How do I prevent Player Neither Portals ignition

Hi how would I go about preventing players from igniting their own neither portals? short of removing the flint and tinder.

One of the aspects I want to add to my mod, is for lit neither portals to be primarily generated within my structures. 

I also want to also prevent the player from lighting their own, and/or tie the mechanic to only be enabled after earning an achievement beforehand.

Any help or advice would be greatly appreciated