[en] Probabilistic safety assessment plays an important role in nuclear technology and other branches of industry. This methodological approach allows optimization of installations with regard to their reliability and technical safety both during planning and operation, in a logical and understandable manner. It also lends itself to the assessment of technical safety in the context of licensing procedures. Despite the obvious strongpoints of the procedure, it is still be set with misconceptions, ambiguities and misinterpretations, as one can tell from discussions about PSA and its use in practice. The article is intended to bring to the reader's awareness and, if possible, eliminate these false notions, which curb the practical value of PSA. (orig./MP)

[en] The direct industrial need for a validated defect assessment procedure stems from a requirement of safe plant operation with extended component life, and improved decision making processes in run/repair/replace situations. To this end, structural integrity assessment is carried out by the power generation and offshore engineering sectors and finds acceptance world wide. It is also addressed by other industrial sectors including chemical and process engineering. During the last decade, a number of fracture mechanics based low temperature assessment procedures have been developed within Europe and worldwide. Guidelines and methodologies for high temperature assessment also exist within several European countries. This means that there is a significant number of procedures available for use in plants. This report identifies the procedures, for both high and low temperatures, which are most commonly used by EU Thematic Network Project PLAN partners both in their projects and in their respective organisations. It is followed by a comparison of the available defect assessment procedures in the light of recent progress made in collaborative programmes of EC Projects. The present work identifies issues associated with defect assessment procedures, and thus forms a contribution to the assessment of service performance of engineering structures at both low and high temperatures, which is the aim of the PLAN Cluster Task ''Defect Assessment Procedures''. (author)

[en] Recent assertions that guiding-center theory breaks down at second order for 3D magnetic fields with nonzero torsion are argued to be incorrect.

[en] This fourth part concerns the radioisotopes and includes: the risks bound to the production and the medical and industrial use of radioisotopes, the regulation of the users of ionizing radiation and the relevance of the experience of nuclear facility operators in litigation, problems relative to the medial, scientific and industrial use of radioelements, standards and rules in the use of radioactive sources in medical sector in Brazil. (N.C.)

[en] The question arises where there is the limit between the scope of minimizing the residual risk and the residual risk that is accepted. The necessity of minimizing the residual risk is balanced against the acceptable residual risk. (orig.)

[en] It is proved that a nodal quartic threefold X containing no planes is Q-factorial if it has at most 12 singular points. An exception here is a quartic with precisely 12 singularities containing a quadric surface. Some geometric constructions relating to such a quartic are presented. Bibliography: 14 titles.

[en] The report on hand presents possible applications of a project planning and coordination system for projects concerning the nuclear fuel cycle, with special regard to waste management. The relevant licencing procedures applied to said projects as well as basic elements of project planning systems, e.g. project structure plan, ''milestone-plan'' and network plan are dealt with in this report. For the licensing procedure under atomic law, a possible project structure is indicated. Furthermore, processes and occurances to be considered in the elaboration of particular network plans are listed. In addition, particulars for the schedules degree of specifications are given. To round up the report, recommendations are given for future lines of proceeding in the introduction of computer-aided information systems for use in projets on the nuclear fuel cycle. (orig.)

[en] The trustworthiness test is an important part of securing nuclear facilities against internal offenders. For performing such a test the supervisory authority, which is the State's physical protection authority, contacts the security offices or authorities regarding persons who work inside the sensitive areas of nuclear power stations - areas containing nuclear material. The trustworthiness test covers the present activities of the employees and gives a prediction for the following five years; after this time the test must be repeated. The trustworthiness test is a prerequisite for a facility to obtain a licence for the use of nuclear material, to hire persons for work in the inner area of a nuclear facility or the hire persons for leading positions. In Germany the content and form of the test as well as the evaluation of the results are regulated in a guideline of the Federal Ministry for the Environment, Nature Conservation and Reactor Safety (BMU) (latest edition in June 1996). The test is performed by the licensing authority or the supervisory authority. the basis of the test is a declaration by the employee concerned, containing personal data and the agreement of the person to the use of the data files by the safety authorities. It the results of the test are positive, the person tested has the possibility to comment on differences or to explain certain facts. The paper presents details of the BMU guideline. (author)

[en] This design feature (DF) is intended to evaluate the effects of continuous ventilation in the emplacement drifts during preclosure and how the effects, if any, compare to the Viability Assessment (VA) reference design for postclosure long term performance. This DF will be evaluated against a set of criteria provided by the License Application Design Selection (LADS) group. The VA reference design included a continuous ventilation airflow quantity of 0.1 m³/s in the emplacement drifts in the design of the repository subsurface facilities. The effects of this continuous ventilation during the preclosure was considered to have a negligible effect on postclosure performance and therefore is not included during postclosure in the assessment of the long term performance. This DF discusses the effects of continuous ventilation on the emplacement drift environment and surrounding rock conditions during preclosure for three increased airflow quantities. The three cases of continuous ventilation systems are: System A, 1.0 m³/s (Section 8), System B, 5.0 m³/s (Section 9), and System C, 10.0 m³/s (Section 10) in each emplacement drift split. An emplacement drift split is half total length of emplacement drift going from the east or west main to the exhaust main. The difference in each system is the quantity of airflow in the emplacement drifts

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