A sample of ink, a package of chicken and electronic components for a satellite. All of these things seem unrelated, but for Andrew Kauffman, associate director of the nuclear reactor laboratory at Ohio State, the connection is simple.
All of those items have been irradiated at the nuclear reactor lab, located off Kinnear Road on West Campus.
The nuclear reactor lab tests a variety of items for various reasons.
Radiation is much higher in space than on Earth and the electronic components for satellites need to be tested to see the effect the higher radiation will have on them, Kauffman said.
The nuclear reactor can be used to determine the composition of certain samples. Geologists have taken soil and rock samples and used the nuclear reactor for just such a purpose.
The process called Neutron Activation Analysis consists of first irradiating a sample with neutrons in a nuclear reactor to produce specific radionuclides. The radionuclides begin to decay and give off a specific gamma radiation signature indicative of the radionuclide.
These signatures can be studied to determine the concentrations of various elements in a sample.
Such a process was used in determining the composition of an ink, Kauffman said.
“We had a company that produces ink come to us because they suspected that a competitor had stolen their formula,” he said. “We used the neutron activation analysis to determine the formula used by the competitor to make the ink. The company then compared the results to their own formula.”
Besides the nuclear reactor, researchers use a gamma irradiator at the lab.
“This device uses cobalt-60 to emit gamma radiation,” Kauffman said. “Researchers sometimes want to irradiate items with only gamma radiation, and not the neutrons emitted by the nuclear reactor.”
An example is food irradiated in experiments by OSU’s Food Science and Technology. The experiments are used to extend the shelf life of the food, Kauffman said.
“The gamma radiation kills bacteria which shortens the shelf life of the food,” he said.
But Kauffman said the gamma irradiator is very safe. The items irradiated in the gamma irradiator can be removed and handled right after the experiment because they don’t give off radiation like things that have been irradiated in the nuclear reactor.
The nuclear reactor lab was built in 1960. OSU’s lab is one of about 25 or 30 labs operated by universities, Kauffman said. “There aren’t many nuclear reactor labs at universities. OSU is one of the few that has one.”
The nuclear reactor is very small. In comparison to a commercial nuclear reactor which has a rating of 500 to 1,000 megawatts, OSU’s nuclear reactor only generates up to one-half a megawatt.
The nuclear reactor uses uranium-235 as its fuel for reactions.
“The uranium is actually on loan from the Department of Energy,” Kauffman said. “The uranium is theirs. We are actually just borrowing it.”
The catalyst for the reactions is a source, made up of plutonium and beryllium, placed near the core, which emits neutrons. The neutrons react with the uranium-235 and create more neutrons.
The newly created neutrons react further with the uranium-235, creating even more neutrons. This self-sustaining reaction is called “bringing the reactor up to critical,” Kauffman said.
To control the reaction the reactor has four long rods which absorb the neutrons. The rods can be moved into and out of the core of the reactor to control the levels of neutrons produced. Without the neutrons feeding the reaction, the reactor is no longer at critical levels.
“The rods are held up by electromagnets,” Kauffman said. “In the event that there was ever a power failure, the electromagnets would no longer hold the rods up. The rods would drop down preventing reactions in the core.”
Because the reactor generates a lot of heat, the reactor is situated at the bottom of a 15 feet deep pool of water.
“The water acts as a protective barrier as well,” Kauffman said.
The nuclear reactor is small and isn’t brought up to its full power level, Kauffman said. “We generate only low level radioactive waste.”
The radioactive waste is put into cardboard boxes to be disposed of later. Although the waste has a very low level of radioactivity, they can’t just be thrown in the regular trash. The boxes go to the Office of Radiation Safety to handle the disposal, Kauffman said.
Experiments with radioactive material are not just conducted at the Nuclear Reactor Lab. OSU has over 400 labs which use radioactive material, said Robert Peterson, university radiation safety officer.
Peterson’s office handles the delivery and disposal of radioactive material.
“On a daily basis we handle anywhere from five to 15 packages of radioactive material,” Peterson said.
“Safety and security of the radioactive materials is a major concern for us,” Peterson said.
Everyone who handles the radioactive material wears a badge which measures radioactivity. These badges are sent in monthly and tested to determine the level of exposure, if any, Peterson said.
“In addition to the badges, we also use pocket dosimeters which give us an immediate reading on radiation levels when we handle the material,” Kauffman said. “The results from the badges are from a month of exposure. It’s nice to have something that tells us now what the levels were when we handled the material.”
The Nuclear Reactor Lab has several safety devices, such as sensors which measure the level of radioactivity around the lab and controls which keep the reactor at safe levels.
The applications for radioactive material are numerous, Peterson said.
“Bio-medical research using radioactive material is very big,” he said. “The use of radioactive material in cancer research and veterinary science is big as well.”
Subir Nag, chief of Brachytherapy at the James Cancer Hospital and Research Institute, uses radioactive material to treat cancer patients.
Brachytherapy is a procedure in which the radiation is given directly to the tumor site by putting the radioactive material (in the form of seeds or pellets) inside or close to the tumor.
“There are several places that we use this procedure – the cervix, endometrium, lung, prostate, head and neck,” Nag said.
Brachytherapy is less commonly used to treat tumors of the esophagus, eye, liver, brain, bladder, breast, rectum, pancreas, or in children. The side effects of brachytherapy are generally minimal because only a small area receives the radiation, Nag said. The advantage is that little radiation goes to healthy tissues around the tumor.
Besides cancer treatment, brachytherapy can be used following coronary angioplasty. Coronary angioplasty is a medical procedure in which narrowed arteries that supply blood to the heart muscle are widened. This allows for improved flow of blood through these arteries to the heart, without the need for open-heart surgery.
“We use the radioactive implants to prevent the regeneration of the arterial lining,” Nag said. “Following angioplasty the walls of the arteries begin to replicate, which could cause narrowing of the artery. The radioactive implants prevent the cells in the lining from replicating.”
