Abstract: A neutronic reactor comprising an active portion containing material fissionable by neutrons of thermal energy, means to control a neutronic chain reaction within the reactor comprising a safety device and a regulating device, a safety device including means defining a vertical channel extending into the reactor from an aperture in the upper surface of the reactor, a rod containing neutron-absorbing materials slidably disposed within the channel, means for maintaining the safety rod in a withdrawn position relative to the active portion of the reactor including means for releasing said rod on actuation thereof, a hopper mounted above the active portion of the reactor having a door disposed at the bottom of the hopper opening into the vertical channel, a plurality of bodies of neutron-absorbing materials disposed within the hopper, and means responsive to the failure of the safety rod on actuation thereof to enter the active portion of the reactor for opening the door in the hopper.

Abstract: A valve for adding ingredients to or sampling the fluid flowing through the valve includes an adjustable solid stem which can be extended through the flow path of a pipeline to form a seal with a seat positioned directly opposite the stem. An injection nozzle is fitted into the seat to permit addition of ingredients or sampling of the fluid when the stem is retracted from the seat. When the stem is seated, flow still occurs in the flow path.