Deflagration Calculations For Reactors?

HQ has suggested that this be our default basis for our calculations and recommends 12" rupture discs for all tanks and reactors even though we frequently would use a 2" disc unless we have a gas generation reaction.

Does anyone else use this as a basis? We normally take credit for our nitrogen purge systems, lack of an ignition source and procedures and declare this to not be a credible relief scenario.

If anyone is doing this, what calculation method do you use?

Thanks for any suggestions!