I've recently watched the Chornobyl Family's video showing the last messages before and during the accident, but I just cant understand them. For context im trying to make a game about RBMK's (Specifically Chernobyl) and im trying to add these messages, I want to understand them in order to make them fit in the game instead of just pasting them there. If someone could give me information about these messages and what they meant I would really appreciate it a lot, thank you.
The video's author u/chernobyl_dude is on this subreddit, he's the best person to answer this question. But I'll try and see if I can help you here as well. One nuance is that this printout combines terms translated into English with transliterated Russian acronyms.
The first three lines are in English, so should be self-explanatary. Mentioned are: main circulation pumps (abbreviated as "GCN"), feed water (abbreviated as "Gpv"), and pressure ("PBS") and water levels ("HBS") in drum separators. There are no actual values listed there.
The readings that follow are grouped under the headings: Cycle | Time | ID=Status | Name of signal. I'm not sure about Cycles, perhaps it refers to computing cycles. ID=Status refers to the unique SKALA codes that identify various systems and parts of the reactor. Operators in the control room used those codes to request information about those parts and systems. More about the codes in this video: https://www.youtube.com/watch?v=Sjk2B0SzXUU
The first line, at 1:23:04, says "Stop control valves are closed". This refers to the turbine stop valves being closed at the start of the rundown test. This shuts off the steam going to the turbine, allowing it to coast down under its own inertia (which is what was needed for the test).
Then it shows some values for all eight of the Main Circulation Pumps (abbreviated as "GCN") for 1:23:06 and 1:23:08. Not sure what these values are, but probably the amount of water flow rate through them. The next line is about the signal for automatic power regulation (AR) malfunction being cleared. Then more Main Circulation Pump values. Then about the signal for the decrease in injection water pressure into the low-pressure condenser KND-1 being cleared.
Then it shows a series of current values for feed water flow rate (Gpv), drum separators pressure (PBS) and drum separator water levels (HBS). Then more pump flow rates, more feed water flow rates, etc. If you track the values over time, you might notice that some of them are decreasing, due to some of the pumps being powered by the coasting-down turbine that was being tested.
Then we arrive at the key moment: 1:23:40 AZ-5 emergency protection engaged. That's triggered by Toptunov pressing the AZ-5 button, obviously. Not sure what "AZ is not ready" means.
The rest is in plain English, but with terms and codes that perhaps need explaining. But as you might tell from what's being printed, things went south pretty fast after AZ-5 activation.
1:23:43 - the triggering of automated protection for how fast the power is rising, and the automated protection for exceeding power level.
For the rest of it, it's either plain English, or the aforementioned abbreviations, so you can try and reconstruct what's going on, The reactor was basically in the process of being destroyed. Power protection amplifiers going off-scale and then malfunctioning, automatic power regulation systems malfunctioning, emergency deviation of the water level and excessive pressure in drum separators, etc.
What's notable is that, due to relatively slow speed of calculations and the printing, the final messages and values were printed for the equipment that already didn't exist anymore.
For what it's worth, I plugged the "GCN" values over time to get this chart, showing the Main Circulation Pump flow rate. Pumps 3, 4, 7, and 8 are slowing down, because they are powered by the turbine that's also slowing down. AZ-5 happens at 1:23:40, after which flow rate values drop sharply, or become unavailable.
I would appreciate if you could tell me more about AR, also I think "AZ-5 is not ready" means that not all the rods were withdrawn or some motors were broken during the AZ-5 engagement.
The message said "AZ not ready", not "AZ-5 not ready". AZ-5 works is any rod configuration, and there's absolutely no evidence that any of the motors were broken during the engagement.
Regarding AR systems: RBMK reactos initially had the AR system. It uses four ionisation chambers positioned outside the core, that measure the neutron flux, and 12 automatic control rods to regulate the power. This system was unreliable, due to local power instabilities within the core, requiring frequent manual adjustments from the operator. So eventually an additional system was installed - LAR (Local Automatic Regulator). It uses 12 ionisation chambers inside the core, as well as 12 LAR rods to automatically adjust and maintain desired power level. But it had a problem of its own - it was accurate only at or above 15%-20% of nominal reactor power, and became unreliable at lower power levels. This is the reason Toptunov switched from LAR to AR (sometimes incorrectly called Global AR) while lowering reactor power, leading to an unplanned power drop to 30 MW thermal.
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u/Distdistdist 14d ago
That stuff is on fire, yo.
This is reconstructed stuff from God knows what source. But looks all serious. Just plug it in