JPS59131199A - Device for detecting abnormality in main steam circuit of bwr type reactor - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to a main steam system abnormality detection device for a boiling water reactor (BWR).

[Technical background of the invention]

The BWRO main steam system is constructed as shown in FIG. That is, four main steam pipes 48 to 4d that lead steam from the reactor 1 to a main steam header 3 that penetrates the reactor 1 and the wall 2 of the reactor containment vessel and are provided outside the vessel, and four main steam pipes 48 to 4d that lead steam from the reactor 1 to the main steam Lada 3
Piping 5a to guide steam from the turbine to each turbine (not shown)
5d, steam flow rate detectors 6a to 6d provided on the most upstream side of each main steam piping 4a to 4d, and first main steam isolation devices provided on the upstream and downstream sides of wall 2 of each main steam piping 4a to 4d. Valve 78~
7d, and second main steam isolation valves 88 to 8d.

In the above configuration, the first and second main steam isolation valves 7a to
7d and 8a to 8d are closed in the event of an accident such as a leakage of the main steam pipe, thereby restricting the release of coolant and radioactive materials inside the reactor 1 to the outside of the containment vessel. Further, the outputs of the steam flow rate detectors 6a to 6d are used as one of the control inputs in a reactor feed water control system that maintains the water level in the reactor 1 constant.

[Problems with background technology]

If the steam flow rate detectors 6a to 6d fail and their output signals become larger than the actual one, the main steam flow rate will be overestimated, and if it becomes smaller than the actual one, the main steam flow rate will be underestimated.

Therefore, if the steam flow rate detectors 6a to 6d fail, the reactor feed water control system will not be able to maintain the reactor water level constant. Therefore, if the steam flow rate detectors 6a to 6d are out of order, the BWR operator will be notified immediately.
Appropriate measures must be taken.

In addition, the control panel of the BWR central control room is equipped with lamps that indicate the open/closed status of the first and second main steam isolation valves 7a to 7d, and 8a to 8d. You can know whether the valve is open or closed. However, even if the output signal of the steam flow rate detectors 6a to 6d, that is, the steam flow rate signal, becomes small, if the lamp is malfunctioning or there is an abnormality in the opening/closing signal of each main steam isolation valve, the steam It is not possible to determine whether the low flow signal is due to the closure of the main steam isolation valve or a failure of the steam flow detector. This may result in a reactor trip, for which BWR operators can take appropriate action immediately. Note that, contrary to the above, even if the steam flow rate signal maintains a certain value despite the indication that the main steam isolation valve is closed, a reactor trip may occur in the same way.

[Purpose of the invention]

The present invention has been made based on the above-mentioned circumstances, and even when the value of the steam flow rate signal becomes small even though the main steam isolation valve close signal is not output, or conversely, even when the close signal is displayed. The object of the present invention is to obtain a BWR main steam system abnormality detection device that can detect the cause and location of an abnormality when a steam flow rate signal maintains a certain value regardless of the situation.

[Summary of the invention]

The present invention includes an analog signal input section that inputs the steam flow rate signal of the steam flow rate detector provided in each main steam pipe, and a digital signal input section that inputs the valve opening/closing signal of the main steam isolation valve of each main steam pipe. , the maximum absolute value of the difference between the average steam flow rate calculated based on these input signals and the main steam pipe abnormality flag as a result of self-diagnosis and the steam flow rate of each main steam pipe is determined by a predetermined positive value. If the value is larger than a small value, it is assumed that an abnormality has occurred in the main steam system, and the system has an abnormality diagnosis section that diagnoses the location and cause of the abnormality, and a display section that displays the diagnosis results. The above objective is achieved by configuring a system abnormality detection device.

[Embodiments of the invention]

FIG. 2, in which the same parts as in FIG. 1 are given the same reference numerals, shows an embodiment of the present invention. An input analog signal input section 10 and first and second main steam isolation valves 7a to 7d.

It has a digital signal input section 11 into which opening/closing signals 8a to 8d are input. The steam flow rate signal is input to the analog signal input section 10 as steam flow rate m19m2. WL3゜4th (t
/hr). Furthermore, the main steam isolation valve opening/closing signal is input to the main steam isolation valve closing flag g1. g2. ga, converted to g4. Here, gI (i = 1 to 4) is the second main steam pipe installed in the first main steam pipe.
If at least one of the main steam isolation valves has a close signal,
gI-〇, otherwise g1=1.

The input result m+gt is input to the abnormality diagnosis section 12, and the diagnosis result is displayed on the abnormality display section 13 composed of a CRT, a lamp, or the like.

The abnormality diagnosis section is composed of a microcomputer, etc.
Diagnosis is performed as follows. That is, the abnormality diagnosis section 12
A flag processing unit 14, an average steam flow rate calculation unit 15, an abnormality detection unit 16, a deviation sign determination unit 17, a first abnormality location search unit 18, and a second abnormality search unit 19 are provided within the flag processing unit 14. The abnormality location search unit 18.19 sets a main steam pipe abnormality flag f, which is set to 0 if there is any abnormality in the main steam pipe, and 1 if it is normal, and a main steam isolation valve closing flag g.
.

The sum T of the products is calculated. Next, the average steam flow rate calculation unit 15 calculates the average pressure loss coefficient KA from the following equations (1) and (2).
Find V and the average steam flow rate of 771 AV. However, the total T
When is O, mAV is forcibly set to 0.

mAV-'Σ・Right"g tr-mt"' (2
) T-JT': ' In the two equations, K is the pressure drop coefficient of the first main steam pipe, and from Bernoulli's law, the differential pressure between reactor 1 and Herada 3 is △
P is determined by detailed calculation or actual measurement for each main steam pipe 4a to 4d so that it satisfies the following formula (8).

△P=to+m+ ・・・・・・・・・・・・・・・・
(8) The abnormality detection unit 16 searches for the maximum absolute value of the deviation coefficient given by the following formula (4), and sets it as E and the binding Ej. and a predetermined small positive number ε. E.

If is smaller than ε, it is assumed that no new abnormality has occurred, and the diagnosis is terminated. If E is larger than ε, the cause of the abnormality is investigated in the deviation sign determining section 17 and thereafter.

E+ =f + (Kmlgt π・m~)...
(4) That is, the deviation sign determination unit 17
Then, determine E, fJ-pressure/negative, and if positive, the second
The process moves to the abnormal location search section 19. If it is negative, the first abnormality location search unit 18 determines that the main steam isolation valve of the j-th main steam pipe is closed, that is, as gj"O, the average steam flow rate "'AV Recalculate.

T=Σft g+ ・・・・・・・・・・・・・・・
・・・・・・・・・(5) After that, l mAV −'
If AY I is smaller than a certain positive small number η, it means that the main steam isolation valve of the j-th main steam pipe is closed, but the valve close signal is not output; if it is larger than η, jth
The steam flow rate detector of the th main steam pipe is malfunctioning and its output signal is abnormally low, and this is displayed on the abnormality display section 13 to notify the BWR operator, and the main steam pipe abnormality flag fj = 0 shall be.

Next, the second abnormality location search unit 19 detects the presence or absence of steam leakage based on the signal from the steam leakage detection system installed in the BWR power plant, and if there is steam leakage, it displays this on the display unit 19.
3, and at the same time set the main steam pipe abnormality flag f,=0. If there is no steam leak, contrary to the case of the first abnormality location search unit 18, assuming that the main steam isolation valve provided in the j-th main steam pipe is open, that is, g'-1, the formula ( 5)～(
Recalculate the average steam flow rate mχV from 7) and obtain l mA
If V "AV l <'7, even though all the main steam isolation valves of the j-th main steam pipe are open,
In addition, l mvAm'hv indicates that the valve close signal is being output.
If l > η, the steam flow rate detector of the j-th main steam pipe has failed, and the display section 13 displays the fact that its output is abnormally high. At the same time, the main steam abnormality flag f,
−〇.

The abnormality diagnosis section periodically performs the above diagnosis.

〔Effect of the invention〕

According to the present invention, when an abnormality occurs in the main steam system of a BWR and the steam flow rate detector of each main steam pipe malfunctions, it is possible to know the malfunctioning detector and the increase/decrease in output. It is also possible to know if the main steam isolation valve is open but the valve close signal is being output, or conversely if the main steam isolation valve is closed but the valve close signal is not being output. Therefore, B
The WR operator can promptly take action to prevent a reactor trip.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of a conventional BWR main steam system, FIG. 2 is a schematic diagram of an embodiment of the present invention, and FIG. 3 is a block diagram of the main parts thereof. 1... Nuclear reactor, 2... Wall body, 3...
Header, 4a-4d...Main steam pipe, 6a-6d...
...Steam flow rate detector, 7a-7d, 8a-8d...Main steam isolation valve, 10.
...Analog signal input section, 11...Digital signal input section, 12...Anomaly diagnosis section, 13...Display section Application agent Patent attorney Kikuchi Gobu

Claims (1)

[Claims] An analog signal input section that inputs the steam flow rate signal of the steam flow rate detector installed in each main steam pipe, a digital signal input section that inputs the valve opening/closing signal of the main steam isolation valve of each main steam pipe, and these input signals. If the maximum absolute value of the difference between the average steam flow rate calculated based on the main steam pipe abnormality flag as a result of self-diagnosis and the steam flow rate of each main steam pipe is larger than a predetermined small positive value. Main steam system abnormality detection for a boiling water reactor, characterized in that it has an abnormality diagnosis section that assumes that a main steam inconvenience abnormality has occurred and diagnoses the location and cause of the abnormality, and a display section that displays the diagnosis result. Device.