The decision means cutting 10% to 15% of Germanys power consumption, using the net power production median of the weakest nuclear powerplants (890 MW) and the median of the overall powerplants (1288 MW)
Update: they named the plants in question
de.wikipedia.org/wiki/Liste_der_Kernreaktoren_in_Deutschland
| Unterweser | KKU |  NI | E.ON | 1.410 | 1.345 |
| Biblis B | KWB B |  HE | RWE | 1.300 | 1.240 | |||||||||
| Biblis A | KWB A | HE | RWE | 1.225 | 1.167 | |||||||||
| Philippsburg 1 | KKP 1 |  BW | EnBW | 926 | 890 | |||||||||
| Isar/Ohu 1 | KKI 1 | .svg&filetimestamp=20080511230206){kind=small} BY | E.ON | 912 | 878 | |||||||||
| Neckarwestheim 1 | GKN 1 | BW | EnBW | 840 | 785 | |||||||||
| Brunsbüttel | KKB |  SH | Vattenfall | 806 | 771 |
These have a net power of 771+785+878+890+1167+1240+1345= 7076 MW or 11.3% of annual consumption.
Update: the last data on power trade balance shows a surplus of 22 TWh
