Induced nuclear reactions: processes – systems – and elements – Control component for a fission reactor – Nonconventional control material
Patent
1996-09-18
1997-11-04
Jordan, Charles T.
Induced nuclear reactions: processes, systems, and elements
Control component for a fission reactor
Nonconventional control material
376419, 376327, G21C 700
Patent
active
056848471
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The invention relates to a silver-based alloy containing indium and cadmium for the production of neutron-absorber components in the core of a nuclear reactor.
BACKGROUND OF THE INVENTION
Nuclear reactors, and in particular, nuclear reactors cooled by pressurized water, contain a core consisting of prismatically shaped fuel assemblies arranged vertically and juxtaposed. Each of the fuel assemblies consists of a bundle of mutually parallel fuel rods which are held by a framework consisting of spacer grids and guide tubes connected rigidly to the spacer grids which are distributed along the length of the fuel assembly.
During operation of the nuclear reactor, it is necessary to provide means for controlling the power delivered by the core in which fission reactions that liberate energy in the form of heat take place. It is also necessary to provide means for shutting down the nuclear reactor at the end of an operating cycle or in the event of an incident requiring an emergency shutdown.
Control of the power of the core and shutdown of the reactor are carried out using neutron-absorber components and, in particular, absorber components which can be inserted to a greater or lesser extent into the core, depending on the control or shutdown phases of the nuclear reactor.
Use is made, in particular, of absorber components in the form of rod clusters which can be introduced and displaced inside guide tubes of some of the fuel assemblies.
The rods in a given cluster are connected at one of their ends to a support which includes radiating arms and a hub for connecting the cluster to a follower, this cluster support being generally referred to by the term "spider".
The absorber rods in clusters for controlling and shutting down a nuclear reactor have a tubular casing in which pellets of absorber material are stacked.
The absorber materials most commonly used include boron carbide B.sub.4 C and ternary alloys of silver, indium and cadmium (SIC).
Depending on the use of the absorber rod clusters, for controlling or shutting down the nuclear reactor, the composition of the absorber rods may vary, so that these rods may contain only pellets of B.sub.4 C or SIC, pellets of both B.sub.4 C and SIC, or else pellets of highly absorbent materials (B.sub.4 C or SIC, for example) and materials which are weaker absorbers of neutrons.
One of the objects in the design of the rods in the absorber rod clusters of a nuclear reactor is to extend the lifetime of the rod clusters as much as possible, so as to reduce the operating costs of a nuclear reactor to a maximum extent.
The lifetime of the rod clusters for controlling and shutting down a nuclear reactor is generally expressed in numbers of cycles, each of the cycles corresponding to a period of operation of a nuclear reactor between two core assembly refuelling operations.
The lifetime of the absorber rod clusters of a nuclear reactor is limited because of the appearance and development, during operation of the nuclear reactor, of cracks which penetrate the casing of the rods containing the pellets of absorber material, and because of the swelling of the absorber material.
Because of the development of these cracks, it is necessary to remove and discard the rod clusters after they have been used for some time in the nuclear reactor.
The pellets of absorber material have a nominal diameter, when they are loaded into the casings, which is less than the nominal internal diameter of the casing. Some degree of clearance therefore remains between the lateral surface of the pellets and the inner surface of the casing of an absorber rod at the end of manufacture. The absorber pellets are held inside the casing by plugs for closing the ends of the casing and by a coil spring interposed between one of the closure plugs of the casing and the corresponding end of the column of absorber pellets.
The internal volume of the casing, which is closed in a completely leaktight manner by the plugs, may be filled with a pressurized gas.
In an operating reactor, the pellets o
REFERENCES:
patent: 2935401 (1960-05-01), Anderson
patent: 3074871 (1963-01-01), Lustman et al.
patent: 3923502 (1975-12-01), Portnoi et al.
patent: 4172762 (1979-10-01), Anthony et al.
patent: 4695476 (1987-09-01), Feild, Jr.
patent: 4699756 (1987-10-01), Nguyen
patent: 4752440 (1988-06-01), Ahlinder et al.
patent: 4762675 (1988-08-01), Feilds, Jr.
patent: 4874574 (1989-10-01), Igarashi et al.
patent: 5064607 (1991-11-01), Miller et al.
Patent Abstracts of Japan, vol. 16, No. 68, "Power Control Rod For Pressurized Water Reactor", Feb. 19, 1992.
DeFoort Fran.cedilla.oise
Pillet Luc
Chelliah Meena
Framatome
Jordan Charles T.
LandOfFree
Silver-based alloy containing indium and cadmium for the product does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Silver-based alloy containing indium and cadmium for the product, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Silver-based alloy containing indium and cadmium for the product will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1839481