you cant put a dst / squall with heavy water or isotopes in a rorqual
which does not make sense cause of you can put stront for dreads and other modules and charges in there
maybe time to change this heavy water is only usefull if you are boosting so has nothing to do with a combat rorq
there was a topic about this in 2018
[Proposal] Add heavy water and isotopes to charge list for storage - Council Of Stellar Management / Assembly Hall - EVE Online Forums