North Korea resumes work on reactor
The analysis was based on satellite photographs taken on 30 April showing new construction at the Yongbyon site.
Pyongyang is ''now close to completion'' of the reactor containment building, the institute said.
But it may take one to two more years before the site is fully operational.
The reactor, which Pyongyang says is to meet energy needs, is a prototype for other, larger reactors already in the pipeline, says the BBC's Lucy Williamson in Seoul.
The ''next major step in construction'' following the completion of the building would be the loading of ''heavy components, such as the pressure vessel, steam generator and pressuriser'' through the roof, said the analysis published on the 38north website .
The institute at the Paul H. Nitze School of Advanced International Studies (SAIS) at Johns Hopkins University has been analysing satellite photographs of the experimental light water reactor since last year, Kazinform cites BBC News.
It tracked ''rapid progress'' in 2011 and found that work at the site stopped in late December.
''Exactly why the work stopped remains unclear,'' the institute said.
It could have been partly due to the death of North Korean leader Kim Jong-il in December, or more likely, the approach of winter, it added.
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