Abstract:
A high-temperature nuclear reactor, cooled by a liquid fluoride salt, is described. The reactor uses an annular fuel pebble comprised of an inert graphite center kernel, a TRISO fuel particles region, and a graphite outer shell, with an average pebble density lower than the density of the liquid salt so the pebbles float. The pebbles are introduced into a coolant entering the reactor and are carried into the bottom of the reactor core, where they form a pebble bed inside a plurality of vertical channels inside one or more replaceable Pebble Channel Assemblies (PCAs). Pebbles are removed through defueling chutes located at the top of each PCA. Each PCA also includes channels for insertion of neutron control and shutdown elements, and channels for insertion of core flux mapping and other instrumentation.
Abstract:
Bei einem Sicherheitssystem (1) für eine kerntechnische Anlage mit einer Anzahl von katalytischen Rekombinatorelementen, die jeweils bei in einem anströmenden Gasstrom mitgeführtem Wasserstoff eine Rekombinationsreaktion mit Sauerstoff auslösen soll auch unter Zugrundelegung von vergleichsweise extremen Bedingungen oder Szenarien der genannten Art mit besonders hoher betrieblicher Sicherheit eine verlässliche Beseitigung des Wasserstoffs aus dem Gasgemisch gewährleistet sein. Dazu sind erfindungsgemäß die Rekombinatorelemente und/oder die jeweils zwei Rekombinatorelemente gasseitig verbindenden Strömungswege derart ausgestaltet sind, dass ein durch eine Zündung bei der Rekombinationsreaktion in einem ersten Rekombinatorelement im Gasmedium ausgelöster Druckpuls im Anströmbereich eines zweiten, benachbarten Rekombinatorelements einen Gasverschiebevorgang mit einer Strömungsgeschwindigkeit von mindestens 5 m/s auslöst.
Abstract:
The invention provides a method and tool to perform an analysis of CRUD on a nuclear fuel rod. The method recites providing a nuclear fuel rod with a layer of CRUD on an exterior of the fuel rod, scraping the CRUD from the fuel rod with a CRUD scraping tool and collecting CRUD flakes from the CRUD scraping tool. The method also provides for sorting the CRUD flakes into particle fractions, and analyzing the CRUD with a scanning electron microscope, wherein the scraping tool has a blade with a rigidity that is matched to an anticipated CRUD deposit shear strength.
Abstract:
The invention relates to a lead-free radiation protection material which is made of elastomer or a plastomer as matrix material wherein elements having an atomic number greater than 50 or compounds thereof are incorporated as radiation-absorbing materials. The aim of the invention is to improve said radiation protection material in such a manner that safe radiation absorption can be achieved and that it can be produced in an economical manner and that it is simple to process. As a result, the radiation-absorbing materials are made of a combination of antimony and bismuth. Said materials can also be made of tungsten and/or elements from the rare earth group.
Abstract:
A system, method and apparatus for transporting and/or storing radioactive materials, such as spent nuclear fuel. In one embodiment the invention is a jacket apparatus that is filled with a neutron absorbing fluid and adapted to facilitate a cyclical thermosiphon flow of the neutron absorbing fluid within the jacket when the neutron absorbing fluid is subjected to heat emanating from the cavity. In another embodiment the invention is a system, apparatus and method of processing and/or removing radioactive materials from a body of water that utilizes the buoyancy of the water itself to minimize the load experienced by a crane and/or other lifting equipment. In a third embodiment the invention utilizes a sleeve-iike structure that is slid over a container holding high level radioactive materials to add radiation shielding protection. Because the sleeve-like structure and container are non-unitary and slidably separable from one another, crane lifting capacity is not affected.
Abstract:
The reactor vessel of a nuclear reactor installation which is suspended from the cold leg nozzles in a reactor cavity is provided with a lower thermal insulating barrier spaced from the reactor vessel that has a hemispherical lower section that increases in volume from the center line of the reactor to the outer extent of the diameter of the thermal insulating barrier and smoothly transitions up the side walls of the vessel. The space between the thermal insulating barrier and the reactor vessel forms a chamber which can be flooded with cooling water through passive valving to directly cool the reactor vessel in the event of a severe accident. The passive inlet valve for the cooling water includes a buoyant door that is normally maintained sealed under its own weight and floats open when the cavity is flooded. Passively opening steam vents are also provided.
Abstract:
The invention relates to a system (1) for evacuating the residual heat from a nuclear reactor (2), wherein the residual heat is evacuated by irradiation from the main tank (3) of the nuclear reactor towards a ring of substantially U-shaped tubes (15), inside which external air circulates in natural circulation and which are arranged circumferentially around the tank (3). The tubes (15) are grouped together in modules (11), each of which is made up of a set of U-shaped tubes (15) inserted inside one another with respective side-by-side branches (16) facing the tank (3) and arranged on opposite sides of a common central axis (X) and laterally separated from one another by empty spaces. A radiant heat reflecting wall (30), which also constitutes a structure (33) for containing an insulation filling (34) of the nuclear-reactor well (5), is set behind the tubes (15) with respect to the tank (3) to reflect back onto the tubes (15) the radiant heat passing through the empty spaces between one tube (15) and another. The reflecting wall (30) is shaped in such a way as to be partially inserted between the branches (16) of the tubes (15) to define a longitudinal channel (31) set substantially around each branch (16).