AFP reported today:
Operators of a South Korean nuclear power plant said Thursday that a stray screwdriver was most likely to blame after a reactor had to be shut down for three days.
The reactor in Yeonggwang, about 260 kilometres (160 miles) south of Seoul, stopped working on February 4. It was restarted after engineers carried out repairs to the cooling pump, a company spokesman told AFP.
Link to AFP story: