JPS6011200A - Boiling water 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 boiling water nuclear reactor, and more particularly to a control device for controlling the main steam (separate valve closing method) inserted in the main gas piping system. .

[Technical requirements for invention]

For example, a boiling water reactor (hereinafter referred to as BWR) has the following configuration. That is, a nuclear reactor 1 vessel is provided in the reactor building, and a reactor pressure vessel iiQ is provided in this reactor containment vessel. Inside this reactor pressure reactor are cooling water and multiple fuel collections, bodies and
1 tilj 1 From Kabaji Temple, it becomes a two-phase flow situation. Then, the steam and moisture B(1) are separated into water and steam by a steamer, and ρ and steam are turned into dry steam by a steam dryer.

This dry steam is sent to the turbine via the main oil piping system connected to the reactor pressure vessel, causing the turbine to erect.

One drive of this turbine causes centering (the ridge rotates and centering occurs).

The air generated by driving the turbine once is pumped into the water vessel and becomes condensed water, which is then re-supplied into the reactor pressure valley vessel.

The reactor flame of the main air piping system has a volume of 1 meter, a 1m section, and a king steam separation: "11i", valve (hereinafter referred to as MSIV).
is inserted. This IJsIV is designed to prevent the above-mentioned radiation cage disease leak from occurring in the event that the main steam piping system ruptures and steam containing radioactive materials leaks out of the reactor. In addition to the above cases, for example, when the reactor water level is low, 4. It is also done in Nyoyo. Generally, BVll'R has a negative reaction amount coefficient, and when the void collapses, a positive reactivity is imparted to the reactor, and the reactor output increases by -l-. Therefore, if all MSIVs are closed at once in a short period of time, the positive reactivity applied to the reactor becomes large, and accordingly, g+, child reactor output, and reactor F[-k also rise.

Normally, the safety design of nuclear power plants is such that the reactor can be shut down with sufficient margin even if a scram (emergency shutdown of the reactor) is not performed normally, and in the case of Shio 11, the MSIV was closed. and the reactor is separated by 1%.
By injecting a sex poison (boron in the list) into all the reactors, the I sub-reactors will be shut down. Therefore, an explanation will be given for an example (a plan with an all-number bypass system).For example, the most severe type of disturbance on the power system side (due to breakdown rules in the power transmission system, etc.) for an individual power station or a group of power plants. It is assumed that full load is cut off due to generator disconnection.In such a plant with a small turbine bypass capacity, 1 detects the sudden closing of the turbine steam control valve and scrams the reactor.However, if F>il Note 1: Since the load shedding of the pump is not based on any equipment abnormality on the power plant side, if the plant enters isolated operation at the time of grid disconnection, it is possible to immediately start transmitting power as a nuclear power plant after the system is restored.Full capacity Bypass is a method to achieve this.

That is, in a plant with a full capacity bypass, if a load failure occurs during rated output operation, the PA valve is opened.

This allows approximately 100% of the main steam flow to be bypassed and processed by the condenser.

In addition, dozens of predetermined control rods will be inserted into the reactor Q (selective control rod insertion), and at the same time, the output will be lowered by lowering the degree of sliding of the JFK monkey pump. Furthermore, it is also possible to reduce the subcooling of the reactor core population by reducing the number of water pumps, thereby reducing the reactor output. In this way, in a plant with a full-capacity bypass system, even if a negative t'ar cutoff occurs, islanding operation starts without a reactor scram. It is possible to restore the rated output to the rated output in a short period of time when the reactor is completed.Of course, the reactor can be scrammed if the turbine bypass valve does not operate normally.

[The middle ground of background technology]

Rated output in the above J and 4 configurations, full negative bend during jJi rotation,
When J1 occurs, as mentioned in MiT, the selection control rod intermediary is performed, but if this does not work properly, a scram signal is output due to power failure, and the reactor is forced to shut down. do. If the control rod cannot be inserted, the output is completely stopped by stopping the pump again. In this case, the indeterminate state g1 of extremely low flow and high output will persist for some time. Under such circumstances, the steam The generation is foamy water γI'
When C'fjt'C-hi turns, the reactor water level will drop and the reactor water level will be low and = will be output. Due to this low reactor water level signal, the MSIV is reduced to M and the reactor is isolated. Simultaneously with this reactor separation, the emergency core cooling system and the sub-reactor separation 411 system are activated, thereby allowing the reactor water level to recover. The injection of this cooling water adds positive reactivity to the reactor, but a high pressure signal causes a relief safety valve connected to the main steam distribution system to open, allowing steam to enter the pressure suppression chamber and condense. Then, in order to finally shut down the nuclear reactor, the neutrons -Id\7I are supplied to the core V'', thereby placing the reactor in a high temperature shutdown state 1['l. In this way, even if the scram fails, the reactor k l□h H”
1tfl, and the structure is such that the safety of the reactor can be maintained.

However, M S I V has short side 1i4[
If the valves were closed, the voids would collapse and positive reactivity would be added to the reactor core, increasing the reactor output and raising the reactor pressure.

[Purpose of the invention]

The object of the present invention is to control the closing method of the main steam 1i1flt valve when the main steam control valve is closed due to No. 11 caused by a reason other than radioactivity leakage. The object of the present invention is to provide a boiling water reactor that can suppress as much as possible the positive reactivity imparted to the reactor.

[Summary of the invention]

The boiling water reactor according to the present invention includes a reactor pressure responder that accommodates a reactor core and cooling water, and a plurality of main steam piping systems that supply steam generated in the reactor pressure vessel to a turbine system.
In a boiling water reactor equipped with a plurality of main steam isolation valves (a plurality of main steam isolation valves inserted in a pneumatic piping system), a reactor isolation request signal other than a radioactivity leakage signal causes isolation of the plurality of main steam In addition to isolating the reactor by closing the valves, it is equipped with a reactor separation t111 system control device that controls the 0'j valve system of the plurality of main steam isolation valves to suppress one positive reaction in the reactor core. It is the composition.

In other words, the reactor isolation system iI is responsible for isolating the reactor based on the reactor isolation request (I) other than the radioactivity leak signal;
l'i Pi (This is a configuration that suppresses the positive reactivity that affects the Q core by closing one valve.

Therefore, the positive reactivity applied to the reactor core can be suppressed, and the rise in reactor pressure can be alleviated, making it possible to greatly improve safety and soundness.

[Fees for Practicing the Invention J Hereinafter, an embodiment of the present invention will be described with reference to FIGS. 1 to 4. FIG. 1 is a system diagram showing the general configuration of a BWR. Reference numeral 1 in the figure indicates a reactor containment vessel installed in a reactor building (not shown), and a scissor reactor pressure vessel 2 is accommodated within this reactor containment vessel l. A reactor core 3 consisting of a plurality of burnt assemblies, 1lfl control rods, etc. is installed within the reactor pressure vessel 2. In addition, cooling water 4 is accommodated in the reactor pressure vessel 2, and a jet pump 5 provided on the outer periphery of the reactor core 3 and a refueling pump 6 and a refill pump 6 provided on the outer periphery of the reactor pressure vessel 2 are used.
J # j Bulk 11 It is forcedly circulated from the self-pipe 2 by the orange recirculation system 8 (1 to 1). The main A/gas pipe 9.10゜11 is connected to the upper part of the reactor pressure vessel 2. These main 2.≦Presence 9゜10.11
The turbine 12 is disposed through the turbine 12. Main steam isolation valves (MsIV) 13A and 13B are installed before and after the penetration part of reactor class 7 and 4j 11 in the main steam arrangement 9.10.11 above.
.

14, 14B, 15A, and 15B are inserted, respectively. Further, a main steam stop valve 16.17.1B and a main steam control valve 19.20.21 are inserted into the main steam pipes 9, 10.11, respectively.

The steam generated in the reactor pressure passenger unit 2 is then supplied to the turbine 12 via the main steam piping 9, 10.11,
This drives the turbine 12 and rotates the generator 22. Turbine 12! After being moved to z, the steam is introduced into the 1-9 water basin 23 and becomes 1υ water, which is returned to the reactor pressure vessel 2 via the feed water heater 24 and the feed water pump 25.
・It is 6th generation. MIl18 of main steam pipe 9, 10.11
．． ■26'' and 27.28 with turbine bypass are installed between v13B, 74B, 15B and the stop valve 16, 17, I'S and the condenser 23, respectively. Turbine bypass valves 2'9 and 30°31 are inserted into these turbine bypass pipes 26°27.
, , 20 , 21 Fully close the above turbine/bypass valve 2
9,30.31 Fully open valve and turbine bypass pipe 26 +
Main steam via 27 + 28? This is a configuration in which water is discharged to the r qMr water dispenser 23.

Aff=1'', main group gas, tubes 9, 1θ, 11 reactor pressure vessel 2 and = s: cv 2 s A, J 4 A,
Main steam relief safety valves 32, 33.
34f inserted main steam relief pipes 3s, s6, s7 are connected to Qi6, respectively, and these main steam relief pipes -f! 3
5, 36°37 is YId set up to pressure suppression ¥38. Then, in the warehouse where the reactor is isolated and the pressure has increased excessively, the main steam relief safety valves 32, 33, 34 are opened and the main steam is released into the pressure suppression chamber 38 through the main steam relief pipes 35, 36, 37. It is configured to escape into the water. In addition, the reactor pressure vessel 2 is equipped with a poison injection system 5 as a backup reactor shutdown device.
LC39 continues. Medium injection into this 9'; Q 1
i'l: 39 is configured to inject a neutron poison (for example, boron) into the reactor pressure vessel 2 via a valve 40 to stop the nuclear reaction in the reactor core 3.

BW R with the above configuration has 1visIV 13A
, 13B.

14, 14BI'15A, 15B valve closing method open side 1
A reactor partition h1F system control i11 unit #441 is provided. The configuration and functions of this reactor isolation system control device 4f and i'vJ41 will be explained below. h4sIV is activated by the fully closed shell request signal, the relay is activated by the scram failure θυ signal S1 and the reactor water level low signal S2, and the bypass valve IA'i signal S
3 and main steam 11 Output reducing valve closing signal S4 and bypass valves 29, 30.31 and main steam regulating valve 19.20,
21 to II, 11 to the next close, and MSIV 1
3A, 13B, 1'4A, 14B.

15, it has a function to sequentially close the valves 15B at a predetermined time with 14 hours, and a timer device for that purpose, (
(not shown).

The action is based on the above configuration, 71! I will clarify. Figure 2 is a flowchart for the case where the power generator Isogai I bypass occurs in a plant that uses the full capacity St bypass system. The power reduction valves 19, 20.21 are closed and the bypass valves 29, 30.'31 are opened.At the same time, the recirculation pump 6 is tripped (or partially tripped), and the water pump 25 is partially tripped and previously selected. The reactor output is then reduced by rapidly inserting the i+L11 rod, which controls f￥i≦.
This is a mock-up, taking into consideration the fact that the supply water temperature will drop due to the loss of the heating source. At this point, if the selective control rod insertion does not operate normally, the recirculation pump 6 will trip (or partially trip) and the feed water heating source will be lost as described above, as shown by the solid box in Figure 3. The reactor operating point is low core flow rate, atomic! Shift the state of P output high. Flood 3 has Furano-ra flow flk 4M on the horizontal axis, and A'υC! 1
Ilil shows the reactor output signal, the reactor core Sif, t, and the reactor output. Point 0 is the initial point, the back part is when the control rod insertion fails, and the broken line is; , a-fold system inno 1
When the uniform insertion is successful, the dashed-dotted lines indicate the reactor scram request signal setting curves. And will the reactor output continue to increase due to subcooling? Does the reactor scram request signal surface continue to rise as shown by the flow line? The reactor is scrammed to cross sections. However, if scram becomes impossible at this point, all recirculation pumps 6 are tripped by a scram failure signal outputted by the hand that confirms the position of the 1h11 rake rod. Due to this Jt, the forced circulation system for subcooling water to the reactor core 3 is stopped, but since water supply continues, the reactor output increases, and after that, the flow rate exceeds the rated flow rate of the water supply pump 25 that has not tripped. flows out. Therefore, the reactor water level decreases, and the reactor water level signal (4 signals), which is one of the Junshi reactor isolation request information, is output.

Even after all 25 reactors were shut down, the water level dropped +-r iih and a reactor water level low signal was sent, causing reactors 1'4+ and 71 system f.
itll@i device 41 is activated. The reactor remote pm system 1HII l'l device 41 first turns the turbine valve 29 into the 1-valve.

As a result of the closing of the turbine output valve 29, the MS engineering signals V13A, 13BI, and 11 S are output, and the main steam isolation valves 13A, 13B are activated. After a predetermined period of time has elapsed, the reactor V'A Mt system control unit 41 opens the turbine (pass valve 5okf) by the built-in timer Pk''. VLSIV14A, J4 by closing the valve.
B opening +386 is output and main steam 1 isolation valve 14A,
14B closes. Similarly, after a predetermined period of time has elapsed, the turbine exhaust valve 31 is closed by the operation of the timer device. When the turbine valve 31 is closed, the VLSIV 75A and 15B are closed, and the output is output to the main steam valve 15 and 15B.

With this, all the main benefit interval t41F valves are closed, and the 1st ward sub-furnace is 1l.
Hr)! be criticized. Main steam isolation 4F1 like this
．． To 9, 13B.

14A, 14B, 15A, and 15B are not closed at the same time as in the past, but are closed at a predetermined time difference, so the effect of crushing voids in the reactor water 4 is small, and therefore the total positive reactivity added to the reactor core 3 is Can be suppressed. To explain this with Figure 4, Figure 4 shows time (seconds) on the 51 yellow axis, reactor pressure (% rating) on the vertical axis, and time changes in reactor output (9). The opening shows the case of this embodiment, and the broken bamboo shows the conventional example. As is clear from this, the rise in reactor pressure has been slower than in the past. After that, reactor separation F! By starting the 11 o'clock cooling system and the emergency core cooling system, the reactor water level will be reversed. Then, by activating the neutron poison injection system 5LC39', the reactor is brought to a high temperature shutdown.

That is, the main steam isolation valves 13A, 13B, 14A, and 14B are controlled by the reactor isolation system control i device t4Z.

15, by sequentially closing the valves 15B with a predetermined time difference, the effect of crushing voids in the reactor water 4 can be reduced compared to the conventional case where all valves are closed at once. The positive reactivity caused by the collapse can be completely suppressed, making it possible to alleviate the rise in reactor pressure.

〔Effect of the invention〕

As detailed above, according to the boiling water reactor according to the present invention, the reactor ff: is activated when the reactor is isolated in response to a reactor isolation request signal other than a radioactivity leak signal, thereby eliminating voids when isolating the reactor. Since the effect can be reduced, the positive reactivity caused by the collapse of voids can be suppressed and the rise in reactor pressure can be alleviated, making it possible to significantly improve safety and soundness.

[Brief explanation of the drawing]

Figures 1 to 4 are diagrams showing one embodiment of the present invention, and Figure 1 shows the general P@ configuration of a boiling water reactor.
The figure is a flowchart showing the operation when a load shedding occurs, and Figure 3 shows the curve of reactor output and core flow rate when a load shedding occurs. Figure 4 is a diagram showing the change in reactor pressure when the valve is closed and the reactor is isolated. 2...Reactor pressure vessel, 3...Reactor core, 4...Cooling water, 9.10.11...Main group signs;, 12...
Turbines, 13A, 13B, 14A, 14B, 15A. z5B...Main steam isolation valve, 41...Reactor isolation system control (i+i) device. Applicant's representative Patent attorney Takehiko Suzue-he34- Figure 4

Claims (1)

[Claims] A reactor pressure vessel that accommodates the reactor core and cooling water, a plurality of main piping systems that supply the steam generated in this reactor pressure vessel to the turbine system, and In a boiling water reactor equipped with a main steam isolation valve with 77 double ridges, reactor corner failures and
When the plurality of main steam valves are closed to isolate the reactor in accordance with the request signal, the closing method of the plurality of main steam valves is controlled to generate a positive reaction in the reactor core. A boiling water reactor characterized by being equipped with a reactor isolation system control device to suppress the reactor isolation system.