Covers the interaction of those low pressure systems with the high pressure portions of the reactor coolant pressure boundary (RCPB) which, if assumed over-pressurized by the reactor coolant, could result in failure of the low pressure system and (1) the prevention of an orderly reactor shut-down or (2) the inability to maintain a safe shut-down condition assuming makeup is provided by normal makeup systems only or (3) the release of radioactive material at the site boundary exceeding 0.5 rem to the whole body or its equivalent to any part of the body. It also covers design and testing requirements for equipment, controls and instrumentation necessary for over-pressure protection of such low pressure systems.