[en] A new method is described for localizing failures on the nuclear fuel elements during reactor operation. The fuel rods contain a mixture of ''N'' different pairs of rare gas isotopes. The mixture is composed in a way that it is possible to localize ''I'' failures which occur simultaneously. This is achieved if the points which signify each single fuel element within the N-dimensional isotope-room are chosen in a way that with each point newly to be chosen in a way that with each point newly to be chosen all linear combinations of ''I'' points of the multitude of points now existing coincide with a minimum of linear combinations of ''I'' other points of the same multitude of points. The cover gas is continuously analysed with regard to the appearance of such rare gase isotopes. (P.K.)

[en] The COVA (COde VAlidation) programme undertaken by UKAEA and JRC-Ispra consists of a series of scale model explosive experiments performed to provide data for the validation of dynamic fluid/structure codes to be used eventually for fast reactor containment studies. In the test series loop and pool type reactor designs are simulated by two length-to-diameter ratios represented by long and short tanks, respectively. The programme has been completed and the analysis of the results reveals that containment codes generally give sufficiently accurate predictions of the main phenomena involved such as pressure wave propagation and fluid motion. Nevertheless, there are two areas, namely roof loadings and structural deformations, where all the codes used consistently give not negligible discrepancies with the experimental results. In particular the trend observed is a general underprediction of hoop strains and an overprediction of roof impulses for tests using long tanks. This paper deals with the roof loading overpredictions, the problem of the strain underpredictions being treated in a complementary paper. It has to be noted that the measured pressure records on the roof for long and short tanks are generally quite different in character. Long tank records tend to be smooth and it is thought that, due to the cover gas, little or no contact of the fluid with the roof occurs, this observation is confirmed by the computed results. In contrast, the short tank records change rapidly and the fluid contact with the roof takes place except for the extreme outer region of the roof. In order to reduce the complexity of the reasons for the overpredicted roof loadings, results from calculations of simple COVA tests such as IT6, a thick overstrong bare cylindrical vessel, are mainly considered in this paper. (orig.)

[en] A system of standard components is shown which can used to produce protective gas chambers in module principle of construction. (author)

[en] Purpose: To provide the subject device wherein a follow-up control rendering the difference between the pressure of freeze seal backup gas and that of reactor vessel cover gas into a predetermined value is preformed, thereby to lower the height of the gutter of a rotary plug freeze seal, to improve the real function and to facilitate the manufacture of the seal gutter. Constitution: A signal generated from a pressure converter for detecting the pressure of reactor cover gas is supplied as input to an adjustment station for reading a signal generated from a volumeric tank gas pressure converter, where a control command is issued on the basis of the constant of PID most adapted for the response of the control system so that the differential pressure becomes constant. This output signal is converted into a signal for actuating a pressure control valve by V/I converter and I/P converter, and actuates an argon inlet valve and the like. (Yoshino, Y.)

[en] This patent describes a solid tag material for identifying a nuclear reactor component when placed within the component comprising: solid materials which contain at least one non-gaseous element that undergoes nuclear transmutation into one or more detectable, identifiable, and measurable tag gases on irradiation in a nuclear reactor. The tag gases generated are stable, are not fission products, and are generated in predetermined proportions different from their natural occurrence. Upon the failure of a component the tag gases can be detected in the reactor cover gas and the failed component identified according to the tag gas composition

[en] This invention provides a method for the identification of failed fuel assemblies in a nuclear reactor having a cover gas therein wherein multiple assembly failures can be distinguished from single assembly failures comprising the steps of incorporating a blended mixture of inert, non-radioactive gas tags in each fuel pin of each of the fuel assemblies, the blended mixture of inert, non-radioactive gas tags having gas tag ratios that are located, when plotted in a three dimensional rectilinear coordinate system, on a curved surface, and thereafter monitoring the cover gas for the presence of the blended mixture of the inert, non-radioactive gas tags. (author)

[en] The system for dismantling an installation under a controlled atmosphere is made by a tool polluting the atmosphere, a gas blanket creating a continement zone around the tool, an extractor removing polluted gas from the zone, a purifier for the extracted gas and a controller regulating the flow of gas in the blanket and keeping the installation at constant pressure

[en] Several plate filters are piled on top of one another on a pipe where plate rim and base support each other and thus form collecting spaces. Each collecting space is connected to the pipe. The entire arrangement is in a container into which the Na-containing protective gas is introduced. The sintered metal plate filters retain the Na, and the gas disperses via the pipe which serves as a hanging device for the plate filters. (DG)

No abstract available

[en] This document details the Software Acceptance Testing of gas characterization systems. The gas characterization systems will be used to monitor the vapor spaces of waste tanks known to contain measurable concentrations of flammable gases