WO1999054886A1 - Systeme d'alimentation de securite pour systeme de refroidissement a l'arret - Google Patents

Systeme d'alimentation de securite pour systeme de refroidissement a l'arret Download PDF

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Publication number
WO1999054886A1
WO1999054886A1 PCT/US1999/004975 US9904975W WO9954886A1 WO 1999054886 A1 WO1999054886 A1 WO 1999054886A1 US 9904975 W US9904975 W US 9904975W WO 9954886 A1 WO9954886 A1 WO 9954886A1
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WO
WIPO (PCT)
Prior art keywords
pipe
pump
cavitation
shutdown cooling
shutdown
Prior art date
Application number
PCT/US1999/004975
Other languages
English (en)
Inventor
Terrel K. Samuels
Daniel A. Peck
Original Assignee
Abb Combustion Engineering Nuclear Power, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Abb Combustion Engineering Nuclear Power, Inc. filed Critical Abb Combustion Engineering Nuclear Power, Inc.
Priority to AU34503/99A priority Critical patent/AU3450399A/en
Publication of WO1999054886A1 publication Critical patent/WO1999054886A1/fr

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Classifications

    • G—PHYSICS
    • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
    • G21D—NUCLEAR POWER PLANT
    • G21D1/00—Details of nuclear power plant
    • G21D1/02—Arrangements of auxiliary equipment
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E30/00—Energy generation of nuclear origin

Definitions

  • the present invention is directed to a safety feed system for a shutdown cooiing system of a nuclear power plant.
  • the novel system is designed to minimize pump cavitation or near cavitation from entrained air by feeding additional coolant to the shutdown cooling system pump in the event of low coolant level in the hot leg between the nuclear reactor and the steam generator or other pump cavitation producing anomalies such as entrained air voids produced by flowing vortices.
  • coolant fluid which is borated water
  • PWR pressu ⁇ zed water reactor
  • the circulating pressu ⁇ zed coolant absorbs heat released by the thermonuclear reaction occur ⁇ ng in the reactor.
  • the heated coolant flows through a main pipe which is appropriately known as the
  • hot leg of the circulation loop.
  • the hot leg delivers the hot coolant to a steam generator.
  • the coolant fluid circulates through a heat exchanger.
  • the heat exchanger cools the p ⁇ mary coolant fluid and uses the heat removed from the coolant to produce steam in the secondary system. This steam is eventually used to drive turbines and generate electricity.
  • a circulation pump removes the coolant from the steam generator via a "suction leg” and returns it to the reactor via a "cold leg” and inlet. The coolant is then reheated in the reactor and the cycle repeats.
  • This circulation of coolant through one or more loops is critical for the operation of the power plant. Not only does it deliver heat energy to the 2
  • Nuclear power plant systems including the steam generators, require periodic maintenance.
  • the fluid circulation system must be inspected for potential degradation of the steam generator tubes and nozzle dams are normally installed and removed from the steam generator hot and cold legs to allow inspection and maintenance to be performed in a dry environment
  • the coolant fluid In order to install and remove nozzle dams, the coolant fluid must be drained from the steam generator This requires lowering the fluid level in the main circulation loop and consequently the hot leg or main pipe.
  • a 'shutdown ' the coolant continues to be heated by decay heat from the reactor core but it is cooled by an alternate heat exchanger and auxiliary circulatory system know as the "shutdown cooling system"
  • the water level In order to lower the coolant or water level in the shutdown reactor system to allow maintenance operations on portions of the system above the lowered water level, the water level must be controlled and maintained at a minimum level while the core flow rate must be maintained to provide adequate core cooling. This minimum water level is about midway within the reactor coolant system mam loop piping (the hot leg) and is commonly referred to as "midloop".
  • the shutdown cooling line on each hot leg communicate with the lower region of the hot leg or of the main loop pipe to draw the heated water from the core for cooling by the alternate heat exchanger in the shutdown cooiing system and subsequent recirculation of cooled water to a reactor inlet and thus to the core 3
  • the current methods to avoid vortex formation attempt to keep the water level as high as possible and/or reduce the flow rate, resulting in a conflict between the need to lower the water level for maintenance service, and the need to keep the water level high and at a sufficient flow rate for safe core cooling.
  • Midloop liquid level sensor systems in use are related to a detection of the water elevation and inference of the status of any drain vortex therefrom.
  • a midloop ultrasonic measuring instrument for this purpose is disclosed in co- pending U.S. patent Application Serial No. 08/864,644, assigned to the same assignee as the instant application and filed May 29, 1997.
  • Another co- pending U.S. Patent Application Serial No. 08/783,978, assigned to the same assignee as the instant application and filed January 15, 1997, is for a system which reduces air entrainment and pump cavitation by inserting a vortex breaker in the shutdown cooling pipe adjacent the main pipe or hot leg.
  • the RCS water level measurement accuracy is limited by the instrument technology used and the process parameter changes such as temperature, pressure and boric acid concentration.
  • the shutdown cooling pump current measurement alarm occurs only after air has already been ingested into the pump, thus it cannot be used to avoid the air vortex.
  • a shutdown cooling system of a nuclear power plant includes a main pipe or hot leg lower region which is connected to a shutdown cooling pump for circulation of a portion of the hot leg flow through an auxiliary heat exchanger and back to an inlet of the reactor. Provision for by-passing the heat exchanger for draining water to create an appropriate midloop water level is also provided by another system (not shown). In any event, whichever drain method is used, drains water from the reactor coolant system to the desired level for maintenance in the steam generator and shutdown cooling system and recirculates coolant to the reactor core for core cooling.
  • the present invention is a safety feed system for a shutdown cooling system of a nuclear power plant to eliminate or minimize entrained air or cavitation in the shutdown cooling drain pump(s). This is accomplished by providing a reservoir with a make-up feed pipe intersecting and in communication with the drain pipe between the hot leg pipe or hot leg and the shutdown cooiing pumps.
  • the make-up feed pipe has a modulated control valve therein responsive to signals from a liquid level sensor in the hot leg and an air entrainment or pump cavitation sensor which is within, across or adjacent to the shutdown cooling or drain pump.
  • Signals from the liquid level sensor and the air entrainment or pump cavitation sensor are typically based on pump current, pressure across the pump or flow rate through the pump and are processed in a controller of the elect ⁇ cai circuit which is connected to and controls and modulates the valve in the make-up feed pipe.
  • the novel safety feed system may utilize for the detection of air entrainment or air vortexmg commercially available portable clamp-on ultrasonic flowmeters as disclosed in the above cited Application Serial No. 08/783,978. These instruments are mounted for the detection of air entrainment or air vortexing and provide a cavitation sensor when mounted across or adjacent the shutdown cooiing pump either upstream or downstream thereof. In the event of air entrainment, an air vortex, air void or other flow anomalies, a disruption of the flow meter ultrasonic signal triggers an alarm and provides a signal to the controller of the valve in the make-up feed pipe. Pump current sensors within the pump may also be used to trigger a signal and indicate a flow anomaly to the controller which controls and modulates the make-up feed pipe valve. 6
  • FIG. 1 is an isometric schematic drawing of a nuclear power plant having two steam generators with a shutdown cooling system and safety feed system of the invention illustrated in connection with only one of the steam generators, for clarity
  • FIG. 1 illustrates a nuclear power plant incorporating the safety feed system of the present invention
  • the numeral 10 generally designates a pressurized water reactor type of plant in which water is continuously transferred through a closed circulation loop between a reactor 12 and each of two steam generators 14 and 16, respectively.
  • the water coolant from reactor 12 flows through ma pipes or hot legs 18 to the respective steam generators 14 and 16, each of which has similar piping.
  • a coolant system circulation pump 20 circulates water, which has been cooled in the steam generator, through a suction leg pipe 22, and back to the reactor 12 via cold leg 24 and reactor vessel inlet 26.
  • the opening 30 of pipe 18 is variously termed dram 30 or shutdown cooling system drain 30 and the pipe from it is called dram pipe 28 or shutdown cooling system pipe 28.
  • Flow from the hot leg pipe 18 into the shutdown cooling system or drain pipe 28 may form a vortex at dram 30 which entrains air in the coolant and may create cavitation in shutdown cooling or drain pump 33 which has direct fluid communication from the hot leg pipe 18 where it intersects with the lower region of hot leg pipe 18.
  • This vortex inhibits flow rate in the drain pipe 28 and drain pump 33 by creating voids and cavitation and can airlock the shutdown cooling pump 33.
  • the shutdown cooling or drain pump 33 discharges through conduit 28' to shutdown cooling auxiliary heat exchanger 34 downstream from it for temperature control of the shutdown cooiing system water.
  • a clamp on portable flowmeter 32 is mounted downstream (but may be upstream or across) of pump 33 to act as a cavitation sensor by sensing entrained air, cavitation or other flow volume anomalies.
  • Transducers for the flowmeter 32 are attached to pipe 28 by chains or straps as taught in
  • the preferred clamp-on portable flowmeter is a Controlotron System 1010 DP which is available from Controlotron, 155 Plant Avenue, Hauppauge, NY 11788. It is specified in their brochure 1010DP-1 , a copy of which is attached hereto and which is considered part of the disclosure hereof.
  • valve 36 in drain pipe section 28" to a drain 38 or to a section of pipe 40 which is connected to the main pipe cold leg 24 and inlet 26 for recirculation through reactor 12 to cool the core during the shutdown period or in an emergency when the auxiliary heat exchanger's capacity is needed for safety reasons.
  • the entrained air or cavitation sensor which is flowmeter 32, is connected in circuit to controller 42 by a cable 46. Controller 42 is also 8 connected in circuit to a liquid level sensor 44 by means of a cable 48. Controller 42 is preferably an ABB (IAD Division), Vasteras, Sweden, Model AC110 Programmable Logic Controller.
  • the liquid level sensor is preferably as disclosed in Application Serial No. 08/864,644. It could also be as disclosed in U.S. Patent No. 5,541.969, assigned to the same assignee as the instant application.
  • Controller 42 acts to control and modulate valve 50 located in make-up feed pipe 52 between reservoir 54 of make-up coolant 56 and the intersection 60 of make-up pipe 52 with loop or drain pipe 28.
  • Valve 50 may be of the pneumatic type sold by Fisher Controls
  • valve 50 Com of Marshalltown, Iowa 50158 as a Full Sized Design ED Linear Cage Valve with a Type 667 Diaphragm Actuator. Motor operated and solenoid valves may also be used for valve 50.
  • valve 50 In operation, as long as the proper midloop fluid level is sensed by liquid level sensor 44 and no significant air entrainment, cavitation or other flow volume anomaly is sensed by flowmeter 32 or an equivalent entrained air or cavitation sensor within, across or adjacent to the drain pump 33, the valve 50 is kept closed by controller 42 through its circuit connection cable 58 with valve 50. If air entrainment or cavitation is sensed by the cavitation sensor 32 or the liquid level sensor 44 senses a too low fluid level in main pipe 18, coolant 56 is fed through modulating control valve 50 to drain pipe 28 via intersection 60. This will minimize cavitation in pump 33 and prevent a dangerous situation in the nuclear plant.

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  • Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Plasma & Fusion (AREA)
  • General Engineering & Computer Science (AREA)
  • High Energy & Nuclear Physics (AREA)
  • Monitoring And Testing Of Nuclear Reactors (AREA)

Abstract

La présente invention concerne un système d'alimentation de sécurité de centrale nucléaire et un procédé de minimisation du phénomène de cavitation, ou proche de la cavitation, dû à un entraînement d'air ou à une anomalie de débit d'écoulement dans la pompe (33) de vidange d'un système de refroidissement à l'arrêt d'une centrale nucléaire pendant la phase de travail où la boucle est à moitié vide. Dans cette invention la centrale comprend une canalisation chaude (18) sur laquelle est montée une conduite de vidange (28), du système de refroidissement à l'arrêt, reliée à sa partie inférieure à une pompe, ledit système comprenant un réservoir (54) et une conduite d'appoint (52) équipée d'une vanne (50) régulée et modulée à l'aide d'un appareil de commande (42) de manière à assurer un appoint de liquide refroidissant à la conduite de vidange, en amont de la pompe de vidange dudit système, au cas où les capteurs détectent un niveau faible de liquide refroidissant dans la canalisation chaude ou bien un phénomène de cavitation, ou proche de la cavitation, ou une anomalie de débit d'écoulement, ce qui déclenche, par l'intermédiaire de l'appareil de commande, un signal d'ouverture à la vanne.
PCT/US1999/004975 1998-04-17 1999-03-05 Systeme d'alimentation de securite pour systeme de refroidissement a l'arret WO1999054886A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU34503/99A AU3450399A (en) 1998-04-17 1999-03-05 Shutdown cooling system safety feed system

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US6211198A 1998-04-17 1998-04-17
US09/062,111 1998-04-17

Publications (1)

Publication Number Publication Date
WO1999054886A1 true WO1999054886A1 (fr) 1999-10-28

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AU (1) AU3450399A (fr)
WO (1) WO1999054886A1 (fr)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004049086A1 (fr) * 2002-11-27 2004-06-10 Endress + Hauser Gmbh + Co. Kg Procede de reglage de pression permettant d'eviter des cavitations dans une installation industrielle
WO2014099101A2 (fr) * 2012-10-04 2014-06-26 Holtec International, Inc. Système d'arrêt pour un système de fourniture de vapeur nucléaire
US10115487B2 (en) 2012-08-14 2018-10-30 Smr Inventec, Llc Shutdown system for a nuclear steam supply system
CN113266756A (zh) * 2021-04-29 2021-08-17 华能国际电力股份有限公司上安电厂 一种机组停机再循环冷却系统及方法
US11935663B2 (en) 2012-05-21 2024-03-19 Smr Inventec, Llc Control rod drive system for nuclear reactor

Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5877698A (ja) * 1981-11-02 1983-05-11 株式会社日立製作所 原子炉残留熱除去系のフラツシング装置
DE3417198A1 (de) * 1984-05-09 1985-11-14 Kraftwerk Union AG, 4330 Mülheim Fluessigkeitsgekuehlter-kernreaktor
JPS62255704A (ja) * 1986-04-30 1987-11-07 株式会社東芝 給水加熱器ドレン制御装置
JPH02161108A (ja) * 1988-12-14 1990-06-21 Hitachi Ltd 湿分分離加熱器のドレンレベル制御装置
EP0509923A1 (fr) * 1991-04-17 1992-10-21 Framatome Réacteur nucléaire refroidi par de l'eau sous pression comportant un dispositif de vidange du circuit primaire à sécurité intrinsèque à niveau bas déterminé
FR2718879A1 (fr) * 1994-04-13 1995-10-20 Framatome Sa Procédé de refroidissement du cÓoeur d'un réacteur nucléaire à eau sous pression pendant un arrêt à froid et circuit primaire pour la mise en Óoeuvre du procédé de refroidissement.
WO1998054549A1 (fr) * 1997-05-29 1998-12-03 Combustion Engineering, Inc. Instrument ultrasonique de type 'midloop'
US5861560A (en) * 1997-09-02 1999-01-19 Combustion Engineering, Inc. Shutdown cooling pump vortex detection system

Patent Citations (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5877698A (ja) * 1981-11-02 1983-05-11 株式会社日立製作所 原子炉残留熱除去系のフラツシング装置
DE3417198A1 (de) * 1984-05-09 1985-11-14 Kraftwerk Union AG, 4330 Mülheim Fluessigkeitsgekuehlter-kernreaktor
JPS62255704A (ja) * 1986-04-30 1987-11-07 株式会社東芝 給水加熱器ドレン制御装置
JPH02161108A (ja) * 1988-12-14 1990-06-21 Hitachi Ltd 湿分分離加熱器のドレンレベル制御装置
EP0509923A1 (fr) * 1991-04-17 1992-10-21 Framatome Réacteur nucléaire refroidi par de l'eau sous pression comportant un dispositif de vidange du circuit primaire à sécurité intrinsèque à niveau bas déterminé
FR2718879A1 (fr) * 1994-04-13 1995-10-20 Framatome Sa Procédé de refroidissement du cÓoeur d'un réacteur nucléaire à eau sous pression pendant un arrêt à froid et circuit primaire pour la mise en Óoeuvre du procédé de refroidissement.
WO1998054549A1 (fr) * 1997-05-29 1998-12-03 Combustion Engineering, Inc. Instrument ultrasonique de type 'midloop'
US5861560A (en) * 1997-09-02 1999-01-19 Combustion Engineering, Inc. Shutdown cooling pump vortex detection system

Non-Patent Citations (3)

* Cited by examiner, † Cited by third party
Title
DATABASE WPI Section Ch Week 8750, Derwent World Patents Index; Class K06, AN 87-352181, XP002110335 *
DATABASE WPI Section Ch Week 8908, Derwent World Patents Index; Class K05, AN 89-059304, XP002110334 *
PATENT ABSTRACTS OF JAPAN vol. 014, no. 416 (M - 1021) 7 September 1990 (1990-09-07) *

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2004049086A1 (fr) * 2002-11-27 2004-06-10 Endress + Hauser Gmbh + Co. Kg Procede de reglage de pression permettant d'eviter des cavitations dans une installation industrielle
US11935663B2 (en) 2012-05-21 2024-03-19 Smr Inventec, Llc Control rod drive system for nuclear reactor
US10115487B2 (en) 2012-08-14 2018-10-30 Smr Inventec, Llc Shutdown system for a nuclear steam supply system
WO2014099101A2 (fr) * 2012-10-04 2014-06-26 Holtec International, Inc. Système d'arrêt pour un système de fourniture de vapeur nucléaire
WO2014099101A3 (fr) * 2012-10-04 2014-08-28 Smr Inventec, Llc Système d'arrêt pour un système de fourniture de vapeur nucléaire
CN113266756A (zh) * 2021-04-29 2021-08-17 华能国际电力股份有限公司上安电厂 一种机组停机再循环冷却系统及方法

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