The positive void coefficient was directly responsible for the disaster: During low power operations the effect caused water vapour bubbles to be created in the reactor. Because of the lower density of the vapour the moderation of the reaction did no longer work and the reactor spiraled out of control. All the while there was no feedback to the control room about the increased reactivity, so the personal had no chance to assess the situation correctly. This lead to the uncontrolled chain reaction and the explosion of block 4.
After a while Nikolai Steinberg conducted an experiment in the other blocks of Chernobyl which showed that the positive void coefficient was causing the reactor to spiral out of control in low energy production scenarios.
That’s not right. The experiment was conducted after the explosion in an effort to prove Nikolai Steinberg’s suspicion that the positive void coefficient caused the disaster. The experiment was a success and Steinberg’s suspicions have been verified.
On 25 April, prior to a routine shutdown, the reactor crew at Chernobyl 4 began preparing for a test to determine how long turbines would spin and supply power to the main circulating pumps following a loss of main electrical power supply. This test had been carried out at Chernobyl the previous year, but the power from the turbine ran down too rapidly, so new voltage regulator designs were to be tested.
Exactly and during that test the positive void coefficient caused the reactor to spiral out of control with no feedback to the control room, as detailed in the earlier post.
The question is how you conduct the tests, and of course we have learned a lot since that time. Modern reactors incorporate these lessons making them much safer.
What caused the accident?
The positive void coefficient was directly responsible for the disaster: During low power operations the effect caused water vapour bubbles to be created in the reactor. Because of the lower density of the vapour the moderation of the reaction did no longer work and the reactor spiraled out of control. All the while there was no feedback to the control room about the increased reactivity, so the personal had no chance to assess the situation correctly. This lead to the uncontrolled chain reaction and the explosion of block 4.
After a while Nikolai Steinberg conducted an experiment in the other blocks of Chernobyl which showed that the positive void coefficient was causing the reactor to spiral out of control in low energy production scenarios.
Sources:
https://www.oecd-nea.org/jcms/pl_28271/chernobyl-chapter-i-the-site-and-accident-sequence
There’s a really good documentary about that, but alas it’s in German: https://www.zdf.de/dokumentation/zdfinfo-doku/tschernobyl-die-katastrophe-paradies-100.html
Nikolai Steinberg also coauthored a book about the accident: https://www.perlego.com/book/3418623/chernobyl-past-present-and-future-pdf
To sum up, there was an experiment conducted that caused the disaster, as opposed to it being a result of normal operation of the reactor.
That’s not right. The experiment was conducted after the explosion in an effort to prove Nikolai Steinberg’s suspicion that the positive void coefficient caused the disaster. The experiment was a success and Steinberg’s suspicions have been verified.
This is what caused the disaster
https://world-nuclear.org/information-library/safety-and-security/safety-of-plants/chernobyl-accident.aspx
Exactly and during that test the positive void coefficient caused the reactor to spiral out of control with no feedback to the control room, as detailed in the earlier post.
Here’s a paper about that: https://hal.science/hal-03117177/document
Even the nuclear power lobby organisation World Nuclear Association acknowledges that this is a massive design flaw: https://world-nuclear.org/information-library/nuclear-fuel-cycle/nuclear-power-reactors/appendices/rbmk-reactors.aspx
Right, it was a test that was conducted as opposed to normal operation of the reactor itself.
Tests will always have to be conducted to ensure normal operation. That’s nothing out of the ordinary.
The question is how you conduct the tests, and of course we have learned a lot since that time. Modern reactors incorporate these lessons making them much safer.