Leak in radiant system in inaccessible area

hello--Thanks for your help.
I have a radiant heating system in my house. I have had serious problems maintaining heat all season and have made many repairs. I have isolated the problem to a leak in an area of the floor that is completely inaccessible short of jackhammering up my floor. There are supposed to be boiler additives that can seal leaks in a hydronic system but I know nothing about them. Has anyone used them? Do they work? Will they create other problems down the road?
Thanks for your help.