[en] The experimental protocol for an experiment investigating the transport of released plumes of SF₆ and UF₆ were discussed in this report

[en] Under the leadership of the Nuclear Regulatory Commission, design criteria for operator information in control rooms were issued and were made mandatory for all nuclear plants in the United States. The main criteria are given in nuclear regulation (NUREG) document 696 regarding the safety parameter display system (SPDS), and in NUREG 0654 regarding the radiological release and dose assessment display (RRDAD). Subsequently information display systems were added or complemented to the safety assessment. In 1990, CEGELEC together with the Korean Company Hyundai Electronic Industries was chosen to implement such a system on each of the eight PWR units under operation. The systems, called Operator Aid Computer Systems (OACS) for the Korean project under way, are already partly delivered and will be fully commissioned in 1993. The four groups of functions provided by OACS are described, i.e., those related to supervision, to SPDS, RRAD and other functions. The main characteristics of the system are given. (Z.S.)

[en] The Korean nuclear safety authority decided, after the Three Mile Island accident, that the eight PWR units operated by Korea Electric Power should comply with the new regulations issued by the US Nuclear Regulatory Commission. This necessitated an improvement in information display. A new display system, the Operator Aid Computer System (OACS) has been developed for the Korean PWRs. The system carries out four groups of functions. These are: on-line and off-line supervision; safety parameter display; release and dose assessment; long-term data storage. (UK)

[en] A high safety is obtained by International regulations on radioactive materials transport. It is obtained by packaging design adapted to the potential risk. An important accident to consider is fire for two reasons: the probability of fire occuring for time and temperature higher than conditions applied to type B packaging (800 deg C, 1/2 hr) is not negligible, particularly for air or maritime transport. Safety margins are studied by computation and experimental tests. This report presents results obtained for different types of packagings. Results show a large safety margin

[en] The testing station of the Scientific and technique study centre of Aquitaine is described. Materials and systems are evaluated by mechanical tests (vibration, shock, centrifugation), climatic tests, ballistic tests etc. In particular it is equipped for fire test of active container (30 B with UF₆), explosions, UF₆ release. It has the agreement of the Ministry for qualification of packaging for dangerous materials transport

[en] This paper describes the tests which have been performed in France: first to verify the behavior of 30B cylinders with their 21PF.1 protective overpack, and secondly to develop a better mechanical protection of the valve. The thermal tests have been performed on real packagings filled with UF₆, after the mechanical AIEA tests (free drop 9 m and 1 m on a pitch). A methodical approach has been used with large thermal instrumentation: tests with inert material, transposition by calculation of the results of the case of UF₆ filling, confirmation tests with UF₆. The results were very satisfactory, the maximal temperatures which were measured on the external overpack of the 30B cylinder being much lower than the filling temperature. In the Mont Louis wreckage, some of the valves of 48Y cylinders were damaged, as a consequence of the displacement of the protecting cover, and two of them were so damaged as to enable water to enter the cylinder. A new valve protector was designed and was tested under impact situations. The test programme was preformed with the two designs: the standard one the new protecting covers. The tests have demonstrated that the new design which has the same weight as the original one the and which may be used without any modifications of the cylinder, has a better behavior, increasing the safety during transport

[en] The international Regulations for the Safe Transport of Radioactive Materials guarantee a high level of safety, achieved mainly by a packaging design which is suited to the potential risk inherent in the materials being transported. In fact, many of the packages used at present are designed so that they behave satisfactorily in environmental conditions which are much more severe than the regulatory conditions. Any risk evaluation should be made with data which are as realistic as possible, including the behaviour of the packaging in relation to the nature of the accident (fire, collision, immersion and so on) and the associated source term. This is a basic objective for the validation of codes such as INTERTRAN developed by the IAEA. For all these reasons, a databank is needed on the behaviour of the main packagings used. Fire is an example of an accident environment which should be considered for two reasons: the probability of fires occurring with durations and temperatures greater than the conditions applied to Type B packages (800 deg. C for 30 min) is not insignificant, particularly in the case of air and sea transport, and the associated risk may be considerable (transfer by inhalation). Studies have been conducted to identify safety factors for the packagings. These studies have been carried out in some cases by calculations and in others by tests. The paper presents the results obtained for different types of packagings; they show a high safety factor by comparison with regulatory fire conditions (800 deg. C for 30 min). (author)

[en] With regard to the operation of nuclear power plants, Electricite de France formally recognized in 1973 that it was necessary for safety reasons and economically acceptable to adopt organizational principles of quality assurance that would be applicable both to its own activities and to those of its suppliers. Generally speaking, the form and spirit of the quality assurance programme chosen is based largely on the Code of Practice No. 50-C-QA. In particular, the programme focuses on the flexible character of quality assurance requirements and stresses that in the final analysis product quality depends above all on those to whom the project has been assigned, because it is they who are responsible for meeting the quality objectives set. Ten years of experience with the suppliers of Electricite de France has shown that these suppliers, after some initial difficulty, have been able to adapt the application of quality assurance so as to achieve satisfactory quality as regards both safety and availability. In the case of the French standard nuclear power plants, quality assurance is particularly important thanks to the traceability which it affords and to the allowance for corrective measures which it demands. The safety services normally take action related to quality assurance in three ways: through regulation, the analysis of measures to assure plant safety, and plant supervision. As regards regulation, an order has just been published relating to design, construction and operational quality in base-load nuclear power plants. The requirements laid down in this document incorporate the recommendations of the IAEA Code on quality assurance. (author)

[en] The temporary immunological depression previously demonstrated after high level head irradiation of adult rabbits seems to be due to decrease in lymphoblastic transformation capacity connected with encephalon injury

[en] The characteristics of the pressure waves transmitted by detonation of gaseous mixtures to the surrounding air were measured by tests made near the ground level in 1 to 54 m³ spherical balloons containing air-acetylene or air-ethylene mixtures. As concerns the peak overpressure Δp, a theoretical dimensional analysis in accordance with the experimental results shows that Δp can be expressed as a function of two independent variables, which are the radial distance R and the volume V of the balloon . A semi-empirical formula, including ground effects, is proposed and its present validity range is given. (author)