Asian powers aim to cut out N.Korea's nuclear core

SEOUL, Feb 6 (Reuters) North Korea's sole nuclear reactor is the source of its fissile material, it figures prominently in its nuclear ambitions and its shutdown will be a prime goal of six-party atomic talks starting on Thursday.

Regional powers have called on North Korea to start the process leading towards dismantling its nuclear weapons programme in exchange for aid and security assurances.

''As a first step, it is important to get this facility shut down,'' Chun Yung-woo, South Korea's chief envoy to the talks among the two Koreas, China, Japan, Russia and the United States, just days before the talks resume in Beijing.

The reactor was mothballed for several years as part of a deal reached in 1994, which has since collapsed. The United States accused Pyongyang in 2002 of violating the agreement by pursuing a secret plan to enrich uranium for atomic bombs.

North Korea said shortly afterwards that it would resume operations at Yongbyon, about 100 km north of Pyongyang.

The complex, the biggest and most immediate concern for those trying to negotiate an end of the North's nuclear plans, consists of a 5-megawatt reactor built with 1950s technology and a plutonium reprocessing plant where it extracts weapons-grade material from spent fuel rods.

The reactor, barely strong enough to supply electricity to the complex, can produce enough fissile material for one nuclear bomb per year, experts said. The North has already produced enough material for at least six to eight bombs and perhaps more.

''The Yongbyon nuclear centre appears to have fully mastered plutonium metal production and casting, including having prepared the plutonium for the DPRK (North Korea) nuclear test,'' Siegfried Hecker, one of the few international nuclear experts to inspect Yongbyon, said in a report in November.

North Korea, desperately short of electricity, has begun construction of 50- and 200-megawatt reactors.

Those projects were frozen as part of the 1994 deal and were years away from completion, but one day could provide the state with power and even more plutonium, experts said.

PULLING THE PLUG ''It's important to shut down Yongbyon, because that will be a test of the North's commitment to denuclearise,'' said Baek Seung-joo, head of North Korean military studies at the South's government-affiliated Korea Institute for Defence Analyses.

''What is needed are measures that will disable the North from flipping the switch again to restart its nuclear facilities, after they have been frozen,'' Baek said. ''We need mandatory measures that make the freeze irreversible.'' Regional powers also need to learn from the mistakes of the 1994 agreement and come up with penalties for any transgressions by Pyongyang, he said.

Another problem will be how to keep North Korea's nuclear engineers, an elite and privileged group, occupied.

North Korea has set up secret towns with thousands of closely guarded residents whose sole mission is to develop nuclear weapons, a South Korean lawmaker said in a report in October.

Proliferation experts said North Korea wants to improve its plutonium bomb design and miniaturise its warheads so that they can be mounted on missiles.

''What are you going to do with these engineers?'' asked Daniel Pinkston, a North Korea expert at the California-based Center for Nonproliferation Studies.

REUTERS SY BD1521