Liquid purification or separation – With time control
Reexamination Certificate
1999-03-10
2001-03-06
Popovics, Robert (Department: 1723)
Liquid purification or separation
With time control
C210S188000, C210S195100, C210S196000, C210S253000, C210S258000, C210S259000, C210S413000, C210S539000, C210S167050, C588S020000, C588S900000
Reexamination Certificate
active
06197188
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to filtration systems and the disposal of radioactive waste. In particular, the present invention relates to a filtration system for concentrating radioactive particles from a refueling cavity, spent fuel pool or other water volume where small particles must be removed from the water for disposal, improving water clarity, reducing radiation level, or other reasons.
2. Description of the Related Art
Commercial nuclear reactor power plants have various water volumes that are subject to contamination with radioactive debris particulate. These water volumes include, for example, the refueling cavity and the spent fuel pool. The particulate contained in these water volumes typically includes “crud” (corrosion products) and “cutting fines” that may range in size from sub-micron to several millimeters in cross-section. The cutting fines are often mixed with other non-radioactive particles that are byproducts of a cutting operation, such as abrasive or electrode materials.
There are several reasons that the radioactive debris particulate needs to be removed from the various water volumes in the nuclear reactor power plants from time-to-time. For example, the small particles often must be removed from the water for disposal, to improve water clarity, and/or to reduce the radiation level of the water volume. Therefore, there is a need for a system that provides efficient filtration, concentration, and transport to collection canisters of the radioactive particles from the various water volumes.
Vendors performing dismantling operations in the commercial nudear power decommissioning business have experienced significant problems with refueling cavity contamination, increased costs for disposal of waste, and dose rates to personnel that are not As Low As is Reasonably Achievable (“ALARA”). Contamination issues have been partly due to the lack of a control volume and closed-loop filtration system. High waste disposal costs have resulted from a failure to segregate and concentrate the particles by a separate means, rather than relying on the use of conventional cartridge-type filters alone. Minimizing the quantity of cartridge filters, which represent an increased volume of secondary waste, will reduce disposal costs. Dose rates to personnel can be reduced by controlling contamination through a closed loop system.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an improved filtration system for concentrating radioactive debris particulate that solves the problems associated with conventional systems for removing small radioactive particles from volumes of water.
It is a further object of the present invention to provide an improved filtration system that can be used to provide efficient filtration, concentration and transport to collection canisters of radioactive particles from a refueling cavity, spent fuel pool or other water volume where small radioactive particles must be removed from the water.
According to a broad aspect of the present invention, a filtration system is provided for concentrating radioactive debris particulate. The filtration system comprises: a flushing pump module that draws contaminated water from a water volume, the flushing pump module having a separator that removes large size particulate from the contaminated water; a solid media filter module in fluid communication with the flushing pump module, the solid media filter module having at least one solid media filter for removing medium size particulate from the contaminated water, and a structure for ejecting the medium size particulate from the solid media filter, a concentrate handling module in fluid communication with the solid media filter module to receive medium size particulate ejected from the solid media filter, the concentrate handling module comprising a tank and a transfer pump; and a disposal canister station in fluid communication with the transfer pump of the concentrate handling module, the disposal canister station having a structure that fills disposal canisters with the medium size particulate for disposal.
The filtration system also includes a cartridge filter module in fluid communication with the solid media filter module to receive a flushing flow of water from the solid media filter module. The cartridge filter module has at least one cartridge filter for removing small size particulate from the flushing flow of water passing from the solid media filter module. The cartridge filter module preferably has at least one coarse cartridge filter and one fine cartridge filter, whereby the small size particulate is removed in multiple stages.
The filtration system further includes a cut zone enclosure submerged in the water volume for separating and containing a portion of the water volume from a remainder of the water volume. The cut zone enclosure has a suction inlet through which the flushing pump module draws contaminated water from the cut zone enclosure. A floating hood is placed over the cut zone enclosure and has an outlet with a gas filtration system for purging gas from an area above the cut zone enclosure. The cartridge filter module and the disposal canister station are each connected to the cut zone enclosure for returning the filtered water back into the cut zone enclosure, thereby forming a closed-loop. filtration system.
The flushing pump module, the solid media filter module, the concentrate handling module, the cartridge filter module, and the disposal canister station are each provided with remotely operable disconnects and isolation valves that allow separate removal and replacement thereof.
According to another broad aspect of the present invention, a closed-loop filtration system is provided for removing radioactive particulate from a volume of fluid. The closed-loop filtration system comprises: an enclosure submerged in a fluid volume for separating and containing a portion of the fluid volume from a remainder of the fluid volume; and a filtering arrangement having an inlet that receives contaminated fluid from the enclosure, a structure that removes radioactive particulate from the contaminated fluid in multiple stages according to a size of the particulate, and an outlet that returns the fluid back into the enclosure. The filtering arrangement comprises a first means for removing large size particulate from the contaminated fluid, a second means for removing medium size particulate from the contaminated fluid, and a third means for removing small size particulate from the contaminated fluid.
Numerous other objects of the present invention will be apparent to those skilled in this art from the following description wherein there is shown and described a preferred embodiment of the present invention, simply by way of illustration of one of the modes best suited to carry out the invention. As will be realized, the invention is capable of other different embodiments, and its several details are capable of modification in various obvious aspects without departing from the invention. Accordingly, the drawings and description should be regarded as illustrative in nature and not restrictive.
REFERENCES:
patent: 4828691 (1989-05-01), Abbott et al.
patent: 5001870 (1991-03-01), Yokota et al.
Crenshaw, Jr. Esq Henry T.
GE Nuclear Power LLC
Kananen Ronald P.
Popovics Robert
Rader Fishman & Grauer
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