[en] For evaluating the risks in nuclear power plants accidental coincidence analysis is a wide-spread method. The paper describes this method on the basis of the so-called Birkhofer study conducted in the Federal Republic of Germany in 1977. The stages of the analysis are the following: determination of the events capable of bringing about radioactive emission, analysis of the chain of events and reliability, determination of radioactive emissions, study of the consequences of accidents and evaluation of risks. It is concluded that the risk of contamination accidents in nuclear power plants in comparison to other risks (illness, other accidents etc.) are negligible. (N.I.)

[en] A new mathematical method was developed for the evaluation of data of thermocouples used for temperature monitoring in the primary coolant system of WWER-type nuclear reactors. The processes of in-core calibration of the thermocouples and the measurement of mixing factors of different primary cooling loops are combined. The numerical solution of the derived equations makes possible the determination of thermohydraulical mixings, the improvement of estimations concerning water and heat flow and the calibration of thermocouples based on the same measured data. The development of a FORTRAN program for the computerized solution of the equations is going on. (D.Gy.)

[en] The problem was raised whether the change in certain measurable quantities of a reactor can lead to the change of total reactor performance which, in turn, can be utilized for obtaining information on parameters such as radiation shielding materials. The question can be answered by the sensitivity analysis for cross sections. The role of sensitivity analysis is presented for the determination of integral parameters and for the calculation of biological radiation protection data. The results for a sensitivity analysis case are presented in detail. (D.Gy.)

[en] In the secondary coolant circuit of the WWER type reactor of the Paks nuclear power plant there are two steam turbines with a power of 220 MW in each reactor block. The construction characteristics of the high and low pressure turbines are discussed. The structural features of the oil system supplying oil for the bearings and the turbine control system itself are reported. The operational principles of the electrohydraulic signal transformators produced in Harkov, USSR, are presented. (V.N.)

[en] The treatment of condensate at the boiling water reactors is owing to the corrosive and splitting products, as well as condenser leakages obligatory. The various possibilities of condensate treatment flow diagrams are outlined. Then the procedure of the pulver resin onfloating and the functioning phases of the respective equipment are shown by the means of illustration materials. After the startup of the equipment the condensate make-up equipment presented a statisfactory function within a short time. After putting the power plant into service the condensate make-up equipment delivered an adequately clean condenste. The clefts arising under certain operational circumstances caused a weaker quality at the onfloating, but they could be eliminated in a short time. The comparison of costs with the mix-bed filters points out to the advantages of the onfloated filters until 500 l/h condenser leakage. (author)

[en] The main trends of nuclear power researches in the Federal Republic of Germany are analysed. All aspects of the nuclear power engineering are touched and the activities of several research institutions are outlined. (R.J.)

[en] In order to get the required water quality the secondary sides of the steam generators have to be blown down. The blown down water quantity of the 1300 MW power plant is led through a 10 kg/s throughput capacity equipment consisting of two branches provided with an electromagnetic filter each and a mixed bed filter cleaned back to the cycle. To diminute the operational temperature of 280 deg C to the cleaning temperature of 50 deg C an evaporator and a condensate cooler are switched before the equipment. The electromagnetic filter precipitates the ferromagnetic iron oxides (magnetite) with a high filtering velocity. The reflashing by a demagnatized half-filling lasts about a minute. The regeneration is performed by sulphuric acid and sodium hydroxide. (author)

[en] Some components of the WWER-1000 type reactor block are briefly described, including the reactor vessel, the circulating loops of the primary circuit and the turbogenerator, the regeneration system and the feed-water system of the secondary circuit. Their main parameters are given. The safety systems consisting of the electricity and water supply and the monitoring-control systems are based on the principle of three independent lines. The operating principle of the 'passive' safety systems (e.g. containment) is also discussed. (V.N.)

[en] An automatic measuring system was developed for detecting the failures of fuel element sheaths of WWER-type nuclear reactors. The radioactive fission products getting into the cooling water of primary loops are detected without sampling by a continuously working automatic spectrometer system. The fission products to be measured are selected based on previous measurements, experiences of presently operating WWER reactors and on a practically defined criterium for the reliable detectability of gamma lines. The block scheme of the measuring system and some considerations concerning its sensibility are given. The parts and performances of analog and digital subsystems and data acquisition CAMAC moduls are discussed. The semi-automatic prototype of the system will be used in the Paks-1 reactor and the operation experiences will be utilized for the development of a final model. (D.Gy.)

[en] The steam wetness at the entrance of steam turbines in nuclear power plants has to be held expediently low. Therefore a continuous control of steam wetness is of great importance. In the Biblis nuclear power plant this continuous control of operation has been carried out by means of a chemical method beside which the method of throttle calorimeter has been applied, too. During the acceptance test a third method based on light-scattering technique was used. This study presents a report about the experiences gained by applying the three measuring methods as well as the results of the measurements, their accuracy and reliability. (author)