Abstract: A firearm locking device increases firearm safety and security. A receiver cartridge shaped and sized with same caliber as firearm is loaded into bullet chamber. A barrel rod is removably engaged to the receiver cartridge and protrudes from the end of firearm barrel. Protruding end serves as fast visual indicator that firearm is unloaded and safe to handle, store, or display. A light pull on protruding end also serves as indicator that firearm is unloaded and safe. A lock and cable serve to lock the barrel rod to firearm's trigger guard to prevent removal of barrel rod from barrel.

Abstract: A fuel element for a pressurized water reactor is described. The fuel element contains a laterally open skeleton having control-rod guide tubes each with a first end and a second end, spacers fastened to the control-rod guide tubes, a fuel element head disposed at the first end of the control-rod guide tubes, and a fuel element foot disposed at the second end of the control-rod guide tubes. Gastight cladding tubes are inserted into the skeleton and each is filled with a column of fuel pellets. At least some of the gastight cladding tubes have a multilayer wall. The multilayer wall is formed of a mechanically stable matrix containing a first zirconium alloy disposed in a middle of the multiplayer wall; and a thinner protective layer of a second zirconium alloy alloyed to a lesser extent than the first zirconium alloy. The thinner protective layer is bound metallurgically to the matrix and is disposed on an inside of the matrix facing the fuel pellets.

Abstract: A reactor pressure vessel supports the flanges of a core barrel assembly and an upper support plate. These flanges have aligned holes for diverting inlet coolant water to the vessel head for cooling the head. The aligned holes have different cross-sectional areas for controlling unexpected backflow of coolant water from the vessel head around the periphery of the upper support plate.

Abstract: A dual powered fiber optic sight for a gun, which can be illuminated either by ambient light or by a light source. The light source is preferably a light-emitting diode (LED). Ambient light and light from the LED are carried by a fiber optic rod and the rod appears as a bright dot on the front sight of the gun. The electronics are enclosed and protected from the environment by a water-proof adhesive. The end of the fiber optic rod may be cut at a 45 degree angle to increase the rod's light-gathering ability.