Nuclear meltdown, also known as nuclear energy leakage, is a serious sequelae that occurs when a nuclear energy reactor fails. Although the radiation emitted by nuclear energy leakage is far less powerful and ranged than nuclear weapons, it can also cause a certain degree of biological casualties. Such as the recent 2011 Fukushima Daiichi nuclear power plant disaster and other events.
nuclear power plant
In fact, while nuclear power plants can't produce a Hiroshima-style nuclear explosion, the meltdown is just as bad as it is. Throughout the atomic age of mankind, there have been countless nuclear accidents, although fortunately there have been only four large-scale incidents in civilian factories. The first occurred at the Lukens reactor in Switzerland in 1969. Ten years later, the Three Mile Island accident followed by the Chernobyl disaster in Russia in 1986 and the Fukushima Daiichi nuclear power plant accident in 2011.
The International Atomic Energy Agency (IAEA) classifies nuclear incidents from zero to seven, ranging from simple deviations without safety significance (level 0) to major accidents such as Chernobyl (widespread damage to health and the environment).
Chernobyl Nuclear Power Plant
Interestingly, neither the IAEA nor the U.S. Nuclear Regulatory Commission has officially recognized the term "nuclear meltdown," but it's a word that elicits fear. In this article, we will break down how nuclear reactors work and how nuclear meltdowns occur.
Don't worry too much about complex equations, because the whole situation ultimately boils down to heat. Proper control of heat inside the reactor helps generate electricity. On the other hand, runaway heat can cause the reactor itself to melt and contaminate the surrounding environment with dangerous radiation.
<h1 class="pgc-h-arrow-right" > in functional nuclear reactors</h1>
Heat makes all the difference. This is key to understanding how healthy nuclear reactors work and how damaged nuclear reactors occur.
First, let's look at a basic coal-fired power plant: we burn coal to generate heat. Heat causes the water to boil into expanding pressurized steam, which then flows to a turbine, which rotates the generator to produce valuable electrical energy.
Diagram of the working principle of a nuclear power plant
Nuclear power plants operate in a similar way, with only heat coming from induced fission reactions that occur in reactors. Fission refers to the stable division of a material's atoms into two parts, releasing a large amount of energy and heat, which we call attenuated heat. It can be seen that uranium and other radioactive elements have spontaneously fissioned at a very slow rate without any artificial help. In a nuclear power plant, operators artificially stimulate or induce fission reactions by bombarding uranium-filled fuel rods with neutrons from previous fission reactions. This means more heat to boil the water into steam.
Of course, you don't want the temperature inside nuclear reactors to rise too high so that they don't damage the reactor and release harmful radiation. Therefore, the coolant (usually water) inside the reactor core can also be used to slow the temperature of the nuclear fuel rod.
The cooling of a nuclear reactor is similar to that of a car engine
It's like driving a car: you don't want to overheat the engine because that could damage the engine. However, the difference is that you can turn off the vehicle and let its engine cool down. Cars only generate heat while driving and for a short period of time afterwards.
However, the radioactive material inside nuclear reactors is different. Even if plant operators shut down all induced fission reactions, uranium and even radiation tools and parts will continue to produce decay heat. They can be done in minutes.
< h1 class= "pgc-h-arrow-right" > melts the interior</h1>
In a nuclear meltdown, the reactor we face burns out of control so that its own heat continues to cause damage. Usually, this is due to a coolant loss accident (LOCA). If the circulation of the coolant through the reactor core slows down or stops completely, the temperature will rise.
The Three Mile Island nuclear accident of 1979 belongs to the genus
The first thing to melt is the fuel rod itself. If plant personnel can resume coolant circulation at this point, the accident can be considered partial nuclear melting. The Three Mile Island nuclear accident of 1979 fell into the following category: The core of Reactor No. 1 melted, but the protective casing around the core remained intact. In fact, Reactor No. 2 of the Three Mile Island nuclear power plant continues to generate electricity in the shadow of its deactivated nuclear power plant.
However, if left unchecked, some of the meltdown could deteriorate into a full meltdown. Emergency teams try to cool core residues before they melt through the protective shell or even the containment itself, and that becomes a race against time. In 1986, a Russian team chased melted remnants of a reactor core at the Chernobyl nuclear power plant into the basement of a facility and flooded it with water to cool the material before it could burn the containment and contaminate groundwater.
Japan's Fukushima Daiichi Nuclear Power Plant
In March 2011, a powerful earthquake struck the Fukushima Daiichi Nuclear Power Plant in Japan, damaging a backup generator that supplied the plant's cooling pump, resulting in a coolant accident. Subsequent events illustrate some of the other complications that can occur during a nuclear meltdown.
Radiation from the fukushima Daiichi nuclear power plant's overheated reactors (which have six at the facility) began to split water into oxygen and hydrogen. The resulting hydrogen explosion destroyed the secondary containment structure (or secondary protection) of at least three reactors, allowing more radiation to escape. The ensuing explosion shook the device, causing it to damage the reactor's main containment structure.
So, how to stop the occurrence or exacerbation of nuclear disasters?
<h1 class="pgc-h-arrow-right" > how to stop a nuclear meltdown</h1>
Similarly, nuclear melting boils down to heat, and there is an urgent need for a running coolant system to control the condition. The Fukushima Daiichi nuclear power plant disaster reminds us that the system is critical even if all fission activity has been shut down. When seismic activity increased, the Japanese plant automatically immersed the fuel rods in the water, effectively stopping all fission reactions within 10 minutes. But those rods still generate attenuated heat and require a functional coolant system.
A factory building after a nuclear meltdown at the Fukushima Daiichi Nuclear Power Plant in Japan
This is also why highly radioactive wastes, such as radiation or used nuclear reactor fuel, are attracting this attention. It takes tens of thousands of years for these materials to decay to safe levels of radioactivity. During this time, they will need a coolant system or adequate sealing measures. Otherwise, they will exhaust everything you put in.
However, past nuclear power plant designs have proven more likely to collapse. In the event of their respective accidents, the Fukushima Daiichi Nuclear Power Plant and the Michirishima Power Plant used not only water as a coolant, but also a palliative. Moderators reduce the speed of fast neutrons, making them more likely to collide with fissile fuel components and less likely to collide with non-fissile fuel components. In other words, moderators increase the likelihood of fission in the reactor. Therefore, when water is discharged from the core of such a reactor, the fission automatically stops.
Nuclear reactors are reactor cores
Chernobyl, on the other hand, uses solid graphite as a moderator. If the coolant is discharged, the moderator remains behind. Thus, dehydration from Chernobyl reactors actually increases the rate of nuclear fission.
To prevent water loss accidents from turning into meltdowns, nuclear power plant operators must cool the reactor core. This means that more coolant is flushed through overheated fuel rods. The newer the fuel rod, the faster it cools.
Wreckage of a factory building after the Chernobyl nuclear leak
If partial melting begins to occur, the rod will collapse. If left unchecked, the collapse rod will melt and accumulate at the bottom of the reactor core, forming a large amount of molten sludge. Radioactive sludge will pose a greater cooling challenge. Not only is it a single clump (as opposed to several independent rods), but one side of it is pressed against the bottom of the reactor core and burns stably through the heat it generates.
In the case of Chernobyl, the emergency response team pumped hundreds of tons of water to cool the reactor core. Next, they used helicopters to dump boron, clay, dolomite, lead and sand on burning nuclei to extinguish the fire and control radioactive particles into the atmosphere. In the months that followed, they sheltered the destroyed plants with concrete, often referred to as sarcophagus.
Chernobyl nuclear power plant exclusion zone
Similarly, nuclear power plants eventually generate heat, and their maintenance depends on the proper regulation of heat. If the cooling system fails, the situation can spiral out of control.