And now for something entirely different! Today we leave the Middle East and return to the site of the Chernobyl nuclear disaster in the Ukraine. In 1986, a power surge triggered an emergency shutdown of the reactor. A huge spike in power to the reactor resulted in a rupture of the reactor vessel and releases of steam. Ultimately, the moderator rods caught fire and huge plumes of radioactive smoke were released into the atmosphere. The plumes drifted over Europe, dropping radioactive fallout. Over half a million workers were deployed to deal with the emergency and cleanup. At a cost of billions of dollars, the reactor was entombed in a giant concrete shell and the surrounding cities and countryside were abandoned. Tests at the Chernobyl site show that the level of dangerous cesium-137 has not been dropping as rapidly as estimated. It was thought that half of the cesium would be gone in the twenty seven years that have passed but that is not the case. Scientists are unsure of why the site is still so radioactive.
Recently a robot was sent into the reactor to check conditions. The operators of the robot were astonished to find black slime growing inside the reactor vessel. The level of gamma rays (highly energetic photons) inside the reactor is very high and it had been assumed that nothing living aside from a particularly radiation resistant bacteria could survive and grow in such an environment. The robot brought a sample of the slime out of the reactor for examination.
The slime turned out to be composed of several types of fungi. In the lab, the slime grew faster when the gamma radiation was raised to five hundred times above the normal background level of gamma radiation. The reason that the slime was black is that it contained high levels of melanin which is a dark pigment found in many animals. It is the primary determinant of skin color in human beings. It appears that the slime is using melanin to extract energy from the gamma radiation in a way similar to the use of chlorophyll in plants to use the energy in visible light to power biological processes. When a gamma ray hits a melanin molecule, its structure is altered and the slime is able to use the energy released in the reaction.
The reactor at Chernobyl is going to be enclosed in a steel dome to prevent further release of radiation into the environment. The slime might be able to continue to grow because it is not dependent on sunlight for energy. There is some concern that the slime could spread beyond the Chernobyl reactor and possibly pose a threat to plants and animals around the reactor. Life is tenacious and some forms thrive in very hostile environments. Even so, the discovery of this slime living in a highly radioactive environment is surprising.
Chernobyl power plant after the accident:
