Prize Bonds are a Government Scheme, guaranteed by the State. Why are you so scared ? All and sundry are listening to Media reports about Ireland. Today the ECB clearly stated that they would stand by Ireland, so IMO this mans they are not going to let Ireland go bankrupt or anything like it, in the case it might happen.
If I was you OP, I would be more worried of your chances of winning a prize in the Prize Bonds which is a dead duck. I would say your money is safe but not against inflation.