Reactor (over)correcting itself and causing a meltdown on every round start despite automatic control being set to Manual

[cl0ck-byte]

Disclaimers

• I have searched the issue tracker to check if the issue has already been reported.
• My issue happened while using mods.

What happened?

Before I started the next round in Campaign gamemode, I set the reactor's automatic control mode to be on Manual and set both Fission rate and Turbine output to be at 0 while being docked to an Outpost.

On these screenshots I am not operating the reactor. The reactor itself behaves like if it was set to Automatic for 5 seconds, hence why it can't handle 4 Fuel Rods at the same time, resulting in a meltdown. Happens every round start - on undocking and docking to the Outpost.

Definitely related to the 2024 Winter update's Overvoltage prevention fix:

3db0da2454: Measures to prevent overvoltage from damaging the sub at the start of a round. The load on the electrical grid often changes between rounds (due to e.g. engines resetting to 0, and the sub receiving power through an outpost's docking port), and the reactor may not react to the changes fast enough. Now the reactor does rapid automatic adjustments in the first 5 seconds of the round (unless it's being operated by a player), and overvoltage doesn't damage devices during those 5 seconds. #15135

Barotrauma/Barotrauma/BarotraumaShared/SharedSource/Items/Components/Machines/Reactor.cs

Lines 250 to 255 in 8f0d89a

	//rapidly adjust the reactor in the first few seconds of the round to prevent overvoltages if the load changed between rounds
	//(unless the reactor is being operated by a player)
	if (GameMain.GameSession is { RoundDuration: <5 } && lastUser is not { IsPlayer: true })
	{
	UpdateAutoTemp(100.0f, (float)(Timing.Step * 10.0f));
	}

What's worse - the reactor overrides circuits with its reaction speed despite being set on Manual during these 5 seconds. It might not be much, but it's enough to cause a meltdown with publicly available control circuits, not to mention the excess overvoltage burning junction boxes.

Reproduction steps

1. Start a campaign with a Dugong (or any other submarine)
2. Set reactor's automatic controller to Manual mode
3. Get one Memory Component, place it and set the value of it to 0, then wire SIGNAL_OUT of Memory Component to reactor's SET_FISSIONRATE and SET_TURBINERATE pins
4. Fill the reactor with 4 Fuel Rods (the type does not matter) and start it
5. Dock to an Outpost or undock from it
6. The reactor is operating by itself, ignoring the values of SET_FISSIONRATE and SET_TURBINERATE, causing a meltdown shortly afterwards

Bug prevalence

Happens every time I play

Single player or multiplayer?

Happens in both single player and multiplayer

-

No response

Version

v1.7.7.0 (Winter Update)

-

No response

Which operating system did you encounter this bug on?

Windows

Relevant error messages and crash reports

No response

[cl0ck-byte]

Before anyone mentions that #15362 exists - it is a suggestion (or at least the category says so) and doesn't research the issue deep enough.

Irrevelant now since it's gone

[Ydrec]

TLDR: At round start reactor always goes into automatic mode regardless if it was in manual or receives 0 0 on control inputs.

This causes problem with 3/4 rod setups using custom ARC as auto can't handle it and instantly overheats reactor with roundstart buff

[cl0ck-byte]

Auto can handle 4 rods just fine but only if the temperature and load is stabilized, otherwise yes - it will cause a meltdown.

[cl0ck-byte]

Oh and additional bug related to this one, just visual - despite sliders being at 0, you can still move the spindles to the left.

And the proposed solution would be to check for autoTemp if it's enabled
and if it is, then check for any input on SET_FISSIONRATE / SET_TURBINERATE (this one could be omitted, but circuit control/Automatic can control the reactor at the same time)

while removing the need of checking if it's a player, since you can't control the reactor if it's set to Automatic.

Edit: For the time being, have this dirty patch that effectively disables the Winter Update fix whenever Automatic is turned off here

[pavel4win]

I can add that the reactor is now turned on for 5 seconds at the beginning of any round even if the reactor was turned off at the end of the round. And reactor uses up small amount of rods.

[cl0ck-byte]

Still relevant on 1.9.8.0 anyway

[Regalis11]

Thank you for the report! I finally got around to taking a proper look at this (sorry for taking so long!). I couldn't find a way to get the reactor to meltdown or cause overvoltages in the provided save - the automatic control seems to have no trouble keeping the output below the load and preventing overheating:

And after the 5 seconds passes, it seems to immediately power down due to the signals sent by the memory components. It takes 2 minutes for the reactor to melt down, so I don't see how it could happen during those 5 seconds it's on autocontrol.

I do still agree there's an issue here we need to address (perhaps it could be enough to disable this behavior when the reactor is being controlled by some kind of a circuit?), but I feel like I'm probably missing something since I couldn't find a way to make the reactor melt down using the suggested steps. :/

[cl0ck-byte]

Anyway the memory example was only to show how it can overpower the circuit control. Try not wiring up anything and the reactor will operate by itself with buggy UI showing 0 fission/0 turbine on sliders. If it's powered off before level change, it will just wind down but if it was powered up then it'd most likely never wind down and cause a meltdown.

A small note: It will stop operating by itself whenever player intervenes, otherwise it will keep doing whatever it wants.

For circuits, mostly the ones that just use 100 turbine rate and operate on fission have this issue. It's either the reactor threatening to blow up or burnt up junction boxes at the start of the round.

In general vanilla Automatic is pretty bad especially if the load is low or if total sum of heat potential is too high for it to handle. It's not fuel efficient nor it is smart enough to not implode with high heat potential.

There is a common misconception among newer players that vanilla reactor controll cannot handle 4 stock uranium rods at the same time, but that's mostly due to reactor not being able to stabilize by itself (it will overshoot/undershoot due to slower reaction rate) and will most likely cause a meltdown. For high heat potential rods like Volatile Fulgurium yes, it is the case despite full manual stabilization, but otherwise no. New players also tend to use the temperature regulator buttons on the right which doesn't do much besides destabilizing the reactor even more while trying to quench the temperature.

And let's not forget how the UI is misleading with the fission rate if your rods can satisfy the heat potential of the reactor. Or how can someone mess up the reactor if they're walking around since you can operate it with WSAD controls.

[cl0ck-byte]

I've also seen your commit which seems like a huge win from my side. Hopefully it will fix the issue once it rolls out on Unstable.

[Regalis11]

This has now been addressed in our private repo: this autocontrol logic no longer runs at the start of the round if the reactor is controlled by signals or on manual. Fix coming up in a future unstable build and update!

[pavel4win]

let be reactor turned off at start of round if reactor was off at end of round. Please.
"controlled by signals" is addressed both to "turbine" and "fusion rate".
If at least one of them is controlled by the circuit, I mean.
I would be very grateful.

[pavel4win]

I don't think the vanilla reactor automation needs improving, because if everything works perfectly, we'll have nothing to play.
Let the newbies suffer. When I was young, I even blew up a submarine, ruining a round.
That gave me incentive to improve.
But the reactor's automatic activation at the start of a round needs to be fixed.

[Regalis11]

As mentioned above, we've implemented a fix for this in our private repo, should be coming up in an unstable build soon! And to clarify, how we've changed it is that the "automatic correction" at the start of the round doesn't run if the reactor is off, being operated manually or controlled by signals.

I'm sorry for the inconvenience!