If we freeze-frame right here, the scenario is grim. The core is quickly generating steam and heat in a runaway reaction. All but six of the plus control rods have been removed from the core and the water is no longer providing any cooling effects. The core is now a giant kid's ball pit in an earthquake, with neutrons bouncing around the chamber and constantly colliding with one another.
At a. This forces all of the control rods back into the core. The control rods should decrease the reaction but because they are tipped with graphite, they actually cause the power to spike even more. Over the next five seconds, the power increases dramatically to levels the reactor cannot withstand. The caps on the top of the reactor core, weighing more than pounds, begin to literally bounce in the reactor hall.
The plus pound steel blocks resting on top of the reactor core started rumbling around and being lifted into the air in the moments before the explosion. Then, at a. It's not a nuclear explosion, but a steam explosion, caused by the huge buildup of pressure within the core.
That blows the biological shield off the top of the core, ruptures the fuel channels and causes graphite to be blown into the air. As a result, another chemical reaction takes place: air slips into the reactor hall and ignites causing a second explosion that terminates the nuclear reactions in the core and leaves a mighty hole in the Chernobyl reactor building.
It's kind of insane to think that humans can control the power of the atom. The Fukushima disaster that affected a Japanese nuclear plant in demonstrates that catastrophes still lurk within reactors around the world and we are not always prepared for them. Today, 10 such reactors still exist in operation across the country -- the only place where they are currently operating.
Those sites were retrofitted with safety features which aim to prevent a second Chernobyl. The control rods were made more plentiful and can be inserted into the core faster. The fuel rods feature slightly more enriched uranium which helps control the nuclear reactions a little better.
And the positive void coefficient, though it still exists in the design, has been dramatically reduced to prevent the possibility of a repeat low-power meltdown.
Of course, the one thing that hasn't changed is us. Chernobyl was a failure on the human scale, long before it was a failure on the atomic one. There will always be risks in trying to control nuclear fission reactions and those risks can only be mitigated -- not reduced to zero. Chernobyl and other nuclear reactors aren't nuclear bombs waiting to detonate.
The HBO series teaches us that they can become dangerous if we fail to understand the potential of atomic science. So can this kind of nuclear catastrophe happen again? As long as we try to harness the power of the atom, the odds will fall in favor of disaster. But should we stop trying to do so? Harnessing the power of the atom and mitigating the risks of nuclear energy as best we can is one of the ways to a cleaner energy future.
Across the planet, reactors are currently in operation -- only 10 of them are RBMK reactors with enhanced safety features -- and as we look at ways to reduce our reliance on harmful fossil fuels, nuclear energy must be considered as a viable alternative.
We can't continue to burn coal like we do and expect the climate crisis to disappear. Health Long-Term Care. For Teachers. NewsHour Shop. About Feedback Funders Support Jobs. Close Menu. Email Address Subscribe. Yes Not now. By — Jenny Marder Jenny Marder.
Leave your feedback. Share on Facebook Share on Twitter. The process is regulated with so-called control rods located between the fuel rods. The control rods can be used to regulate the water temperature by absorbing neutrons floating in the water. To shut down a power plant, engineers activate the control rods to cut off the process of nuclear fission inside the fuel rods. This stops the nuclear reaction from continuing, but the fuel rods are still extremely hot.
As a way to cool them down, the entire apparatus is submerged in water. It takes electrical power to maintain the water flow, so if there is a power failure, the nuclear plant's situation becomes critical. Without maintaining the water flow, temperature and pressure in the reactor will continually rise.
At the Fukushima Daiichi plant, a power failure after Friday's earthquake disrupted safety circuits at one of the station's reactors. Diesel-powered generators at the site also failed. Electric batteries were the only resource left to keep the water-cooling process going, although those had a limited lifespan. In other words, plant operators could not replace the water - which was quickly heating up and turning into steam - quickly enough.
If the process goes unabated, the fuel rods' protective covering can be corrupted or even destroyed, which can then release radioactive gases and hydrogen into the outside environment - a likely cause of the Saturday explosion. Increasing temperatures inside the reactor were producing steam, which caused pressure in the reactor to go up. To prevent an explosion, engineers released some of the slightly radioactive steam through a valve. Since that measure was only partially successful at lowering the reactor's pressure, officials began to fill the damaged reactor with sea water.
If it is bad enough, the molten, radioactive uranium could burn through all the protective layers surrounding the reactor and get released into the surrounding environs. The most famous nuclear accident here in the United States, Three Mile Island in , is called a partial meltdown because the fuel rods were only partially exposed, though melting did occur. Washington Post : How the nuclear emergency unfolded. Sarah Zielinski is an award-winning science writer and editor.
She is a contributing writer in science for Smithsonian.
0コメント