An Operational Reactor Safeguard Examination (ORSE) is an examination conducted by senior United States Navy personnel on board U.S. Navy nuclear-powered ships, specifically supercarriers and submarines. The purpose of an ORSE is to ensure that the engineering (submarines) or reactor (aircraft carriers) department of a nuclear-powered vessel is operating their reactor(s) in a safe manner. The exam also ensures the readiness of the engineering department to safely respond to nuclear power plant casualties.