Nuclear industry explores accident-resistant fuel

Published on NewsOK Modified: June 14, 2014 at 10:38 am •  Published: June 14, 2014
Advertisement
;

ATLANTA (AP) — The explosions that rocked a crippled Japanese nuclear plant in 2011 show what happens when nuclear fuel fails during severe accidents.

Now researchers are trying to develop tougher types of fuel that might reduce the damage during extreme events like the one at the Fukushima Dai-ichi nuclear plant. While scientists have been experimenting with these ideas for years, the U.S. Department of Energy increased research funding after the crisis in Japan.

Their goal is to create nuclear fuel that gives plant workers more time before an accident spirals into a more-serious meltdown.

Here are five things to know about the effort:

WHAT IS NUCLEAR FUEL?

Radioactive uranium powers most nuclear reactors. Uranium dioxide is compressed into pellets about the size of a fingertip. The pellets are stacked into a hollow metal tube typically made of a zirconium alloy. The tubes are up to 15 feet tall and are collected in bundles. These bundles are eventually loaded into a nuclear reactor.

IS THE FUEL SAFE?

Generally, yes. Federal regulators say modern fuel has a safe track record. Engineers settled on the current metal alloys protecting fuel pellets because they resist corrosion, are strong and stand up well to heat. They are designed to withstand accidents. Rules set by the U.S. Nuclear Regulatory Commission require that emergency cooling systems in a nuclear plant keep the cladding from exceeding 2,200 degrees Fahrenheit. The rules also set limits on how much of the cladding can undergo the chemical reactions that create explosive hydrogen gas and give off excess heat.

SO WHAT'S THE PROBLEM?

The disaster at the Fukushima Dai-ichi nuclear plant showed that severe accidents can expose nuclear fuel to far worse conditions. On March 11, 2011, a series of tsunami waves knocked out the power needed to run cooling systems at the Fukushima Dai-ichi nuclear plant. Without those cooling systems, the nuclear fuel at the plant overheated. As cooling water boiled away, the resulting steam reacted with the zirconium alloy cladding on the fuel. That created a chemical reaction which produced explosive hydrogen gas and even more heat. Investigators blame the hydrogen gas for fueling several explosions at the site that damaged buildings, injured workers and flung around radioactive debris. The explosions significantly complicated efforts to fix the plant. The chemical reactions produced even more heat in an already over-heated reactor, speeding along fuel meltdowns.

Continue reading this story on the...