> Germany's main source of heating is gas and yes, gas is used to generate electricity, so nuclear can reduce gas consumption. However, only about 10% of gas is used for electricity and Germany has enough electricity. In a worst-case scenario, those nuclear power plants can help stabilize the grid, but they are not needed in general.
A number of cities also use district heating, where the heat is taken directly from the cooling circuits of nearby power stations. No idea what percentage of total heating this is and if nuclear plants are involved here, but this would be another way how those plants could (theoretically) contribute to heating.
I usually belong to the anti-nuclear crowd, but even I don't think that would be an issue.
From what I know, one of the iron rules of nuclear plant design is that the contaminated stuff never leaves the reactor building. Even the steam circuit that powers the generator is separated from the (contaminated) primary circuit and receives energy through a heat exchanger [1].
The lines for district heating would probably be separated from the primary circuit by several of those.
A number of cities also use district heating, where the heat is taken directly from the cooling circuits of nearby power stations. No idea what percentage of total heating this is and if nuclear plants are involved here, but this would be another way how those plants could (theoretically) contribute to heating.