You can either follow the Exploiter Orb around Fortuna which will passively spawn in more Coolant Raknoids, or play through the Exploiter Orb quest.
If you want to farm the roaming Exploiter orb, I would probably try using Ivara and using Prowl to loot. Take a Chesa Kubrow with you for a chance to get some extra drops on death (you can try the new Elusive Posture mod for Claws to keep it from running off) and you can also stack on Petrify with the Ore Gaze Augment for an extra shot at getting drops. You can find her doing laps in the north around the Tower of Profit.
If you’re trying to farm her in the Exploiter Orb quest, Nekros with the Ripkas and their Almalgam Ripkas True Steel mod. You can also try Ore Gaze on Nekros too, enemies dying while petrified replaces the need for Amalgam Ripkas True Steel, and the Chesa Kubrow does not stack with Desecrate. You can put on Shattering impact to armor strip the Exploiter Orb for a bit more damage during the damage phase if you really want to. If you plan on completing the quest, stockpile (4-5 extra canisters) some charged Thermia Canisters before entering the final phase. She bugs out and rarely opens fissures unless she starts to overheat a little. If you don’t care about actually finishing the quest then you don’t need a stockpile of canisters for the final phase.
Qorvex’s +3m of punch through is nice to have if you’re using non AOE weapons/innate punch through, typically these mods have a fairly high capacity drain making them harder to slot on some builds.
Chyrinka Pillar is okay at providing some minor CC around points/objectives but enemies with Overguard really hurts its effectiveness by preventing the enemies from being CC’d, and enemies with Overguard seem to be becoming more common with newer updates.
Containment Wall works well in hallways and groups enemies into a line making his passive more effective assuming you’re making use of punch through. The enemies are also Rad proc’d so they typically keep attacking each other in a large group rather than spreading out afterwards.
Disometric Guard is great to have on Radiation based sorties to prevent your teammates from killing each other or the objective. Also good to have against lichs/sisters that can inflict Radiation status, and a lot of tenet weapons have Radiation as base part of their base damage.
Crucible Blast is basically Sol Gate but with more base damage.
With his damaging abilities being Radiation, he’s not very effective in most missions. It’s probably a worse damage/status type since the update to simplify damage. Sentients are rare in most content and the Murmur are the only other faction it’s strong against. This is also the tileset where you commonly get modifiers like enemies with Overguard when playing Deep Archimedean missions diminishing the effectiveness Radiation’s friendly fire.