A reactor pressure vessel in a nuclear power plant is the pressure vessel containing the nuclear reactor coolant, core shroud, and the reactor core.

A condition when the voltage and current are 90 degrees out of phase.

Design of a Turbine where energy is extracted from the steam predominantly by a change in pressure of the steam. The vanes (stationary components fixed to the casing) direct the steam toward the blades (rotating components attached to the rotor) which produce a force on the rotor.

In electric and electronic systems, reactance is the opposition of a circuit element to the flow of current due to that element's inductance or capacitance.

The RBMK is a class of graphite-moderated nuclear power reactor designed and built by the Soviet Union

A raw material, also known as a feedstock, unprocessed material, or primary commodity, is a basic material that is used to produce goods, finished products, energy, or intermediate materials that are feedstock for future finished products.

The lowest wind speed at which the rated output power of a wind turbine is produced.

See "Nameplate Capacity"

The Rankine cycle is the ideal form of a vapor power cycle. The ideal conditions can be reached by superheating the steam in the boiler and condensing it completely in the condenser.

The Rankine scale is an absolute scale of thermodynamic temperature.

A Scottish mechanical engineer who developed the Rankine scale, an equivalent to the Kelvin scale of temperature, but in degrees Fahrenheit rather than Celsius.

To increase (or decrease) a rate or volume over a time period.

A radioisotope thermoelectric generator is a type of nuclear battery that uses an array of thermocouples to convert the heat released by the decay of a suitable radioactive material into electricity.

A radioisotope is an atom that has excess nuclear energy, making it unstable.

See "Radioactive decay"

Radioactive waste is a type of hazardous waste that contains radioactive material.

A radioactive source is a known quantity of a radionuclide which emits ionizing radiation; typically one or more of the radiation types gamma rays, alpha particles, beta particles, and neutron radiation.

Radioactive decay is the process by which an unstable atomic nucleus loses energy by radiation.

Radioactive contamination, also called radiological contamination, is the deposition of, or presence of radioactive substances on surfaces or within solids, liquids or gases (including the human body), where their presence is unintended or undesirable.

Radiators are heat exchangers. They are used for either cooling or heating purposes.