I agree with what the others have said.

We have an issue at work where one of our workers continually works through his lunch (despite being told to take the time off) and then he approached us and asked to have it all accrued so that he can take a week off!!!!
I have explained that he MUST take his breaks, it is a health and safety issue to continually work through.

Your DH is quite within his rights to take his break, he should also be allowed to leave the premises if he chooses (so long as he is able to resume his duties 30 minutes after clocking off.) OHS legislation doesnt ACTUALLY say that you must have 30 minutes break, just as it no longer gives weight limits on things that you can lift... it gives recommendations and guides to which must be applied to tasks... this is to safeguard staff in other areas, ie continuous repetitive tasks should not be performed for more than 2 hours without a break - this doesnt mean that you have to have a full break, but just rotate tasks IYKWIM... So he can work through his break, he just has to be paid for it.
His bosses also need to realise that productivity will decrease the longer a staff member workes without a rest - so it would probably be to their advantage for your DH to have a break...

If we ask our staff to work through their break (rarely but occasionally occurs) they leave early and are paid for the time that they work OR they accrue time in lieu (we only put our foot down when staff make their own decisions about working through and then requesting time)

Honestly, how does this boss expect your DH to continue to function without a break throughout the day? Imagine if he was diabetic and needed to eat...
i am assuming the machine must be manned the whole time that it is in operation? what about if he needs to wee???? (this would be a massive issue for me!)

Good luck with it all. It does seem a bit unreasonable to have him working alone and without the ability to have a break.