[en] The state of the art is presented for testing procedures for tightness inspections of WWER-440 type reactor hermetic spaces, using measurements of the time dependence of pressure. A new evaluation method is described providing an unambiguous value of leak rate even if this value is extrapolated from low level overpressure measurements to maximum accident overpressure. If the leak test initial overpressure is different in two measurements for one hermetic space, the extrapolated leak rates have equal values. Application of this method allows NPP operators to find physically well-founded results for hermetic spaces tightness quality evaluation which can be used for time reviews of tightness development and also as basic data for nuclear power plant safety calculations. (J.B.) 11 figs., 3 refs

[en] More than one million and a half houses have too important levels of radon. This gas is a carcinogen gas but it is easy to get rid of it. This article reviews the different possible techniques. (N.C.)

[en] When the temperature in the airtight radon chamber was adjusted, it would induce the frequent changes of the air pressure in chamber, then the radon concentration in the radon chamber would continuously reduce, which could seriously destroy the stability of the radon concentration in radon chamber. In this paper, on the study of the effect reasons to the stability of radon concentration in airtight radon chamber due to the thermoregulation, a new amendment scheme was put forward, and the solutions of the relevant parameters were discussed. The amendment scheme had been successfully applied to HD-6 radon chamber, and achieved good results. (authors)

[en] Indoor radon concentrations were estimated for various ventilation conditions, the differences being mainly related to the airtightness of the dwelling and the ventilation behavior of its occupants. The estimations were aimed at describing the variation in air change rates and radon concentrations to be expected in the representative newly built Dutch dwellings and identifying the most important parameters determining air change rate and indoor radon concentration. The model estimations were compared with measurements. Most of the air was predicted to enter the model dwelling through leaks in the building shell, independent of the ventilation conditions of the dwelling. Opening the air inlets was shown to be an efficient way to increase infiltration and thus to decrease radon concentration. The effect of increasing the mechanical ventilation rate was considerably less than opening the air inlets. The mechanical ventilation sets the lower limit to the air change rate of the dwelling, and is effective in reducing the radon concentration when natural infiltration is low. Opening inside doors proved to be effective in preventing peak concentrations in poorly ventilated rooms. As the airtightness of newly built dwellings is still being improved, higher radon concentrations are to be expected in the near future and the effect of occupant behavior on indoor radon concentrations is likely to increase. According to the model estimations soil-borne radon played a moderate role, which is in line with measurements. (au)

[en] Radon measurements in some buildings in the town of Jachymov indicated that the limiting volume activities were exceeded substantially. Remedial actions were made in the nursery school building. These included gravitational ventilation of the cellar, fitting of all doors and passages between the cellar and school rooms with packing, installation of overpressure ventilation with heat recuperation, and sealing of all window gaps. (J.B.). 2 refs

[en] Subject of a research project carried out at Material Testing Institute (MPA) University of Stuttgart was the investigation of bolted flange connections (DN100 PN100 and PN160) of metal-to-metal contact type. In a special test rig external loadings (axial forces, bending and torsional moments as well as shearing forces) can be applied in addition to the internal pressure. Further on an analytical approach was developed for the determination of the loading in different cross sections of the flanges and for the tightness proof by means of the gap between the flanges at the position of the gasket. On the basis of a comparison of the experimental results and those of numerical calculations with results according to the new developed analytical approach the latter can be regarded as validated as far as investigated. In the nuclear code KTA 3211.2 (draft 2003) [1] the flange rotation at metal-to-metal contact (MMC) is restricted globally to 0.1 . This limitation does not comply with a lot of bolted flange connections in service although the strength and tightness criteria are met. This problem is now resolved with the new developed analytical approach which takes also into consideration the non-negligible influence of the assembly bolt load exceeding the minimum required bolt load for metal-to-metal contact. In a following project for defined boundary conditions the basis for the strength and tightness proof for bolted flange connections (MMC type) without explicit calculation shall be created. (orig.)

[en] Radon concentrations and external exposure by nuclides of the U-238 decay chain were quantified for a typical Dutch townhouse using a series of interconnected computer models. The effect is studied of changes in parameter values which have simulated changes in building practices over the past decades. Three groups of parameters were distinguished: (1) the air-tightness of the building shell and the distribution of leaks over outer walls and ground floor, (2) the radon-relevant characteristics of the building materials, and 3) those characterising 'habits of the occupant', such as changing mechanical ventilation rate and opening of air inlets or doors. The relative importance of increased air-tightness and of substitution of concrete by other building materials in new dwellings is illustrated. On average changes in building practices clearly enhanced the radon concentration in the living room without affecting external exposure. In new, airtight dwellings the relative effect of occupant behaviour is demonstrated as considerably larger than in old ones

[en] A light permeable cover covers an opening perforated to a ceiling wall of a glove box for handling radioactive materials in an isolated state. The light permeable cover comprises a protruded portion fitted to the opening and an end edge portion which is contiguous with the protruded portion and is wider than the opening. A sealing material is disposed to portions in contact with the circumferential edge of the opening and the end edge of the light permeable cover to make the air tightness of the inside of the glove box reliably. An illuminator is disposed by way of the light permeable cover to the outside of the glove box for illuminating the inside. The illuminator is held to an illuminator holding plate by way of a reflection plate. The holding plate is fixed together with the light permeation cover to the ceiling wall of the glove box by screws. The illuminator is not exposed to the inside of the glove box. Accordingly, the lamp of the illuminator can be exchanged easily. (I.N.)

[en] The geo-membranes in high density polyethylenes have a big development. They can be used in ground disposal because of their quality of airtightness and watertightness. However, the membranes can suffer of stress cracking and then tear, in other words a crack under some constraints, that sometimes happened with high density polyethylene. (N.C.)

[en] Objective: To evaluate the influence of indoor air filtration by air purifier on the behavior of indoor radon progeny and estimate its effects on indoor radon exposure to residents. Methods: The concentrations of indoor radon progeny with and without the air filtration were calculated by the theoretical model developed in this study. Based on the dose conversion factors of attached and unattached radon progeny, the mitigation effects of indoor radon exposure due to the air filtration were estimated. Verification experiments were conducted in an airtight room. Results: With the air filtration rate increased, the removal efficiency of indoor radon progeny would appear more obvious. For an airtight room with its initial aerosol concentration of 10000 cm^-3, the concentration of total radon progeny would decrease by more than 90% when the air filtration rate exceeded 10 h^-1. But the concentrations of indoor unattached radon progeny would increase by using the air purifier in different extents. The variations of radon progeny concentrations and the decrease of internal doses were closely related to the filtration rate of air purifier. With the air filtration rates increased, the mitigation effects would be better and faster. The internal dose would reduce by more than 70% when the filtration rate exceeded 5 h^-1. Conclusions: Although the indoor concentration of unattached radon progeny will increase by using the air purifier, it is still effective in reducing the exposure dose to residents due to the inhalation of radon progeny. (authors)