Abstract: A cylindrical electric penetration assembly carrying instrumentation leads from the interior of a nuclear reactor and having thin layers of polyethylene and lead radiation shielding installed at both its entrance and exit regions, the shielding layers being separated by a large hollow cavity located inside the central portion of the penetrator nozzle. Each layer attenuates and extinguishes either gamma ray or neutron radiation emanating from the reactor's core. The combination of the shielding and central air pocket prevents excessive radiation leakage through the penetration assembly and excessive heating inside the penetration nozzle.

Abstract: A system for maintaining seal integrity under pressure and monitoring leakage within an electric penetration assembly of the type which extends through a containment wall of a nuclear reactor installation. The manifold passage in the penetration header plate is filled with a dielectric liquid and is pressurized by an apparatus which includes an accumulator containing the dielectric liquid and located inside the penetration header plate to supply the liquid thereto. The liquid in the accumulator is kept under pressure by a diaphragm separating the liquid from an inert gas which is under pressure.