N. Korea cannot make weapons with enriched uranium: experts

SEOUL, Sept. 4 (Yonhap) -- North Korea has made progress in uranium enrichment
technology, but it probably does not have the capability to make nuclear weapons
with it, local experts said Friday
Intelligence analysts and experts from the military and state-run think tanks
speculated that Pyongyang may have completed research and acquired the necessary
know-how to operate centrifuges imported from Pakistan in the 1990s.
"The North may be in a position to start full-fledged research that can lead to
uranium enrichment," Lee Chun-geun, research fellow in charge of inter-Korean
cooperation at the Science and Technology Policy Institute (STEPI), said.
He pointed out that if the announcement is true, it is an admission that the
communist country has been engaged in a clandestine nuclear enrichment program
for a very long time.
The remark comes after the North claimed earlier in the day it has nearly
completed experimental uranium enrichment and has entered into a completion
phase.
In the past, the North used plutonium as its base material to build the two
nuclear devices it detonated. The United States dropped a plutonium bomb on
Nagasaki, while a uranium weapon was dropped on Hiroshima, ending World War II.
Pyongyang allegedly admitted it tried to enrich uranium in late 2002, although it
quickly denied the existence of such a program and objected to the matter being
included in the six-way talks aimed at ending the country's nuclear ambitions.
The North has since walked out of the talks, detonated two nuclear devices and
fired a long-range missile in defiance of warnings by the United Nations.
Experts in South Korea and the United States have long suspected that the North
acquired 20 P1 centrifuges from Pakistan from 1998-2001 and obtained blueprints
for more advanced P2 machines.
Centrifuge machines spin natural uranium at 50,000-70,000 rotations per minute to
separate U-235 from U-238. Higher concentrations of U-235 obtained through this
process can be used for both light water reactors and nuclear bombs.
Those used for power production need to be 3-5 percent pure, while purity has to
reach 90 percent levels for so-called weapons grade materials.
This means 20-30kg of highly enriched U-235 made from roughly 3.5t of natural
uranium is needed to make one nuclear device.
Other local experts in the military said if the North has built an enrichment
facility, it can produce enough highly enriched uranium to produce one or two
nuclear devices per year.
This can pose a serious security threat because plutonium weapons are made in
large facilities that are hard to hide, but uranium can be enriched in small
labs. Such secrecy can make it hard for such facilities to be destroyed through
military strikes.
Meanwhile, intelligence sources said Seoul and Washington have very little
information on the North's uranium enrichment program and don't know where such a
research facility could be located.
"There are several candidate locations like Yongbyon, where the North had a
5-megawatt graphite moderated reactor, yet nothing is certain," said an official
who declined to be identified.
He added that because enrichment facilities can be very small, finding
information may be hard.
yonngong@yna.co.kr
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