Metamorphic rock the foliation is called "gneissosity"), granoblastic (includes granulite, some marbles and quartzite), and hornfelsic (includes hornfels and skarn). Metamorphic rock Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means "change in form". The original rock (protolith) is subjected to heat (temperatures greater than 150 to 200 °C) and pressure ( or more), causing profound physical or chemical change. The protolith may be a sedimentary, igneous, or existing metamorphic rock. Metamorphic rocks make up a large part of the Earth's crust and form 12% of the Earth's land surface. They are classified by
Loss-of-pressure-control accident being generated, potentially causing a nuclear meltdown. Because of this potential, all nuclear power plants have reactor protection systems that automatically shut down the reactor if the pressure in the primary circuit falls below a safe level, or if the subcooling margin falls below a safe level. Once the reactor is shut down, the rate at which residual heat is generated in the fuel rods is similar to that of an electric kettle, and the fuel rods can be safely cooled just by being submerged in water at normal atmospheric pressure. Loss-of-pressure-control accident A loss-of-pressure-control accident (LOPA) is a mode