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The Chernobyl Disaster

The Chernobyl Disaster

On April 26th, 1986, a nuclear power plant in Chernobyl, Ukraine failed violently during a scheduled test of the turbine system. The power of the reactor increased out of control from a low-power state, rapidly boiling water and causing a steam explosion that blew the roof off the the reactor. A graphite fire was ignited, spewing toxic radioactive substances into the atmosphere. 31 people were killed during the accident, and it has been estimated that the released radiation has caused an additional 4,000 cancer deaths.

Here, you can find out what caused the Chernobyl accident and why we are convinced that nothing like this could happen again. Check the links to the right for our collection of information on Chernobyl.

The Sort-of Short Story

The Soviet government ordered the operators of Chernobyl to perform a test on their reactor. The test was supposed to measure how long the spinning generator would continue producing electricity after the reactor was shut down before it slowed and stopped. The test was to happen with the reactor at low power. As the operators were about to start slowly and carefully bringing the reactor to low power, the utility company called and said that a nearby coal plant just shut down unexpectedly and asked Chernobyl to stay at full power for a while longer to keep the nearby homes lit. After peak hours, the operators brought the plant to low power rapidly. Nuclear engineers can explain to you that this kind of shut-down would result in an unusually large amount of Xenon build-up in the reactor fuel. Xenon eats up neutrons, thus making the chain reaction more difficult to maintain. Because of this, the operators were surprised when the reactor went to a lower power than they had expected.

To get the power of the reactor to its expected value, the operators pulled the control rods out further than they would ever do in any normal situation. Finally, the reactor went up to the power level needed for the test. Unfortunately, the Chernobyl reactor was designed in a dangerous manner, allowing the reactor to get hotter if bubbles formed in the water coolant flowing past the fuel. As water boiled in certain locations of the reactor, this power instability started rearing its head. Apparently, one of the operators noticed this highly unstable situation and pressed the button to insert the control rods and shut down the reactor. But, an even more serious design flaw was in the control rods. The neutron poison in most of each rod had a small graphite tip on the bottom. This graphite is beneficial to chain reactions. So with the control rods all the way out, inserting them for the first few inches actually increased the power of the reactor. This led to more boiling of the water, which resulted in even more power and then positive feedback took the reactor power sky-high, immediately boiling all the water to steam. The steam pressure was so great that it blew the lid right off the reactor and through the roof of the reactor building (which was not one of those steel containments, by the way. It was just a concrete building).

With no more coolant, the fuel heated up and became molten. Standing graphite rods in the reactor ignited into a very hot graphite fire that began spewing bits of the radioactive fuel into the open air. The fire took over a week to extinguish, costing the lives of about 30 emergency responders due to acute radiation poisoning.

The really short version

Because Xenon built up due to a rapid shut-down mainly caused by nearby coal plant problem, operators at Chernobyl retracted the control rods all the way out of the core only to notice power instabilities due to the inherent positive coolant void coefficient of the RBMK reactor and reinsert them. But since the tips of the rods were graphite, this increased the power rather than decreasing it and the positive void coefficient allowed the reactor to undergo a runaway power excursion, resulting in a catastrophic steam explosion and graphite fire that killed 30 workers and released radiation in levels that were soon detected in Finland.

Can this happen again?

Modern reactors have reinforced steel-concrete containments domes that would not be so easily penetrated by a steam explosion. Control rods are designed such that all parts of them are neutron poisons, including the bottom. Reactors are designed to have NEGATIVE void coefficients, meaning boiling water would result in power decreasing automatically rather than increasing. Also, graphite is not typically put in reactor cores. Short answer: no.

More info

Plug-in hybrid electric vehicles (PHEVs)

A sustainable transportation idea

A plug-in  hybrid-electric vehicle (PHEV)Every so often, humanity comes up with great ideas. The plug-in hybrid electric vehicle (PHEV) is one of them, and here’s why. PHEVs allow sustainable personal travel without compromising freedoms. At the same time, they provide the missing energy storage required to get the most out of the intermittent renewable energy sources such as wind and solar power. PHEVs, primarily charged by nuclear power and intermittently by renewables, literally provide a vehicle to wean us of our oil addictions by providing domestic transportation energy.


What are plug-in hybrids?

  • Plug-in hybrids are cars that have an electric motor and a gasoline engine.
  • Unlike most current hybrids, plug-ins can get energy from plugs in your garage as well as from the gasoline.
  • The gasoline engine would only turn on if you ran out of electricity between charges, whereas in today’s hybrids, the gas engine must always turn on after a set number of miles to charge the batteries.

What are some problems with PHEVs?

  • PHEVs will strain the current electric grid, requiring more power plants to be built. If nuclear power plants are built, the environmental impacts of PHEVs will be much less than if coal plants are built. The ability of the grid to handle PHEVs is a current research topic.
  • Because they have internal combustion engines and transmissions, PHEVs are heavier than pure electric vehicles. Therefore, pure electric vehicles could get more miles per charge than the hybrids.
  • PHEVs still require some gasoline.
  • With advanced batteries and computer controls, PHEVs will probably be more expensive than standard cheap cars.

The bottom line

PHEV + Nuclear power = sustainable, domestic, extremely low-carbon, wind & solar enhancing, long-distance capable transportation for all.

Why plug-in hybrids?

  • Plug-in hybrids drastically reduce the amount of oil we need. Since the average daily commute is less than 30 miles, the vehicles would run off of electricity (generated from domestic coal, nuclear, renewable energy, etc.) for the vast majority of the time.
  • Long trips are still an option. Unlike pure electric cars, these vehicles will have ranges comparable to today’s fleet. These trips will, of course, require gasoline.
  • If the wind is blowing at night, windmills could store the energy in the cars. Then, the energy that would have been wasted is used for transportation.
  • Plug-in hybrids could also send stored electricity back to the grid with so-called Smart Grid technology. If the grid demands high peak power and there are a large number of PHEVs plugged in while parked, the cars could act as the energy reservoir. This stabilizes the electric grid, reducing the need for standby natural gas generators. You would get credits for all the electricity your car provided.
  • Even when the PHEV is running on gasoline, it can make use of standard hybrid technology, such as regenerative brakes to charge the batteries, maximizing efficiency. In its worst performance, a PHEV will act as today’s hybrids.