A device for removing foreign objects from nuclear reactor vessel includes a suction pipe; a suction opening structure disposed at a lower end of the suction pipe, an electric valve disposed at a connection of the suction pipe and the suction opening structure, a filter mesh and a suction pump sequentially located in the suction pipe and above the electric valve. The suction opening structure has a suction opening thereon, a water inlet of the suction pump is communicated with the suction opening, and a water outlet of the suction pump is communicated with the outside space of the suction pipe though a drainage pipe. The device further includes a touch switch disposed on the filter mesh which is in operative connection with the electric valve. A foreign object impact force to the filter mesh triggers the touch switch to close which causes the electric valve to close.

Mobile apparatuses move within contaminated fluid to create fluid flows against structures that remove and prevent contaminant deposition on structure surfaces immersed in the fluid. Unsettling flows in water may exceed approximately 2 m/s for radionuclide particles and solutes found in nuclear power plants. Mobile apparatuses include pressurized liquid from a pump or pressurized source that can be chemically and thermally treated to maximize deposition removal. When spraying the pressurized liquid to create the deposition-removing flow, mobile apparatuses may be self-propelled within the fluid about an entire surface to be cleaned. Mobile apparatuses include filters keyed to remove the contaminants moved into the coolant by the flow, and by taking in ambient fluid, enable such filtering of the ambient fluid along with a larger flow volume and propulsion. Propulsion and the pressurized liquid in turn enhance intake of ambient fluid.

Mobile apparatuses move within contaminated fluid to create fluid flows against structures that remove and prevent contaminant deposition on structure surfaces immersed in the fluid. Unsettling flows in water may exceed approximately 2 m/s for radionuclide particles and solutes found in nuclear power plants. Mobile apparatuses include pressurized liquid from a pump or pressurized source that can be chemically and thermally treated to maximize deposition removal. When spraying the pressurized liquid to create the deposition-removing flow, mobile apparatuses may be self-propelled within the fluid about an entire surface to be cleaned. Mobile apparatuses include filters keyed to remove the contaminants moved into the coolant by the flow, and by taking in ambient fluid, enable such filtering of the ambient fluid along with a larger flow volume and propulsion. Propulsion and the pressurized liquid in turn enhance intake of ambient fluid.

Controlled-debris elements inhibit the formation of a fibrous/particulate debris bed that unduly increases the pressure head loss through the perforated plates of strainers in a nuclear power plant emergency core cooling system. In a loss of cooling accident, pumps draw cooling water through the plates, which retain on their surfaces fibrous material in the circulating water to prevent it from reaching the pumps while permitting entrained particulate matter to pass through the perforations. The controlled-debris elements have a specific gravity substantially the same as the circulating water so they are entrained in the cooling water that is drawn toward the strainers and intimately intermix with the fibrous and particulate matter in the cooling water. The elements are configured to provide open structures in the bed formed on the plate surfaces to distribute fibers in the flow away from the surface and maintain cavities between the elements for the particulates.

Controlled-debris elements inhibit the formation of a fibrous/particulate debris bed that unduly increases the pressure head loss through the perforated plates of strainers in a nuclear power plant emergency core cooling system. In a loss of cooling accident, pumps draw cooling water through the plates, which retain on their surfaces fibrous material in the circulating water to prevent it from reaching the pumps while permitting entrained particulate matter to pass through the perforations. The controlled-debris elements have a specific gravity substantially the same as the circulating water so they are entrained in the cooling water that is drawn toward the strainers and intimately intermix with the fibrous and particulate matter in the cooling water. The elements are configured to provide open structures in the bed formed on the plate surfaces to distribute fibers in the flow away from the surface and maintain cavities between the elements for the particulates.

A film forming apparatus is connected to a carbon steel purification system piping of a BWR plant (S1). Formic acid (surface purification agent) is injected into a circulation piping of the film forming apparatus (S4). A surface purification agent aqueous solution containing 30000 ppm of formic acid is contacted with the inner surface of the purification system piping, and a large amount of Fe.sup.2+ is dissolved from the purification system piping, and a large amount of electrons are generated by this dissolution. Thereafter, a formic acid Ni aqueous solution is injected into the surface purification agent aqueous solution to produce a film forming aqueous solution (S5). The film forming aqueous solution storing the electrons is contacted with the inner surface of the purification system piping, and Ni ions incorporated into the inner surface are reduced by the electrons, and a Ni metal film is formed on the inner surface. Platinum ions and a reducing agent are injected into the circulation piping (S9, S10), and an aqueous solution containing the platinum ions and the reducing agent is supplied to the purification system piping to deposit platinum on the surface of the Ni metal film.

Some embodiments include a molten salt system comprising a reactor with a salt mixture. In some embodiments, the salt mixture includes uranium and a eutectic salt. The eutectic salt may include one or more of sodium fluoride, potassium fluoride, aluminum fluoride, zirconium fluoride, lithium fluoride, beryllium fluoride, rubidium fluoride, magnesium fluoride, calcium fluoride, sodium chloride, potassium chloride, aluminum chloride, zirconium chloride, lithium chloride, beryllium chloride, rubidium chloride, magnesium chloride, and calcium chloride. The eutectic salt may have a melting point less than about 800 C.

Some embodiments include a method comprising: flowing a molten salt out of a molten salt reactor at a first temperature, heating the molten salt reactor to a second temperature above the melding point of the second salt mixture causing the second salt mixture to melt; flowing the second salt mixture out of the molten salt reactor; flowing a third salt mixture into the molten salt reactor; and cooling the molten salt reactor from the second temperature to a third temperature causing the third salt mixture to solidify on the interior surface of the housing. In some embodiments, the molten salt may include a first salt mixture comprising at least uranium. In some embodiments, the first temperature is a temperature above the melting point of the first salt mixture.

A sample container, sampling system and operating methods permit representative sampling from a liquid phase or boiling liquid, a gaseous phase, a containment sump, containment atmosphere, or condensation chamber of a nuclear power plant following a severe accident. A sample container obtaining an environmental sample includes an outer chamber surrounded by an outer container wall, being directly fluidically connected to the environment through a passage opening in the outer container wall and being fillable with a liquid at least in a base region. An inner chamber surrounded by an inner container wall is fluidically connected to the base region through a passage opening in the inner container wall, has connections for sampling and conveyor medium lines and is otherwise pressure and media tightly sealed from the environment. A pneumatically or hydraulically actuatable closure device for the passage opening between the outer and inner chambers has an actuation medium line connection.

A valve assembly includes a flange connected to a vessel penetration of a reactor pressure vessel of a nuclear reactor. A valve is disposed inside the flange or protrudes from the flange into the vessel penetration. The valve includes a valve seat and a movable valve member positioned so that pressure inside the reactor pressure vessel urges the movable valve member against the valve seat to close the valve. The valve assembly further includes a plenum having an inlet via which the plenum can be pressurized to apply pressure to the movable valve member that urges the movable valve member away from the valve seat to open the valve. The plenum may be defined in part by a surface of the movable valve member. The valve assembly preferably does not include a valve actuator.