The Philippine Nuclear Research Institute – Department of Science and Technology (PNRI – DOST) is establishing an Electron Beam (EB) Irradiation Facility at the PNRI compound in Diliman, Quezon City, bringing the country’s technology at par with the international community through the applications of radiation processing in various industries.
With this new facility, the PNRI takes the next step in its use of irradiation technologies. PNRI’s present Cobalt-60 Multipurpose Irradiation Facility has demonstrated many of the applications of radiation processing using gamma-rays and has been regularly serving clients from the food, packaging, medical products and pharmaceutical industries.
While the facility operates on a semi-commercial scale, the institute currently encourages industries to establish commercial irradiators to make an impact on the country’s sustainable development.
Over the past 30 years, both developed and developing countries all over the world have already established around 1,200 E-beam accelerators dedicated to commercial and industrial purposes. In Asia, electron accelerators are already used for commercial and industrial purposes in China, Korea, Malaysia, Indonesia, Thailand and Vietnam.
PNRI’s 2.5 MeV electron beam accelerator will be the first in the country intended for full-scale research and development and semi-commercial E-beam services.
While irradiation through gamma rays has certain advantages in radiation processing such as the deeper penetration of gamma rays for thicker materials, electron accelerators are capable of delivering higher dose rates than gamma radiation sources, speeding up the irradiation process. Electron beams can deposit the same energy as gamma radiation would, but in seconds instead of hours, allowing for applications which would otherwise be impractical using radiation sources since it would take extremely longer periods of time.
Hence, faster irradiation opens the doors to more potential applications such as improving the quality of automobile parts, plastics, fibers and semiconductors, better waste management, nanotechnology and jewelry – in addition to the already well-proven capabilities of gamma radiation.
Instead of using chemicals to harden, cure or change the composition of polymer and plastic-based products, radiation from electron beams can induce the cross-linking of molecules in various materials.
In cross-linking, polymers interact with each other to form a three-dimensional network, making tires, rubber sheets, wires, batteries and electrical industrial cables tougher and more resistant to heat, corrosion and chemical damage. The same process may also be applied to improve fabrics, paints, and food packaging materials.
“When you do cross-linking, you can practically increase the toughness of much lighter materials such as carbon fiber or reinforced plastic,” said Jordan Madrid, a Science Research Specialist from PNRI’s Chemistry Research Section.
Madrid participated in a regional training course in Korea in 2013 under a project entitled “Electron Beam Applications for Value Addition to Food and Industrial Products and Degradation of Environmental Pollutants in the Asia- Pacific Region.” The project was spearheaded by the United Nations Development Program (UNDP) and the Regional Cooperative Agreement for Research, Development and Training Related to Nuclear Science and Technology for Asia and the Pacific (RCA).
E-beams may also be used for polymer grafting, where polymer chains are “grown” from the surfaces of polymers.
“There are so many possible applications of polymer grafting, but for the meantime, PNRI scientists are focusing on developing applications such as metal ion absorbents for water purification, catalysts for desired chemical reactions and chemical sensors, among others.” said Madrid, who also worked with electron beams in his research on polymer grafting under the Japanese government’s MEXT program.
In agriculture, electron beams will prove useful in irradiating food products for sprout inhibition, delaying fruit ripening, pasteurization and microbial decontamination.
Its applications in the medical field ranges from sterilizing medical pharmaceuticals and “high-purity” equipment such as scalpels and syringes to reinforcing specialized membranes with electronic and biological sensors without damaging sensitive components. Electron beams can also be used for synthesizing nanogels and microgels such as PNRI’s recently commercialized hydrogels for wounds and burns.
The higher dose rates would allow for faster irradiation of food and medical products, said Biomedical Research Section head Zenaida De Guzman.
“If it takes six to seven hours to irradiate our samples with gamma rays, the electron beam could deliver the same results in two hours. Overseas, however, electron beams could do it in as fast as thirty minutes,” she said.
The Biomedical Research section will be actively involved in research and development studies on the effects of the E-beam to meat and poultry or fully cooked meals such as chicken and pork adobo developed for patients needing clean or sterile diets.
“We aim to be able to extend the shelf-life of meals such as adobo compared to our previous results with gamma rays. With electron beams, we could even get faster results at even lesser doses of radiation,” she said.
Their more recent research on rice-in-a-box-style emergency meal for calamity victims consists of fried rice and chicken adobo. The experimental meal may also be developed to serve as military and relief rations.
The accelerator’s capabilities are also a welcome development in fighting pollution, particularly the E-beam’s potential in “hygienizing” sewage sludge and in treating or reprocessing of waste water and flue gases.
With enough doses, electron accelerators are able to alter the color and composition of gemstones, proving itself useful to the jewelry industry.
The establishment of the electron beam facility in the Philippines received financial support from the International Atomic Energy Agency, the Japanese and US governments, and the Department of Science and Technology. After completing the installation and commissioning of the electron beam facility targeted in the middle of this year, PNRI will conduct trial runs on different samples and products.