With the release of Plutonium Energy 1.2.12, Pu-238, Pu-239 and used up MOX fuel can be incinerated.

Thank you! I have added information about your mod, and update the FAQ recipe table too.

I have a technical question though.
From what I read from your code, you have used shorter time mutlipliers (0.5 or 0.75), and relatively lower emissions multipliers.
A/ Firstly, time multiplier of 0.5 are suggesting that they use only half the heat to boil them from room temperature. I do not have molar heat capacity and heat of vaporization of plutonium from scientific source, so I cannot say your values are correct or not. English Wiki pages (U and Pu) values are suggesting they are surprising very close. I used a formula:

Total energy = Heat of fusion + Molar heat capacity × Temperature difference + Heat of vaporization

For Uranium, E_U = 9.14 + 27.665/1000 × (4404-293) + 417.1 = 540 kJ/mol
For Plutonium, E_Pu = 2.82 + 35.5/1000 × (3505-293) + 333.5 = 450 kJ/mol
So it is correct that Plutonium uses less energy than Uranium, but the ratio is 0.83, not so extremely low as 0.5.
Maybe if you have better source for values and formula. I could be wrong though.

B/ The overall amount of pollution released is scaled with Time multiplier × Emissions multiplier. My general impression (could be wrong though) is plutonium is much more radioactive and toxic than uranium. Your values are rather low, especially when compared to my uranium-239 and used-up-uranium-fuel-cell... So are plutonium actually less radioactive and less toxic than uranium?

Please consider revising the values. Let me know if my above analysis are wrong.

PS1:
I have just released Schall Radioactive Waste 0.17.3 / 0.18.3 / 1.0.1 / 1.1.1. Now allows adding "radioactive contamination effects" to nuclear projectiles. You may apply such effects to your plutonium projectiles as well.
I have added relevant instructions in FAQ, so please see if you are interested to add such support.

PS2:
Because of PS1 and testing with it, I have found a bug in your Plutonium Energy code.
Your line 36:

sc_plutonium_aa_sh.projectile = 'Schall-plutonium-atomic-artillery-projectile'

is doing nothing, because it has a wrong path. (You can look into my ammo.lua for verification. Vanilla ammo also has such path.)
The correct line should be:

sc_plutonium_aa_sh.ammo_type.action.action_delivery.projectile = 'Schall-plutonium-atomic-artillery-projectile'

Your other ammo (lines 11, 21) are likely suffering from the same problem too.
As a result of such bugs, your artillery shells simply are still using their original (uranium) projectiles.

Thanks for all the info. For the time multiplier, I simply compared melting points. Yeah, this is wrong... I'll update multipliers. Also I didn't know that total emission is also scaled with time multiplier, good to know.

Welcome. Let me know when you have an update, so I can update my FAQ table as well.

Yea, just imagine the incineration process is just like recipes for ordinary products, with emissions are like from assemblers/furnaces.
Time multiplier determines the recipe time (production duration). Emissions multiplier affects the pollution emissions from the assembler/furnace (like how productivity and speed modules increase pollution multiplier). Hence the pollution generated by a machine (say, assembling machine 3) is Recipe time × Base emission of AM3 × Emissions multiplier (from modules or recipe) for each production cycle. So entirely not new creation, but merely like ordinary recipes.

Alright, 1.2.13 is uploaded, it now has different multipliers (2.1 & 0.9 for used up MOX fuel and 2.35 & 0.85 for Pu-23[89]) and also radiactive effects (84, 2.8, 70; basically 1.4 x defaults).

And again thanks for pointing out at bugs.

Thank you.
The new values look much more reasonable now, although still lower than my uranium-235 and used-up-uranium-fuel-cell values.
But I know it can be a formidable thing to tune, if having to balance between recipe ratios and IRL physical properties. So take your time, no rush.
Also I have updated my FAQ tables, you may check them out too.

Oh, now I see. I've tweaked the values even more in 1.2.14 now, so they should be much more reasonable.

Wow, you are quick. This looks even better now.
Tables updated.