Liquid purification or separation – Plural distinct separators – Filters
Reexamination Certificate
1999-10-25
2001-07-03
Savage, Matthew O. (Department: 1723)
Liquid purification or separation
Plural distinct separators
Filters
C210S332000, C210S238000, C210S456000, C376S313000
Reexamination Certificate
active
06254774
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to apparatus for filtering particulate matter from a fluid flow, and more particularly pertains to the structure of a system for filtering radioactive particles from coolant associated with a nuclear reactor.
It is common practice in a nuclear power plant to utilize demineralized water in a coolant pool as a heat transfer medium around the core of the reactor. It is also common for the pool water to be contaminated by corrosive by-products, taking the form of fine radioactive particles. These particles are commonly referred to in the industry as “CRUD”, an anacromyn for Clinch River Unidentified Deposits, a term coined in the industry to describe the usually black or gray highly radioactive particles that were first noted in the very early experimental light water reactors, most notably at the Clinch River facility of the Tennessee Valley Authority. Such CRUD deposits are a primary source of occupational radiation exposure in a nuclear facility and pose a continuing problem that must be dealt with by continuous filtration.
Other systems have been devised for filtration removal of particulate matter from the nuclear reactor coolant fluid. Representative of apparatus of such a system is the subject matter disclosed in U.S. Pat. No. 3,890,233 and in U.S. Pat. No. 4,883,588. A common problem associated with such systems involves the procedure for exchange or change-out of filter cartridges which are designed to entrain the particulate matter from the coolant processed through the cartridge media. Once a filter cartridge has accumulated and entrained a high density of radioactive particles, handling the spent cartridge and its safe removal is a severe problem due to its intense concentration of CRUD and its associated high radiation level.
Despite systems for particulate filtration that have been contributed by the prior art, there remains a need for apparatus for coolant filtration in a nuclear facility capable of containing a multiplicity of disposable filter cartridges disposed within a containment vessel to simultaneously receive contaminated coolant which is cleansed by the filters and expelled back to its pool of origin, and to provide such apparatus with the capability of relatively rapid and safe filter cartridge exchange during apparatus shut-down.
In other non-nuclear industries, systems have been provided for multiple cartridge filtration of fluids used in food, chemical, pharmaceutical, and general manufacturing industries. The apparatus of such a system is disclosed in U.S. Pat. No. 4,257,888, however, such a system does not address the specific problems associated with personal exposure to high levels of radiation emitted from the concentration of CRUD, also known as Radwaste, collected by the use of high-efficiency filtering media.
Accordingly, it is a general objective of this invention to provide improved apparatus for filtration of radioactively contaminated coolant of a nuclear reactor.
It is also an objective of the present invention to provide such coolant filtration apparatus that is capable of significantly extended filtration run time and which can be rapidly and safely serviced during non-operative down time and then quickly restored to its functioning mode.
It is a further objective of the present invention to provide apparatus for radioactive particulate filtration which uses a significantly large number of commercially available filter cartridges to simultaneously obtain an improved high level of particle removal efficiency.
Other objectives and desirable characteristics of the present invention will become apparent from the ensuing detailed description of the invention when read in reference to the accompanying drawings.
SUMMARY OF THE INVENTION
This invention comprehends apparatus which includes a substantially large stationary vessel defining an interior chamber in which a basket-like turntable structure is mounted on a vertical axis within the chamber. The turntable supports a large plurality of disposable filter cartridges standing vertically and in spaced-apart relation to each other in a special radial pattern relative to the central axis. Part of the turntable structure is a coolant distribution manifold adapted to sealably removably receive the upper ends of the filter cartridges. The manifold has a conduit section projecting centrally upwardly through the top wall of the vessel and in improved flow communication with an inlet which conducts coolant from a coolant pool. The incoming coolant flow passes downwardly through the conduit section and then radially outwardly through a distributor section and thence into the filter cartridges which have their intake ends in sealed connection with the distributor section. The coolant flow passes through the filtering media within the cartridges and thence radially outwardly into the chamber of the vessel whereby, once the chamber's vessel is totally filled, the filtered coolant is piped outwardly through a discharge port on the vessel and back to the pool.
During the time that the apparatus of the invention is being utilized for continuous coolant filtering, the turntable structure on which the filter cartridges are supported is maintained in a predetermined fixed position until it is determined through a test procedure that the entrained particulate matter within the cartridges has reached a predetermined level, requiring cartridge replacement. The replacement or cartridge change-out procedure involves curtailment of the coolant flow to the vessel and complete evacuation of coolant from the vessel through a drainage port. Additional structure on the vessel, which may be broadly described as gate means, allows manual or mechanized use of special tools during change-out to accomplish repositioning of the turntable structure followed by removal and replacement of spent cartridges.
More specifically, a first gate means, preferably a substantially large ball valve mounted on and centrally above the vessel top wall, permits downward insertion of a tool for controlling limited movement of the turntable structure. A second gate means preferably comprises a plurality of identical ball valves which are mounted, relative to the turntable structure, in a specific predetermined pattern across the top wall of the vessel and which enable cartridge manipulation during change-out. A third gate means is preferably a plurality of ball valves mounted in a special alignment pattern below the turntable structure and on the underside or bottom wall of the vessel, which permit the passage therethrough of filter cartridges during the change-out procedure.
A feature of the present invention is that it can be almost constantly performing its coolant filtering action which is interrupted only by infrequent down time periods for full filter cartridge renewal and limited servicing.
REFERENCES:
patent: 1547368 (1925-07-01), Dehne
patent: 3064818 (1962-11-01), Kasten
patent: 3615016 (1971-10-01), Soriente et al.
patent: 3838289 (1974-09-01), White
patent: 3890233 (1975-06-01), Gishel
patent: 4032449 (1977-06-01), DeVisser et al.
patent: 4224160 (1980-09-01), Wendlund
patent: 4257880 (1981-03-01), Kudryavtsev et al.
patent: 4280906 (1981-07-01), Lijergren
patent: 4283282 (1981-08-01), Saint-Dizier et al.
patent: 4572710 (1986-02-01), Stock et al.
patent: 4828691 (1989-05-01), Abbott et al.
patent: 4883588 (1989-11-01), Primavera et al.
patent: 5017330 (1991-05-01), Hurdiel
patent: 5347554 (1994-09-01), White et al.
patent: 5379330 (1995-01-01), Lovell et al.
patent: 5478469 (1995-12-01), Bryan et al.
patent: 4118432 (1992-12-01), None
Atwell George C.
Savage Matthew O.
LandOfFree
Apparatus for radioactive particulate filtration does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Apparatus for radioactive particulate filtration, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Apparatus for radioactive particulate filtration will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2541144