Classifications

• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21C—NUCLEAR REACTORS
  • G21C7/00—Control of nuclear reaction
  • G21C7/06—Control of nuclear reaction by application of neutron-absorbing material, i.e. material with absorption cross-section very much in excess of reflection cross-section
  • G21C7/22—Control of nuclear reaction by application of neutron-absorbing material, i.e. material with absorption cross-section very much in excess of reflection cross-section by displacement of a fluid or fluent neutron-absorbing material, e.g. by adding neutron-absorbing material to the coolant
• • G—PHYSICS
  • G21—NUCLEAR PHYSICS; NUCLEAR ENGINEERING
  • G21C—NUCLEAR REACTORS
  • G21C15/00—Cooling arrangements within the pressure vessel containing the core; Selection of specific coolants
  • G21C15/18—Emergency cooling arrangements; Removing shut-down heat
• • 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
  • Y02E30/30—Nuclear fission reactors

Definitions

• the invention relates to an auxiliary control circuit for light and chemical control designed to be connected to the primary circuit of a pressurized water nuclear reactor and to act as an expansion vessel.
• the primary circuit of such a reactor comprises a tank in which the reactor core is placed, as well as several loops each containing a steam generator and a circulation pump.
• the water in the primary circuit passes through the core, where it is heated to a temperature generally close to 328 ° C. It then passes through the steam generators, in which it is cooled to a temperature generally close to 293 ° C., then the circulation pumps, before returning to the reactor vessel.
• This primary circuit is usually associated with a complex set of auxiliary circuits.
• This set includes in particular a pressurizer circuit, a volumetric and chemical control circuit RCV and RIS safety injection circuits.
• the function of the pressurizer is to impose a pressure, for example close to 155 bars (15.5 MPa), on the primary circuit at the outlet of the core. To this end, the primary water is electrically heated there to ensure the formation of a volume of vapor.
• the pressurizer is further provided with relief valves for limiting the pressure.
• the discharged steam ends up in a balloon or discharge tank of the RDP pressurizer provided with a cooling circuit and a rupture disc to limit the pressure. If the disc ruptures, water vapor from the primary circuit, possibly charged with fis- sion, spreads in the containment. Under normal conditions, the condensate is sent to a TEP recoverable effluent treatment plant.
• the RCV circuit usually placed ⁇ with the TEP installation, in a large "nuclear auxiliary" building separate from the reactor enclosure, processes a small part of the flow of water circulating in the primary circuit.
• This circuit includes in particular filters and resins making it possible to eliminate from the primary water corrosion products, radioactive in the core, as well as dissolved solid fission products, having diffused fuel. It also makes it possible to eliminate, by reservoir skies (under 2 bars of hydrogen), dissolved gaseous fission products (xenon, krypton) and nitrogen residues capable of forming nitric acid which is corrosive during of the radiolytic breakdown of water in the heart.
• the RCV circuit also has the function of limiting the tritium content of the primary water, by means of a low purge flow to the environment of hydrogen and tritiated water. It also makes it possible to maintain a suitable pH by the addition of lithium enriched in lithium 7 and an excess of hydrogen ions by the addition of ammonia or hydrazine.
• the RCV circuit also regulates the boron content of the primary water. This adjustment is made by adding boric acid (with very low action on the pH) or deboration in evaporators of the TEP reusable effluent treatment installation.
• the RCV circuit provides volumetric compensation of the primary circuit, the specific mass of the water in this circuit passing for example from 990 kg / m 'at 45 ° C to 690 kg / m 3 at 310 ° C in a reactor of 1300 MWe containing 380 m 3 of water, which requires evacuation 114 tonnes of water for heating and its return to cooling.
• RCV is reinjected into the primary circuit by means of charge pumps, in particular by means of water dams at the joints of the circulation pumps of the primary circuit.
• the RIS circuits make it possible, in the event of a breach in the primary wall, to inject borated water either from storage tanks under nitrogen pressure, or from low pressure tanks, generally outside the 'enclosure, through injection pumps. When these tanks are emptied, the injection circuits are put into suction on the excess water present in the enclosure, recovered in sumps and cooled on exchangers by an auxiliary RRI intermediate cooling circuit, itself cooled on exchangers by an external raw water circuit.
• These three combined circuits require powerful pumps which receive their electrical energy either from the network or from diesel generators. Several pumps and several diesel generators must be provided to avoid possible unavailability.
• a reserve of borated water can be placed inside the confinement enclosure, above the level of the nuclear core, that is to say in high-pressure tanks capable of pouring into the primary circuit as soon as when the heart is in danger of being dried up and before balancing the pressure between the primary circuit and the enclosure, either in a low-pressure tank which can only flow to the heart when the balancing has been carried out of the breach.
• the tanks added to the primary circuit find their utility in the event of a primary accident, in particular for at least partially replacing the accumulators under nitrogen pressure and the injection pumps of the RIS circuits. .
• the fact of eliminating nitrogen is interesting for safety because the nitrogen likely to be injected in the primary circuit is found at the high points of this one and then breaks the natural circulation.
• replacing the RIS circuit pumps with passive systems can obviously improve the overall reliability of safety systems in the event of primary breaches.
• Such tanks also have utility in normal operation, by reducing the strain associated with the discharge of the pressurizer and by participating in the cooling of the reactor and in keeping it stopped. However, they do not participate in the functions of the RCV circuit previously described.
• the subject of the invention is precisely an auxiliary volumetric and chemical control circuit providing
• an auxiliary circuit of volumetric and chemical control capable of being connected to a primary circuit of a pressurized water nuclear reactor containing primary water, this auxiliary circuit comprising means of removal of water from the primary circuit, means for purifying this water and adjusting its boric acid and hydrogen content, and adjustable m ⁇ yervs for reinjecting water into the primary circuit, characterized by the fact that at least one water-steam tank is placed in the auxiliary circuit, downstream of the withdrawal means, these comprising means for adjusting the flow rate of primary water inlet into the tank, which provide relaxation of water at its saturated vapor pressure, in the tank, all of the means for adjusting the inlet and outlet flow rates allowing control of the volume of water present in the tank and, consequently, of the volume d water u in the primary circuit.
• the water is in quantity imposed in the tank and a saturated vapor sky is formed above it, at a temperature can be little lower than the minimum temperature of the water in the circuit primary, for example 290.5 ° C.
• the pressure can be relatively high (7.5 MPa for 290.5 ° C) while remaining significantly lower than that of the primary circuit (15.5 MPa at the pressurizer ).
• the reservoir constitutes a high pressure safety reserve comparable to that described above. As we will see, it allows volumetric compensation linked to the dilatation of water in the primary circuit, as well as the chemical treatment of water.
• the means for sampling and adjusting the flow rate entering the tank are then essentially regulators associated with jet pumps or ejectors, which allow the reintroduction into the tank of certain flow rates withdrawn for purification purposes.
• the reinjection means are constituted by the usual charge pumps, adjustable in flow rate. It should be noted that the auxiliary circuit according to
• the invention which relates to the relatively high pressure parts of the primary circuit, is preferably coupled to the use of a large reserve of water inside the enclosure and situated above the level of the tank, in accordance à The description given in LE Conway's communication cited above.
• the auxiliary circuit according to the invention which has just been given that by imposing the amount of water present in the tank and without water exchange with the outside, the amount of water can be adjusted. 'water in the primary circuit, that is to say maintain the free level of the pressurizer.
• the tank can receive 110 tonnes of water when the temperature rises, without any purging to the outside and, conversely, return them during cooling without being have to provide fresh water as is the case in current circuits.
• the tank can also be used for partial draining necessary to open the cover of the tank.
• the water-vapor tank of the auxiliary circuit according to the invention is connected to the primary circuit by a pipe of relatively large diameter provided with a valve, to ensure a powerful injection of borated water into the primary circuit, in the event of a breach. It is possible to interpose on this pipe an additional tank containing a boric acid concentrate, to ensure the required anti-neutron reactivity.
• the auxiliary circuit according to the invention also makes it possible to ensure the regulation of the gases dissolved in the primary water while remaining at the general level of pressure of the water-steam tank and without using the hydrogen skies of external tanks.
• the decreasing flow of vapor is enriched in gas until it becomes a practically pure gas at the top of the column, while the liquid formed, more and more enriched in gas upwards, becomes poorer. descending and falls partially degassed into the tank.
• the upper chamber of the degasser is connected to a hydrogen separator such as a permeator comprising a selective membrane which practically lets through only hydrogen.
• a hydrogen separator such as a permeator comprising a selective membrane which practically lets through only hydrogen.
• the latter which appears in the low pressure chamber of the permeator, is aspirated by one of the jet pumps serving the introduction of water into the reservoir.
• the gases to be eliminated, which are concentrated in the high pressure chamber of the permeator, can then be stored to ensure their radioactive decay, before discharging them into the atmosphere through a purge chimney.
• the auxiliary circuit according to the invention can also at least partially ensuring the purification of primary water, vis-à-vis radioactive dissolved solids, remaining at the general pressure level of the water-vapor reservoir.
• part of the water in the tank can be cooled to around 50 ° C in a recovery exchanger, introduced into a half resin regenerator, saturated with boron, then returned after reheating either to the tank by the intermediate of one of the jet pumps used for the introduction of primary water into the tank, or in the primary circuit via a charge pump, the entire installation being placed at the inside the reactor enclosure.
• the auxiliary circuit according to the invention can also be used to ensure at least partially the adjustment of the boron content in the primary circuit, with respect to the daily variations in power imposed by the electrical network, in remaining at the general pressure level of the water-steam tank.
• the tank then serves as a distiller, from which the outlet flow is taken either from the liquid in the lower part or from the vapor in the upper part.
• the vapor thus withdrawn is slightly compressed by one of the jet pumps supplying the reservoir, so as to be able to condense in an exchanger submerged in the lower part.
• the liquid water obtained, very charged with gas flows at the top in the vapor, where it largely gives up these gases and then leaves the tank.
• the liquid water contained in the tank is enriched with boron from the primary circuit, while the latter, correlatively, becomes depleted in boron.
• a withdrawal of liquid in the lower part of the tank makes it possible to gradually return to the equality of contents between the liquid water contained in the tank and the water contained in the primary product.
• the auxiliary circuit according to the invention also has the advantage of making it possible to use the water-vapor reservoir as a discharge tank for the RDP pressurizer.
• the vapor discharge pipe of the pressurizer opens into a bubbler placed in a lower zone of the water-steam tank.
• This arrangement allows the recovery of the released vapor without requiring its treatment and external purification as it was rule before.
• the purge operations necessary to limit the gas concentration in the pressurizer vapor are therefore facilitated.
• the reservoir can be dimensioned to allow complete discharge of the pressurizer until the pressures in the primary circuit are equalized, without any discharge into the enclosure by rupture of the disc, as may be the case according to the prior art.
• the various pipes connecting the water-steam tank of the auxiliary circuit according to the invention to the primary circuit which preferably incorporate an exchanger for cooling the water withdrawn from the circuit.
• auxiliary can of course be used at least partially for the cooling function when the reactor is stopped.
• a purge to the outside can be provided at the base of the tank, to eliminate the deposited bodies and Let escape every day a few cubic meters of primary water, by means of the reinjection of new water, in order to limit Accumulation tritium in the form of tritiated water.
• Reference 10 designates the vessel of a pressurized water nuclear reactor.
• This tank contains the core 12 of the reactor.
• Several primary loops are connected to this tank, only one of which is shown in the figure, and which constitute with tank 10 The primary reactor circuit.
• Each of the loops of the primary circuit includes a line 14 connecting the tank 10 to a steam generator 16, a line 18 connecting the steam generator 16 to a primary pump 20 and a channel 22 through which the water from the primary circuit is discharged by the pump 20 into the tank 10.
• the primary water is heated by the core 12 to a temperature close to, for example, 328 ° C.
• This primary water is cooled in the steam generator 16, which it leaves at a temperature in the region of 293 ° C.
• the primary circuit of the reactor also comprises, in a known manner, a pressurizer 24 connected to the pipe 14 of one of the loops of the circuit.
• An electric heating device 26 placed in the pressurizer 24 makes it possible to form a volume of vapor inside the latter.
• the primary water contained in the circuit is thus pressurized.
• a suction manifold 28 placed in this volume of steam is connected to the pipe 22 by a pipe 30 controlled by a valve 32, in order to allow a reduction in the pressure when necessary.
• the circuit of the pres ⁇ suriser 24 thus makes it possible to establish and control the pressure prevailing in the primary circuit, the value of this pressure generally being approximately 15.5 MPa corresponding to a temperature at the pressurizer of 345 ° C.
• the reactor vessel 10 and all of the loops forming with it the primary circuit are placed inside a confinement enclosure one of the walls of which is shown diagrammatically at 34 on the figure.
• an auxiliary circuit of volumetric and chemical control of original design located essentially inside L'en- reactor containment, is associated with the primary reactor circuit.
• This auxiliary circuit comprises one or more water-steam tanks 36.
• a tank 36 can in particular be associated with each loop of the primary circuit.
• This or these reservoirs 36 are supplied with water taken from the primary circuit by a sampling pipe 38, which is connected to the pipe 18 of one of the loops of the primary circuit, between the steam generator 16 and the circulation pump 20 of this loop.
• the sampling line 38 is connected to each of the tanks 36 by a set of incoror ejectors to jet pumps such as the pumps 40a, 40b and 40c in the figure.
• the supply of each of these jet pumps is controlled by a valve 42a, 42b and 42c respectively.
• the number of jet pumps is chosen so as to make it possible to control the inlet flow rate of the tanks 36 by opening a more or less large number of valves such as 42a, 42b and 42c, each of the jet pumps preferably operating at full jet flow.
• the ejectors incorporated in the jet pumps have the effect of relaxing the water taken from the primary circuit to its saturated vapor pressure, which leads to the formation of a sky of saturated vapor above the liquid water in the reservoir 36.
• the temperature of the water taken from line 18 is around 293 ° C for a pressure of 15.1 MPa
• the temperature in the tank can be established at around 290.5 ° C for a saturated pressure 7.5 MPa.
• the auxiliary circuit according to the invention also comprises a line 44 for reinjection of The water in the primary circuit, in which are placed one or more charge pumps 46.
• this pipe can be supplied by several branches at different levels in each of the tanks 36 and it is connected to one of the loops of the primary circuit, for example by means of water dams at the joints of the circulation pumps 20, in the traditional way.
• the valves 42a, 42b and 42c associated with the jet pumps 40a, 40b and 40c, as well as the charge pump 46 constitute flow control means making it possible to control at will The volume of water present in each of the tanks 36 and, consequently, the volume of water contained in the primary circuit of the reactor.
• a safety pipe 48 connects the bottom of each of the tanks 36 to the pipes 22 of the primary circuit, downstream of the primary pumps 20.
• a valve 50 is placed in this pipe 48, at the bottom of the tank 36. This valve, normally closed, opens automatically when the pressure in the circuit primary drops below the pressure in the tank. In the event of a breach in the primary circuit, a powerful injection of water is thus carried out.
• an additional reservoir 52 is advantageously provided containing a concentrate of boric water.
• the safety line 48 opens into the bottom of the additional tank 52, in which the valve 50 is provided.
• a second valve 54 is placed between the tank 36 and the tank 52 so as to protect itself of water mixtures in normal operation between the tanks 36 and 52. The two valves open simultaneously when there appears, in the pipe 48, a pressure lower than that prevailing in the tank 36.
• a degasser such as a distillation column 56, which is placed at the top of the water-steam tank.
• This distillation column 56 preferably of the plate or granular bed type, is cooled for example to 20 ° C. in its upper chamber 56a, by an external cooling device 58.
• a mixture of gases is obtained, the total pressure of which is equal to that prevailing in the tank 36, with a high predominance of hydrogen and containing traces of nitrogen and radioactive gases such as xenon. and krypton.
• This mixture is taken up by a tube 60 emerging in the upper chamber of the distillation column 56 and descending below the latter, inside the tank 36 to ensure heating of the gases, for example to around 290 ° C.
• the gas mixture is then conveyed out of the reservoir 36 through the tube 60 to a hydrogen separator 62 constituted for example by a selective membrane permeator of the pa L Ladi um-silver type, with very high selectivity, operating at around 250-300 ° C.
• the separator 62 comprises a low pressure chamber 62a which is connected to one of the jet pumps 40a by which the water taken from the primary circuit by the pipe 38 is injected into the tank 36.
• the residual gas is concentrated in a high pressure chamber 62b of the separator 62, which communicates with a storage tank 64 in which this gas is
• the gas can be discharged into the atmosphere through a pipe 66 controlled by a valve 68 and connected to an external purge chimney 70.
• the liquid water formed in the distillation column 56 becomes depleted in gas by redescending in this column and falls partially degassed in the tank 36.
• one or more resin linkers 72 pre-saturated with boron are used so as not to act on the boron.
• Each demineralizer 72 communicates with the Liquid phase of the water contained in the reservoir 36 by an outlet pipe 74 in which a cooler exchanger 76 is placed which has the effect of lowering the temperature of the water to a value close to, for example, 50 ° C. which corresponds to the usual operation of resins.
• the pressure resistance of demineralization containers should be increased to 10 MPa for example, instead of 1 MPa in usual installations.
• the purified liquid phase is reheated in a reheater exchanger 78 coupled to the cooler exchanger 76.
• the outlet pipe 74 Downstream of the reheater exchanger 78, the outlet pipe 74 comprises a bifurcation of which a first branch supplies one of the jet pumps 40b through which the sampling line 38 supplies the reservoir 36.
• a second branch of this bypass is connected directly to the line 44 by which the water is reinjected into the primary circuit, upstream of the charge pump 46.
• a set of valves 80 and 82 placed in the two branches makes it possible to control the reinjection of the purified water either in the tank 36, or directly in the primary circuit.
• At least one other semi-mineralizer 84 is also provided in the auxiliary circuit according to the invention.
• This half nera L i seur 84 communicates with the Liquid phase of the water contained in the reservoir 36 by an outlet pipe 86 in which is placed a heat exchanger ref king di sseur 88 making it possible to lower the temperature of the water arriving in demineralizer 84 at a temperature of about 50 ° C.
• This also makes it possible to use half nera li ers of conventional design for this function, the maximum pressure of which is simply increased.
• the water applied in boron passes through a heat exchanger 90 coupled to the cooler exchanger 88. Downstream of the heat exchanger 89, the pipe 86 passes through a valve 90, before being connected to line 44 of reinjection of water into the primary circuit, upstream of the charge pump 46.
• the variations in the boron content of the primary water can be obtained by a distillation system associated with the reservoir 36 containing the Liquid and its vapor.
• the outlet flow rate is taken either from the liquid phase, which contains boron, or from the vapor phase which does not contain it, whence variations in the boron content in the tank and inverse variations in the primary circuit.
• the output flow containing boron is, for example, that which passes through the half-nerenerizer 72 and the valve 82.
• at least one 40c of the pumps is placed jet in the upper part of the reservoir 36 containing water in the vapor phase.
• the jet pump 40c then drives this vapor into a condenser exchanger 92 which is immersed in the liquid phase of the water contained in the tank 36.
• the vapor phase sucked in by the jet pump 40c is slightly compressed, so that it condenses in the condenser exchanger 92.
• a degassing streamer 94 placed in the upper vapor phase of the tank 36.
• the water in the liquid state coming in this trickle 94 being very charged with gas, it yields a large part of these gases in the steam in the trickle, the tank of which consequently receives distilled water, subject to certain quantities of dissolved body coming from the ejection water.
• the distilled water thus collected in the tank of the streamer 94 is evacuated from the water-steam tank 36 by an outlet pipe 96 controlled by a valve 98 and connected to the pipe 44 for reinjecting water into the primary circuit. , upstream The pump 46.
• the liquid water contained in the tank 36 is thus enriched with boron from the contributions of the primary circuit, while the latter is correspondingly depleted in boron.
• Such distillation actions to be repeated very often, become too important as soon as the average boron content has greatly decreased during the operating period.
• the water-steam tank 36 of the auxiliary circuit according to the invention is used in addition to the discharge tank of the RDP pres ⁇ suriser which is usually connected to the pressurizer discharge pipe.
• the discharge pipe 100 connected in the usual way to the upper vapor phase of the pressurizer 24 and controlled by a valve 102, ends at its opposite end by a bubbler 104 placed in the lower zone of the water tank.
• -vapor 36 that is to say in the Liquid phase of the water contained in this tank.
• the reservoir according to the invention can be dimensioned to admit, if necessary, a total discharge of the pressurizer, the discharge valve 102 remaining open. voluntarily (to ensure a significant drop in primary pressure if necessary) or involuntarily (Three Mile Island accident).
• the tank 36 contains for example 150 m 3 of liquid water and 20 m 3 of steam at 290.5 ° C, 7.5 MPa.
• the average temperature of the water in the primary circuit is 311 ° C, which corresponds to a saturated vapor pressure of 10 MPa. It can be calculated that the total discharge of the pressurizer in the tank 36 makes it possible to achieve a pressure of less than 10 MPa.
• the primary pressure can be rapidly lowered to 10 MPa by discharging the pressurizer, without any other particular precaution.
• the discharge of the pressurizer can, of course, be actuated when it is desired to make the injection of water from the reservoir 36 into the primary circuit earlier in the event of a breach therein.
• the above case corresponds to the supply of the reservoir 36 with primary water directly taken from the outlets 18 of the steam generators.
• the primary water can be cooled from 290 °, 5 to 270 ° C corresponding to a pressure of 5.5 MPa in the tank.
• the discharge of the pressurizer could however give rise, under the preceding conditions, to a maximum pressure slightly less than 10 MPa, taking into account the heat reserve contained in the entire primary circuit.
• the auxiliary volumetric and chemical control circuit according to the invention finally comprises purge and make-up installations 110 situated outside the enclosure 34 and very simplified compared to the comparable installations existing in nuclear reactors. current pressurized water. These installations 110 communicate with the water-steam tank 36, at the base thereof, by a pipe 112 controlled by a valve 114. They also communicate with the additional tank 52 containing a boric water concentrate by a pipe 116 controlled by a valve 118. Finally, they communicate by pipes, not shown, with the half-heatsinks 72 and 84.
• the line 112 and the valve 114 which it comprises constitute a purge circuit which makes it possible, on the one hand, to eliminate the bodies deposited in the bottom of the tank and, on the other hand, to allow a few m 3 to escape each day.
• Primary Liquid and reinjecting New Water in order to Limit The accumulation of tritium in the primary circuit.
• the installations 110 outside the reactor enclosure make it possible to treat the water purged as well as that obtained in the leakage recovery circuit, ensuring the corresponding reinjection of new water, controlling the boron concentration in the tank 52, and regenerating the deminerals. Readers 72 and 84 When the reactor stops.
• the fact that a large part of the functions of the auxiliary circuit can be ensured inside the enclosure allows considerably limit the complexity of the size of these external installations 110, compared to current installations.
• the auxiliary circuit according to the invention corresponds to a significant reduction in installation compared to the conventional volumetric and chemical control circuit and its associated installations, which currently occupy a building of very great importance.
• the auxiliary circuit according to the invention is entirely enclosed in the security enclosure, with the minimum of connections to the outside, which has a clear advantage over possible external pollution.
• the circuit essentially comprises a large tank whose size and operating pressure are lower, for example than that of the pressure body of a steam generator in a reactor with four generators. As the quantity of hot primary water contained in the confinement enclosure is increased, it may be necessary to increase the pressure-volume product thereof.
• the economy compared to a conventional installation remains significant.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• General Engineering & Computer Science (AREA)
• High Energy & Nuclear Physics (AREA)
• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Structure Of Emergency Protection For Nuclear Reactors (AREA)
• Physical Water Treatments (AREA)

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• 1989
  • 1989-02-01 FR FR8901280A patent/FR2642559B1/fr not_active Expired - Lifetime
• 1990
  • 1990-01-31 KR KR1019900702176A patent/KR910700530A/ko not_active Application Discontinuation
  • 1990-01-31 JP JP2502983A patent/JPH03503805A/ja active Pending
  • 1990-01-31 EP EP90902794A patent/EP0408725A1/de not_active Withdrawn
  • 1990-01-31 WO PCT/FR1990/000076 patent/WO1990009025A1/fr not_active Application Discontinuation

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