Gamma Irradiators

Gamma radiation has been used in refining, mining, chemicals, food, soaps and detergents, and pulp and paper industries, to measure of levels of materials, density, and thicknesses. Gamma radiation can also be used to kill living organisms, in applications of the sterilization of medical equipment (as an alternative to autoclaves or chemical means), the removal of decay-causing bacteria from many foods and the prevention of the sprouting of fruit and vegetables to maintain freshness and flavor. The NSC is equipped with two separate locations (Tube A & B) for irradiation of samples with gamma radiation.

The Cobalt-60 pencil source always remains underwater to provide adequate shielding for radiation workers and the public. Samples to be irradiated are placed in a basket and lowered to the Co-60 gamma source, down either Tube A or B, for a designated amount of time. The basket is 5″ in diameter and 9″ in length. Samples must fit in this basket to be run. Samples are lowered down to the source cask in a basket within a watertight guide tube. The basket is lowered by NSC staff with a manual crank on the platform located over the East side of the reactor bay. The facility utilizes two guide tubes for irradiations. One tube is stationary, and the source is brought up to the sample laterally. The second tube is on an adjustment drive which allows for the angle of the tube to be adjusted. The samples are lowered down either guide tube then the source is drawn up, out of the storage position for a predetermined time to achieve a desired absorbed dose (Gy). The source is lowered and secured before the sample can be pulled up and removed. Experiments are limited to the dimensions of that basket use to lower the samples to the Co-60 source.

Previous irradiations at the NSC have been used for a wide array of research including cell, plasma, and biological material/soil sterilization. The gamma-ray source has also facilitated the mutation of seeds, the examination of the radiation degradation effects of various compounds, and the performance of radiation damage studies in electronic components.

Samples are not radioactive after removal from the Co-60 source and can be handled under normal protocols. The average dosage of Co-60 source in Tube A, as of November 16th, 2021, is: 62 Rad /min (37 Gy/hour). This tube has a max dose rate of 79 Rad/min (42 Gy/hr) at the bottom of the basket and 39 Rad/min (23 Gy/hr) at the top. Extended irradiations will need to be rotated at a specified schedule to obtain uniform irradiation.

Please note that there are additional requirements for training, access, sample submission, and analysis of radioactive samples.

The Co-60 source was last calibrated on November 16, 2021.