[en] This paper presents briefly some aspects thought to be important in what concerns the diminution of the total impact that the realization and operation of nuclear facilities bring about. Particularly, highlighted is the reconstruction of ecological equilibrium, the change of which is induced by the whole chain of activities implied in the nuclear fuel cycle, starting with uranium extraction from uranium ores, up to its use in the nuclear power plant. Predictive estimates are attempted in connection with cessation of implied activities. As solutions for ecological reconstruction, the following are considered: land reclamation by re-shaping the slopes and by covering with fertile earth the sterile dumps resulting from exhausted uranium mines and by implanting fresh vegetation with deeply penetrating roots able to stabilize the ground; cleaning the access galleries of the access and ventilation wells; drying and draining the access water in bulk solid wastes and in the open decantation pools; slope stabilization, covering with fertile soil and grass and bush cultivation; decontamination of buildings; utilisation of inactive and isolated mines for low and intermediate activity radioactive waste disposal; closing and covering with layered structure of earth, draining materials, clay, fertile soil and grass and bush cultivation of organized containerized low and intermediate activity radioactive waste repositories; long-term monitoring of surfaces and underground waters at closed mines, decantation pools underground or overground radioactive waste repositories; storing the plutonium contaminated soil in trenches covered by a layer of non-infested earth of minimum 5 m thickness and in-situ vitrification by means of a high intensity current. These are principles set forth by IAEA concerning the radioactive waste management

[en] The paper reports results of a study on the seasonal distribution and abundance of jelly fishes in the coastal waters of Kalpakkam in the context of their ingress into the cooling system of a power plant. Three species of jelly fishes Dactylometra quinquicirrha (L. agassiz), Crambionella stuhlmanni (Chun) and Chiropsalmus buitendijki (Horst) were found in such abundance as to cause blockage of the cooling water intake screens. The seasonal variation in the incidence of the jelly fishes clearly showed that the periods of maxima and minima were different for each species. During the period of study (February 1988 to April 1989) three maxima were noted - May, July and October. On any given single day, maximum quantity of jelly fishes collected from the travelling screens was 29 tonnes (21 July 1988). The data are discussed with respect of (i)qualitative and quantitative variations in the ingress of jelly fishes at Kalpakkam, (ii)operational problems associated with jelly fish ingress and (iii)possible approaches to combat the problem. (author). 1 tab., 4 figs., 9 ref s

[en] The radioactivity background level of enviromental medium around a pulsed reactor for 5 km and external penetrating radioactivity dose level for 10 km are given. mediums measured include air, water, soil, organisms, fallout, etc

[en] Models of long-term environmental change are described with regard to the assessment of low and intermediate level radioactive waste disposal sites. For shallow repositories, containing low level waste only, the time to the next glaciation needs to be considered, but for deeper repositories the occurrence of multiple glacial cycles, which may change the hydrogeological context of the repository, needs to be modelled. The models use Monte Carlo simulations in which realistic sampled sequences of discrete climate states are derived for each simulated future. For each sequence, environmental changes are determined from a series of generalised sub-models of erosional, depositional and hydrogeological processes. These models also account for the crustal response to glacial advance and retreat. Human intrusion effects are simulated but are not fully integrated with the climate-driven sub-models. (author)

[en] The input motion in the seismic design of a nuclear power plant is generally defined by peak ground acceleration and by a free field response spectrum characterized by a certain standard shape. Usually, the peak ground acceleration is obtained as a result of a site specific seismic risk analysis using seismological variables such as Richter magnitude and epicentral distance. The standard shape of the response spectrum could be that defined by IAEA's Safety Guide 50-SG-SI (IAEA, 1979) or similar. This approach could bring along a substantial cost in the seismic engineering effort and, in some cases, non-realistic designs for specific sites, specially when referred to low seismicity zones where historical information is not available. This paper reports on a new approach (Riera et al., 1986 and 1987) is applied to the seismic analysis of a specific site located in the Eastern region of Argentina, next to the Atlantic coast, thus obtaining the horizontal acceleration spectrum mentioned above. The method is based on the selection of random variables (earthquake magnitude and epicentral distance), which are needed to describe the motion of the base rock, as ordinates of the seismic response spectrum, on the basis of regression studies

[en] The hybrid modeling method (Gupta and Penzien 1980) and associated analysis procedure for solving a three-dimensional soil-structure interaction problem was developed by Gupta and Penzien (1981) and Gupta et al.(1982). Subsequently, successive modifications have been made to the original modeling method and analysis procedure allowing more general treatment of the SSI problem (Penzien, 1988). Through many correlation studies of field test data obtained under forced-vibration and earthquake-excitation conditions, it has been shown that the HASSI programs can effectively predict the dynamic response of a soil-structure system, if realistic soil parameters are adopted. In the above, the entire structure-foundation system is considered to respond in a linear fashion. Since the reflected three-dimensional waves at the soil-structure interface decays very rapidly with distance away from the structure (Katayama, 1987 (a)), the response of the soil close to the base of the structure may greatly affect its response; therefore, proper modeling of the non-linear soil behavior characteristic is essential. The nonlinear behavior of near-field soil has been taken into consideration in HASSI-7 by the standard equivalent linearization procedures used in programs SHAKE and FLUSH

[en] The nuclear reactor building is required to be constructed on a bedrock stratum in Japan. According to the seismic analysis for the structural design, it is indicated that the base mat uplift occurs partially. The tests, therefore, were performed to elucidate the uplift phenomenon of the reactor building through fundamental experiments which consist of two parts: the laboratory test using the shaking table and the field test using the exciter and hydraulic jack. This paper describes the laboratory test. Based on test and analytical results, estimations on the following subjects have been made: input level and contact ratio, contact ratio and response spectrum and effects due to the simultaneous horizontal and vertical excitation. The validity of the present design method has been ascertained

[en] Fish abundance has been monitored with fyke nets in 1976-1987 at the cooling-water outlet from the Ringhals nuclear power plant at the Swedish west coast and in a reference area. Judging from the dependence of the catches on temperature, Myoxocephalus scorpius, Zoarces viviparus, Gadus morhua and Platichtys flesus can be classified as cold-water species and Symphodus melops, Ctenolabrus rupestris, Carci nus maenas and Anguilla anguilla as warm-water species. As a rule the warm-water species were more and the cold-water fishes less abundant in the outlet area than in the reference area. The catch of the economically important Anguilla was about three times greater in the heated area. A lower abundance than expected of Ctenolabrus and Myoxocephalus at the outlet may be caused by a loss of eggs and larvae in the cooling-water system. (author)

[en] The measured results in some cases still reflect the effects of the Chernobyl reactor accident. Although the activity concentrations of Cs-134 and Cs-137 have diminished in almost all food samples, they still are higher than before Chernobyl. The level of activity concent ration varies in the different types of food and exhibits significant fluctuations depending on site of measurement and time.The high activity levels measured in milk in autumn 1986, going up to 26 and 58 Bq/l, respectively, the data measured in the Schwandorf region in spring 1987 were considerably lower again, and in 1988 remained on this lower level, ranging from 0.4 to 11 Bq/l. Local gamma activity measurements at 80 different measuring points in the period 1986 until 1988 show the following mean values: 1.01 mSv/a in 1986, 1.05 mSv/a in 1987, and 0.96 mSv/a in 1988. Judging from the data measured in the early 1960s, which reflect the overground nuclear weapons tests, it can be expected that Cs-134 and Cs-137 from the Chernobyl fallout will continue to contribute most to radioactivity levels in the environmental samples. (orig./HP)

[en] During the 40-year existence of the INEL site, the criteria used for the seismic design of facilities have evolved based on the increased understanding of earthquakes, their effect on structures, and the specific seismic characteristics of the INEL. Several studies, including one scheduled for completion this year, have been initiated since 1970 for the purpose of utilizing evolving technology to better define reasonable, yet conservative, seismic design criteria. 26 refs., 1 fig