background current setting interface is displayed on the display. Therefore, the reactivity meter can operate on the background current setting interface at any time to deduct the background current, so that the reactivity measurement precision is ensured, the power level range during the zero-power physical test is enlarged, and the measurement error of the reactivity during the test is reduced. As shown in fig. 2.
It should be noted that, although the above embodiments have been described herein, the invention is not limited thereto. Therefore, based on the innovative concepts of the present invention, the technical solutions of the present invention can be directly or indirectly applied to other related technical fields by making changes and modifications to the embodiments described herein, or by using equivalent structures or equivalent processes performed in the content of the present specification and the attached drawings, which are included in the scope of the present invention.

Claims (6)

1. A reactivity meter with background current correction, said reactivity meter configured to: when the reactor is not critical, the background current measured by the detector when the detector is just connected to the reactivity meter is received.
2. A reactivity meter with background current correction according to claim 1, wherein said reactivity meter is configured with a display;
a system setting interface of the reactivity instrument is provided with a background current setting interface;
the background current setting interface is displayed on the display.
3. The reactivity meter with background current correction according to claim 1, further configured to: and calculating current caused by neutrons according to the background current, and calculating reactivity according to the current caused by the neutrons.
4. A system with background current correction, comprising: a reactivity meter and detector;
the detector is used for: measuring to obtain background current when the reactor is not critical and is just connected into a reactivity instrument, and sending the background current to the reactivity instrument;
the reactivity meter is used for: the background current is received.
5. A system with background current correction as described in claim 4, wherein said reactivity meter is configured with a display;
a system setting interface of the reactivity instrument is provided with a background current setting interface;
the background current setting interface is displayed on the display.
6. A system with background current correction as claimed in claim 4, wherein said reactivity meter is further configured to: and calculating current caused by neutrons according to the background current, and calculating reactivity according to the current caused by the neutrons.
CN202111147553.6A 2021-09-29 2021-09-29 Reactivity instrument and system with background current correction Pending CN113871040A (en)

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CN109961861A (en) * 2017-12-14 2019-07-02 中国核动力研究设计院 Reactivity measurement instrument under a kind of nuclear power plant reactor depth subcritical state
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CN101105986A (en) * 2007-08-03 2008-01-16 蔡光明 Reactor reactivity measuring method
CN101252026A (en) * 2008-03-25 2008-08-27 蔡光明 Reactor neutron source and gamma noise measuring method
US20100150295A1 (en) * 2008-12-11 2010-06-17 Westinghouse Electric Company Llc Subcritical reactivity measurement method
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CN109961861A (en) * 2017-12-14 2019-07-02 中国核动力研究设计院 Reactivity measurement instrument under a kind of nuclear power plant reactor depth subcritical state
CN112086212A (en) * 2020-09-15 2020-12-15 三门核电有限公司 Reactivity instrument offline calibration test method and system
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