[en] Sweden benefits in many ways from the reactor safety research work performed in other countries. Its own activity is complementary to this effort but a certain fraction is oriented towards safety issues which are intimately related to the special design of the ASEA-ATOM boiling water reactor design. Through the availability of the decommissioned Marviken reactor plant Sweden has been able to pay a leading role in integral containment experiments with international participation. Joint efforts with other countries are now devoted to defining new large scale experiments to be performed in the unique Marviken facility. The largest portion of the safety research program in Sweden is performed by Studsvik Energiteknik AB but various universities, consultant firms and research institutes are also involved. In addition, large efforts are made by the reactor vendor ASEA-ATOM but this work is not included in the present report. The overall annual budget is at present between M dollars 7 and 8 with three governmental authorities as the main financing bodies. (author)

[en] Recently, two different reactor safety studies of the Barsebaeck 2 BWR plant were concluded in Sweden. One was sponsored by the Swedish Nuclear Power Inspectorate and performed by Studsvik Energiteknik AB. The other study was sponsored by the governmental Energy Commission and performed by the American consultant firm MHB Technical Associates. Both studies have used the WASH-1400 method of analysis. In the Studsvik study the probability for core melt accidents have been calculated, as well as the impact of large releases of radioactivity. The MHB study, which is critical of the WASH-1400 report, covers in addition the question of release categories. The methodology and results of these studies are valuable tools for the Swedish safety authorities to use in their regulatory work. (author)

[en] Studsvik was founded as a national laboratory and is now wholly commercial. The activities of Studsvik's different firms are outlined

[en] A general description of the R2 reactor, its associated facilities and its history is given. The facilities and range of work are described for the following types of activities: fuel testing, materials testing, neutron transmutation doping of silicon, activation analysis, radioisotope production and basic research including thermal neutron scattering, nuclear chemistry and neutron capture radiography. (author)

[en] A general description of the R2 reactor, its associated facilities and its history is given. The facilities and range of work are described for the following types of activity: fuel testing, materials testing, neutron transmutation doping of silicon, activation analysis, radioisotope production and physics research, including neutron capture radiography. (author). 8 refs

[en] The FILTRA project is a cooperative Swedish programme which started in February 1980. It is aimed at investigating the possibility of reducing the risk for a large release of radioactivity, assuming a severe reactor accident. The project has been focused on filtered venting of the reactor containment. The first stage of the project has dealt with two types of severe accident sequences, namely core meltdown as a result of the complete loss of water supplies to the reactor pressure vessel and insufficient cooling of the reactor containment. Some important conclusion are the following. The applicability of computer models used to describe various phenomena in the accident sequence must be scrutinized. The details of the design of the containment are important and must be taken into consideration in a more accurate manner than in previous analyses. A pressure relief area of less than 1 m² appears to be adequate. The following principles should guide the technical design of filtered venting systems, namely reduction of the risk for the release of those radioactive substances which could cause long term land contamination, provision for a passive function of the vent filter system during the first 24 hours and achievement of filtering capabilities which make leakages in severe accidents comparable to the leakages of radioactive substances in less severe accidents, which do not necessarily actuate the pressure relief system. Nothing indicates that a system for filtered venting of a BWR containment would have a significant negative effect on the safety within the framework of the design basis. Efforts should be directed towards designing a filtered venting system for a BWR such as Barsebaeck. (authors)

[en] A general description of the R2 reactor, its associated facilities and its history is given. The facilities and range of work are described for the following types of activities: fuel testing, materials testing, neutron transmutation doping of silicon, activation analysis, radioisotope production and basic research including thermal neutron scattering, nuclear chemistry and neutron capture radiography. (author). 15 refs, 12 figs, 4 tabs

[en] The different types of BWR fuel R and D programs at Studsvik are discussed. The R2 test reactor, its facilities for irradiation experiments and post-irradiation examinations are described. Reviews are given of some of STUDSVIK's earlier international fuel R and D programs, of STUDSVIK's defect fuel degradation experiments and of the following new upcoming international fuel R and D projects: the DEFEX II, ULTRA-RAMP, SUPER-RAMP III/10 x 10, STEED, Post-DO/DNB and TRANS-RAMP III Projects. (author)

[en] An investigation of filtered atmospheric venting of LWR containments has been recommended by a governmental reactor safety committee as a means of reducing the large releases of radioactivity which it is believed could arise as a result of accidents beyond the design bases (class 9) in nuclear power plants. The purpose of the project is to provide the technical basis for evaluating the feasibility, effectiveness and costs of some vent filter design concepts. The main design objective is substantially to reduce releases to the atmosphere of those radioactive substances which could cause long-lasting contamination of large land areas resulting from accidents beyond the design basis. The degree to which that objective can be reached by applying vent-filter functions becomes the main design evaluation criterion. The governing principle for the vent filter design is to utilize passive components and functions to the greatest possible extent. The design concept is to vent the stream and gases from the containment into an underground tunnel containing a large bed of gravel where the steam is condensed. Non-condensable gases are vented through a sand filter at the outlet of the tunnel via a stack to the atmosphere. The tunnel volume envisaged is of the order of 100,000m³, and the length about 1000m. A deep tunnel in rock can be made to withstand the pressures from the burning of hydrogen-air mixtures. As an alternative method the condensing and filtering functions can be achieved by utilizing water pools built sub-surface in concrete structures. Concrete structures can also be built to withstand hydrogen burning. (author)

[en] For pt.III see ibid., p.167-76 (1997). Reviews are given of seven new upcoming international fuel R and D projects: DEFEX II, ULTRA-RAMP, SUPER-RAMP III/10 x 10, STEED, PDO-RAMP, TRANS-RAMP III and INCA. (orig.)