Why did chernobyl happen?

Answer 1

The chernobyl explosion was created by a growing pocket of chemical-created steam which, along with a stuck injector rod which hindered emergency on/off procedures, created a domino effect of explosive chain reactions, causing radioactive material and flames to engulf reactor 4

Answer 2

1. Bad engineering design
2. Rushed construction schedule waving multiple safety tests
3. Scheduling waved safety test to be done in scheduled shutdown
4. Test procedure used was a multiple markup, unapproved procedure requiring operators to violate procedural rules by turning off all emergency cooling water valves and padlock them so test could be repeated if needed.
5. Controller in Kiev requested postponing shutdown due to extra demand
6. Postponed shutdown caused high buildup of xenon in reactor poisoning it
7. When shutdown began, xenon poisoning caused too rapid shutdown
8. Operators violated procedural rules by removing more control rods than allowed in attempt to overcome xenon poisoning
9. Reactor entered a very unstable low power operating range, procedural rules required immediate shutdown for safety, but manager ordered them not to shutdown so he could do his test, if they wouldn't he would replace them with someone who would
10. As xenon poisoning decayed reactor began to reactivate, very rapidly.
11. One of the operators hit the SCRAM button to stop it, but the control rods oddly enough were designed with a 3 foot tip of graphite moderator which all entering at once spiked the reactor power
12. This surge of power caused a steam explosion in the steam generator tanks which blasted the reactor building roof off
13. Sudden release of Wigner Energy in the already hot graphite and exposure to air ignited the graphite (both fragments blasted out of the reactor by the steam explosion and the graphite remaining in the core)
14. The burning graphite melted the fuel in the core

An RBMK reactor could never have gotten US NRC licensing to even be built here, the design itself violates too many NRC rules.

Answer 3

There is a long and detailed description of this in Wikipedia-see 'Chernobyl disaster', and it seems unecessary to transcribe all this to this answer. The following para is a summary, but I recommend reading the full article.

It should be noted that the Russian RBMK reactor design is very different to PWR and BWR reactors built in the US or Western Europe, and did not have secondary containment or indeed any containment capable of stopping the reactor internals being ejected, which would not be permitted in the US or W Europe. Moreover the training of the night shift who in the end had to carry out the experiment was completely inadequate, and safety systems were bypassed. This indicates the great importance of correct planning and documentation of any unusual operations, and ensuring that the operating crew are well trained for it.

On 26 April 1986 at 1:23:45 a.m., reactor 4 suffered a massive, catastrophic power excursion, resulting in a steam explosion, which tore the top from the reactor, exposed the core and dispersed large amounts of radioactive particulate and gaseous debris, allowing air (oxygen) to contact the super-hot core containing 1,700 tonnes of combustible graphite moderator. The burning graphite moderator increased the emission of radioactive particles. The radioactivity was not contained by any kind of containment vessel (unlike in Western plants, Soviet reactors often did not have them) and radioactive particles were carried by wind across international borders. Although much of the nuclear fuel in the reactor core did ultimately melt, it should be noted that the disaster was not a "nuclear meltdown" in the usual sense; the fuel melting was not a significant contribution to the radiological consequences of the accident, and the accident was not caused by a loss of coolant.

Differing opinion:

The accident was caused by a deliberate loss of coolant, which caused the reactor to go prompt critical, which means that prompt (or immediate) neutrons participated in the ensuing reaction. (In a prompt criticality accident, you do not have the luxury of time on your side.) Unfortunately, the design of the Soviet reactors used graphite instead of water as a moderator, and it had a positive temperature coefficient, which means that loss of the coolant (water) resulted in increased reactivity, as opposed to the normal US design. (Normally, a loss of coolant would force a US reactor to immediately go sub-critical, which did not happen in the Soviet design.) This meant that they had no control over the reaction once it went prompt. The reactor "disassembled" itself from prompt dispersal and the exposure to oxygen ignited the carbon moderator. The only thing stopping it from being a full fledged nuclear detonation was that there was no mechanism in place (thank God) for the core to be held in prompt criticality long enough for true nuclear detonation.

Answer 4

the cause of Chernobyl was that reactor 4 at the power plant had a melt down because the graphite tip caused an increase in radioactivity and effectively had a meltdown

Answer 5

It happened at the station in Chernobyl and how it happened is that the temperature went 23,000 degrees exploded so "Dead Zone" and everyone and everything got radioactive. But the explosion can happen again.

Answer 6

A meltdown. This occurs when the reactor core isn't sufficiently cooled enough. At Chernobyl, a system flaw caused the computers to read that water was circulating through one of the reactor cores, when in fact just the opposite was happening. With no water, the reactor became incredibly hot and eventually breached any protective concrete barriers and casings, hence, melting the reactor core. Explosions of radioactive materials also occurred later, escaping into the air and jet streams, killing hundreds and potentially poisoning hundreds of thousands of Russian citizens for years to come.

Answer 7

the reactor was bad and the clients or workers were porly trained

Answer 8

IN Chernobyl, which is in Southern Russia.

Answer 9

when the reactor over heated from having enofe water it esploded!