The Mystery of the Chernobyl Reactor 'Shining Cloud'

On April 25th-26th, 1986, the World's worst nuclear power accident occurred at Chernobyl in the former USSR (now Ukraine). The Chernobyl nuclear power plant located 80 miles north of Kiev had 4 reactors and whilst testing reactor number 4 numerous safety procedures were disregarded. At 1:23 a.m. the chain reaction in the reactor became out of control creating explosions and a fireball which blew off the reactor's heavy steel and concrete lid.

As fire, smoke and steam raged from the shattered reactor hall building, residents of the nearby city of Pripyat, standing atop the tallest apartment building in the city, spoke of a beautiful "shining cloud" pluming from the shattered reactor.

What was this "shining cloud?" How did it come into being?

In order to understand, one first must examine this excerpt from Chernobyl plant operator Alexander Yuvchenko, who was one of very few control room operators on duty that fateful day to survive the accident. After the explosion, he and a colleague went outside of the reactor building to "get a better look at the damage." Yuvchenko stated: "From where I stood I could see a huge beam of projected light flooding up into infinity from the reactor. It was like a laser light, caused by the ionization of the air. It was light-bluish, and it was very beautiful."

Cerenkov Radiation emanating from a reactor core under "controlled" conditions. The blue glow is caused by high energy electrons traveling faster than the speed of light in a medium, in this case, water. To better understand this bluish light, one must first understand Cerenkov Radiation. In 1934, while he was studying the effects of radioactive substances on liquids, Pavel Cerenkov noticed that water surrounding certain radioactive substances emitted a faint blue glow, which is now termed Cerenkov radiation.

Cerenkov Radiation comes from particles traveling at a speed greater than the speed of light in the medium in which they are moving. Electrically charged particles emit Cerenkov Radiation, and in the case of the Chernobyl accident, an intense flux of high energy electrons emitted by the molten, naked core ionized the surrounding moist air and steam droplets belching from the reactor hall after the explosion, and caused them to glow light blue, as plant operator Yuvchenko observed.

No known pictures of the "shining cloud" have been published, as the accident occurred when the Ukraine was part of the Soviet Union, and all controversial media deemed damaging to the State was censored, seized or destroyed. Above is an artist's rendition of the "shining cloud" above Chernobyl shortly after the accident. Steam and fire rages from the shattered reactor hall, the laser-like beam of Cerenkov Radiation extending up into infinity, ionizing the surrounding moist air and water droplets in the steam. The glowing cloud would have diminished as soon as the run amok nuclear fission reaction died away, or was "poisoned" by helicopters that dumped Boron powder (An element that naturally absorbs neutrons that cause nuclear fission) into the reactor's gaping maw.