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The County of Hawaii has indicated that the Hilo irradiator will be considered an agricultural processing facility, suitable for agricultural or industrial zoned property. Plans for the modestly sized facility total less than 5,000 square feet.

Inside the radiation chamber, a 16' square stain-less steel containment pool safeguards the radiation source, known as Cobalt-60 "pencils." When sterilization operations are conducted, the cobalt pencils, mounted on racks, are raised from the containment pool to bombard products with specified doses of ionizing radiation. While the process is occurring, workers are protected by thick concrete walls, airlock doors, and a number of redundant back-up safety systems. When the process is completed, the cobalt racks are re-submerged in the containment pool, where water serves as a highly effective shield against ionizing radiation.

Each pencil consists of Cobalt-60 pellets coated with a nickel plating, then encapsulated in zirconium. This assembly is then encapsulated in a stainless steel rod, about 18 inches long, to further prevent any breach of the radiation source. Inside the containment pool, a series of filters, monitored continually by highly sensitive detection equipment, are deployed to absorb any cobalt contamination. Unlike Cesium-137, another radioisotope, Cobalt-60 is not water soluble. Cobalt isotopes do not present an environmental risk of groundwater contamination.

The Hilo irradiator will use approximately 150,000 curies of Cobalt-60, considerably less than the 4-4.5 million curies employed in other Isomedix facilities on the mainland. The half-life of Cobalt-60 is 5.3 years. It is produced by subjecting Cobalt 59, a rare metal mined in Canada, to neutron bombardment in a nuclear reactor. Cobalt-60 is a commercially manu-factured radioisotope, not a nuclear waste product. Its manufacture and commercial applications are totally unrelated to the nuclear weapons industry.

When the gamma-emitting energy of cobalt is depleted, typically after about 15 years, "spent" pencils are retrieved by the manufacturer for re-use, recycling or disposal. When the facility is eventually decommissioned, all Cobalt-60 products are returned to Nordion in Canada. Operation of the Hilo irradiator presents no "nuclear waste" disposal concerns for the State of Hawaii.

Cobalt-60 is transported by common carrier throughout the world in licensed, lead-shielded containers. Nordion's initial shipment to the Hilo irradiator will consist of 2.5 pounds of cobalt pencils. Since 1955, Nordion has shipped more than 270 million curies of Cobalt-60 to its customers worldwide without incident of radiation hazard to the public or to the environment.

Both Nordion and Isomedix are registered to the International Standards Commission, known as ISO 9001.

MDS Nordion provides a 20-year manufacturer's warranty for its cobalt products. Throughout Nordion's years of supplying Cobalt-60 to industrial facilities worldwide, there has been never been an occurrence of a breached source wherein contamination has leaked into a containment pool or the surrounding environment.

The radiation chamber for the Hilo irradiator will be constructed of reinforced concrete walls, six foot thick, built to American National Standards Institute specifications published in the Federal Register. The structure will be built to meet earthquake code for the Hilo area, a Seismic 4 Zone. As directed by the Hawaii County Council, Isomedix already has conferred with U.S. Geological Survey staff at Volcanoes National Observatory to assess seismic construction requirements for the facility. Since 1984, Isomedix has safely operated a commercial irradiator in Sandy, Utah, also a Seismic 4 Zone.

There are approximately 40 commercial irradiators in the U.S. Cobalt-60 radioisotopes also are used in hundreds of other hospital and research settings. Gamma radiation is used worldwide in radiotherapy cancer treatment, metallurgy, and materials calibration. Every-day, in America's hospitals and clinics, doctors depend on gamma-sterilized scalpels, surgical gloves, sutures, dressings, and other disposable products. Consumer items commonly sterilized by irradiation include milk cartons, baby bottle nipples, corks, talc, plastic wrap, saline solutions and tampons.

In recent years, gamma sterilization has steadily replaced the use of chemical fumigants such as ethylene dibromide and methyl bromide. These chemicals have been banned by the U.S. Environmental Protection Agency because of the damage they do to the earth's ozone layer. That development, coupled with growing inter-est in the role of irradiation as a commodity treatment, led the Hawaii Department of Agricul-ture to undertake its trial investigation of irradiated Hawaiian fruit on the mainland in 1995.

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