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The Chernobyl reactor was designed to produce a maximum of 3.2 megawatts of power. It is now estimated to have produced 3.2 gigawatts of power in the final second of its life.

The original hypothesis is that the the explosions at Chernobyl were either steam/steam or steam/hydrogen explosions.

A new hypothesis is that the first explosion was actually a small nuclear detonation of the runaway fissioning. The total energy released in the first blast was 320 gigawatt thermal.

This new hypothesis is based on observations from witnesses who were nearby and saw the explosions. The first explosion turned the air blue from fluorescence of excited oxygen and nitrogen atoms in the air.

Is there a way to determine how powerful the explosion was? Also is it possible this was a quasi atomic explosion due to runaway fissioning?

The paper I am reading is linked below.

https://www.tandfonline.com/doi/full/10.1080/00295450.2017.1384269

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    $\begingroup$ The Chernobyl reactor was designed to produce a maximum of 3.2 megawatts of power. This seems much too low. $\endgroup$ – G. Smith Sep 15 at 4:40
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    $\begingroup$ The total energy released in the first blast was 320 gigawatt thermal. Energy is not measured in watts. $\endgroup$ – G. Smith Sep 15 at 4:41
  • $\begingroup$ @G.Smith - you are right. I apologize. It was designed to produce 3200 MWth and 1000 MWe $\endgroup$ – Rick Sep 15 at 12:34
  • $\begingroup$ @Rick So you say the reactor has been designed to operate 3.2 hours. The units are MW ( megawatt, power ) and MWh ( megawatthour, energy, the power of 1 MW in duration of 1 hour ) $\endgroup$ – Poutnik Sep 18 at 2:07
  • $\begingroup$ @Poutnik - Where do you see in the above that I said it was designed to run for 3.2 hours? My mistake was under reporting the power output of the reactor not in its units of measure. According to estimates it was designed to run at 3200 megwatt therm...not 3.2. Please stop trying to nitpick everything I write and help me understand what the difference is between a runaway and uncontrolled fission process in a reactor and a small atomic detonation.... both are self sustaining chain reactions leading to an explosion. $\endgroup$ – Rick Sep 19 at 12:53
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Nuclear reactors have too low uranium enrichment to be capable of nuclear explosion, not even a detonation(explosion with supersonic velocity of propagation).

But the thermal power of uncontrolled fission may lead to mechanical explosion by pressurised gas or water vapour, or there can occur secondary chemical explosion by ignition of developed and escaped hydrogen.

RBMK-1000 reactor, used in Chernobyl, had nominal power 1000 MW. There were/are in use also RBMK-1500 and some designs were projected up to 2400 MW.

Explosion can be defined as very fast energy release, with extremely high power and very short time duration, with sharp begin and end.

Detonation is explosion propagating in exploding material by speed exceeding speed of sound in material. Additionally, explosion is not matter of total released energy but matter of way how it is released.

Nuclear detonation of fissionable material requires for this material to sustain runaway chain reaction of fast (x MeV ) neutrons.

2-3% 235U, additionally with fission products absorbing neutrons, scattered in small pieces across the big volume, cannot nuclearly detonate.

If it could, the detonation would not be small, but huge, temperature would reach some 100 millions K instead of few thousands and all power plant and close neighborhood would evaporate.

TNT explosive energy ( about 10% of coal energy ) is approx 4.2 MJ / kg. 3.2 GW of thermal power is equivalent cca 760 kg TNT/s. Equivalent of 75 ton TNT is released during less than 2 minutes of nominal reactor function.

Overheating of pressured casserole, just little bigger and dramatic for lifes of too many people.

That means, if the power of energy being released is just in range of few multiples of nominal power, being increased gradually and continually, it can hardly be consider as a nuclear explosion.

OTOH, the sudden reactor break can be, but as a mechanical explosion, even if based on originally nuclear energy.

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  • $\begingroup$ At what point is a runaway fission process = small atomic detonation. I believe the estimate was 75 tons of TNT for the main blast..... Could steam alone account for such an energetic explosion. Please remember that the reactor had only about a 1/3 the water in it that it was supposed to have due to the pumps shutting down and a lot had already flashed to steam.... $\endgroup$ – Rick Sep 15 at 12:31
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    $\begingroup$ Detonation is explosion propagating in exploding material by speed exceeding speed of sound in material. Additionally, explosion is not matter of total released energy but matter of way how it is released. If there exploded equivalent to 75 kt TNT, there would be no reactor to cover and spreading of radioactivity would my much worse. $\endgroup$ – Poutnik Sep 15 at 12:34
  • $\begingroup$ Not 75 kT - just 75 tons. $\endgroup$ – Rick Sep 15 at 12:39
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    $\begingroup$ Nuclear explosion equivalent to 75 ton TNT is not possible even for pure 235U, not speaking of enriched uranium with just max 3% of fissibke 235U. $\endgroup$ – Poutnik Sep 15 at 12:43
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    $\begingroup$ But W54 did not use 235U. It's critical mas is 52 kg, in the most efficient spherical shape. W54 mass of the while package was less than half of that. Difference ? Huge. 2-3% 235U, additionally with fission products absorbing neutrons, scattered in small pieces across the big volume, cannot nuclearly detonate. Full stop. If it could, the detonation would not be small, but huge, all power plant and close neighborhood would evaporate. $\endgroup$ – Poutnik Sep 15 at 23:39

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