Seems mod is still not working properly. Even without filtering it making ~80-90% of bad radiation on random. Radiation blocker is not working at all.

it doesn't really matter - even with high radiation there are only a few burns, and the advantages of permanent mutations far outweigh the possible (mostly temporary) damage

It is a math problem. When using the Intermediate Irradiator a single one will output per second: 0.75 burn, 0.16 normal and 0.02 rare radiation.
So what you want to do is get as much rare radiation as possible.
To do this you have 2 filtertypes: filter for burn and other radiation as well as the filter for normal radiation.
If you put in a single filter for rare radiation the multiplier of 0 to rare radiation will eleminate all the rare radiation, so don't use them to get good mutations at all.

My setup uses 6 intermediate irradiators shooting into a radiation extender which passes it through 4 filters and then into the next radiation extender, and so forth until the end, while having a single advanced radiation blocker just before the chamber.
On my setup I have decreased the normal radiation 7 times by 40%,
17 times the burn radiation by 40% and all other radiations by 20%,
and to get the resulting extremely low amount of radiation back up to a number that has effects in time I doubled all radiation up 8 times.
The results lead to 20% burn radiation, 14 % normal and 65% rare radiation being measured by the radiation monitor.
On tests I had a few more doubled up radiation filters but I disabled them because it was going too fast and mutations started to spread far too quickly, bad results were being added to body parts with good mutations destroying the use of the body part for me.

I am not sure how low rounded numbers can go in rimworld, technically you should be able to get it down so low that it is either considered 0 or creates an overflow, but I was quite happy with my setup so I did not go further into it to try out how far I have to go down on the numbers until the doubling up of radiation won't increase burn or normal radiation anymore.

EDIT:
Further Testing...
Setup is 6 Intermediate Irradiators into radiation extender, 2 Filter Burn, 1 Filter Normal, 1 Filter Double, next extender. Repeat until 16 of those 4 Filter combinations have been set, then add 2 more Filter Burn before the chamber.
Make sure there are no other moving things in the chamber when using it otherwise it won't work. (Well technically it still works but all the filtering is getting broken.)
Results: 99% Rare, 0% burn, 0% normal, 100% prisoner abuse.

Is it possible to get a screen shot or something for this set up?

Alright, that actually works. But it does have to be a completely closed room, otherwise the whole system doesn't work. And you cannot have a prison bed in the room. Needs to be only the 16 extender-filter setups.

Originally posted by Bean Boy:

Is it possible to get a screen shot or something for this set up?

Sorry for the late reply, haven't been following the discussion itself.
Here is an example:
https://imgur.com/foSd0Av

If you have Blueprints mod installed you can export a random blueprint, then edit that xml file after the <meta>-information with the code below to get it copy pasted into the game. The filters for sure still need to be configured and sadly can't be configured in bulk.


<Blueprint>
<BuildableThings>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-16, 0, -6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-15, 0, -6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-14, 0, -6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-13, 0, -6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-10, 0, -6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-9, 0, -6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-8, 0, -6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-7, 0, -6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-4, 0, -6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-3, 0, -6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-2, 0, -6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-1, 0, -6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-17, 0, -4)</Position>
<Rotation>2</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-17, 0, -3)</Position>
<Rotation>2</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-17, 0, -2)</Position>
<Rotation>2</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-17, 0, -1)</Position>
<Rotation>2</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-16, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-15, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-14, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-13, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-10, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-9, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-8, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-7, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-4, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-3, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-2, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-1, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(2, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(3, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(4, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(5, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(8, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(9, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(10, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(11, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(14, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(15, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(16, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(17, 0, 0)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(19, 0, 2)</Position>
<Rotation>2</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(19, 0, 3)</Position>
<Rotation>2</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(19, 0, 4)</Position>
<Rotation>2</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(19, 0, 5)</Position>
<Rotation>2</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-14, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-13, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-10, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-9, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-8, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-7, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-4, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-3, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-2, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(-1, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(2, 0, 7)</Position>
<Rotation>1</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(3, 0, 7)</Position>
<Rotation>1</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(4, 0, 7)</Position>
<Rotation>1</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(5, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(8, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(9, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(10, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(11, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(14, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(15, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(16, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyFilter</ThingDef>
<Position>(17, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyExtender</ThingDef>
<Position>(-12, 0, 6)</Position>
</li>
<li>
<ThingDef>RadiologyExtender</ThingDef>
<Position>(-6, 0, 6)</Position>
</li>
<li>
<ThingDef>RadiologyExtender</ThingDef>
<Position>(0, 0, 6)</Position>
</li>
<li>
<ThingDef>RadiologyExtender</ThingDef>
<Position>(6, 0, 6)</Position>
</li>
<li>
<ThingDef>RadiologyMonitorMutation</ThingDef>
<Position>(-19, 0, 9)</Position>
</li>
<li>
<ThingDef>RadiologyMonitor</ThingDef>
<Position>(-17, 0, 9)</Position>
</li>
<li>
<ThingDef>RadiologyRadiationChamber</ThingDef>
<Position>(-18, 0, 6)</Position>
</li>
<li>
<ThingDef>RadiologyExtender</ThingDef>
<Position>(-18, 0, 0)</Position>
</li>
<li>
<ThingDef>RadiologyExtender</ThingDef>
<Position>(-18, 0, -6)</Position>
</li>
<li>
<ThingDef>RadiologyExtender</ThingDef>
<Position>(-12, 0, -6)</Position>
</li>
<li>
<ThingDef>RadiologyExtender</ThingDef>
<Position>(-12, 0, 0)</Position>
</li>
<li>
<ThingDef>RadiologyExtender</ThingDef>
<Position>(-6, 0, 0)</Position>
</li>
<li>
<ThingDef>RadiologyExtender</ThingDef>
<Position>(-6, 0, -6)</Position>
</li>
<li>
<ThingDef>RadiologyIrradiatorIntermediate</ThingDef>
<Position>(0, 0, -8)</Position>
</li>
<li>
<ThingDef>RadiologyIrradiatorIntermediate</ThingDef>
<Position>(1, 0, -8)</Position>
</li>
<li>
<ThingDef>RadiologyExtender</ThingDef>
<Position>(0, 0, -6)</Position>
</li>
<li>
<ThingDef>RadiologyIrradiatorIntermediate</ThingDef>
<Position>(3, 0, -6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyIrradiatorIntermediate</ThingDef>
<Position>(3, 0, -5)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyIrradiatorIntermediate</ThingDef>
<Position>(0, 0, -3)</Position>
<Rotation>2</Rotation>
</li>
<li>
<ThingDef>RadiologyIrradiatorIntermediate</ThingDef>
<Position>(1, 0, -3)</Position>
<Rotation>2</Rotation>
</li>
<li>
<ThingDef>RadiologyExtender</ThingDef>
</li>
<li>
<ThingDef>RadiologyExtender</ThingDef>
<Position>(6, 0, 0)</Position>
</li>
<li>
<ThingDef>RadiologyExtender</ThingDef>
<Position>(12, 0, 0)</Position>
</li>
<li>
<ThingDef>RadiologyExtender</ThingDef>
<Position>(18, 0, 0)</Position>
</li>
<li>
<ThingDef>RadiologyExtender</ThingDef>
<Position>(12, 0, 6)</Position>
</li>
<li>
<ThingDef>RadiologyExtender</ThingDef>
<Position>(18, 0, 6)</Position>
</li>
<li>
<ThingDef>RadiologyBlockerAdvanced</ThingDef>
<Position>(-16, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
<li>
<ThingDef>RadiologyBlockerAdvanced</ThingDef>
<Position>(-15, 0, 6)</Position>
<Rotation>3</Rotation>
</li>
</BuildableThings>
<Name>RadChamber99Rare</Name>
<Size>(39, 18)</Size>
</Blueprint>

A good stock of harvested organs and limbs decreases the chance of permanent damage to your pawns... :D

@Shadowhunter
It appears the filters are right now broken as they do not filter anything for this 1.2 update.

Might be, I have not played with the mod in a long time and the set up was calculated and tested before 1.2.
If the filters don't filter anymore, the mods needs fixing first by the author.
But remember that other things in the rad chamber can also ruin the filtering and really mix things up, so check if there was only the pawn you wanted inside and noone else, including animals.

@Shadowhunter What percentages did you mean here?

> 2 Filter Burn, 1 Filter Normal, 1 Filter Double

Edit: Nvm, guessing all maxed versions

SInce Mr. Samuel Streamer used the mod again in his recent series and mentioned this post, I had a quick look at some of the source code again on github.

And I found out that I might have missed a times 8 multiplier. Not sure how much trouble that one does, but when I calculated that one in, it resulted in 8 more sets of the filters double/burn/burn/normal and an about 7.2 times stronger value on rare radiation.

All values and calculations were done with maxed out research, so if you don't set it to the 40% 20% values but instead use lower ones, you need to increase the amount of filter sets by either double for the lowest setting or 1.5 times for the middle one.
A filterset still consist of Filter Double Filter Burn Filter Burn Filter Normal with extender in between those so the rads can keep flowing past the max distance.

Currently I am copying over my my steam installation from the soon to be dead hdd to a new one, so I can't check if the filters are working in the current version neither if the calculated setup still works or how the new one performs.
When the slow cloning of my defective 4TB HDD is done, probably in a day at current speed cause it says 5hrs left since 8 hrs, I will give it another live test.

EDIT:
I did some testing. The setup still works, it is quite efficient in producing mutations. However you do need to be ready to chop some limbs off and extract some organs.
While rare radiation allows the best mutations to come, it does not mean that you only get those. All other mutations can and will still be applied.

My test setup is still quite powerful, so don't use it on fast speeds if you may want to stop at a mutation, because mutations happen every 1 - 2 seconds, meaning your pawn will probably be full of cancer on fast speed in just a few seconds.
There are some exclusive mutations like crippled leg and super speed which as soon as one of those is there the other will not come.
There are also some mutations like spiked shoulder or green thumb which give a bonus to a skill as soon as the mutation happens, meaning that you can chop off the limb after that and the skill will still have the +8 or +10.
For good mutations I found that battery in the brain is not one of them, while it gives a good boost of 25% to health stats, it will drop down to -25% pretty quick once the pawn is not standing next to a battery anymore.
If you have a mod with a moving battery next to your pawn it might be good.
Another thing not mentioned in tooltips is that cancer gives pain, so if you got all the arms, legs, feet and toes filled with cancer you probably gave your pawn a lot of pain.
Cancer seems to be only coming to those regions, so maybe you can prevent it with another few sets of advanced blockers and selct arms and legs to not get irradiated.
I guess something between 12-16 blockers at the end should give sufficient shielding on those body parts.
If you want slower results or less blockers, you could reduce the amount of advanced irradiators down from my original 6 to a boring normal 1 irradiator, but then mutations take longer and the process might get saver to control, so that's more of a no fun method.

That was my test setup:
https://imgur.com/a/OjV6VIr