A containment seal seals a cable or tube to an opening accessing a containment vessel. The containment seal includes a lower body that attaches over the opening into the containment vessel. The cable or tube is inserted through a hole that extends axially through an upper body of the containment seal. Compression fittings are attached to the top and bottom ends of the upper body sealing the cable inside of the upper body. The cable sealed inside of the upper body in inserted through the lower body and into the opening accessing the containment vessel and a lower portion of the upper body is seated into the opening formed in the lower body. A retaining device compresses the upper body down against the lower body forming a seal between the upper body and lower body.

A nuclear reactor includes a nuclear reactor core comprising fissile material and a pressure vessel containing the nuclear reactor immersed in primary coolant water at an operating pressure. The pressure vessel has a vessel penetration passing through a wall of the pressure vessel. An electrical feedthrough seals the vessel penetration and has an outside electrical connector mounted at the pressure vessel. The outside electrical connector is at atmospheric pressure. The electrical feedthrough may include a flange disposed inside the pressure vessel and sealing against an inside surface of the wall of the pressure vessel. The outside electrical connector of the electrical feedthrough may be inset into the wall of the pressure vessel.

A nuclear reactor includes a nuclear reactor core comprising fissile material and a pressure vessel containing the nuclear reactor immersed in primary coolant water at an operating pressure. The pressure vessel has a vessel penetration passing through a wall of the pressure vessel. An electrical feedthrough seals the vessel penetration and has an outside electrical connector mounted at the pressure vessel. The outside electrical connector is at atmospheric pressure. The electrical feedthrough may include a flange disposed inside the pressure vessel and sealing against an inside surface of the wall of the pressure vessel. The outside electrical connector of the electrical feedthrough may be inset into the wall of the pressure vessel.

A feed-through element for harsh environments is provided that includes a support body with at least one access opening, in which at least one functional element is arranged in an electrically insulating fixing material. The electrically insulating fixing material contains a glass or a glass ceramic with a volume resistivity of greater than 1.010.sup.10 cm at the temperature of 350 C. The glass or a glass ceramic has a defined composition range in the system SiO.sub.2B.sub.2O.sub.3-MO.

A feed-through element for harsh environments is provided that includes a support body with at least one access opening, in which at least one functional element is arranged in an electrically insulating fixing material. The electrically insulating fixing material contains a glass or a glass ceramic with a volume resistivity of greater than 1.010.sup.10 cm at the temperature of 350 C. The glass or a glass ceramic has a defined composition range in the system SiO.sub.2B.sub.2O.sub.3-MO.

A feed-through element for harsh environments is provided that includes a support body with at least one access opening, in which at least one functional element is arranged in an electrically insulating fixing material. The electrically insulating fixing material contains a glass or a glass ceramic with a volume resistivity of greater than 1.010.sup.10 cm at the temperature of 350 C. The glass or a glass ceramic has a defined composition range in the system SiO.sub.2B.sub.2O.sub.3-MO.

A sealing mechanism for a reactor vessel (RV) cable penetration tube improves the functional and structural integrity of a cable inserted in an RV through a penetration tube due to use of a precise thimble. The sealing mechanism includes a penetration tube configured to penetrate an RV from an outside to an inside thereof and having a penetration hole for communication with the inside of the RV, a cable configured to be inserted in the RV through the penetration hole of the penetration tube, and a thimble placed between the cable and the penetration tube, wherein a dimple groove portion is provided on the thimble in a direction from an outer surface of the penetration hole toward the cable.

Apparatus for amplifying low level signals within a nuclear plant's containment building, derived from the ex-core nuclear instrumentation system. The system employs vacuum micro-electronic devices in place of conventional pre-amplifier assemblies to position the pre-amplifier assemblies closer to and within the vicinity of the ex-core detector outputs.

A feed-through element for harsh environments is provided that includes a support body with at least one access opening, in which at least one functional element is arranged in an electrically insulating fixing material. The electrically insulating fixing material contains a glass or a glass ceramic with a volume resistivity of greater than 1.010.sup.10 cm at the temperature of 350 C. The glass or a glass ceramic has a defined composition range in the system SiO.sub.2B.sub.2O.sub.3-MO.

A nuclear reactor having a penetration seal ring interposed between the reactor vessel flange and a mating flange on the reactor vessel head. Radial ports through the flange provide passage into the interior of the reactor vessel for utility conduits that can be used to convey signal cables, power cables or hydraulic lines to the components within the interior of the pressure vessel. A double o-ring seal is provided on both sides of the penetration flange and partial J-welds on the inside diameter of the flange between the flange and the utility conduits secure the pressure boundary.