CN1145975C

CN1145975C - Pump selection logic

Info

Publication number: CN1145975C
Application number: CNB981061435A
Authority: CN
Inventors: S・J・维尔科斯; S·J·维尔科斯; 查里; D·R·查里; 罗伯森; J·E·罗伯森
Original assignee: ABB CE Nuclear Power Inc
Current assignee: ABB CE Nuclear Power Inc
Priority date: 1998-02-19
Filing date: 1998-03-30
Publication date: 2004-04-14
Anticipated expiration: 2018-03-30
Also published as: CN1226732A

Abstract

The operator of a nuclear steam supply system manually selects a lineup of either one, two, or three main feedwater pumps for normal reactor operation to generate power. A system (RPCS) for implementing a step reduction in the power output of the reactor, includes an associated logic circuit which combines signals indicative of tripping of one or more pumps, with the pump status latches, to achieve the following outcomes: (a) with one pump selected, a trip of this one pump does not produce an RPCS trip demand signal (because the reactor will be tripped); (b) with two pumps selected, (i) a trip of one pump will produce an RPCS trip demand signal, whereas (ii) a trip of these two pumps will not produce an RPCS trip demand signal; (c) with three pumps selected, (i) a trip of one pump will not produce an RPCS trip demand signal (because the transient can be handled by the basic control system), (ii) a trip of two pumps will produce an RPCS trip demand signal, and (iii) a trip of three pumps will not produce an RPCS trip demand signal.

Description

Pump selection logic

The present invention is the continuation application of the No.08/724081 patent application of submission on September 30th, 1996.

Technical field

The present invention relates to nuclear power station, more precisely, relate to reactor control system to unexpected, do not have power plant's critical piece merit of expecting vitiable from dynamic response.

Background technology

The nuclear steam feed system (NSSS) in pressurized-water nuclear power station moves under the minimum environment of energy and flowed fluctuation usually. Can pile control system by fundamental reaction in this case processes. Yet it is unbalance some large equipments also can to occur, interrupts or partly lose the water supply capacity of online main feed pump such as large turbine load obstacle, turbine. Under these circumstances, can reduce fast the NSSS energy to insert faster speed than the High-speed Control of routine rod, with the NSSS system held in control range. In addition, the NSSS energy reduces fast, can in the situation of not interrupting reactor, obtain enough hot surpluses and depart from (comprising that false control rod falls) to regulate interior control rod.

A known system that reaches this target is can be from Connecticut, USA Wen Suoer city (Connecticut, Windsor) (the ComBustion Engineering of combustion enginnering company, the reactor energy reduction system of Inc) having bought (ReActor Power CutBAck System, RPCS). Promulgate that " the reactor energy reduces system and method " described this type of RPCS in No. the 4th, 075,059, the United States Patent (USP) on February 21st, 1978. Hereby in conjunction with the content of this patent disclosure as a reference. This system is for bulk loads fault, feed pump of forfeiture or control rod internal deviation (comprising that false control rod falls) design, and the step by step minimizing of reactor energy is provided. Reduce being step by step of reactor energy falls to realize when regulating one or more groups preliminary election group that control rod enters reactor core with all strength. These control rod groups fall with their common insertion sequence. This RPCS also after beginning to reduce the reactor energy, provides control signal to turbine, recovering turbine and reactor energy balance, and the conventional controlling value that water level and the pressure of steam raising plant is returned to them.

Traditional NSSS has two steam raising plants and two variable-ratio main feed pumps, and feed pump transmits secondary cooling water to common conduit, and cooling water is through threshold gate distribution and control are sent to each steam raising plant separately. In case generating steam generating means feed pump fault, the secondary cooling water flow that is sent to steam raising plant reduces, because remaining pump can not be supplied with 100% of the desired feedwater of steam raising plant. When this thing happens, it is fast that steam raising plant continuation water consumption (water is become steam) enters steam raising plant than water, thereby cause the steam raising plant middle water level to descend. Reactor and turbine receive the indication excessively low signal of steam raising plant water level and before being opened circuit this situation do not admit of long-time. If the reactor energy at once reduces to rapidly abundant degree, and steam raising plant produces the steam ability and also reduces, thereby avoiding occuring causes the reactor turbine to open circuit because the steam raising plant water level is low. In the general kernel power station, be furnished with two feed pumps with Total Feedwater Flow capacity 65% for each steam raising plant, interrupt, lose for avoiding reactor that a desired energy of feed pump initially reduces is 75% of total reactor energy. Thisly allow that after losing a feed pump restriction energy that continues reactor operation is to be determined by systems pumps capacity and steam raising plant characteristic.

For the power station starting, the person manually boots feed pump by power plant operation, or by to turbine drive machine supply steam and cooling water, perhaps powers to the motorized motions machine. Pump is from drawing water for reservoir or condensation reservoir and making water recycle extremely to reservoir or condensation reservoir. When pump starts, and check that operation is normal, its speed is arranged on minimum control speed by the operator. Allow when the power station state that one or two feed pump switches to by feed water control system and automatically control, the operator with the control mode switching of selected pump to automatically. When automatically controlling, feed water control system will arrange pump speed, and the by-pass valve control position, to keep the predetermined water level of steam raising plant.

In these power stations, feed pump and RPCS move in the following manner:

Energy level	The water supply station state	The RPCS state	Operator's behavior	The power station reaction
Energy level	The water supply station state	The RPCS state	Operator's behavior	The power station reaction	0 to 50%	Feed pump energising (with the speed of service steam raising plant that supplies water) and second pump	Do not use	Before energy is raised to more than 5%, feed water control system is in automatically. This controls feed pump	If the feed pump of operation opens circuit, because steam raising plant water

	Or energising but be in (rotate with minimum circulation rate, do not supply water to steam raising plant) for subsequent use, or outage, stop using.		Rotate with the speed of service. When energy decreases to 5% is following, will be in manually to water management.	The position is low, will start the reactor tripper.
				The position is low, will start the reactor tripper.	50-100％	Two feed pumps are switched on and are supplied water with the speed of service	Use	When about 50% energy (increase), second feed pump is arranged on automatic control by the control room. RPCS is in the use state when second feed pump is in automatic control.	If one of them feed pump opens circuit, start reactor energy reduction system by the RPCS command signal that opens circuit.

So just being necessary provides three main feed pumps to NSSS; The 3rd feed pump be used as stand-by equipment or with other two sharing modes operations. Conventional RPCS can be attached in the NSSS configuration of three main feed pumps at an easy rate, but inventor of the present invention has imagined the improvement to this RPCS logic, the larger operating flexibility that it has utilized three pump NSSS to provide.

Summary of the invention

Therefore, an object of the present invention is to provide improved RPCS logic for the NSSS that has 3 main feed pumps at least.

Also having a purpose is that the RPCS logic is distinguished 2 pump pump groups and 3 pump pump groups when automatically producing the RPCS command signal.

According to the present invention, 1,2 or 3 main feed pump pump groups of the manual selection of NSSS operator are used for the normal reaction heap operation of generating. This selection is provided with the status latch of each pump or it is resetted, and it is pump operated that representative is expected. Logic circuit the signal that opens circuit of the one or more pumps of indication be connected the pump status latch and connect, to reach following result:

(A) have a pump selected, the opening circuit of this pump do not produce the RPCS command signal (because reactor will be disconnected, for example, when the steam raising plant water level is low) that opens circuit.

(B) have two pumps selected, (i) pump opens circuit the generation RPCS command signal that opens circuit, and (ii) two pumps open circuit and will not produce the RPCS command signal that opens circuit.

(c) there are three pumps selected, (i) pump opens circuit and will not produce the RPCS command signal (because this momentary status can be processed by basic control system) that opens circuit, (ii) two pumps open circuit the generation RPCS command signal that opens circuit, and (iii) three pumps open circuit and will not produce the RPCS command signal.

This logic is preferably with sub-logic realization redundant and that determine. For example, each feed pump opens circuit and produces two independently feed pump break signals. Similarly, each pump state selects to start two different status latches. Those pump break signals and pump status latch are independently matching in the logic gate array, so that select opening circuit of a particular pump in the pump of operation, cause producing the redundant RPCS control signal that opens circuit. Yet this RPCS is not opened circuit, and control signal is confirmed unless the RPCS that is all produced by two gates in the described a pair of logic gate array opens circuit.

The inventive method also can comprehensively be used for nuclear power station, and the latter has: nuclear reactor; At least three feed pumps that supply water to steam raising plant; The control rod system of control reactor core energy output; And insert some controls to reactor core fast when losing the operation of at least one feed pump and hold in both hands energy output to be reduced to the system of a non-zero level from previous level. The method according to selected which pump of operator will will be removed from the operation of supplying water for supply water operation and which pump, produce the command signal of quick insertion part control rod to system. The pump of each operation that is intended for supplying water loses the operation of supplying water and all produces a kind of break signal. Only have when all pumps all produce break signal except one in the selected pump, just produce the command signal that start-up system is inserted the part control rod fast.

Description of drawings

Fig. 1 is the function logic figure of the reactor energy reduction system of nuclear steam feed system; With

Fig. 2 is in the most preferred embodiment of the present invention, owing to lose one or more in three main feed pumps, produces the logic chart of the circuit of reactor energy reduction command signal.

The specific embodiment

Fig. 1 illustrates to have illustrated the sketch plan 10 of the funtion part relevant with described reactor energy reduction system (RPCS) 12. When described reactor energy reduction system runs into transition, transmit control signal to CRDM 14, and match with turbine control system 16, with the energy stabilization of NSSS after a minimizing but the level of non-zero. If RPCS can not make NSSS stable by turbine operation being slowed down and regulating the control rod group, then RPCS disconnects one or more groups control rod.

For purposes of the invention, being produced in the situation of reactor energy reduction system break command signal by command block 18, there is a logic mechanism associated, is used for processing at RPCS12. For example, the processing procedure in the functional block 12 comprises control rod choice criteria 20, and itself depends on the NSSS data 22 that the power station sensor provides. The NSSS condition that other will calculate is provided to RPCS12 by functional block 24. RPCS also submits to the operator in the control of reactor energy reduction control panel 26, and produces warning by RPCS12, is shown in the warning part of operating console 28.

Fig. 2 has shown the pump selection logic circuit 100 of A, B, C three main feed pumps. This circuit can be divided into 4 funtion parts: (1) pump is selected and actuating section 102; (2) feed pump break signal part 104; (3) the logic realization part 106; (4) the RPCS command component 18 that opens circuit. The function of command component 18 among Fig. 2, just the present invention describes, and can think identical with the function of module 18 among Fig. 1.

Described part 102 has a switch 108 at least to each main feed pump A, B and C, and a switch 110 is preferably arranged at least again, and whether the operator can select that specific pump to want at full capacity in the situation of the normal generating in power station with it. When oepration at full load, pump speed control example such as power station electric power will be regulated automatically by self water feeding control system (not shown) more than 5%. When being not oepration at full load, pump or energising but be in stand-by state, perhaps outage is stopped using. Therefore, which pump the operator can specify have a mind to withdraw from from automatic controlling run. Self water feeding control system control changes in pump speed and threshold gate position are to keep the predetermined water level of steam raising plant. Although not in NSSS normal use in service, in fact the pump of operation can manually be in " for subsequent use " state under the control the operator, thereby pump is with the minimum recirculation rate rotation corresponding to the flow of the steam raising plant that is produced by other pumps.

In illustrational embodiment, main feed pump A has a switch 108A, and it is positioned at the master board of Control of Power Plant chamber or in the motor control center that for example interrelates with feed-water pump, all can manually pull to starting or the position that stops. " starting " position is corresponding to selecting such state: pump is wanted oepration at full load. " stop " positional representation and from oepration at full load, withdraw from, be i.e. " outage " or be in for subsequent use. As used " RUN " meaning " oepration at full load " hereinafter. The logical condition of 108A and each switch of 110A passes among a pair of logic sum gate 112A, the 114A, and circuits for triggering 116A is imported in their output into. The output Q of circuit 116A on the online 118A, when the operator when switch 108A or 110A select the beginning condition of pump A, it will be logical one. This logical one is delivered to AND gate 120A, and it plays a part to start latch, indicates this particular pump state whether can supply operation.

Should be pointed out that each main feed pump B and C all have relevant switch 108B and C; 110B and C; 112B and C; 114B and C; 116B and C; 118B and C; And 120B and C, this is extremely important.

Described status latch preferably also has redundancy, and the logical condition of 118A, 118B and 118C output will pass to separately the second AND gate 122A, 122B and 122C like this. Like this, as an example, if the operator manually selects the beginning condition of main feed pump A by switch 108A or 110A, so, latch 120A and 122A will be activated in the mode of redundancy.

Described feed pump break signal part 104, comprise three main feed pump A, B and C that represent with 124A, 124B and 124C respectively, in them each is to from main control panel, shown in 126A, B and C, and come freely that the input signal of the one or more feed water control systems shown in 128 responds. The relevant control logic of feed water control system 128 and generation break signal is not a part of the present invention. Yet what be worth to propose is, for each pump such as 124A, this pump opens circuit and can cause producing two break signal 130A, 132A, and they send among latch 120A and the 122A separately. Similarly, break signal 130B, 132B and 130C, 132C pass among latch 120B, 122B and 120C, the 122C separately. When the input of any one specific latch door 120A, B, C or 122A, B, C is logical one, at corresponding line 134A, B or C, or just produce corresponding logical one output signal on 136A, B or the C.

Logic realization part 106 comprises the RPCS control gate 138 that opens circuit, and its control signal that in specific situation the RPCS on the line 142 opened circuit is passed to RPCS system 18. Another RPCS control gate 140 that opens circuit is preferably arranged, pass to command block 18 from its control signal that opens circuit along the line 144. Like this, in most preferred embodiment, pass to the actual RPCS break signal of reactor energy interrupt system 12 and do not produce (referring to Fig. 1) at 18 places, unless online 142 and 144 the control signal that opens circuit all occurs.

The signal that OR-gate 138 receives from 146,148 and 150 3 AND gates. If any one in three AND gates produces logical one output, OR-gate 138 is to produce control signal on online 142. Similarly, as the part of above-mentioned redundancy, if with " door " 152,154 or 156 in any one logical one that is output as, then OR-gate 140 will be transmitted the control signal that opens circuit on online 144. When having a logical one to input this AND gate in the signal of response two different pump situations that and if only if, each among the AND gate 146-156 will produce the logical one output signal.

Be worth to propose be the present invention can distinguish very significantly only have in three feed pumps two can be for the situation of operation, and all three feed pumps all can be for the situation of operation. OR-gate 160-182 be placed on AND gate array 120,122 and 146-182 between, but for example play the part of when one of only two operating pumps open circuit, produce the RPCS command signal that opens circuit; But and when only having one to open circuit in three operating pumps, the role that the command signal that suppresses to open circuit produces. Substantially, need to two situations about opening circuit in three pumps under, AND gate 146-156 just transmits the logical one signals to OR-gate 138,140. For example, if but main feed pump A is not operating equipment, such as being used as stand-by equipment etc., it is having three pumps to be considered to be equal to the pump that has opened circuit in the configuration for operation. Therefore, in the situation that switch 108A, 110A are all stopping, the output signal Q-of the upper trigger 116A of line 158A is logical one. In such cases, output signal Q is logical zero, thereby door 120A does not start. But, for reaching when one of pump B or C open circuit, the desirable control signal that opens circuit of upper generation of online 142 (with line 144), logical gate 106 must produce such output, and it is identical with the output that produces of logical gate 106 in the situation that power station run duration pump A that all can be when operating at all three pump A, B and C and B open circuit. Therefore, the Q-output logic " 1 " of trigger 116A is sent to OR-gate 160, in order to make logical one can be sent to AND gate 146. If, opening circuit as example take pump B, AND gate 120B passes to AND gate 146 by OR-gate 162 with logical one, and AND gate 146 will pass to OR-gate 138 to logical one, and pass to command component 18 by line 142.

Door 146 is in this way made response to the situation of pump A and B. Because aforesaid redundancy, door 152 is subjected to the impact of pump A and B state equally. Door 146 and 152 output will be logical one, and and if only if: (A) result that arranges according to part 102 " stops ", and pump A or B are counted as and can not operate, and correspondingly pump B or A open circuit; Or (B) pump A and B can be for operations shown in switch sections 102 " startup " arranges, and produce the break signal of self-pumping A and B.

Be also pointed out that if shown in the pump that can move open circuit simultaneously,

door

138 or 140 does not all transmit the RPCS control signal that opens circuit to the command component 18 that opens circuit. In this case, because the action of RPCS 12, reactor will all break when the steam raising plant water level is low, make fission energy reduce to zero, rather than only energy be reduced to a nonzero value that hangs down some.

In the NSSS with three main feed pumps, each pump provides 33.3% of the required feedwater of steam raising plant, but each water supplying pump maximum capacity will reach 50% at least. Reactor energy reduction of the present invention system preferably uses following manner:

Energy level	For water state	The RPCS state	Operator's behavior	The power station reaction
Energy level	For water state	The RPCS state	Operator's behavior	The power station reaction	0 to 40 %	A feed pump energising (supplying water to steam raising plant with the speed of service); Second pump energising, but be in stand-by state (with the minimum speed operation, not supplying water to steam raising plant); The 3rd pump outage.	Do not use	Before energy rises to 5 %, feed water control system is placed automated manner. The operator selects pump to be in operation or stand-by state by pump selection logic.	If opening circuit, the feed pump of operation may cause the power station to cut off.
40％	Two feed pumps are logical	About 50%	At about 40% energy	If be in the speed of service	0 to 40 %		Do not use

To 70 %	Electricity supplies water with the speed of service, and the 3rd pump energising is in stand-by state.	Bring into use during to 60% energy level	The time, the second feed pump is brought into use. The operator is at the pump of water supply system control panel selection operation, and this selects to select logic identification by RPCS.	A feed pump open circuit, feed water control system will increase by second the operation feed pump speed. According to original energy level, RPCS will produce the interruptive command signal, by the very fast minimizing energy of lower scram, energy be reduced, and the turbine rotation is slowed down. If two feed pumps open circuit, reactor will cut off because the steam raising plant water level is low.
To 70 %		Bring into use during to 60% energy level			40% to 100 %	Two feed pump energisings, the 3rd pump cuts off the power supply, do not use	Bring into use during to 60% energy level about 50%	When about 40% energy, the second feed pump is brought into use. The operator selects the pump of operation at the water supply system control panel. This selects to select logic identification by RPCS.	If a pump opens circuit, RPCS will produce RPCS interruptive command signal. If two feed pumps open circuit, the power station will cut off.
70% to 100 %	Three pumps are all switched on, and supply water with the speed of service.	Use	The 3rd feed pump is brought into use 70% the time, and this selects logic identification by RPCS.	If a pump opens circuit, two pumps compensate losing of the 3rd pump in addition. If lose two pumps, RPCS produces RPCS interruptive command signal.	40% to 100 %		Bring into use during to 60% energy level about 50%

Can see that from above-mentioned explanation only RPCS just brings into use when at least two feed pump oeprations at full load and feed water control system are in automated manner. Traditional RPCS is at reactor energy at least 50% (50%-60%), and feed water control system is in use when being in automated manner all the time. Feed water control system is switched on all the time when energy at least 50%. Reactor energy reduction system and feed water control system Relations Among can be realized in several ways. RPCS preferably detects (need not the operator participates in) which pump automatically from feed water control system will be moved. Therefore, the switching device of selecting which pump will be moved and specify which pump to withdraw from from pump operation can be the same switching device that pump is in use that the operator uses at control panel. When energy level surpasses 50% and when bringing into use RPCS, RPCS " reads " the pump state of originally being selected by the operator. Perhaps, RPCS can design like this, so that when the energy level increase surpasses about 50%, bring into use RPCS, operator manually to select which feed pump to be moved by the special-purpose switch of RPCS.

It may be noted that above-described function can realize with the whole bag of tricks that one of ordinary skill in the art is easy to grasp. For example, can use programmable logic controller (PLC), use other FPGAs of computer software to replace.

Claims

1. a pressurized-water nuclear power station comprises: nuclear reactor; At least one steam raising plant; Some feed pumps to steam raising plant water supply; Thereby insert control rod to the control rod system of reactor core control reactor core energy output with normal speed; With comprise with than described normal speed faster speed some control rods are inserted the reactor energy reduction system of the device of reactor cores, thereby when the feed pump operation is broken down, energy output is kept to nonzero value from original value; It is characterized in that also be included as the pump selective system that described steam raising plant is furnished with the power station of three feed pumps, this system comprises:

Being used for three which pumps of pump of manual selection will be for supplying water running and specifying three which pumps of pump from the switching device that removes in service that supplies water;

When the particular pump that is intended for the confession water running can not supply water basically fully, from each pump that is intended for moving, produce respectively the device of pump break signal;

The device of in described reactor energy reduction system described switching device and described generation pump break signal device being reacted is used for only just producing command signal under following situations, with some control rods of rapid insertion:

Select two pumps when, only a pump from selected pump produces the pump break signal, or

Select three pumps when, only from selected pump any two but each pump in non-all three produces pump break signal.

2. the nuclear power station of claim 1 is characterized in that, the device that responds described switching device and generation pump break signal device comprises:

The circuits for triggering relevant with the switching device of described each pump, described pump is selected then to produce a signal at the first circuit if be respectively applied to, and perhaps, produces a signal if described pump is removed then at the second circuit;

Start AND gate circuit, be electrically connected with each described the first circuit in the described flip flop equipment respectively, and, be electrically connected with the device that produces the pump break signal respectively, so that only when the signal on the first circuit and pump break signal overlap, each starts AND gate and just transmits the logical one output signal; And

Respectively with described each output that starts AND gate be connected the OR-gate that the second line electricity is connected.

3. the nuclear power station of claim 2 is characterized in that, the device that responds described switching device and generation pump break signal device comprises:

Be used for each the logical “and” door in the possible combination of two pumps of described feed pump, each logical “and” door responds the output signal of the described OR-gate of second connection relevant with pump in two pumps, the output signal of another described OR-gate of second connection relevant with another pump in two pumps with response.

4. be that reactor energy reduction system produces command signal with the method for rapid some control rods of insertion in the pressurized-water nuclear power station, wherein said pressurized-water nuclear power station comprises: nuclear reactor; At least two steam raising plants; Three feed pumps to steam raising plant water supply; Thereby insert control rod to the control rod system of reactor core control reactor core energy output with normal speed; With comprise with than described normal speed faster speed some control rods are inserted the reactor energy reduction system of the device of reactor cores, thereby when at least one feed pump operation is broken down, energy output is kept to nonzero value from original value; It is characterized in that, said method comprising the steps of:

Set for manually three which pumps of pump of selection will be for supplying water running and three which pumps of pump of appointment from the switching device that removes in service that supplies water;

From each pump that is intended for basically can not supplying water fully for water running, produce the pump break signal;

The setting of responding to switch device and pump break signal only just are second system generation command signal under following situations, with some control rods of rapid insertion:

(a) in the situation that selecteed pump opens circuit selecting a pump operation, do not produce command signal,

(b) selecting two pump operations, only having in the situation that a selected pump opens circuit, produce command signal, and

(c) selecting three pump operations, only having in the situation that two selected pumps open circuit, produce command signal.

5. the method for claim 4 is characterized in that:

The step that produces command signal is carried out in the logic circuit with pump status latch relevant with each pump, and whether each pump of the STA representation of each latch is predetermined for water running; And

The step that switch is set produces the starting state of corresponding latch, can pass through described logic circuit thereby make from the break signal of corresponding pump.