Abstract: A system and method for determining a noble metal concentration in a sample that is representative of a noble metal concentration in either a volume of water circulated through a nuclear reactor or a surface of a nuclear reactor component exposed to the volume of water. The system comprises: at least one standard having a predetermined concentration of the noble metal disposed its surface; an electrolyte bath for immersing one of the sample and the standard therein; an auxiliary electrode connectable to one of the sample and the standard; a power source connectable to a reference electrode and one of the standard and the sample; and a current measurement device capable of measuring a current passing between the auxiliary electrode and one of the sample and the standard.

Abstract: A novel high-purity polymer dispersant and sludge conditioner added to the feedwater entering the secondary side of a nuclear steam generator for minimizing the accumulation of metal-oxide deposits within the nuclear steam generator during the continuing operation of the generator is disclosed. The high-purity polymer is selected from a group consisting of acrylic acid polymer, methacrylic acid polymer, acrylate polymer, methacrylate polymer, copolymers, and terpolymers, acrylate/acrylamide copolymer, acrylate/methacrylate copolymer, terpolymers, and mixtures thereof. Methods of making and applying the polymer dispersant and sludge conditioner are described. Means for removing the metal oxides and polymer from the blowdown stream are disclosed.

Abstract: Method for reducing corrosion of alloy components in a water cooled nuclear reactor or associated components comprising the step of injecting into the water of the reactor in the presence of zinc a noble metal cation-releasing compound which releases noble metal cations or cationic species containing noble metal species into the reactor water under operating reactor thermal conditions.

Abstract: A jet pump for a nuclear reactor includes a riser and an inlet mixer having a set of nozzles and a mixing section for receiving coolant flow from the nozzles and suction flow from an annular space between the reactor vessel and the shroud core. To minimize or eliminate electrostatic deposition of charged particulates carried by the coolant on interior wall surface of the inlet-mixer of the jet pump, and also to inhibit stress corrosion cracking, the interior wall surfaces of the nozzles and mixing section are coated with a ceramic oxide such as TiO2 and Ta2O5 to thicknesses of about 0.5-1.5 microns.

Abstract: A metal cooling tube of a water-cooled nuclear reactor, having an inner surface thereof exposed to an aqueous cooling medium containing hydrogen peroxide. The cooling tube has its inner surface coated with matter selected from the group consisting of the element manganese, molybdenum, zinc, copper, cadmium for absorbing such hydrogen peroxide and then affecting decomposition of the hydrogen peroxide in the aqueous medium. In preferred embodiment such coating is manganese and oxides thereof. A method for lowering the electrochemical corrosion potential of a metal allow cooling tube exposed to an aqueous medium in a water-cooled nuclear reactor is also disclosed. Such method comprises the step of coating an inner surface of such tube with matter selected from the group of elements comprising manganese, molybdenum, zinc, copper, cadmium, so as to permit absorption and hydrogen peroxide in such aqueous medium and effect decomposition of hydrogen peroxide in such aqueous medium.

Abstract: Method for controlling erosion and cracking in a metal component of a nuclear reactor, particularly in the highly concentrated primary and secondary systems of a PWR, comprising creating a catalytic surface on the component; and generating a stoichiometric excess of reductant the water of the reactor to reduce the oxidant concentration at the surface to substantially zero.

Abstract: A method for controlling water quality in a nuclear reactor comprises a first and second steps. The first step is to make an amount of iron, which is carried into the nuclear reactor and corrosively eluted from structural material within the nuclear reactor into reactor water, at least twice as much as any one of an amount of nickel, which is carried into the nuclear reactor, and an amount of nickel, which is generated in the nuclear reactor. The second step is to limit an upper limit of concentration value of iron in system water supplied into the nuclear reactor to up to 0.10 ppb.

Abstract: A novel high-purity polymer dispersant and sludge conditioner added to the feedwater entering the secondary side of a nuclear steam generator for minimizing the accumulation of metal-oxide deposits within the nuclear steam generator during the continuing operation of the generator is disclosed. The high-purity polymer is selected from a group consisting of acrylic acid polymer, methacrylic acid polymer, acrylate polymer, methacrylate polymer, copolymers, and terpolymers, acrylate/acrylamide copolymer, acrylate/methacrylate copolymer, terpolymers, and mixtures thereof. Methods of making and applying the polymer dispersant and sludge conditioner are described. Means for removing the metal oxides and polymer from the blowdown stream are disclosed.

Abstract: A metal cooling tube of a water-cooled nuclear reactor, having an inner surface thereof exposed to an aqueous cooling medium containing hydrogen peroxide. The cooling tube has its inner surface coated with matter selected from the group consisting of the element manganese, molybdenum, zinc, copper, cadmium for absorbing such hydrogen peroxide and then affecting decomposition of the hydrogen peroxide in the aqueous medium. In preferred embodiment such coating is manganese and oxides thereof. A method for lowering the electrochemical corrosion potential of a metal allow cooling tube exposed to an aqueous medium in a water-cooled nuclear reactor is also disclosed. Such method comprises the step of coating an inner surface of such tube with matter selected from the group of elements comprising manganese, molybdenum, zinc, copper, cadmium, so as to permit absorption and hydrogen peroxide in such aqueous medium and effect decomposition of hydrogen peroxide in such aqueous medium.

Abstract: Disclosed is a process for introducing zinc into a water-containing component of the primary system of a nuclear power plant, in particular for preventing the deposition of radioactive cobalt and/or for reducing the possible susceptibility of materials in the component to corrosion. An effective level of zinc is introduced into the component as a dissolved zinc compound which is a zinc complex and/or metal zincate.

Abstract: Method for controlling the introduction of zinc to a nuclear power reactor to control radiation build-up wherein zinc ions are introduced into the reactor water to counteract loss of zinc within the reactor system. In the process, the rate of introduction of zinc ions into the reactor water is balanced with the rate at which zinc ions are lost from the reactor.

Abstract: A metal cooling tube of a water-cooled nuclear reactor, having an inner surface thereof exposed to an aqueous cooling medium containing hydrogen peroxide. The cooling tube has its inner surface coated with matter selected from the group consisting of the element manganese, molybdenum, zinc, copper, cadmium for absorbing such hydrogen peroxide and then affecting decomposition of the hydrogen peroxide in the aqueous medium. In preferred embodiment such coating is manganese and oxides thereof. A method for lowering the electrochemical corrosion potential of a metal allow cooling tube exposed to an aqueous medium in a water-cooled nuclear reactor is also disclosed. Such method comprises the step of coating an inner surface of such tube with matter selected from the group of elements comprising manganese, molybdenum, zinc, copper, cadmium, so as to permit absorption and hydrogen peroxide in such aqueous medium and effect decomposition of hydrogen peroxide in such aqueous medium.

Abstract: A method for reducing the corrosion potential of steel vessels and piping used in nuclear reactors, in particular steel vessels and piping carrying high temperature water and/or steam which has a concentration of oxygen therein. A metal hydride is added to the water, the hydrogen of such metal hydride combining with oxidizing agents, typically oxygen, present in the water to reduce the concentration of such oxidizing agents. In the preferred embodiment the metal of the metal hydride is a metal that is capable of reacting with oxygen to form a substantially non-water soluble and substantially electrically insulating compound on the surface of the steel, and in particular is one that may react with and become deposited or incorporated into a pre-existing thin oxide film layer on the surface of the steel to thereby render such thin oxide layer substantially non-electrically conducting.

Abstract: The method is to develop an anticorrosive cover out of oxides of structural steel components on a circuit internal surface in which in the course of the circuit operation, the oxygen concentration, which is dissolved in the coolant, is maintained not lower than the value, which has been determined from the expressionIgC=-0.33-2790/T+IgC.sub.S +IgJC.sub.Pb,whereC is the concentration of oxygen, dissolved in the coolant, mass %;T is the coolant maximum temperature in the circuit, .degree. K.;C.sub.S is the saturated concentration of oxygen dissolved in the coolant at the temperature T, mass %;J is the thermodynamic activity coefficient of lead in the coolant, inverse mass %; andC.sub.Pb is the lead concentration in the coolant, mass %.

Abstract: A mixture of metal ions is added to the primary cooling water of a water-cooled nuclear reactor to inhibit deposition of radioactive materials in the cooling water on the inner surfaces of pipes. The mixture of metal ions added to the cooling water introduced into the primary cooling system simultaneously comprises two to four of the metal ions, Mn ion, Mg ion, Ni ion and Zn ion, one of these ions being manganese ion.

Abstract: Metal ions are added to a circuit (20, 30) for the reactor water or feed water of a nuclear plant. This is accomplished by dissolving a soluble metal compound the counter-ion of which is possible to decompose to gaseous products and water in water in a reaction vessel (41) in an equipment arrangement (40). The solution is subsequently conducted to a series of vessels (42) for the decomposition of the counter-ion. The solution is then possibly transformed to a mixture or a slurry which is conducted to a vessel (43) for degassing the gaseous products before the addition to the circuit (20, 30) for the reactor water or feed water.

Abstract: A reactor water clean-up system is provided with a first filter demineralizer having a filter resin containing an alkali substance and a second filter demineralizer with a filter resin not containing an alkali substance. The reactor water is supplied to the first filter demineralizer during the term from the starting operation of the preoperating test of the nuclear reactor and of each fuel cycle to 2000 EFPH. The alkali substance contained in the filter resin is guided into the nuclear reactor to change the pH of the reactor water in the nuclear reactor to the weak alkali side. The Cr quantity which is taken in the oxide film of the fuel cladding tube surface is reduced. After 2000 EFPH from the starting operation, the supply of the reactor water to the first filter demineralizer is stopped, and then, the reactor water is supplied to the second filter demineralizer.

Abstract: The method is to developed a two-phase flow in the circulation circuit. This method is defined by the fact, that a two-phase flow is developed by means of hydrogen introduction into the coolant. Hydrogen can be introduced in mixture with an inert gas or water steams.

Abstract: Methods are provided to at least slow the dissolution of silica in an aqueous environment. In the subject methods, the silica surface is contacted with a multivalent metal cation capable of complexing with oxygen atoms present on the silica surface, where contacting is preferably accomplished by introducing a source of the multivalent metal cation into the aqueous environment. The subject methods find particular use in the inhibition of the dissolution of silica comprising neutron poisoning materials employed in the storage of spent nuclear fuel.

Abstract: A novel high-purity polymer dispersant and sludge conditioner added to the feedwater entering the secondary side of a nuclear steam generator for minimizing the accumulation of metal-oxide deposits within the nuclear steam generator during the continuing operation of the generator is disclosed. The high-purity polymer is selected from a group consisting of acrylic acid polymer, methacrylic acid polymer, acrylate polymer, methacrylate polymer, copolymers, and terpolymers, acrylate/acrylamide copolymer, acrylate/methacrylate copolymer, terpolymers, and mixtures thereof. Methods of making and applying the polymer dispersant and sludge conditioner are described. Means for removing the metal oxides and polymer from the blowdown stream are disclosed.

Abstract: A method for operating the LOMI decontamination process in a regenerative manner. The method incorporates an initial injection of a dilute LOMI solution (vanadous formate, picolinic acid and sodium hydroxide) into a decontamination circuit followed by operation of a small cluster of cation exchange columns during the decontamination process. The cation exchange resin is used to remove metals in the same manner as in prior decontamination processes but operation of the cation exchange resin is continued to allow picolinic acid initially bound to the cation exchange resin to be released and recycled to the LOMI solution. Operation of the cation exchange columns ceases after the picolinic acid has been released but before the metals (e.g. sodium, iron and vanadium) are released back to the LOMI solution. The cluster of cation exchange columns are operated according to a sequence wherein one column is releasing picolinic acid while another is binding picolinic acid.

Abstract: A method for mitigating crack growth on the surface of stainless steel or other metal components in a water-cooled nuclear reactor. A compound containing a noble metal, e.g., palladium, is injected into the water of the reactor in the form of a solution or suspension. This compound has the property that it decomposes under reactor thermal conditions to release ions/atoms of the noble metal which incorporate in or deposit on the interior surfaces of the crack. The compound may be organic, organometallic (e.g., palladium acetylacetonate) or inorganic in nature. The palladium deposited inside a crack should exhibit catalytic behavior even if the bulk surface palladium is depleted under high fluid flow conditions. As a result, the electrochemical potential inside the crack is decreased to a level below the critical potential to protect against intergranular stress corrosion cracking.

Abstract: An apparatus for controlling dissolved oxygen concentration in primary and secondary cooling water in boiling water and pressurized water atomic reactors is disclosed. The apparatus contains an electrolytic cell having an anode chamber and a cathode chamber separated from one another by a diaphragm of a solid polymer electrolyte membrane. The diaphragm contains: (a) an ion exchange membrane and (b) a pair of multilayered electrodes chemically plated to both surfaces of the ion exchange membrane. The electrolytic cell is operatively connected to a circular route for cooling water in the reactor, and hydrogen gas generated through electrolysis of deionized water in the cathode side of the cell is introduced into the circular route for the cooling water to control the dissolved oxygen concentration of the cooling water.

Abstract: A method for mitigating crack initiation and propagation on the surface of metal components in a water-cooled nuclear reactor. A metal coating having an electrically insulating outer layer is applied on the surfaces of IGSCC-susceptible reactor components. The preferred metal coating is a zirconium alloy with a zirconia outer layer. The presence of an electrically insulating layer on the surface of the metal components shifts the corrosion potential in the negative direction without the addition of hydrogen and in the absence of a noble metal catalyst. Corrosion potentials.ltoreq.-0.5 V.sub.SHE can be achieved even at high oxidant concentrations and in the absence of hydrogen.

Abstract: A method for mitigating general corrosion and crack initiation and growth on the surface of a metal components in a water-cooled nuclear reactor. A compound containing a non-noble metal such as zirconium or titanium is injected into the water of the reactor in the form of a solution or suspension. This compound decomposes under reactor thermal conditions to release ions or atoms of the non-noble metal which incorporate in the surfaces of the components, including the interior surfaces of any cracks formed therein. The preferred compounds are zirconium compounds such as zirconium acetylacetonate, zirconium nitrate and zirconyl nitrate. Zirconium incorporated in the oxided surface of a metal component will reduce the electrochemical corrosion potential at the surface to a level below the critical potential to protect against intergranular stress corrosion cracking without the addition of hydrogen.

Abstract: A method of depositing noble metals on surfaces or matrices to manufacture industrial catalysts that can be used in a variety of applications. Such deposition of noble metals can be achieved by treating the surfaces in high-temperature (150.degree. C. or higher) water containing dissolved noble metal ions or its colloidal suspensions. The method consists of the steps of placing the surface of a metal substrate in contact with a volume filled with high-temperature water; injecting a solution of a noble metal compound into the volume for a predetermined duration; and removing the surface of the metal substrate from contact with the high-temperature water after expiration of said predetermined duration. The noble metal compound has the property that it releases species of the noble metal in high-temperature water. These noble metal species deposit on or incorporate in the oxide film on the surface of the metal substrate.

Abstract: A method for improving the performance and longevity of coatings of metal deposited from aqueous solutions of inorganic, organic or oraganometallic metal compounds. The method involves co-deposition of noble metal or corrosion-inhibiting non-noble metal during growth of oxide film on a component made of alloy, e.g., stainless steels and nickel-based alloys. The result is a metal-doped oxide film having a relatively longer life in the reactor operating environment. In particular, incorporation of palladium into the film provides greatly increased catalytic life as compared to palladium coatings which lie on the oxide surface.

Abstract: Method and apparatus for enhancing removal of corrosion products from a nuclear reactor piping system. A reagent is supplied into a multi-part reactor piping system to react with the corrosion products therein. The corrosion products dissolve into the reagent to define a contaminated solution. The contaminated solution is brought into contact with an ion exchange resin bed that absorbs the corrosion products from the contaminated solution to define a reagent-containing contaminant-free solution. In this regard, a circulation pump having a predetermined net positive suction head (NPSH) interconnects the system with the resin bed for pumping the contaminated solution from one part of the reactor piping system and into contact with the resin bed and thereafter pumping the contaminant-free solution from the resin bed and to another part of the reactor piping system to remove the corrosion products.

Abstract: In reactor water control for a BWR power plant during an operation cycle after loading new fuel rods in the BWR power plant, an operation is performed which accelerates deposition of crud on the fuel rods until the deposition amount of the crud on the fuel rods reaches a predetermined target value within the operation cycle concerned. After the deposition amount of the crud has reached the predetermined target value, the crud deposition accelerating operation is terminated, whereby even when loading new fuel rods such as Zr liner type fuel rods having a surface on which metal ion deposition has been difficult, radioactivity in the reactor water is efficiently reduced.

Abstract: A method for mitigating initiation or propagation of a crack in a surface of a metal component in a boiling water reactor. The method includes the step of injecting a solution or suspension of a pH-adjusting compound into the bulk water of the reactor. The compound has the property of changing the pH of high-temperature water inside the crack from a value outside a predetermined pH range (namely, pH 6.0 to 8.0) to a value within the predetermined pH range without causing any significant change of the bulk water pH. The growth rate of the crack when the crack pH is outside the predetermined pH range is greater than the growth rate of the crack when the crack pH is within the predetermined pH range.

Abstract: A pre-oxidation treatment for decreasing the amount of chromium deposited on out-of-core surfaces such as the internal surfaces of recirculation piping. Hydrogen peroxide is injected into the reactor coolant through the recirculation line during reactor shutdown after H.sub.2 addition has been terminated. A dilute acid solution (e.g., nitric acid) is also injected into the loop to serve as a catalyst to accelerate the oxidation reactions. An appropriate water pH (e.g., in the range of 5-6) is maintained by acid injection. The coolant temperature during shutdown is maintained at approximately 150.degree. C. or lower. The peroxide concentration in the recirculation piping is maintained at approximately 1 ppm or higher as needed. The oxidation process should be allowed to take effect in the proposed temperature range with the recirculation pump in operation for at least a few hours to 24 hours, depending on the temperature and the oxide film thickness.

Abstract: A method for ensuring the distribution of noble metal in the reactor circuit during plant application without measuring the reactor water for noble metal content by chemical analysis. The method involves the measurement of electrochemical corrosion potential in an autoclave or a high-flow test section that is connected to the reactor water circuit through sample lines downstream of the injection port, preferably the point in the reactor circuit which is furthest from the injection port. If the noble metal flows into the autoclave or test section at these distant points in the reactor circuit, then the noble metal will deposit on the test specimens inside the autoclave or test section.

Abstract: A method for improving the performance and longevity of coatings of metal deposited from aqueous solutions of inorganic, organic or oraganometallic metal compounds. The method involves co-deposition of noble metal or corrosion-inhibiting non-noble metal during growth of oxide film on a component made of alloy, e.g., stainless steels and nickel-based alloys. The result is a metal-doped oxide film having a relatively longer life in the reactor operating environment. In particular, incorporation of palladium into the film provides greatly increased catalytic life as compared to palladium coatings which lie on the oxide surface.

Abstract: A method for mitigating crack growth on the surface of stainless steel or other alloy components in a water-cooled nuclear reactor wherein a solution or suspension of a compound containing a noble metal is injected into the coolant water while the reactor is not generating nuclear heat, e.g., during shutdown or recirculation pump heatup. During shutdown, the reactor coolant water reaches temperatures as low as 120.degree. F., in contrast to the water temperature of 550.degree. F. during normal operation. During pump heatup, the water temperature reaches 400.degree.-450.degree. F. At these reduced temperatures, the rate of thermal decomposition of the injected noble metal compound is reduced. However, radiation-induced decomposition also occurs inside the reactor. In particular, the noble metal compound can be decomposed by the gamma radiation emanating from the nuclear fuel core of the reactor.

Abstract: A method for mitigating crack growth on the surface of stainless steel or other alloy components in a water-cooled nuclear reactor wherein a solution or suspension of a compound containing a noble metal is injected into the coolant water along with a reducing agent. The presence of the reducing agent will assist in better deposition of the noble metal, for example, palladium, on metal surfaces, thereby increasing the noble metal loading and also improving the tenacity with which the noble metal is bound onto the metal. The extent of noble metal doping is important in providing a better (lower) ECP response of the metal in the presence of a stoichiometric ratio of H.sub.2 to O.sub.2, which reduces the hydrogen demand considerably. The more tenacious the noble metal is bound to the metal surface, the longer its expected life will be, particularly under in-reactor Situations where the metal surfaces are subjected to a variety of hydrodynamic conditions.

Abstract: A method for mitigating crack growth on the surface of stainless steel or other metal components in a water-cooled nuclear reactor. A compound containing a noble metal, e.g., palladium, is injected into the water of the reactor in the form of a solution or suspension. This compound has the property that it decomposes under reactor thermal conditions to release ions/atoms of the noble metal which incorporate in or deposit on the interior surfaces of the crack. The compound may be organic, organometallic (e.g., palladium acetylacetonate) or inorganic in nature. The palladium deposited inside a crack should exhibit catalytic behavior even if the bulk surface palladium is depleted under high fluid flow conditions. As a result, the electrochemical potential inside the crack is decreased to a level below the critical potential to protect against intergranular stress corrosion cracking.

Abstract: A system for monitoring the operation of a plant, which includes the facility of simulating the corrosion potential of a material and which can assess the effect of a countermeasure for mitigating the corrosion environment of the material, with the corrosion potential obtained by the simulation. The corrosion potential of the structural material of the plant is computed through a numerical analysis by applying an electrochemical mixed-potential theorem on the basis of the analytical result of a charge transfer reaction. Programs for such potential computations are prestored in a computer system from which data are accepted into a host computer. The computed corrosion potential is related with water quality data (for example, the concentration of hydrogen injected into the plant), and the relationship is output to a display unit.

Abstract: A nuclear reactor, in particular a pressurized water reactor, has a containment, a containment shell surrounding the containment and a concrete construction of a reactor building surrounding the containment shell. A heat dissipation system for the nuclear reactor includes a sump volume disposed in a lower region of the containment shell for receiving coolant. A sump cooler is disposed inside the sump volume, has cooling tubes with a primary side and a secondary side and has feed and return lines. The primary side of the cooling tubes is covered at least when the sump volume is largely filled with coolant. An intermediate cooler has a tertiary side and is connected through the feed and return lines of the sump cooler to the secondary side of the cooling tubes. A heat sink is disposed outside the reactor building and is connected to the intermediate cooler on the tertiary side.

Abstract: In a method of decontaminating a primary loop of a pressurized water reactor, including a steam generator, reactor coolant pump and hot and cold legs in the loop, the primary loop is isolated from a nuclear reactor vessel by closing hot leg and cold leg loop stop valves. Decontamination process water is circulated from one side of the steam generator channel head to the other side of the channel head via a bypass pipe extending between the cold leg and the hot leg without bypassing the water through steam generator tubes extending between the sides of the channel head. The level of the decontamination water in the steam generator is maintained at two to three feet in the tubes.

Abstract: A supercritical water oxidation reactor includes a vessel with an interior urface, two cooling sections, a heat exchanger, an oxygenating section, a pump, and a trap. The interior surface of the vessel has a corrosion-resistant, artificial ceramic or diamond-like coating. The artificial diamond coating is thin and crystal-like in structure. The heat exchanger is located between the two cooling sections. The heat exchanger and the two cooling sections surround the exterior of the vessel. The oxygenating section comprises a porous cylindrical baffle positioned within the vessel. The porous baffle transfers oxygen, hydrogen peroxide, or other oxygenating substances to an aqueous hazardous waste introduced into the reactor.In accordance with another aspect of the invention, the oxygenating section includes a shaft having a helical extension. The shaft has a corrosion-resistant, artificial diamond or diamond-like coating on its outer surface.

Abstract: A water quality control method for a nuclear power plant comprising the steps of maintaining the iron concentration in the feed water below 0.05 ppb by increasing iron removing rate at a condensed water purifying loop, shifting the pH of the reactor water below a pH of 6.8 determined at a room temperature by injecting carbon dioxide gas in the primary cooling system and further optionally reducing the dissolved oxygen concentration in the reactor water below 20 ppb by injecting hydrogen gas into the primary cooling system, whereby .sup.60 Co ion concentration in the primary cooling system is maintained low for a long interval.

Abstract: A water chemistry factor which is specific to a specific portion of a primary cooling system and universal is decided to be a standard target. The concentration of an agent for mitigating corrosion damage of structural material of the primary cooling system is controlled so that the target will be in a desirable range. All sensor groups provided in the primary cooling system are separated into sensor groups in different lines, of which a specific sensor group are connected to an arithmetic unit and a data base and are for always monitoring a plant process. For example, concentration distribution agreed with measured value oxidation component in the reactor water at the measurement points is selected from the data base, and it is used to estimate the standard target.

Abstract: An object of the present invention is to provide a method and a nuclear plant capable of preventing deposition and activation of crud to a nuclear fuel rod and decreasing the radioactivity level in reactor water. Metal ions solely having a low deposition rate coefficient are made to coexist to prevent or decrease deposition of radioactive corrosion products to the nuclear fuel rod. A method and a nuclear plant capable of preventing deposition and activation of crud to the nuclear fuel rod and decreasing the radioactivity level in reactor water can be provided.

Abstract: A method for preventing or reducing the formation of Co-60 contaminated material on the surfaces of a cooling water circuit of a nuclear reactor. The method is carried out during shutdown of the reactor. First, Co-60 contaminated material formed on the surfaces of the cooling water circuit is chemically removed. Then at least one iron compound is added to the cooling water in an amount sufficient to scavenge cobalt from the cooling water. Thereafter, oxygen is injected into the cooling water to provide a dissolved oxygen concentration sufficient to form an oxide film on the surfaces of the cooling water circuit. The oxide film so formed is substantially free of Co-60 isotope. This treatment reduces the radiation hazard to nuclear reactor personnel.

Abstract: A method and apparatus decrease the release of volatile radioactive iodine from a nuclear reactor pressure vessel containing a reactor core having fuel rods submerged in water. The method includes monitoring the pressure vessel to determine an accident condition and then injecting into the pressure vessel a stable iodide in liquid solution to mix with the reactor water for decreasing vaporization of volatile radioactive iodine discharged from the fuel rods. A reservoir initially stores the stable iodide in the liquid solution and is operatively joined to the pressure vessel through a supply conduit and a normally closed valve which is selectively opened following the accident condition to inject the stored iodide liquid solution into the pressure vessel to mix with the water therein.

Abstract: The invention is of a method for treating the primary cooling medium of a pressurized water nuclear reactor by controlling its efficiency through the H.sub.3 BO.sub.3 content in the cooling medium. Hydrazine hydrate (N.sub.2 H.sub.4 .multidot.H.sub.2 O) is continuously fed to the coolant of a reactor which is charged for energy generation, to such an extent that its content equals 5.10.sup.-6 to 5.10.sup.-2 g/kg coolant medium as well as KOH and/or LiOH which corresponds to the alkaline properties. KOH in an amount of 80 to 56 mg/kg cooling medium with respect to the amount of H.sub.3 BO.sub.3 in a range of 20 to 0 g/kg cooling medium and the excess hydrogen is removed from the system leaving a maximum amount of hydrogen in the coolant medium of 100 n.multidot.ml/kg.

Abstract: A method for treating the primary coolant of a pressure water reactor by controlling its efficiency through the H.sub.3 BO.sub.3 content in the coolant is described. Hydrazine hydrate is continuously added to the coolant cycle of a nuclear reactor which is charged for energy generation in such amounts that its content is 5.multidot.10.sup.-6 to 5.multidot.10.sup.-2 g/kg coolant. Excess hydrogen is removed from the coolant leaving a content of no more than 100 n.ml/kg.

Abstract: A nuclear reactor plant is provided in which the reactor coolant system contains a dissolved solution of enriched boric acid. The boron-10 to boron-11 atomic isotope ratio of the enriched boric acid solution is greater than 19.8:80.2 at the start of the reactor core cycle. The nuclear reactor plant design provides for minimal mixing between the reactor coolant solution containing the enriched boric acid solution and the natural boric acid solution used during refueling operations.

Abstract: A method for chemically controlling cobalt decontaminating the water cooling system of a water cooled nuclear fission reactor to reduce the radiation hazard to personnel.

Abstract: A process for inhibiting corrosion caused by the presence of coolant water passing through a pressurized water nuclear reactor by the addition of an effective amount of an aqueous solution of zinc borate to the reactor coolant water. The transport of corrosion products and radioactive cobalt ions through the reactor primary circuit, as well as levels of radioactivity within the primary circuit, are reduced.