[en] The methods currently in use or under development for testing filter and absorber systems installed on reactors in the United Kingdom Atomic Energy Authority are discussed and some typical results for operational filter and absorber systems are presented. (author)

[en] The development of siting philosophies and criteria during the past decade is reviewed. Experience in applying the criteria is described and the problems arising from their qualitative nature are examined. A new quantitative approach developed by the United Kingdom Atomic Energy Authority and currently being applied to problems of reactor siting is described. It is shown how this approach can facilitate assessment and lead to a quantitative criterion of acceptability. (author)

[en] The impregnation of active carbons is known to be a useful means of improving the ability of these carbons to retain methyl iodide which might be formed during the accidental release of fission products from a reactor. Some basic work was done on both impregnated and unimpregnated materials, which involved: (a) the texture: (b) the reaction of Mel with the impregnants; (c) the adsorption of Mel on the carbons under dry and wet conditions at different temperatures. It was found that the carbons are highly microporous. A large part of this porosity disappears on impregnation with organic amine; These impregnants react chemically with the methyl iodide, which is thereby fixed on the carbon. For carbon which is impregnated with KI, a rapid exchange reaction takes place between the methyl iodide and KI under both dry and wet conditions. Consequently most of the iodine activity can be removed from the gas. (author)

[en] The concrete pressure vessel surrounding an AGR has penetrations through its walls for the gas circulators, steam and feed pipes, control rods and refuelling system and for various reactor services. Retention of the high-pressure gas coolant within the pressure vessel depends on the continuing integrity of these penetrations. The paper describes in detail the large penetrations in the vessel walls of an AGR of the Hinkley Point B type and discusses the criteria governing their design, construction and operation. Arguments are presented which lead to the conclusion that the penetrations, when appropriately designed and constructed, can have sufficient integrity for an AGR to be sited in a densely populated area. (author)

[en] The inherent features of the advanced gas-cooled reactor (A.G.R.) which serve to retain fission products within the system are described. The roles played by the fuel, fuel-can and primary pressure circuit are discussed and illustrated by reference to the Dungeness 'B' reactor design. Some possible additional safety features are described. The effects of possible fault conditions on the retention of fission products within the system are discussed and the extent to which the safety of the reactor depends on design features is evaluated. It is shown that the A.G.R. system provides an exceptionally high degree of safety without the provision of a conventional pressure-retaining secondary containment. (author)

[en] The paper opens with a brief description of the principal features of the reactor system and the general objects of the design, with particular reference to the prototype recently constructed at Winfrith Heath, Dorset. The research, development, design and analytical work carried out in connection with some of the more important features of the reactor, including containment, are outlined,along with the measures adopted during construction, testing and commissioning to support the safety principles. An indication of how the safety analysis is related to the probability approach described elsewhere is given, together with some comments on the application to future designs of the work carried out for the prototype and of the features adopted in the design. (author)

[en] The main characteristics of a site which are relevant for selection of the most convenient location for nuclear power plants from the safety point of view are discussed. Important factors to be considered are earthquake hazards, flooding possibility, tornados, tsunamis and foundation stability. Other site characteristics such as soil retention properties and hydrology can also be reviewed, but always with reference to specific plant features. The factors associated with the exclusion area and population density around the plant need to be examined in the light of the safety assessment of a nuclear power plant as a whole. (author)

[en] Proceedings of a Symposium organized by the IAEA and held in Vienna, 3-7 April 1967. The meeting was attended by 246 participants from 29 countries and 6 international organizations. Contents: National practices in reactor siting (14 papers); Reactor siting considerations (12 papers); Containment for particular reactor types (6 papers); Containment for reactor types - general considerations (6 papers); Release and transport of pollutants (10 papers); Panel discussion. Each paper is in its original language (35 English, 9 French and 4 Spanish) and is preceded by an abstract in English and one in the original language if this is not English. Discussions are in English. (author)

[en] Experiments and calculations on trapping of elemental iodine in laboratory and large-scale boiling water pools are described. Variable parameters are pH (0-12), iodine concentration (0.001-1 ppm) and mass-transfer conditions (bubble size and time of interaction). After reaction of molecular iodine with water, a certain fraction, determined by pH and iodine concentration, is retained as elemental iodine. This part is available for release with exhausted steam according to the partition properties of elemental iodine. Laboratory experiments show that re-establishment of chemical equilibrium did not seem to occur when elemental iodine is removed from the water pool. Thus, practically, the fraction first hydrolysed is permanently trapped. Results from the large-scale study are in agreement with these findings and show that superheated steam, under certain conditions, can be effectively decontaminated from iodine even by a boiling water pool with no net steam condensation capacity. Equations for predicting two-phase (steam-water) transfer of volatile iodine as a function of physical parameters are developed and tested. (author)

[en] A new approach is presented for establishing the performance requirements of containment designs in nuclear power plants. The approach recognizes that containment is only part of a total system, which prevents and limits the consequences of a release of fission products. Containment performance requirements are determined by looking at the overall system, rather than by making arbitrary assumptions about the source of the accident and the effectiveness of some of the provided features. The proposed technique is illustrated for the case of a loss-of-coolant accident in a large power boiling water reactor. The interrelationship of the pressure-suppression containment to other preventive measures is reviewed first. Next, the containment performance requirements are established as part of an overall system evaluation. Finally, possible alternate containment features are evolved from the study. (author)