JPS6091290A - Detector for damage of piping - 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] [Field of Application of the Invention] The present invention relates to a piping breakage detection device, particularly for preventing oxidation of the sodium free surface of an atomic couplant using liquid metal sodium as a coolant. The present invention relates to a pipe damage detection device suitable for detecting pipe damage in an argon gas system.

[Background of the invention]

The coolant used in fast neutron nuclear reactors is immersed in liquid sodium, but it is chemically extremely active, so it is heated using argon gas, which is chemically inert and active.
Cover the sodium free liquid level in the reactor vessel and cooling system equipment.

Figure 1 shows the schematic configuration of the equipment that handles this argon gas. The cover gas leaving the reactor vessel 1 is removed from the reactor vessel mist trap 2 and the reactor vessel vapor trap 31 (from which sodium mist and vapor are removed) and flows into the pressure adjustment tank 4. The cover gas is drawn from the pressure adjustment tank 4 by the compressor 5. After that, in order to keep the concentration of fission product gas in the argon gas, which is completely suppressed by the high-pressure surge tank 6 to suppress pulsations and pressure fluctuations, a rare gas removal/recovery equipment 7 using a conventional activated carbon adsorption tower is provided. The purified argon gas leaving the rare gas removal/recovery equipment 7 is further transferred to a damping tank 8 at 41A.
After the ri is attenuated, it flows into the purified gas supply tank 9 and is sent into the reactor vessel 1 again.
A line is provided for use as primary main circulation pump shaft sealing gas from the reactor and as blowdown gas from the upper furnace equipment.

In pressure adjustment tank 4. Measure the pressure in this tank and calculate the reactor cover gas pressure P k P t to P2 using the following procedure.
control between. When the pressure P detected by the pressure detector 10 becomes P>P2, the valve 11 is closed, the supply of purified gas from the purified gas supply tank 9 is stopped, and the reactor cover gas pressure is lowered. - Valve 11 is fully opened when the pressure returns to normal. The pressure P detected by the pressure detector 10 is P<Pl
In this case, fully open the valve 12, supply the purified gas from the purified gas supply tank 9 to all the reactor vessels, raise the reactor cover gas pressure, and then close the valve 12 when the pressure returns to normal pressure. . In the purified gas supply tank 9, when the pressure of the tank decreases, fresh argon gas is supplied from the argon gas supply system 13.

In the above argon gas system equipment, if damage occurs to the piping inside the equipment, the current method is to detect the radioactivity contained in the leaked argon gas using an atmosphere monitor.
A method that uses a pressure gauge to detect a significant drop in pressure within the system.
Damage can be detected using four methods: (1) detecting an increase in atmospheric pressure using a pressure gauge; and (2) detecting a significant increase or decrease in system flow using a flow meter.

When using the above method, if the damage is large, it can be detected in a short time, but if the damage is small or medium-sized, such as a pipe with a diameter of a few centimeters, it may take a long time to detect the damage. It takes several hours to several days, and a large amount of argon gas flows out.

Among them, especially from the purified gas supply tank 9 to the reactor vessel 1
If a breakage occurs between I'll be late.

In response to this, the following countermeasures can be considered based on similar examples in other industries.

FIG. 2 shows the relationship between the reactor cover gas pressure and the opening/closing of the valve 12 during normal operation. During normal operation.

When the reactor cover gas (pressure adjustment tank 4) pressure P decreases to the lower limit pressure P1'' of the pressure control range, the valve 12 opens and the purified gas is supplied to the reactor vessel side.

As a result, the reactor cover gas (pressure adjustment tank 4) pressure P returns to the normal level and the valve 12 is closed. Thereafter, after a certain period of time has elapsed, the pressure P is reduced to the lower limit pressure Pl again, and the same operation is performed again, and this is repeated.

At this time, the cumulative number of times the valve is opened 12° in the predetermined time T is
shall be. In addition, the purification gas supply time when the valve 12 is opened is tl.

(1) Valve opening/closing frequency (determined by C) Figure 3 shows the relationship between the reactor cover gas pressure and the opening/closing of the valve 12 in the event of small or medium-sized damage to the piping. The decrease in gas pressure P becomes faster than during normal operation, and the frequency of opening and closing of the valve 12 for supplying purified gas increases.
The cumulative number of times N1 is 2° open is greater than N.

At this time, the cumulative number of times the valve 12" is opened during normal operation is set to N + A, with a certain margin A, taking into account errors, variations, etc. Constantly compares the set values N+A and N'. When N1 ≧ N+A, it is determined that there is an abnormality and piping damage is detected.

(2) Judgment based on valve opening time Figure 4 shows the relationship between the reactor cover gas pressure and the opening/closing of the valve 12 when the amount of argon gas flowing out increases due to pipe damage. , the opening time t2 of the valve 12 to return the pressure to the normal pressure level when the pressure drops to the lower limit pressure P1 of the pressure control range is longer than that during normal operation because some of the purified gas leaks out while supplying the purified gas. Valve 12'
The opening time is longer than the opening time 11.

At this time, 1. From the valve 12 open time tl during normal operation, considering errors, variations, etc., the valve 12 is set as the abnormality judgment standard.
“Open” time! +Δt. This valve 12° opening time t2 is measured every time the valve is opened, and compared with the set value t1+Δt. When t2≧11+Δt, it is determined that there is an abnormality and pipe damage is detected.

According to the above two methods, detection can be performed earlier than detection methods using radioactivity, pressure, and flow rate, but there is a problem in terms of reliability. In addition, 1 Reactor cover gas pressure during normal operation 55
Compared to 00 WAq, the amount is 100 NnAq at the time of refueling, so if a pipe breakage occurs during refueling, an even larger amount of argon gas will flow out before it can be detected.

[Purpose of the invention]

The purpose of the present invention is to detect small to medium-sized pipe damage (damage to the pipe with a diameter of several meters) in argon gas equipment quickly and with high reliability without generating false signals, regardless of the plant operation mode. It is an object of the present invention to provide a piping breakage detection device that can detect and notify an operator.

[Summary of the invention]

The present invention is provided with a pipe damage detection device, and with this device,
We constantly monitored the opening/closing frequency and opening time of the valves that adjust the reactor cover gas pressure within the pressure control range, and found that the opening/closing frequency was higher and the opening time was longer than when operating in each plant operation mode. If both of the following conditions are true, it is determined that the pipe is damaged, and a warning signal is issued to notify the operator of the pipe damage.

[Embodiments of the invention]

Hereinafter, one embodiment of the present invention will be explained with reference to FIGS. 5 and 6.

Figure 5 shows the relationship between the reactor cover gas pressure, the number of times the valve 12 that regulates the pressure is opened, and the time the valve 12 is opened in the event of small or medium-sized damage to the piping. The configuration of the device 14 is shown in FIG.

The piping damage detection device 14 includes a valve 12 opening/closing frequency integration circuit 15.
．． Valve 12 "open" time calculation circuit 16. Opening/closing frequency comparison circuit 1
7. Open time comparison circuit 18. Valve 12 opening/closing frequency setting circuit 19
．． Valve 12° open time setting circuit 20. Piping damage judgment circuit 2
1.

In the valve 12 opening/closing frequency integration circuit 15, the valve 12° open” signal/
The valve 12° close signal is increased and the number of times the valve 12 is opened and closed is accumulated. The opening/closing frequency comparison circuit 17 calculates the cumulative frequency from the valve 12 opening/closing frequency accumulating circuit 15 and the valve 12 opening/closing frequency setting circuit 19.
The set number of times are compared and the results are sent to the piping damage determination circuit 21. In addition, in the valve 12 opening/closing frequency setting circuit 19,
Incorporates the plant operation mode signal and changes the set number of times according to the operation mode.

The valve 12' open time calculating circuit 16 calculates the "open" time of the valve 12 by including the valve 12' open time and the valve 12' closed time. The "open" time from the open time calculation circuit 16 is compared with the set time from the valve 12 "open" time setting circuit 20, and the result is sent to the pipe damage determination circuit 21. In addition, the valve 12 "open" time setting circuit 20 increases the plant operation mode signal and changes the set number of times according to the operation mode.

In the pipe damage determination circuit 21, if the results sent from the opening/closing frequency comparison circuit 17 and the opening time comparison circuit 18 both exceed set values and become abnormal, it is determined that the pipe is damaged.
Emit a warning signal.

Let's apply this specifically to the case shown in Figure 5.

The cumulative number N2 of the valve 12 opening/closing frequency accumulating circuit 15 and the set frequency N+A from the setting circuit 19 are compared in the opening/closing frequency comparing circuit 17.

KI=N2 (N+A) Also, the calculation time t3 in the valve 12° opening time calculation circuit 16
and the setting time of the setting circuit 20 1. +Δt is compared by the open time comparison circuit 18.

Kz=tz (t++Δt) When both + and 2 become 1>O, Kz>0, the pipe damage determination circuit 21 determines that the pipe is damaged and issues an obituary signal.

As mentioned above, in the embodiment of the present invention, the valve 12 is 0N-OF.
Although the explanation has been made for the case of the F valve, it is also applicable to the case of a control valve.

In a loop where the cover gas pressure is kept constant by continuously controlling the opening degree of the regulator valve, if a pipe breakage occurs, the reactor cover gas pressure will decrease, and the opening degree of the regulator valve will inevitably be controlled. The operating output in the opening direction from the controller increases compared to normal operation.

Seven set values are set as abnormality determination criteria for a predetermined time T in the integrated value of the operation output M of the controller during normal operation, taking into account errors, variations, etc.

The operation output M' of the controller is integrated over a predetermined time T and compared with the set value.

When this happens, it is determined that there is an abnormality and piping damage is detected. According to this method, detection is possible even if the reactor cover gas pressure P-AI is lower than the lower limit pressure P i of the pressure control range, and compared to the case of the 0N-OFF valve described above, detection is possible more quickly. and is more effective.

〔Effect of the invention〕

According to the present invention fF:, when there is a small or medium-sized breakage in the argon gas system piping, both the opening/closing frequency and the opening time of the valve that controls the cover gas pressure to be constant are adjusted to the plant operation mode. By monitoring the system, abnormalities are automatically detected and alarms are issued, so even if the damage does not reach a level that can be detected by radiation monitors, pressure gauges, and flow meters, pipe damage will occur again. Even after a long period of time has elapsed, there is an excellent effect of being able to detect and notify the operator early and with high reliability without generating false signals in any operating mode. This allows the operator to reliably quickly stop the release of radioactive argon gas to the outside of the system.

[Brief explanation of drawings]

Figure 1 is a schematic diagram of the equipment that handles the argon gas that covers the sodium free liquid level in the reactor vessel and cooling system equipment.Figure 2 shows the reactor cover gas pressure during normal operation and the pressure fully adjusted. Figure 3 is an explanatory diagram of the relationship between the reactor cover gas pressure and the valves that adjust the pressure in the event of small or medium-sized damage to the piping, and the piping damage detection method. Figure 4 is an explanatory diagram of the piping damage detection method. A diagram showing the relationship between the reactor cover gas pressure and the "opening" time of the valve that adjusts the pressure when the amount of argon gas flowing out increases due to a breakage. Figure 2g5 shows the reactor cover gas pressure when a pipe breakage occurs. An explanatory diagram of the pressure, the number of openings of the valve that adjusts the pressure, the opening time, and the piping damage detection method. Figure 6 is a block diagram showing the configuration of the piping damage detection device that is an embodiment of the present invention. It is. l...Reactor vessel, 2...Reactor vessel mist trap/
3... Furnace vessel vapor trap, 4... Pressure adjustment tank, 5... Compressor, 6... High pressure surge tank, 7...
・・Rare gas removal/recovery equipment, 8・Attenuation tank, 9・
...Purified gas supply tank, 10...Pressure detector, 13
... Argon gas supply system, 14... Piping damage detection device, 15... Valve 12 opening/closing frequency integration circuit, 16... Valve 12 'opening' time calculation circuit, 17... Opening/closing frequency comparison circuit, 18... Opening time comparison circuit, 19... Valve 12 opening/closing frequency setting circuit. 20... Valve 12 "open" time setting circuit, 21... Piping damage determination circuit.

Claims (1)

[Claims] 1. To prevent oxidation of the sodium free surface of an atomic couplant using liquid metallic sodium as a coolant. 2. To prevent oxidation of the sodium free surface in the reactor vessel and cooling system equipment by chemically inert argon gas. WUk
(-In response to fluctuations in gas pressure, by opening and closing the valve) A device was installed to monitor the opening degree of the valve, and pipe damage occurred when both the valve opening/closing frequency, the valve opening time, or the operation output for the valve opening direction exceeded the set value set according to the plant operation mode. A piping breakage detection device characterized in that it determines that and issues an official gazette signal.