Upvote:7
You can enter any EU/EEA member country as long as you can prove your nationality by any means, according to Wikipedia:
Strictly speaking, it is not necessary for an EEA or Swiss citizen to possess a valid national identity card or passport to enjoy the right of free movement. In theory, if an EEA or Swiss citizen can prove his/her nationality by any other means (e.g. by presenting an expired national identity card or passport, or a citizenship certificate) he/she must be permitted to enter and reside in the EEA and Switzerland without a visa.
As you can see, as long as you can prove your nationaly by any means then you can travel to any EU/EEA country. Of course presenting a valid passport or national ID card should make things easier but any other document would work as well.