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
  • G21C7/24—Selection of substances for use as neutron-absorbing material
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C19/00—Alloys based on nickel or cobalt
• • 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

• hafnium between 5 and I8;
• the present invention relates to a neutron-absorbing alloy finding application in systems of automatic control and safety of nuclear reactors such as, for example,
• thermal and intermediate reactors used for the generation of power and propulsion.
• neutron-absorbing material comprising the following ingredients in by weight: silver, 80; indium, 15; cadmium, 5. Said material displays the following properties:
• neutron capture efficiency that of boron carbide with a density of 1.8 g/cm taken as unity, 0.1;
• the known neutron-absorbing material displays a number of disadvantages.
• the material is in short supply because it is based on silver. Further, the material has a low capture efficiency in dealing with thermal and intermediate neutrons and its residual neutron capture efficiency is also low, the point being that resulting from the irradiation of the basic ingredient, i.e., silver, is cadmium and of indium is tin. The cadmium produces an isotope, cadmium l 14, which has a small cross section for neutron capture and for this reason the efficiency deteriorates continuously in operation.
• Another disadvantage of the known material is it low corrosion resistance in water at a high temperature and pressure.
• Another object of the present invention is to increase the neutron capture efficiency of the alloy dislosed.
• a further object of the invention is to increase the corrosion resistance of the neutron-absorbing alloy.
• the neutron-absorbing alloy containing indium is, according to the invention, of the following composition in by weight: indium, between 1 and 20; samarium, between 0.5 and 15; hafnium, between 5 and 18; nickel, the balance required to obtain 100.
• a neutron-absorbing alloy of the following composition in by weight: indium, samarium, 8; hafnium, 13.5; nickel 68.5.
• the neutron-absorbing alloy dislosed is melted in vacuum furnaces operating in an inert gas atmosphere under a pressure of 280 to 300 mm Hg.
• the sequence of events is as follows: loading of the charge consisting of nickel placed in a crucible and of indium, samarium and hafnium placed in a metering hopper; evacuation of the system and filling it with an inert gas under a pressure between 280 and 300 mm Hg; heating of the nickel to a temperature of 900 to 1,000C; continuous introducing indium, samarium and hafnium in succession; pouring of the alloy obtained into ceramic, metallie and other moulds at a temperature of 1,500" to 1,510C.
• the alloy disclosed has a corrosion resistance which is 3 to 3.5 times that of the silver-based alloy. Exposed during a 3,000-hr corrosion test to the action of hot water at 350C and 168 atm, the alloy disclosed gave an increase in the weight amounting to a rate of 0.59 mg/md .24 hrs. At the same time, the known silverbased alloy corroded severely at a temperature of 300C (the rate of weight increase was 0.83 mg/dm .24 hrs) and failed to stand the corrosion at all at a temperature of 350C.
• the alloy disclosed has a high neutron capture efficiency in absorbing thermal and intermediate-neutrons and also displays a high residual neutron capture efficiency which is twice that of the known alloy.
• the castability of the alloy allows to fabricate automatic control and safety rods in a variety of sizes with minimum tolerances for machining and the structural strength of the alloy assures good reliability of the control system in power thermal reactors.
• the neutron-absorbing alloy was of the following composition in by weight:
• the sequence of events in preparing said alloy was as follows.
• the charge was loaded a crucible (nickel) and a metering hopper (indium, samarium and hafnium).
• the system was evacuated and then filled with an inert gas under a pressure of between 280 and 300 mm Hg.
• an inert gas under a pressure of between 280 and 300 mm Hg.
• the nickel was heated to between 900 and 1,000C, half of the total amount of indium was added and the heating went of for another 5 to 8 minutes until a melt was obtained.
• Introduced into it was a nickel-samarium alloy and the rest of indium (indium forms an eutectic with nickel with a melting point of 914C).
• the temperature of the melt was increased to between l,400 and 1,450C and the hafnium was added.
• the melt was heated to between 1,500 and 1,510C, kept at this temperature for a period lasting between five and seven minutes and then the alloy was poured into moulds.
• EXAMPLE 2 The composition of the neutron-absorbing alloy in by weight was as follows:
• EXAMPLE 3 The composition of the neutron-absorbing alloy in by weight was as follows:
• a neutron-absorbing alloy consisting essentially of the following ingredients in by weight:
• indium between 1 and 20;
• hafnium between 5 and 18;
• a neutron-absorbing alloy as claimed in claim 1 consisting essentially of the following composition in by weight:

Landscapes

• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Physics & Mathematics (AREA)
• High Energy & Nuclear Physics (AREA)
• Plasma & Fusion (AREA)
• General Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Materials Engineering (AREA)
• Mechanical Engineering (AREA)
• Metallurgy (AREA)
• Organic Chemistry (AREA)
• Manufacture And Refinement Of Metals (AREA)
• Monitoring And Testing Of Nuclear Reactors (AREA)

Priority Applications (3)

Applications Claiming Priority (1)

Publications (1)

Family

ID=23721797

Family Applications (1)

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Cited By (3)

Families Citing this family (4)

Citations (1)

• 1974
  • 1974-01-11 DE DE2401342A patent/DE2401342C3/de not_active Expired
  • 1974-01-16 US US433854A patent/US3923502A/en not_active Expired - Lifetime
  • 1974-02-01 FR FR7403496A patent/FR2260168B1/fr not_active Expired

Patent Citations (1)

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