By Fredrik Dahl
VIENNA (Reuters) - The closing of aging nuclear reactors is expected to peak in 2020-30, posing a major challenge in terms of safety and the environment, a draft U.N. atomic agency report says.
The report, submitted to member states of the International Atomic Energy Agency (IAEA) shortly before Japan's nuclear crisis erupted this month, said the global nuclear sector maintained a high level of safety performance in 2010.
But, it warned, "in some cases, plans for nuclear power program development moved faster than the establishment of the necessary regulatory and safety infrastructure and capacity."
The document, Nuclear Safety Review for the Year 2010, may attract wider interest and scrutiny in light of events at Japan's Fukushima nuclear power plant, which was severely damaged by a massive earthquake and tsunami on March 11.
The U.N. agency was "actively involved in the development of a robust and technically consistent framework for safety goals that broadly defined acceptable levels of radiological risks for installation of nuclear power plants," it said.
The report, obtained by Reuters Thursday, did not name any countries. It invited comment from the IAEA's 151 member states by mid-April, before a final version would be issued.
Japan's nuclear emergency, the worst such accident since the Chernobyl disaster 25 years ago, has sparked debate about the IAEA's role in helping to ensure the safe use of nuclear power and to prevent accidents which can have cross-border effects.
IAEA Director General Yukiya Amano this week said international safety standards needed to be strengthened but the agency was not a "nuclear safety watchdog," stressing safety was the responsibility of individual countries.
But a senior former IAEA official, Olli Heinonen, said in a blog comment that Fukushima "should be a wake-up call to re-evaluate and strengthen the role of the IAEA" in boosting nuclear safety.
Amano's safety report for last year noted that of the 441 reactors now in operation around the world, many were built in the 1970s and 1980s, with an average lifespan of about 35 years. The Fukushima plant also dates back to the 1970s.
"Their decommissioning peak will occur from 2020 to 2030 which will present a major managerial, technological, safety and environmental challenge to those states engaged in nuclear decommissioning," it said.
"The need for national and international mechanisms for early planning, adequate funding and long-term strategies applies not only to decommissioning, but also to radioactive waste management and spent fuel management."
Giving no details about which reactors faced closure, it also said some countries had started to consider extending operations of their nuclear plants beyond the planned timeframe.
The United States has most operating nuclear reactors in the world with 104 units, followed by France with 58 and Japan with 54, according to the IAEA's website.
The report also underlined safety-related aspects as many countries consider introducing nuclear energy programs to help meet growing energy demand and fight climate change.
It was necessary to intensify and improve international cooperation and other efforts "to ensure that a crucial aspect of this growth -- safety and security infrastructure and culture -- keeps pace with global demand."
(Editing by Janet Lawrence)