Perils Of Nuclear Processing

Watchdog groups are focusing their attention on human error in the wake of Thursday's nuclear accident in Japan.

Paul Gunter, Director of the Reactor Watchdog Project for Nuclear Information and Resource Service, told CBS This Morning Anchor Thalia Assuras, "nuclear energy is an extreme threat when left in the hands of humans."

Processing uranium into nuclear fuel, which was taking place at the Japanese plant, can unleash radioactive energy in an uncontrolled way and dramatically raise radiation exposure levels, U.S. experts said.

Gunter said he is concerned about the immediate effects of radiation exposure and about the long-term effects of the release of radioactive gas.

"Our concern has to bring into light that human error will always be the weakest link in this nuclear chain that binds us to an uncertain future for an inherently dangerous technology," Gunter said.

The uncontrolled releases are known in industry jargon as "criticality," which occurs when a nuclear chain reaction becomes self-sustaining.

Generally, nuclear experts said criticality happens when moisture seeps into the process to turn uranium 235 into nuclear fuel.

Workers typically operate complex machinery that forms the uranium into small pellets for loading into fuel rods. The rods are then gathered into fuel assemblies and shipped to nuclear reactors.

If a self-sustaining reaction isn't stopped, it may go out of control, resulting in an accidental release, according to the British-based Uranium Institute.

U.S. nuclear scientists said it appeared that what happened in Japan was far less dangerous than when the Chernobyl nuclear reactor exploded in April 1986, killing 31 people and contaminating areas in the former Soviet Union.