* Extends agreement with OPG for supply of cobalt-60
* Deal does not affect other isotope product segments
* Chalk River plant to restart as early as next week
TORONTO, Aug 13 (Reuters) - Canada's MDS Nordion MDS.TO, one of the world's biggest suppliers of medical isotopes, said on Friday that it has extended until 2020 an agreement with Ontario Power Generation Inc for OPG to supply it with cobalt-60, a radioactive isotope.
MDS is the world's leading supplier of cobalt-60 products, which are used globally for the sterilization of medical equipment such as surgical gloves, syringes, catheters and sutures.
OPG's Pickering, Ontario, nuclear reactors, which produce the isotope, are all expected to be decommissioned by 2020.
Ottawa-based MDS Nordion, formerly known as MDS Inc, sold off its other businesses last year to focus on two main segments: nuclear imaging and radiotherapy, and sterilization technologies.
The company's nuclear imaging and radiotherapy segment was severely affected by the closure of Atomic Energy of Canada's Chalk River nuclear reactor in Ontario in May 2009 due to safety concerns. [nN07109634]
Chalk River supplied the isotopes for MDS's imaging and radiotherapy products.
Chalk River was one of the few reactors in the world that produce commercial quantities of molybdenum-99, the most prominent isotope used in nuclear medicine. It is the parent isotope for technetium-99m, used in most nuclear medicine procedures globally.
"We've actually had no backup supply for the majority of the 15-month shutdown," said Thomas Burnett, MDS's vice president of global sales.
The 53-year-old Chalk River plant -- the world's oldest reactor -- is set to restart as early as next week.
MDS shares were down 23 Canadian cents, or 2.3 percent, at C$9.69 on extremely low volume on the Toronto Stock Exchange on Friday afternoon.
($1=$1.04 Canadian) (Reporting by Solarina Ho; editing by Peter Galloway)