NUCLEAR MEDICINE | Co60
Global healthcare and nuclear power
With demand rapidly increasing, multiple initiaives are underway worldwide
to boost the production of cobolt-60 for use in medical equipment sterilisation applications. While the global supply is currently focused on CANDU and RBMK reactors designs, PWRs hold a great deal of promise
By Martin Comben, General Manager Gamma Irradiation, International Irradiation Association
THE RADIOISOTOPE COBALT-60 THAT is manufactured in some nuclear reactors is used to sterilise approximately 40% of single use medical devices globally. These devices include items such as syringes, catheters, IV sets, surgical gloves, and gauze that used in a wide range of health care applications. A patient in surgery or receiving wound care or simply having a blood sample taken, is highly likely to be treated using products that have been sterilised using cobalt-60 in a process called irradiation. Other important uses of cobalt-60 include the non-invasive treatment of cancers and brain tumours, polymer processing, food treatment and environmental applications.
Cobalt-60 production and supply Cobalt-60 is produced in a small number of reactors located in Argentina, Canada, China, India and Russia. The largest producers are Bruce Power and Ontario Power Generation (OPG) that operate CANDU type reactors in Canada. CANDU reactors are well suited for cobalt-60 production with the technology and processes established in the early 1970s with a history dating back to the 1950s.
CANDU reactors operate with stainless steel adjusters that shape the neutron flux for reactor operations. For cobalt-60 production, these stainless steel adjusters are replaced with adjusters containing bundles of metallic cobalt-59 slugs encapsulated into zirconium alloy capsules. The cobalt-59 adjusters are designed to replicate the neutron absorption characteristics of the stainless adjusters that they replace, so reactor operation is not impacted. While in the reactor core, the cobalt-59 atom absorbs one neutron to become cobalt-60 and over time the ratio of cobalt-60 to cobalt-59 increases. To achieve the required level of cobalt-60, the adjusters are activated over a period of 18-36 months. After this activation period, the adjusters are
removed from the reactor during a routine maintenance outage. They are then transferred to a large pool at the reactor site where the adjusters are disassembled and the individual cobalt bundles are removed. These cobalt bundles are then shipped off site for processing and production of the finished product that is used for irradiation sterilisation.
Above: OPG’s Co-60 producing Pickering units could see their life extension support the medical sector Photo credit: sockagphoto/
Shutterstock.com
22 | May 2024 |
www.neimagazine.com
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