An in-core instrumentation system for a reactor module includes a plurality of in-core instruments connected to a containment vessel and a reactor pressure vessel at least partially located within the containment vessel. A reactor core is housed within a lower head that is removably attached to the reactor pressure vessel, and lower ends of the in-core instruments are located within the reactor core. The in-core instruments are configured such that the lower ends are concurrently removed from the reactor core as a result of removing the lower head from the reactor pressure vessel.

An in-core instrumentation system for a reactor module includes a plurality of in-core instruments connected to a containment vessel and a reactor pressure vessel at least partially located within the containment vessel. A reactor core is housed within a lower head that is removably attached to the reactor pressure vessel, and lower ends of the in-core instruments are located within the reactor core. The in-core instruments are configured such that the lower ends are concurrently removed from the reactor core as a result of removing the lower head from the reactor pressure vessel.

A method for hoisting and transporting assemblies in an underground nuclear power plant, the method including: 1) pouring concrete onto a reactor cavern to form a rock anchor beam; hoisting a circular bridge crane to the reactor cavern through a hoist shaft on a top of the reactor cavern; mounting the circular bridge crane on the rock anchor beam by using a truck crane; 2) installing a containment cylinder and a track beam of a polar crane in the reactor cavern using the circular bridge crane; hoisting a gantry crane on one end of a polar crane girder and sending the polar crane girder to the reactor cavern; hoisting the other end of the polar crane girder using the circular bridge crane; allowing the polar crane girder to be horizontal; and mounting the polar crane girder on the track beam.

A system for refueling a nuclear reactor is provided. The system includes a lower reactor vessel with a plurality of fuel rods and a plurality of control rods disposed therein, the lower reactor vessel further comprising an upper flange. An upper reactor vessel is provided which encloses a steam generator and a pressurizer, the upper reactor vessel further comprising a lower flange that matingly engages the upper flange of the lower reactor vessel. A transporter surrounds an outer surface of the upper reactor vessel, wherein the transporter is configured to translate the upper reactor vessel vertically toward and away from the lower reactor vessel and also to translate the upper reactor vessel horizontally toward or away from alignment with the lower reactor vessel.

A system for refueling a nuclear reactor is provided. The system includes a lower reactor vessel with a plurality of fuel rods and a plurality of control rods disposed therein, the lower reactor vessel further comprising an upper flange. An upper reactor vessel is provided which encloses a steam generator and a pressurizer, the upper reactor vessel further comprising a lower flange that matingly engages the upper flange of the lower reactor vessel. A transporter surrounds an outer surface of the upper reactor vessel, wherein the transporter is configured to translate the upper reactor vessel vertically toward and away from the lower reactor vessel and also to translate the upper reactor vessel horizontally toward or away from alignment with the lower reactor vessel.

A stand for hosting a Multiple Stud Tensioning Machine (MSTM) for tensioning working studs, the stand comprising a first assembly designed to lie on a floor, and a second assembly designed to receive the MSTM and movable in translation with respect to the first assembly thanks to a translation system.

A system for refueling a nuclear reactor is provided. The system includes a lower reactor vessel with a plurality of fuel rods and a plurality of control rods disposed therein, the lower reactor vessel further comprising an upper flange. An upper reactor vessel is provided which encloses a steam generator and a pressurizer, the upper reactor vessel further comprising a lower flange that matingly engages the upper flange of the lower reactor vessel. A transporter surrounds an outer surface of the upper reactor vessel, wherein the transporter is configured to translate the upper reactor vessel vertically toward and away from the lower reactor vessel and also to translate the upper reactor vessel horizontally toward or away from alignment with the lower reactor vessel.

In a panel that uses the gamma radiation emitted by fission to produce electrical power, a source of an electrical current is connected to a layer of the panel made of a metal with a relatively high atomic number (Z) that forms an electron emitter. The emitter layer is surrounded by an insulation layer which in turn is surrounded by a relatively low Z value layer for collecting electrons from the emitter. Another layer of insulation and an outer sheath surround the collector. The improved panel may be used for reactor power level and power distribution measurements, and for initiating, maintaining or returning molten salt or metal coolants in the liquid state.

Provided is a chemical decontamination method that shortens the decomposition time of a reduction decontamination agent. An oxidization decontamination, a decomposition of an oxidization decontamination agent, and reduction decontamination using an oxalic acid aqueous solution are performed on a target piping of a BWR plant. After that, the oxalic acid is decomposed (S7). That is, a part of the oxalic acid is decomposed by irradiating the oxalic acid aqueous solution with ultraviolet rays upstream of a decomposition device (S8), and Fe.sup.3+ in the aqueous solution is converted to Fe.sup.2+. Hydrogen peroxide is supplied to the decomposition device (S9). In the decomposition device, the oxalic acid is decomposed by a catalyst and hydrogen peroxide, Fe.sup.2+ and hydrogen peroxide react to produce Fe.sup.3+ and OH*, and the oxalic acid is decomposed by OH*. A corrosion potential of the aqueous solution flowing out from the decomposition device is measured (S11). A concentration ratio calculation device obtains Fe.sup.3+/Fe.sup.2+ (concentration ratio) based on the corrosion potential (S12), and A control device controls the supply amount of hydrogen peroxide to the decomposition device based on Fe.sup.3+/Fe.sup.2+ (S14 and S16).).

A method for collection of dry samples taken directly from a nuclear reactor core interior. Incremental samples of irradiated metal alloy components of the reactor core may be taken and collected in-situ using a specialized metal-cutting drill bit having a hollow tungsten carbide sampling cutting head, in conjunction with an angled sampling gantry. The drill bit body has an interior airflow passage in hermetic communication with a filter located in a glove box. Air holes are formed through a face of the cutting head. A vacuumed airflow through the airflow passage and at the cutting head causes a sample of any of metal chips, filings, and dust to be obtained directly from the reactor core by being pulled through the air holes and into the airflow passage and ultimately into the filter. A collected sample may be analyzed for radionuclides and radioactivity level.