I think the "irareru" you are talking about is the passive/potential form of the verb "iru" （居る）.
"iru" can mean "to be", "to exist", "to have" when it is being used on it's on as the main verb in a sentence and not as an auxilary verb.
So, depending on the context it is be used, "irareru" could mean "could exist", "could be", or "could have".
There are quite a few verbs in Japanese that are read "iru". It's kinda of hard to tell which one you exactly referring to with out seeing it used in a sentence or seeing how it's is written in kanji.
You can eliminate some of these other possible words, just because they are conjugated differently that the "iru" I have mentioned above.
But, there is another "iru" （鋳る） that means "to cast", "to mold" that also has a passive/potential for "irareru". I am going to take a guess after reading the extra information you added that you're not talking about this "iru".
I am not sure but I don't think that 要られる, or 煎られる would be correct. This is because that even though they are both forms of verbs that are read as "iru" （要る and 煎る）, they are conjugated slightly differently from 居る and 鋳る.
When 鋳る and 居る are conjugated into their masu-forms they become 鋳ます("imasu") and 居ます ("imasu") respectively. But, the other two become 要ります ("irimasu") and 煎ります("irimasu").
I'm pretty sure that the potential forms of 要る and 煎る are 要れる ("ireru") and 煎れる ("ireru") and not 要られる ("irareru") and 煎られる("irareru").