Patent Number: 054003822
Section: summary

BACKGROUND OF THE INVENTION This invention relates to an automated process and facility for treating or sterilizing foods, nutrients, potables, medicine and other products by gamma-irradiation. It provides automatic controls for monitoring, transporting, and irradiating such materials in predetermined programs designed for adequate and uniformly effective processing or sterilization. Gamma radiation for commercial or industrial treatment or sterilization of food substances has been increasingly utilized since its inception in several countries since the 1970's. The commercial application of irradiation to sterilize medical devices has been applied on a worldwide basis because of a continuing concern about the side effects and safety of some of the chemical fumigants vis-a-vis contact with the population in general and also accumulation in the food chain. Irradiation of pork, poultry, grain, potatoes, fruits and vegetables, enzymes, herbs, and spices has been approved by the U.S. Food And Drug Administration. The approval of this treatment has recently been broadened to encompass the disinfestation and shelf-life extension of fruits and vegetables and to increase the maximum doses for spices. Gamma radiation was first observed at the turn of the century and shows many similarities to x-rays. It is, however, of a shorter average wavelength and due to spontaneous disintegration of radioisotopes. Most commonly, Cobalt-60 and Cesium-137 are used as radiation sources for a variety of medical and industrial applications, including sterilization. Small doses of gamma radiation are found sufficient to eliminate the viability of virtually all types of microorganisms, its efficiency being comparable to extreme heat or chemical sterilants. "Rad" is the basic measure for "the radiation absorbed dose" as the amount of irradiation received by a product under treatment. Typically, doses administered may range from a low of 6 kilorads (6000 rads) for sprout inhibition or 25 kilorads (25,000 rads) for insect disinfection of fruit to 2.5 megarads (2,500,000 rad) used for the sterilization of medical products. The advantages of gamma irradiation as a method of processing or sterilization reside in the limited number of variables that have to be controlled as it is independent of temperature, pressure and humidity. Gamma rays can penetrate all forms of packaging materials, including glass and metal containers. Thus foods and the like can be treated uniformly and quickly. At the dosage required for food processing and medical-product sterilization, the molecular structure of these products, is not adversely affected. Moreover, the internationally approved or U.S. approved gamma irradiation process cannot cause any material being irradiated to become radioactive. In order to preserve the nutritious quality of foodstuffs or efficacy of medical and pharmaceutical products during irradiation, the process should involve a great deal of flexibility and adjustability depending on the required radiation dosage. The U.S. Pat. No. 4,029,967 describes a device wherein a radiation source, such as cobalt-60, is surrounded in a circle by an array of shielding means and gaps for controllably irradiating the various goods which are positioned in adjacent cylindrical or box containers. As the distance between radiation source and radiation target center remains constant, the containers must be intermittently or continuously rotated as well as relocated in the circle around the radiation source and shielding means to avoid overdosing the goods. Another approach has been to irradiate the materials by moving them in pallets sequentially on two parallel tracking paths past the radiation source in the source rack, such that first one side and then the other will be exposed for an appropriate amount of time. Given the various dose requirements for different materials being irradiated, location of the pallets close to the gamma radiation source can result in damage to more exposed sections when trying to achieve desired minimum doses. Moreover, large changes in the required product dosage in the known systems would entail hazardous manipulation or exchange of the intensity or strength of the radiation material. This complicated manipulation of the sterilization process thereby resulted often in loss of time, value, and overall efficiency. Moreover, with the growing need for efficiently keeping track of the product location and treatment within the official regulations, the ability to measure and monitor the irradiation process has paramount importance and thus spawned the development of computerized technologies. The problem of the desirable uniformity of irradiation and concomitant efficacy in treatment has led to intensive search for an automated dosimetry of irradiation combined with mechanical features which allow ease of handling and greater economy as well as safety in the use of the irradiator. SUMMARY OF THE INVENTION In order to effect sterilization of materials such as cosmetic, medical and pharmaceutical products, sanitization of cosmetic products, as well as treatment for the preservation of nutrients, food and potables, it is the object of the present invention to provide a securely shielded facility of the gamma-radiation type which comprises a radiation source and a dual means for conveying material to be irradiated in parallel direction at adjustably proximal positions to the radiation source while affording a high throughput rate. For protective shielding the facility has a radiation-absorbing wall enclosure open at one end where recessed within the enclosure an interior wall complex is located and shaped to permit barrier-free conveyance of products to and from the irradiation source. In particular, the present invention is directed to an irradiation facility for controllably irradiating a plurality of products with gamma-rays comprising a radiation source, means for loading product to be irradiated on a plurality of carrier means, conveyor means for conveying product carrier means to two dwell units positioned in parallel proximity of the radiation source, means for adjusting the position of the dwell units on either side of the radiation source, means for adjusting the position of the product carrier means on the dwell units, means for storing the radiation source in a radiation protective storage tank, which comprises a water-filled storage pool or a dry storage shielding cask, means for moving irradiating source into position for applying irradiating dosage to each carrier, and computer-linked automatic controls therefor. In particular, the plurality of material comprises food, nutrients, or potables, cosmetic, medical or pharmaceutical products, toxic or infected waste. The applied irradiation dose serves to preserve, process, sanitize or sterilize. It is the object of the invention to provide a virtually infinite variability of pallet position to adjust the product's centerline dose rate. For that purpose, it is a convenient object of the invention to adjust the position of the dual tracktype conveyance means or carrier means connected thereto, so that the material to be irradiated can be moved laterally or perpendicularly to positions at various distances from the radiation source. It is therefore the object of the invention to provide two parallel dwell units positioned on either side of the radiation source rack wherein the dwell units comprise preferably motorized roller type conveyance sections. The individual dwell units, in turn, are carried by a lorry platform and rail system, thus providing transportation of the product into as close a vicinity of the radiation source as desirable. It is another object of the invention to hold the material to be irradiated on dual track-type conveyance or carrier means, such as dwell units, for different required periods of time. It is also the object of the invention to economically, yet effectively, provide a tote system to convey the treatable product on a pallet-type conveyance or carrier means in sequence to each other. It is further the object of the invention to provide a high pallet capacity, preferably up to 1200 kg, at relatively low cost. It is also the object of the invention to provide a high processing capacity, preferably up to 1440 kg/min at relatively low cost. It is a convenient object of the invention to use a hydraulic hoist operated radiation source rack. It is another convenient object of the invention to provide conveyance of pallets to and from the cell on motorized rollers. Further to the invention, a preferred embodiment is directed to an irradiation facility for the remote-controlled treatment of products or materials comprising a radiation source, a conveyance system for transporting the products or materials on at least two movable parallel conveyors in a suitable proximity of the radiation source, the conveyance system having a plurality of carriers for the products or materials to be irradiated, the carriers being selectively transported to control speed, time and duration of irradiation, the parallel track conveyance system having motorized means to vary the track position relative to the radiation source, and the remote control of the irradiation process being monitored and directed by a computer-linked reader system, the reader system being a laser-equipped detection device. The object of the embodiment includes the remote-controlled use of the facility for treatment of products or materials such as preserving or sterilizing foods, cosmetic, medical or pharmaceutical products; radiation processing of bonding plastics, alloys, or emulsions; sterilizing or inactivating waste products; or radiation processing or sterilizing of food packages or utensils. The remote-controlled treatment further includes a loadshifting adjustment for uniformly irradiating product on pallets which are smaller than standard size. The object of the present invention is directed to a method for controllably irradiating a product with gamma-rays in an irradiation facility, comprising the steps of placing the product to be irradiated in a carrier means mounted on a roller conveyor means; moving the carrier means on the conveyor means with connecting shuttle means to different positions on parallel conveyor tracks in dwell units proximal to the radiation source; adjusting the distance of the parallel conveyor tracks respective the radiation source; placing the radiation source into position for irradiation; irradiating the product with a radiation dosage; and optionally monitoring by a sensor means and controlling by the remote control means, the position of the parallel conveyor tracks, the placement of the radiation source, and the dosage of irradiation. A further object of the present invention is directed to the method wherein the product comprises food, nutrients, or potables, cosmetic, medical or pharmaceutical products, infected or toxic waste substances; wherein the controlled irradiation comprises a preserving, inactivating, or sterilizing dose. One important object of the present invention is directed to a method for treating food, medical or cosmetic products, utensils, devices or other products or materials by the remote-controlled irradiation with gamma-rays comprising the steps of placing product to be irradiated on a plurality of carriers, the carriers being mounted in an assemblyline tote system and being connected to remote control means; the assemblyline tote system comprising at least two parallel conveyor tracks positioned in proximity to a radiation source connected to the remote control means, moving by remote-control the parallel conveyor tracks to different positions in the proximity of the radiation source to effect radiation processing and monitoring the remote-controlled irradiation process by an automated dosimetry system using bar-code labelling and radiation colorimetry. The inventive method is directed to using the assemblyline tote system which comprises conveyance controls allowing loadshifting of smaller than standard size carriers for uniform irradiation. Another object of the invention is the computer-linked sensor means which provides the means to monitor and remotely control the operation of conveying, positioning, and irradiating the material to be treated. In this context, the object of invention uses bar code scanning to control entrance conveyor and to ensure a proper product irradiation cycle. The dosimetry system in accordance with one aspect of this invention is designed to combine specialty polymer, automatic identification and microcomputer technologies into an information and control system for efficiently monitoring and reporting the use of radiation processing. Still other uses and advantages of the present invention will become apparent from the following description of the invention and of the preferred embodiments.