Related Rule
Argentina
Practice Relating to Rule 42. Works and Installations Containing Dangerous Forces
Argentina’s Law of War Manual (1989) states:
Works and installations containing dangerous forces (dams, dykes, nuclear stations or nuclear power plants) must not be attacked, even if they are military objectives, if such attack may cause the release of those forces and cause severe losses among the civilian population. Other military objectives located at or in the vicinity of these works must not be attacked either if such an attack may cause the release of those dangerous forces. This protection will only cease if these objects are being used as a regular, significant and direct support to military operations, and if such attack is the only feasible way to terminate such support. 
Argentina, Leyes de Guerra, PC-08-01, Público, Edición 1989, Estado Mayor Conjunto de las Fuerzas Armadas, aprobado por Resolución No. 489/89 del Ministerio de Defensa, 23 April 1990, § 4.04.
The manual qualifies “attacks against works and installations containing dangerous forces in the knowledge that such attacks will cause loss of life, injury to civilians or damage to civilian objects which are excessive in relation to the concrete and direct military advantage anticipated” as grave breaches of IHL. 
Argentina, Leyes de Guerra, PC-08-01, Público, Edición 1989, Estado Mayor Conjunto de las Fuerzas Armadas, aprobado por Resolución No. 489/89 del Ministerio de Defensa, 23 April 1990, § 8.03.
With respect to non-international armed conflicts, the manual restates the absolute prohibition of attacks against works and installations containing dangerous forces as found in Article 15 of the 1977 Additional Protocol II. 
Argentina, Leyes de Guerra, PC-08-01, Público, Edición 1989, Estado Mayor Conjunto de las Fuerzas Armadas, aprobado por Resolución No. 489/89 del Ministerio de Defensa, 23 April 1990, § 7.09.