I'm no expert, so I'll leave this to Rick Mercer...
http://www.cbc.ca/mercerreport/videos/north_korea.wvx
(Windows Media 9, 15 seconds)
More Mercer archives:
http://www.cbc.ca/mercerreport/backissues.php
North Korea may be preparing to shut down its main nuclear reactor, according to South Korea's Yonhap news agency. Although the reactor at the Yongbyon facility "remained in operation today", as The Telegraph explains, South Korean sources suggest "a high possibility that movement of cars and people at the site recorded in …
The Yongbyon reactor is nothing more than a carbon copy (I was going to say Chinese copy but that'd be wrong) of the World's first large power reactor at Calder Hall. Britain declassified the design of the Magnox stations some time ago and the North Koreans quickly realised that as well as being relatively simple to built, Magnox stations continuously produce lots and lots of lovely bomb grade plutonium.
Of course the news that the North Koreans are giving up their reactor doesn't mean they're out of the bomb business. They have plenty of spent fuel that can be reprocessed for its plutonium content and, thanks to Pakistan's Doctor Abdul Qadeer Khan, they almost certainly have a uranium enrichment centrifuge cascade that will supply them with bomb cores for the foreseeable future.