Hydraulic and earth engineering – Fluid control – treatment – or containment – Fluid storage in earthen cavity
Patent
1985-11-25
1987-11-24
Taylor, Dennis L.
Hydraulic and earth engineering
Fluid control, treatment, or containment
Fluid storage in earthen cavity
405 53, 405128, G21F 700
Patent
active
047085223
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The invention relates to a structural complex for storing radioactive material in rock, and particularly to a structural complex for a long-term storage of spent nuclear fuel obtained from nuclear reactors and radioactive waste formed when reprocessing spent nuclear fuel.
The object of the invention is to provide a structural complex for storing radioactive material in rock in which said material can be stored for an extremely long period of time without resulting in the contamination of ground water.
The fuel elements used in nuclear reactors must be removed after a certain period of time and replaced with fresh fuel elements. The fuel contains uranium, plutonium and fission products. The uranium and plutonium can be recovered by reprocessing the spent product and re-used as fuel. Reprocessing of the spent fuel results in a waste which, in addition to a large number of fission products also contains minor quantities of uranium and plutonium and other transuranic elements. The majority of the waste products are highly radioactive and decompose to gradually form stable basic substances. Various kinds of radiation is emitted during the decomposition period. The half-life of the various waste products differs widely, and may range from fractions of a second to millions of years. The half-life of Plutonium-242 for example is 380,000 years.
Since powerful radioactive radiation is dangerous to living organisms, it is necessary to store such highly radioactive waste safely for very long periods of time (thousands of years) in a manner which isolates it from all living matter (the biosphere).
In the aforesaid reprocessing of spent fuel, the highly radioactive waste is obtained in the form of an aqueous solution, which is concentrated to the highest possible extent. This solution is not suited for long-term storage, and consequently is converted to solid form after being left to cool for a suitable length of time. Vitrification is considered the best method of converting the solubilized waste to solid form. This requires the waste to be vaporized, calcined and then heated to a suitable temperature in the presence of a vitrifying agent. The resultant glass melt is poured into containers, which must then be placed in a suitable storage complex.
It has been suggested that the solidified highly radioactive waste shall finally be stored in rock caves at a great depth in basement rock. One such proposed storage complex comprises a waste-receiving system located at ground surface level. A vertical transport tunnel is drilled from this surface station deep into the basement rock and from the lower part of this vertical tunnel there is drilled a horizontal tunnel. A plurality of vertical walls are drilled in the floor of this horizontal tunnel. The waste containers are intended to be transported with the aid of automatic transporters through the aforesaid tunnels and lowered as plugs in the bore holes extending vertically from the floor of the horizontal tunnel. As the bore holes are filled with waste containers, and encapsulated with or packed in bentonite clay, the upper regions of respective holes are sealedoff with concrete for example.
The expedient of capsulating fuel rods which have not been reprocessed directly from intermediate storage locations and storing the same in a rock-cave complex has also been discussed. Radioactive material storage complexes are known from the Swedish Patents Nos. SE-C-7613996-3; SE-C-7707639-6; SE-C-7700552-8; SE-C-7702310-9 and SE-A-8305025-2. Radioactive material can be stored in the complexes disclosed in these patent specifications for long periods of time without water being able to enter the complex.
The complexes forming part of the present state of the art include a solid, hollow body whose interior forms the storage space for the radioactive material. The hollow body is placed in an inner cavity located in the basement rock and having larger dimensions than the hollow body, the body being placed in the cavity so that no side of the body is in contact with the ca
REFERENCES:
patent: 4192629 (1980-03-01), Hallenius et al.
patent: 4363563 (1982-12-01), Hallenius et al.
patent: 4474506 (1984-10-01), Sagefors
Akesson Bengt A.
Bergman Sten G. A.
Sagefors K. Ivar
Boliden Aktiebolag
Taylor Dennis L.
LandOfFree
Storage complex for storing radioactive material in rock formati does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Storage complex for storing radioactive material in rock formati, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Storage complex for storing radioactive material in rock formati will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2422206