Related Rule
Germany
Practice Relating to Rule 42. Works and Installations Containing Dangerous Forces
Germany’s Military Manual (1992) states:
464. Works and installations containing dangerous forces, namely dams, dykes, and nuclear electrical generating stations, shall not be made the object of attack, even where these objects are military objectives, if such attack may cause the release of dangerous forces and consequent severe losses among the civilian population.
465. This protection shall cease if these works are used in regular, significant and direct support of military operations and such attack shall be the only feasible way to terminate such use. This shall also apply to other military objectives located at or in the vicinity of these works and installations.
466. Regular, significant and direct support of military operations comprises, for instance, the manufacture of weapons, ammunition and defence materiel. The mere possibility of use by armed forces is not subject to these provisions.
467. The decision to launch an attack shall be taken on the basis of all information available at the time of action.
469. The parties to the conflict shall remain obliged to take all precautions to protect dangerous works from the effects of attack (e.g. shutting down nuclear electrical generating stations). 
Germany, Humanitarian Law in Armed Conflicts – Manual, DSK VV207320067, edited by The Federal Ministry of Defence of the Federal Republic of Germany, VR II 3, August 1992, English translation of ZDv 15/2, Humanitäres Völkerrecht in bewaffneten KonfliktenHandbuch, August 1992, §§ 464–467 and 469.
The manual further provides that grave breaches of IHL are in particular “launching an attack against works or installations containing dangerous forces (dams, dykes and nuclear electrical generating stations), expecting that such attack will cause excessive loss of life, injury to civilians or damage to civilian objects”. 
Germany, Humanitarian Law in Armed Conflicts – Manual, DSK VV207320067, edited by The Federal Ministry of Defence of the Federal Republic of Germany, VR II 3, August 1992, English translation of ZDv 15/2, Humanitäres Völkerrecht in bewaffneten KonfliktenHandbuch, August 1992, § 1209.
Germany’s Soldiers’ Manual (2006) states: “Works and installations containing dangerous forces (dams, dykes, nuclear electrical generating stations) may, as a matter of principle, not be attacked.” 
Germany, Druckschrift Einsatz Nr. 03, Humanitäres Völkerrecht in bewaffneten Konflikten – Grundsätze, Erarbeitet nach ZDv 15/2, Humanitäres Völkerrecht in bewaffneten Konflikten – Handbuch, DSK SF009320187, Bundesministerium der Verteidigung, R II 3, August 2006, p. 5.
Germany’s Law Introducing the International Crimes Code (2002) provides for the punishment of anyone who, “in connection with an international armed conflict or with an armed conflict not of an international character, … directs an attack by military means against … works and installations containing dangerous forces”. 
Germany, Law Introducing the International Crimes Code, 2002, Article 1, § 11(1)(2).
In 1981, in reply to a question in Parliament on the legal status of nuclear power plants, the German Government stated that these plants were only used for peaceful purposes in Germany and therefore enjoyed the status of civilian objects and were protected as such. The government stated that this protection was underlined in Article 56 of the 1977 Additional Protocol I. 
Germany, Lower House of Parliament, Answer by the government to a written question, BT-Drucksache 9/327, 10 April 1981, p. 3.
The Report on the Practice of Germany states:
Official correspondence among the responsible ministries reveals that nuclear power plants are seen to be protected under customary international law, insofar as:
–nuclear power plants are civilian objects
–no party to an armed conflict has an unlimited right in its choice of means of warfare
–every attack has to be seen in the light of the proportionality principle and this principle also has to be applied in cases where the nuclear power plant is used for military purposes. 
Report on the Practice of Germany, 1997, Chapter 1.9 (source not quoted).
Germany’s Military Manual (1992) states: “Military objectives shall not be located in the vicinity of works and installations containing dangerous forces unless it is necessary for the defence of these works.” 
Germany, Humanitarian Law in Armed Conflicts – Manual, DSK VV207320067, edited by The Federal Ministry of Defence of the Federal Republic of Germany, VR II 3, August 1992, English translation of ZDv 15/2, Humanitäres Völkerrecht in bewaffneten KonfliktenHandbuch, August 1992, § 468.
In 1983, questions were raised in the German Parliament concerning the planned construction of an ammunition depot 7 kilometres from a nuclear power plant. The government responded that these plants were granted the status of civilian objects under international law and were to be protected as such. The distance between the depot and the plant was construed as being in compliance with international law. 
Germany, Lower House of Parliament, Answer by the government to a written question, BT-Drucksache 10/101, 27 May 1983, p. 14.