In 1975, during the final days of the Vietnam War, most of the world was unaware that the North Vietnamese were advancing a new breed of nuclear reactor, gifted to the South by the United States government.

Not only was it technology the North's Russian allies did not yet have, it was also a source of weapons-grade nuclear fuel.

As a last resort, the US discussed bombing the facility, risking nuclear fallout, rather than risk the technology falling into Soviet hands.

To avoid humanitarian and environmental disaster, a physicist from Idaho in the US, called Wally Hendrickson, volunteered to be dropped into the front line to remove the fuel rods from the reactor.

He speaks to Ramita Navai. A Two Degrees West production for BBC World Service.

(Photo: Dalat nuclear institute. Credit: Diane Selwyn)