Is there any evidence that Iran is an irrational actor? My limited understanding of history is that anything "irrational" is better explained by "blowback". Give me some reasons why they wouldn't make a good member of the mutual destruction club.
All things considered I'd say Iran is a pretty rational actor. Conservative, pragmatic, and interested in preserving their regime above all else. The ayatollahs are religious fanatics, but they're not suicidal. With regards to the nuclear power issue, they are signed to the NPT and have in the past allowed inspectors at their facilities. Between inspections and intelligence gathering, it has been pretty convincingly determined that they're not working on a bomb, but are looking to move forward on power generation.
Despite all the apocalyptic rhetoric from Israel and some really stupid American Senators, they're still willing to sit down at the negotiating table and engage in give and take over what for most other countries would be a non-issue: Nuclear power generation.
As for the oft-repeated claim that they're just stalling in order to advance their nefarious plans to build a bomb and nuke Israel out of existence? That's a charge that has been made against Iran since Disco was still a thing. Either they're really, really, really good at putting things off, or they're not actually that dedicated to building a nuclear weapon.
Now, this doesn't mean everything is unicorns and rainbows. The Iranian regime is still repressive, still supports Hezbollah and Hamas, and the Iranian people would be much better off if the Ayatollahs sailed off into the sunset but that's not going to happen anytime soon. 35 years of sanctions haven't dislodged them, so maybe it is time for a new approach.