(Editor’s note: This is the second of two stories about nuclear energy. The first “Nuclear Energy Provides Reliable, Clean Energy” appeared on July 21.)
BY REECE PASCOE
It started with Marie Curie in 1902 with the discovery of radioactive elements. A 1919 film “Radioactive” tells her story of being in a male-dominated field while making a groundbreaking discovery. She was the first woman to win a Nobel Prize in 1903 and the only woman to win the award in physics and chemistry.
Over the years, radiation has been made into the bogey man, an invisible adversary that can strike at any time.
Curie discovered that radiation is found in everything, food we eat, clothes we wear, there is no way to get around the fact that we are exposed to radiation every second of our lives. We consume about 30 mm radiation a year from food alone, and about 620 mm radiation a year in total. To put that into focus one chest x-ray is about 60 mm.
In Germany, in 1938 Otto Hahn was experimenting with uranium and came to a conclusion, that many considered impossible, he had split a uranium atom.
Dumbfounded he turned to Lise Meitner, a Jewish physicist, and explained what happened, she said, “we have experienced so many surprises in nuclear physics that one cannot say without hesitation about anything: ‘it’s impossible’.”
Meitner talked with her nephew Otto Frisch, and came to a realization that if one atom splitting could make a grain of sand jump what could a pound do or even five pounds.
Word got around to Niels Bohr and then to J. Robert Oppenheimer and with the advent of World War II, Oppenheimer theorized a WMD (weapon of mass destruction) was possible.
In Chicago in 1942, physicist Enrico Fermi was conducting an experiment trying to prove that fission was possible (fission occurs when a neutron slams into a large atom, forcing it to split. When an atom splits energy is released. Uranium and plutonium are most commonly used for fission reactions because they are easy to control).
There were small amounts of uranium inside a box filled with graphite (important) and cadmium, both were used to slow down the rate of fission. The experiment went off without a hitch, proving that splitting the atom was possible.
Heavy water (D2O) substitutes the hydrogen atom for a heavier and denser atom. Heavy water is better at controlling the fission then graphite.
Heavy water is why there were fears about Germany having nuclear capabilities. Adolph Hitler was shipping barrels and barrels of heavy water into Germany. Realization hit the physicist community that Hitler could have a bomb or at least be making one. Two physicists Leo Szilard and Eugene Wigner drove to Albert Einstein, and they drafted and sent a letter to President Franklin D. Roosevelt to urge him to look into the matter.
The Allies made a daring attempt to blow up the facility and stop the supply of heavy water. Fears about Hitler having nukes were abated after the war when German scientists were shown footage of the nukes being dropped and they thought it was fake. They couldn’t believe it was possible.
Oppenheimer was leading research and development at the Trinity test site, located at the White Sands Missile Range in New Mexico. He was credited with the success test of a Plutonium bomb. “Now I am become death, the destroyer of worlds,” he said, quoting the Hindu God Vishnu. The uranium-based bomb was dropped on Hiroshima on September 6, 1945, and then the subsequent bombing of Nagasaki three days later was done with a plutonium-based bomb.
Fission is the process of spitting the uranium or plutonium atom into smaller elements. In a nuclear power plant, plutonium is the principal fuel, which is a byproduct of uranium 238, and comes from neutron capture.
Nuclear reactors control the rate of fission and use its exothermic reaction to heat water to produce steam to turn turbines (Cliff Notes version). To control the rate of fission the uranium is encompassed by control rods, made from boron, cadmium, and hafnium. The rods are like the on and off switch, they encase the uranium.
It’s kind of like a drink cozy, cover more of a drink it stays cooler or take the cozy off and one’s drink will get hot.
About radiation, some of the elements in the fission are unstable so they get broken down farther and farther until it becomes to a stable element.
These elements are radioactive and have different half lives – some a couple of days and some a couple of months. That is why people are living in Hiroshima and Nagasaki, but not Chernobyl. (Half life is the time it takes for half of the substance to decay. Uranium-2332 has a half-life of about 69 years, Plutonium-238 has a half live of 88 years.)
With the man-made Chernobyl accident, linked to inadequately trained personal, happened in April 1986, about 400 times more radioactive substances were released than in Hiroshima.
Iodine, strontium and ceasim were released with half lives of 8 days, 19 and 30 years respectively. Plutonium 238, 239, 340 and 241, formed in the explosion in the reactor. Plutonium-241 has beta radiation, which turns into americium-241 – a dangerous alpha radiation. During the first 14 years after the accident there was no americium, but now plutonium has degraded to americium, and it will take 4,330 years for this to cease to be dangerous.
Now, scientists are working on fusion, which is combining atoms together, like when two hydrogen atoms fuse to form one helium atom. This idea first appeared at Trinity about how to reduce fallout from bombs by using fusion. This is the same process that powers the sun. Fusion power releases no carbon dioxide and is dubbed “clean energy.”
(Note: Nuclear energy produces more carbon-free power on less land than any other clean-air source. A typical 1,000-megawatt nuclear facility in the United States needs a little more than 1 square mile to operate. To put that in perspective, you would need more than 3 million solar panels to produce the same amount of power as a typical commercial reactor or more than 430 wind turbines.)