CN103871511A - Method for monitoring axial power distribution of reactor in nuclear power station - Google Patents

Abstract

The invention discloses a method for monitoring the axial power distribution of a reactor in a nuclear power station. The method comprises the following steps: acquiring system signals of a nuclear instrument system, a rod control and rod position system and a reactor coolant system, obtaining core parameters, determining the operation area based on the system signals and the core parameters, acquiring core operation points, and determining the real time states of the core operation points in the operation area to monitor the axial power distribution of the reactor in the nuclear power station. The power distribution signal reflecting the operation states of the cores of the reactor can be obtained by calculating the acquired system signals and the core parameters of the reactor through the method. The monitoring method simultaneously takes thermal power, LOCA margin and the operation area into account, provides reliable bases for alarm and subsequent operations, is systemic and complete, and is in favor of maintaining the set safety.

Description

The monitoring method that a kind of nuclear power plant reactor axial power distributes

Technical field

The invention belongs to nuclear power technology field.More specifically, the present invention relates to the monitoring method that a kind of nuclear power plant reactor axial power distributes.

Background technology

In PWR nuclear power plant, conventionally regulate reactor core reactivity by the concentration that changes the position of control rod in reactor and adjust boron in moderator, reach startups, the reactor and change the object of piling power of closing down.Under without rod part, presurized water reactor axial power is scattered in cosine distribution, and radially power becomes Bessel's function to distribute.Radially power distribution can be arranged by the radial symmetry with variable concentrations subregion fuel arranged, burnable poison rod and control rod, Optimal Control rod divides into groups and carry/plunger program design measure flatten, and it is in operation and changes not quite, and can accurately predicting.Axial power is distributed in service variation, because moderator temperature effect, burnable poison effect, Doppler effect and power level effect, fission product effect, control rod assembly move with burnup and all axial power distributed and exerted an influence.Therefore the monitoring that the monitoring that reactor capability distributes, particularly axial power distribute just seems especially important for reactor control.In prior art, also not existing can be to the axial power of the reactor complete scheme of carrying out accurate and effective monitoring that distributes.

Summary of the invention

The technical problem to be solved in the present invention is, for still not existing in prior art, the axial power of reactor is distributed and carries out the effectively problem of the complete scheme of monitoring, the monitoring method that provides a kind of system and perfect reactor axial power to distribute, the axial power distribution signal obtaining based on this monitoring method can further provide and shows and report to the police.

The technical problem to be solved in the present invention is achieved by the following technical programs: the monitoring method that provides a kind of nuclear power plant reactor axial power to distribute, comprises the following steps:

Gather the system signal of core instrument system, Rod control and position indication system and reactor coolant loop;

Obtain reactor core parameter;

Determine operation area based on described system signal and described reactor core parameter; And

Gather reactor core operating point and determine the real-time status of described reactor core operating point in described operation area, distribute to monitor described nuclear power plant reactor axial power.

In the monitoring method distributing at above-mentioned nuclear power plant reactor axial power, determine that the real-time status of described reactor core operating point in described operation area comprises: determine whether described reactor core operating point exceeds the scope being limited by described operation area.

In the monitoring method distributing at above-mentioned nuclear power plant reactor axial power, if described reactor core operating point exceeds the scope that described operation area limits, send the first warning; Otherwise, continue described nuclear power plant reactor axial power to distribute and monitor.

In the monitoring method distributing at above-mentioned nuclear power plant reactor axial power, the calculating of described operation area comprises left limit value line, right limit value line, left physics limit value line and the right physics limit value line of determining described operation area.

In the monitoring method distributing at above-mentioned nuclear power plant reactor axial power, carry out the calculating of described left limit value line by formula (1-1) and formula (1-2):

$\mathrm{PR}\left[K\right]>\frac{-100\×P4}{P3-P4+100}:\mathrm{DPAXG}\left[K\right]=\left(\frac{(P3-P4)\×\mathrm{PR}\left[K\right]}{100}\right)+P4$ Formula 1-1

$\mathrm{PR}\left[K\right]\≤\frac{-100\×P4}{P3-P4+100}:\mathrm{DPAXG}\left[K\right]=-\mathrm{PR}\left[K\right]$ Formula 1-2

PR[K] be quadrant core power, DPAXG[K] be the trapezoidal left margin axial deviation value of operation, Axial power difference when P3 is 100%NP, the P4 Axial power difference of extrapolating while being 0%NP;

In the monitoring method distributing at above-mentioned nuclear power plant reactor axial power, carry out the calculating of described right limit value line by formula (1-3), formula (1-4) and formula (1-5):

$\mathrm{PR}\left[K\right]>\frac{100\×Z}{(100-\mathrm{DPAXREF})}:\mathrm{DPAXD}\left[K\right]=\left(\frac{\mathrm{DPAXREF}\×\mathrm{PR}\left[K\right]}{100}\right)+Z$ Formula 1-3

$\mathrm{PR}\left[K\right]\≤\frac{100\×Z}{(100-\mathrm{DPAXREF})}:\mathrm{DPAXD}\left[K\right]=\mathrm{PR}\left[K\right]$ Formula 1-4

DPAXREF[K]=DPAXREF × PR[K] formula 1-5

PR[K] be quadrant core power, DPAXREF is with reference to Axial power difference, DPAXD[K] and be the trapezoidal right margin axial deviation value of operation, Z is adjustable parameter.

In the monitoring method distributing at above-mentioned nuclear power plant reactor axial power, described method also comprises based on described system signal and reactor core parameter is carried out thermal power calculating and LOCA nargin is calculated, and obtains respectively thermal power value and LOCA nargin monitoring result.

In the monitoring method distributing at above-mentioned nuclear power plant reactor axial power, described method also comprises determining whether described LOCA nargin monitoring result exceeds Core Design LOCA nargin threshold value, distribute with nuclear power plant reactor axial power described in indirect monitoring.

In the monitoring method distributing at above-mentioned nuclear power plant reactor axial power, if described LOCA nargin monitoring result exceeds Core Design LOCA nargin threshold value, send the second warning; Otherwise, continue described nuclear power plant reactor axial power to distribute and carry out indirect monitoring.

In the monitoring method distributing at above-mentioned nuclear power plant reactor axial power, carry out described evenly heat power calculation by formula (2):

$\mathrm{Pthavg}=\left(\frac{Q+\mathrm{POWA}}{\mathrm{POW}0}\right)$ (formula 2)

Pthavg is nondimensionalization evenly heat power, and Q is Dynamic Thermal power, and POWA is static heat power, and POW0 is unit name thermal power.

In the monitoring method distributing at above-mentioned nuclear power plant reactor axial power, described LOCA nargin is calculated and is comprised linear power density distribution calculating, wherein carries out described linear power density distribution by formula (3-1) with (3-2) and calculates:

PL[Z] [K]=CK × POWZ[Z] [K] × FXYZ[Z] × KGL × Pthavg (formula 3-1)

$\mathrm{MLOC}\left[K\right]={\mathrm{Min}}_z(\frac{\mathrm{DLOC}\left[K\right]}{\mathrm{PL}\left[Z\right]\left[K\right]}-1)\×\mathrm{Pthavg}$ (formula 3-2)

PL[Z] [K] be heap linear power density corresponding to external pelivimetry passage K, MLOC[K] be the LOCA nargin of each measurement passage, Pthavg is evenly heat power, FXYZ[Z] be the radially power peak of axial node, POWZ[Z] [K] be that quadrant reactor core axial power distributes, KGL is grid correction factor, DLOC[Z] be axial nodal line power limit under LOCA operating mode, KGL is grid correction factor, and CK is the mean linear power density density under maximum reactor power level.

The present invention is by gathering the system signal (the especially heap external power based on RPN systematic survey) of core instrument system (RPN), Rod control and position indication system (RGL) and reactor coolant loop (RCP), and carry out thermal power calculating, the calculating of LOCA nargin and determine the processing such as operation area in conjunction with reactor core parameter, obtain can reactor in-core running status reactor axial power distribution signal, realize power distribution monitoring, the monitoring of LOCA nargin and acceptable operating point monitoring that reactor is carried out.In a treatment cycle, gather related system signal, and in signal acquisition process, 4 long ion chamber of RPN system power range adopt respectively 6 sensitive section, its object is to produce the axial average power distribution of reactor core, and the method is than the conventional axial dipole field parameter running status of reactor in-core better.

Therefore, known based on above narration, implement the power distribution signal that the present invention can obtain by the calculating operation that the reactor core parameter of the system signal gathering and reactor self is carried out reflection reactor in-core running status, this monitoring method has been considered the monitoring of thermal power, LOCA nargin and operation area three aspects: simultaneously, and can provide and report to the police and provide reliable basis for subsequent operation, monitoring method system and perfect, is conducive to safeguard unit safety.

Accompanying drawing explanation

Below with reference to the drawings and specific embodiments, the present invention is described in further details.In accompanying drawing:

Fig. 1 is the process flow diagram of the monitoring method of nuclear power plant reactor axial power distribution of the present invention;

Fig. 2 is another process flow diagram of the monitoring method of nuclear power plant reactor axial power distribution of the present invention;

Fig. 3 is the schematic diagram of the operation area that calculates in one embodiment of the invention.

Embodiment

For making object of the present invention, technical scheme and effect clearer, below with reference to the drawings and specific embodiments, the present invention is described in further details.It should be understood that following examples are only in order to explain the present invention, and the present invention is not done to any restriction.

The monitoring method that nuclear power plant reactor axial power provided by the present invention distributes as shown in Figure 1.The method comprises the following steps:

The system signal of step S11, collection core instrument system (RPN), Rod control and position indication system (RGL) and reactor coolant loop (RCP).This step is carried out signals collecting in a treatment cycle.

Step S12, obtain relevant reactor core parameter, Axial power difference etc. for example, during with reference to Axial power difference, 100%NP.The processing that required reactor core parameter is specifically carried out by observation process operates decision, in actual monitoring process, after definite processing operation, obtains relevant reactor core parameter again.

Step S13, determine operation area based on system signal and reactor core parameter.In the time determining operation area, especially calculate the left limit value line of operation area, right limit value line, left physics limit value line and right physics limit value line, the while need to be determined left early warning line and right early warning line according to concrete monitoring accuracy.For example, shown in Fig. 2, be the schematic diagram (A, B, C and the D of Fig. 2 represents to determine the right definitely point of limit value line) of determined operation area in one embodiment of the invention.

Definite feature modeling that refers to running status point (core power, Axial power difference) of operation area; Its processing procedure comprises calculates left margin and right margin, specifically comprises respectively the calculating of left and right limit value line, left and right early warning line and left and right physics limit value line.

Left limit value line computation:

$\mathrm{PR}\left[K\right]>\frac{-100\×P4}{P3-P4+100}:\mathrm{DPAXG}\left[K\right]=\left(\frac{(P3-P4)\×\mathrm{PR}\left[K\right]}{100}\right)+P4$ Formula 1-1

$\mathrm{PR}\left[K\right]\≤\frac{-100\×P4}{P3-P4+100}:\mathrm{DPAXG}\left[K\right]=-\mathrm{PR}\left[K\right]$ Formula 1-2

Right limit value line computation:

$\mathrm{PR}\left[K\right]>\frac{100\×Z}{(100-\mathrm{DPAXREF})}:\mathrm{DPAXD}\left[K\right]=\left(\frac{\mathrm{DPAXREF}\×\mathrm{PR}\left[K\right]}{100}\right)+Z$ Formula 1-3

$\mathrm{PR}\left[K\right]\≤\frac{100\×Z}{(100-\mathrm{DPAXREF})}:\mathrm{DPAXD}\left[K\right]=\mathrm{PR}\left[K\right]$ Formula 1-4

DPAXREF[K]=DPAXREF × PR[K] formula 1-5

LVI (intersection point of left physics limit value line and left limit value line):

formula 1-6

Left physics limit value line: PR=-DPAX; Formula 1-7

Right physics limit value line: PR=DPAX; Formula 1-8

DPAXG[K in above formula] (K=1-4) for moving trapezoidal left margin axial deviation value, DPAXD[K] (K=1-4) for moving trapezoidal right margin axial deviation value, PR[K] (K=1-4) be quadrant core power, DPAXREF (trial value) is with reference to Axial power difference, DPAX is quadrant Axial power difference, it is the difference of 3 reactor core tops and 3 reactor core bottom institute power scale values in power range, Axial power difference when P3 is 100%NP, the P4 Axial power difference of extrapolating while being 0%NP, Z is adjustable parameter.Its validation verification is: input data PR[K] invalid, DPAZG[K], DPAZD[K] and, DPAXREF[K] invalid.

Determine left early warning line and right early warning line based on left limit value line and right limit value line, for example, can determine that its value is respectively 90% of left and right limit value line.Concrete ratio value is determined by the accuracy requirement of monitoring.

After calculating the left early warning line (LPL) of definite operation area, right early warning line (RPL), left limit value line (LL), right limit value line (RL), left physics limit value line and right physics limit value line, monitoring method of the present invention can further be carried out following operation, provide stable, reliable information to show and report to the police, to safeguard the stable and safe operation of reactor:

(1) in the time that the Axial power difference of 2 passages in 4 power range passages exceeds LPL, RPL, system is sent warning, early warning operator.

(2) in the time that the Axial power difference of 2 passages in 4 power range passages exceeds LL, RL, send warning, send C21 signal simultaneously and send reactor core control system to fall power for steam turbine.

(3) part and left restricted area LVI point below the part of right restriction outer core power below 15%, reports to the police and C21 is blocked.

(4) when power is lower than 50% full power (FP), in right restricted area, C21 signal is blocked, and in nearest 12 hours, the time that Axial power difference exceedes right limit value line will add up, and the largest cumulative time can not exceed 90 minutes.

Step S14, collection reactor core operating point are also determined its real-time status in definite operation area, so that nuclear power plant reactor axial power is distributed and to be monitored; This real-time status specifically refers to whether reactor core operating point exceeds operation area limited range.

If so, in step S15, send the first warning according to the concrete situation that does not meet limited range, or further transmission the signal of steam turbine power is fallen and is calculated the time that Axial power difference exceedes right limit value line.On the contrary, in the time that calculated monitoring result meets requiring of corresponding limited range, be considered as the current normal operation of unit, and continue nuclear power plant reactor axial power to distribute and monitor.

As shown in Figure 2, another monitoring method provided by the present invention comprises the following steps: the system signal of step S21, collection core instrument system (RPN), Rod control and position indication system (RGL) and reactor coolant loop (RCP).

Step S22, obtain relevant reactor core parameter, such as enthalpy setting value, density setting value, a circuit cools agent active volume etc.The processing that required reactor core parameter is specifically carried out by observation process operates decision, in actual monitoring process, after definite processing operation, obtains relevant reactor core parameter again.

Step S23a, determine operation area (detailed process is the same) based on system signal and reactor core parameter;

Step S23b, carries out thermal power calculating and the calculating of LOCA nargin based on system signal and reactor core parameter, obtains respectively thermal power value and LOCA nargin monitoring result.Thermal power value is further to calculate the parameter value of LOCA nargin, the direct purposes of LOCA nargin monitoring result is to realize the monitoring of the linear heat generation rate to fuel rod, it can reflect the axial power distribution in reactor indirectly, in order to nuclear power plant reactor axial power is distributed and carries out indirect monitoring.

In step S23b, mentioned thermal power is calculated and is mainly referred to evenly heat power calculation, and it is undertaken by method shown in formula 2:

$\mathrm{Pthavg}=\left(\frac{Q+\mathrm{POWA}}{\mathrm{POW}0}\right)$ (formula 2)

Pthavg is nondimensionalization evenly heat power, and Q (MW) is Dynamic Thermal power, and POWA (MW) is static heat power, and POW0 (MW) is unit name thermal power (constant, and relevant with concrete unit).

In step S23b, mentioned LOCA nargin calculating mainly refers to that linear power density distribution is calculated and radially power peak distribution.

Linear power density distributes to calculate and is undertaken by method shown in formula 3-1-3-2:

PL[Z] [K]=CK × POWZ[Z] [K] × FXYZ[Z] × KGL × Pthavg (formula 3-1)

$\mathrm{MLOC}\left[K\right]={\mathrm{Min}}_z(\frac{\mathrm{DLOC}\left[K\right]}{\mathrm{PL}\left[Z\right]\left[K\right]}-1)\×\mathrm{Pthavg}$ (formula 3-2)

Now axial location POS[K]=Z is the position MLOCAMIN=Min (MLOC[K]) of the minimum LOCA nargin that produces of this measurement passage; The channel number that produces the minimum LOCA nargin of full heap is KMIN; POSMIN=MLOC[KMIN].

PL[Z in above formula] [K] (Z=1-NDECP, K=1-4) be linear power density corresponding to heap external pelivimetry passage K, MLOC[K] (K=1-4) be the LOCA nargin of each measurement passage, POS[K] (K=1-4) be the corresponding position of the minimum LOCA nargin of each passage, MLOCAMIN is the minimum value in minimum LOCA margin value in 4 passages, POSMIN is position corresponding to minimum value in minimum LOCA margin value in 4 passages, KMIN produces measurement channel position corresponding to MLOCAMIN, Pthavg is evenly heat power, FXYZ[Z] (Z=1-NDECP) be the radially power peak of axial node, POWZ[Z] [K] (Z=1-NDECP, K=1-4) be that quadrant reactor core axial power distributes, KGL is grid correction factor, DLOC[Z] (Z=1-NDECP) be axial nodal line power limit under LOCA operating mode, NDECP (constant) calculates linear power density axial node number in the height of active region, CK (constant) is the mean linear power density density under maximum reactor power level.

Radially power peak distribute refer to according to control rod axial location and radially power peak number value general radially power peak be assigned to each axial node.Processing procedure comprises that the radially power peak of 24 points is assigned in each axial node, when control rod misalignment to axial node radially in the correction at power peak and heap axially between control rod configuration mode conversion to the radially correction at power peak of axial node.Specific as follows:

The radially power peak of (1) 24 point is assigned in each axial node

I=1，NDECP-1：

NF=INTEGER[I/10]+1

J=GONFIG[I]

IF(J=9)：FXYZ[I]＝2.5

ELSE：FXYZ[I]=MAX(FXY[NF][J])，

FXY[NF+1][J])

END?IF

FXYZ[I]=FXYZ[I]×FACTP[J]

(2) when control rod misalignment to the radially correction at power peak of axial node

FXYZ[I]=FXYZ[I]×C

(3) in heap axially between control rod configuration mode conversion to the radially correction at power peak of axial node:

FXYZ[I]=FXYZ[I]×PF

Wherein, CONFIG[Z] (Z=1-NDECP) be axial node control rod configuration mode, ZG[J] (J=1-4) be four positions that control rod group is inserted respectively reactor core, FACTP[J] (J=1-9) be the Fxy correction factor corresponding to different control rod configuring conditions under certain power level, FXY[N] [I] (N=1-24, I=1-8) be the distribution of axial 24 points in radially power peak under 8 kinds of control rod configuration modes, FDES[I] (I=1-8) be control rod insertion position misalignment correction factor, DESGR is that parameter is adjusted in control rod misalignment, NDECP (constant) calculates linear power density axial node number in the height of active region.Its validation verification is: input data CONFIG or the invalid all output data COR of FACTP are invalid.

Next step S24a, collection reactor core operating point, determine that in conjunction with definite operation area whether this reactor core operating point exceeds the scope that operation area limits, and if so, sends the first warning, otherwise be considered as the current normal operation of unit, and continue the distribution of monitoring nuclear power plant reactor axial power.In step S24b, determine whether LOCA nargin monitoring result exceeds Core Design LOCA nargin threshold value, so that nuclear power station axial power is distributed and carries out indirect monitoring simultaneously; If so, send the second warning, otherwise be considered as the current normal operation of unit, and continue the distribution of indirect monitoring nuclear power plant reactor axial power.Core Design LOCA nargin threshold value herein requires to be determined according to concrete monitoring, and first reporting to the police and second reporting to the police to be illustrated under two kinds of monitoring results and sends different alarms is herein convenient to confirm to cause in time the reason of warning.

In sum, implement the power distribution signal that the present invention can obtain by the calculating operation that the reactor core parameter of the system signal gathering and reactor self is carried out reflection reactor in-core running status, this monitoring method has been considered the monitoring of power distribution, LOCA nargin and operation area three aspects: simultaneously, and can provide and report to the police and provide reliable basis for subsequent operation, monitoring method system and perfect, be conducive to safeguard unit safety, for the reliability service of unit and operator's proper operation provide necessary, correct information.

The foregoing is only the preferred embodiments of the present invention, its object does not also lie in the present invention's restriction or is constrained in above-mentioned implementation.All any modifications of within the scope of the invention the present invention being made and replacement all should be included in the scope of the claims in the present invention.

Claims (10)

1. the monitoring method that nuclear power plant reactor axial power distributes, is characterized in that, comprises the following steps:

Gather the system signal of core instrument system, Rod control and position indication system and reactor coolant loop;

Obtain reactor core parameter;

Based on described system signal and described reactor core parameter determineoperation area; And

Gather reactor core operating point and determine the real-time status of described reactor core operating point in described operation area, distribute to monitor described nuclear power plant reactor axial power.

2. the monitoring method that nuclear power plant reactor axial power according to claim 1 distributes, is characterized in that, determines that the real-time status of described reactor core operating point in described operation area comprises:

Determine whether described reactor core operating point exceeds the scope being limited by described operation area.

3. the monitoring method that nuclear power plant reactor axial power according to claim 2 distributes, is characterized in that, if described reactor core operating point exceeds the scope that described operation area limits, sends the first warning; Otherwise, continue described nuclear power plant reactor axial power to distribute and monitor.

4. the monitoring method distributing according to the nuclear power plant reactor axial power described in arbitrary claim in claim 1-3, is characterized in that, described operation area determinecomprise and calculate the left limit value line of described operation area, right limit value line, left physics limit value line and right physics limit value line.

5. the monitoring method that nuclear power plant reactor axial power according to claim 4 distributes, is characterized in that, carries out the calculating of described left limit value line by formula (1-1) and formula (1-2):

$\mathrm{PR}\left[K\right]>\frac{-100\×P4}{P3-P4+100}:\mathrm{DPAXG}\left[K\right]=\left(\frac{(P3-P4)\×\mathrm{PR}\left[K\right]}{100}\right)+P4$ Formula 1-1

$\mathrm{PR}\left[K\right]\≤\frac{-100\×P4}{P3-P4+100}:\mathrm{DPAXG}\left[K\right]=-\mathrm{PR}\left[K\right]$ Formula 1-2

PR[K] be quadrant core power, DPAXG[K] be the trapezoidal left margin axial deviation value of operation, Axial power difference when P3 is 100%NP, the P4 Axial power difference of extrapolating while being 0%NP;

Carry out the calculating of described right limit value line by formula (1-3), formula (1-4) and formula (1-5):

$\mathrm{PR}\left[K\right]>\frac{100\×Z}{(100-\mathrm{DPAXREF})}:\mathrm{DPAXD}\left[K\right]=\left(\frac{\mathrm{DPAXREF}\×\mathrm{PR}\left[K\right]}{100}\right)+Z$ Formula 1-3

$\mathrm{PR}\left[K\right]\≤\frac{100\×Z}{(100-\mathrm{DPAXREF})}:\mathrm{DPAXD}\left[K\right]=\mathrm{PR}\left[K\right]$ Formula 1-4

DPAXREF[K]=DPAXREF × PR[K] formula 1-5

PR[K] be quadrant core power, DPAXREF is with reference to Axial power difference, DPAXD[K] and be the trapezoidal right margin axial deviation value of operation, Z is adjustable parameter.

6. the monitoring method that nuclear power plant reactor axial power according to claim 1 distributes, it is characterized in that, described method also comprises based on described system signal and reactor core parameter is carried out thermal power calculating and LOCA nargin is calculated, and obtains respectively thermal power value and LOCA nargin monitoring result.

7. the monitoring method that nuclear power plant reactor axial power according to claim 6 distributes, it is characterized in that, described method also comprises determining whether described LOCA nargin monitoring result exceeds Core Design LOCA nargin threshold value, distribute with nuclear power plant reactor axial power described in indirect monitoring.

8. the monitoring method that nuclear power plant reactor axial power according to claim 7 distributes, is characterized in that, if described LOCA nargin monitoring result exceeds Core Design LOCA nargin threshold value, sends the second warning; Otherwise, continue described nuclear power plant reactor axial power to distribute and carry out indirect monitoring.

9. the monitoring method that nuclear power plant reactor axial power according to claim 6 distributes, is characterized in that, described thermal power is calculated and comprised evenly heat power calculation

Wherein, carry out described evenly heat power calculation by formula (2):

$\mathrm{Pthavg}=\left(\frac{Q+\mathrm{POWA}}{\mathrm{POW}0}\right)$ (formula 2)

Pthavg is nondimensionalization evenly heat power, and Q is Dynamic Thermal power, and POWA is static heat power, and POW0 is unit name thermal power.

10. the monitoring method that nuclear power plant reactor axial power according to claim 6 distributes, it is characterized in that, described LOCA nargin is calculated and is comprised linear power density distribution calculating, wherein carries out described linear power density distribution by formula (3-1) with (3-2) and calculates:

PL[Z] [K]=CK × POWZ[Z] [K] × FXYZ[Z] × KGL × Pthavg (formula 3-1)

$\mathrm{MLOC}\left[K\right]={\mathrm{Min}}_z(\frac{\mathrm{DLOC}\left[K\right]}{\mathrm{PL}\left[Z\right]\left[K\right]}-1)\×\mathrm{Pthavg}$ (formula 3-2)

PL[Z] [K] be heap linear power density corresponding to external pelivimetry passage K, MLOC[K] be the LOCA nargin of each measurement passage, Pthavg is evenly heat power, FXYZ[Z] be the radially power peak of axial node, POWZ[Z] [K] be that quadrant reactor core axial power distributes, KGL is grid correction factor, DLOC[Z] be axial nodal line power limit under LOCA operating mode, KGL is grid correction factor, and CK is the mean linear power density density under maximum reactor power level.

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