Abstract: A drain valve comprising a body, an inlet for fluid to enter the drain valve, an outlet for fluid to exit the drain valve, a piston member having a piston head and a piston shaft, a seat against which the piston head seats in a closed condition of the drain valve, and a rotatable member that is rotatable relative to the body. The rotatable member is rotatably retained with the piston shaft, such that rotation of the rotatable member in one direction causes the piston member to move in a first linear direction away from the inlet such that the valve head is unseated from the seat to open the drain valve and, in use, allow fluid to enter the drain valve via the inlet and discharge via the outlet. Rotation of the rotatable member in the opposite direction causes the piston member to move in a second linear direction toward the inlet to seat the valve head on the valve seat to close the drain valve and, in use, prevent fluid from entering the drain valve via the inlet.

Abstract: A drain valve comprising a body, an inlet for fluid to enter the drain valve, an outlet for fluid to exit the drain valve, a piston member having a piston head and a piston shaft, a seat against which the piston head seats in a closed condition of the drain valve, and a rotatable member that is rotatable relative to the body. The rotatable member is rotatably retained with the piston shaft, such that rotation of the rotatable member in one direction causes the piston member to move in a first linear direction away from the inlet such that the valve head is unseated from the seat to open the drain valve and, in use, allow fluid to enter the drain valve via the inlet and discharge via the outlet. Rotation of the rotatable member in the opposite direction causes the piston member to move in a second linear direction toward the inlet to seat the valve head on the valve seat to close the drain valve and, in use, prevent fluid from entering the drain valve via the inlet.

Abstract: A protection and control system for a nuclear reactor which monitors a variable operating parameter indicative of the state of reactor operation and identifies an abnormal rate of change in reactor operating conditions. The operating parameter monitored at a given time after the abnormal change in operating conditions is identified and is employed as a base for a variable setpoint defining a design limit within which the reactor can continue to operate. At a preselected time following the identification of the abnormal rate of change of the reactor operating conditions, control of the reactor is automatically modified to establish a reactor working environment in which the reactor can continue to operate. Should the established setpoint be exceeded, the reactor will automatically be tripped.In one embodiment the negative rate of change of neutron flux of the nuclear core is monitored and compared to a preselected reference.