No abstract available

No abstract available

[en] The balances consist of a radiation detector, tachodynamo, pulse generator and a recording unit. The radioizotope sensor output is connected through a correcting counter to a resettable counter whose presetting input is connected to one of the outputs of the pulse generator, and the other input is connected to the information input of the accumulating counter. The tachodynamo output is connected to the pulse generator input of the accumulating counter whose output is connected to the recording unit

[en] A review of neutron-physical studies on assessment of core design loading patterns executed in the WWER-440 units of Kozloduy NPP in order to assure safe and reliable reactor performance is made. The studies are done by means of SPPS-1.6, a 3D two-group neutron diffusion code for hexagonal fuel assemblies and HEXAB-2D, four-group fine-mesh diffusion code. Validation data showing adequate prediction of the reactivity effects, the Doppler and xenon poisoning effects and temperature reactivity coefficients are presented. The neutron-physical studies are performed according to the following methodological stages: 1) Loading pattern optimization. The WWER-440 of units 1,2 and 3 are operated at reduced core, with 36 dummy assemblies in the period 1978-1988, in order to reduce fast neutron flux to the reactor pressure vessel. 2) Assessment of compliance with all nuclear safety criteria. A comparison was made between between the admissible limit values of the core power peaking factors and the calculated ones. 3) basic neutron-physical calculations on fuel loading cycle in compliance with all reactor operating conditions and preparation of the final nuclear design report. The conclusions drawn are: the deviation of initial concentration of boric acid is less than 0.2 g/kg; the isothermal temperature reactivity coefficient measured is negative in the interval 250^oC - 260^oC and is in coincidence with the calculated results; the integral and differential worths of the working ACA group are higher than the calculated ones, but the difference is within the test criterion. 4 figs., 8 refs. 12 tabs

[en] The development of MELCOR 1.8.4 input data for units 5 and 6 of Kozloduy NPP (KNPP), for severe accident calculations, was initiated at Argonne National Laboratory (USA). After a transferring program performance, the input data was delivered to KNPP. The current activities continue in analytical studies of MELCOR capabilities to calculate VVER-1000 severe accidents. The status of development allows pursuing of two goals: The first one is testing of MELCOR Computer Code capabilities to model VVER-1000 equipment. The second one is: training of plant analysts to perform safety analyses and self-teaching on the obtained results reading for the purpose of their analytical skills improvement. The presented nodalization scheme of detailed input data includes four loops modelling of primary, secondary circuits and detailed nodalization of containment. Implementation of such expanded of size input data was possible after extension of MELCOR computer code internal arrays. In order to analyze the results of calculation, seven new variables were implemented in the code. To distinguish the expanded version from standard MELCOR v1.8.4, it was named MELCOR/ANL. Initialization procedure, which includes the use of CVHTENDINI variable, is presented. The total initialization time duration is 2500s. Two groups of cases are analyzed. The first one is related to use of non-equilibrium CVH switch in Steam Generators (SG) modelling. The second one is related to use of CVH equilibrium switch in SGs model. Each group consists of three analyzed cases, where CVHTENDINI is equal correspondingly to: 0.0s, 900.0s, 1500.0s. Comparison of calculated and measured parameters at nominal power conditions is performed. The conclusion is that calculated values are very close to designated uncertainty ranges of measured parameters. The SGs flow rate demonstrates an exception, because it shows significant deviation from the designed values. Currently, there is no explanation for relative deviations of 14.8/14.7%. Discussion about the transferring of power to SG, total energy error in COR package, primary pressure, coolant level in pressurizer during initialization addresses specific issues to MELCOR input data for VVER-1000. The corresponding conclusions are withdrawn. (author)

[en] We investigate in detail the Mikheyev-Smirnov-Wolfenstein explanation of the solar neutrino puzzle using analytical expressions for the neutrino transition probabilities in matter with exponentially varying electron number density

No abstract available

[en] The influence of hyperfine interactions (deorientation of the nuclear angular momentum) on the results obtained by means of coincidence RDDS measurements is investigated. It is analytically shown that if the data are analyzed with the differential decay curve method (DDCM) the lifetimes derived are not affected by the deorientation provided the gates are set on transitions which feed directly the level of interest. With gates set higher in the cascade, the arising error is expected to be rather small. ((orig.))

[en] Radioisotope functional investigations of the thyroid gland were carried out with weaned lambs and pigs. The ₁₃₁I captation capacity of the thyroid gland was studied to characterize the inogranic phase of iodine exchange. The evaluation of the hormone producing function of the thyroid gland required the determination of the level of the protein-bound ₁₃₁ I (PB ₁₃₁ I), T³-binding capacity of the thyroxin-binding globulin (TBG) and the ratio of the T³-binding capacity of TBG and the free thyroxine (T⁴) calculated as the FT⁴ index.Established was the species peculiarity of the ₁₃₁ I captation capacity of the thyroid gland in weaned lambs and pigs in the early phases of investigation. At the second hour the percent captation was calculated as 7.2+-0.8 and 1.11+-0.21%, respectively. The values of PB ₁₃₁ I, T³-binding capacity of TBG and FT⁴ of pigs varied within the limits of 1.20+-0.05%, 0.605+-0.012, and 0.976+-0.015 and of weaned lambs they were 0.954+-0.009%, 0.912+-0.017 and 0.890+-0.03. (authors)

[en] The purpose of this publication is to assess the residual resource of evaporator of the Reactor Water Cleanup System (RWCS) 3 of the Kozloduy NPP Unit 1 and 2. This assessment includes an estimate of cyclic strength, mechanical stresses calculation, thermal stresses calculation as well as calculation of the facility resource. In this assessment the correction of data obtained from destructive testing is also considered. Strength calculations of evaporator's components are made in accordance with the legislative requirements and the results are analyzed. The performed calculations indicate that: 1) at 8 mm thickness of the cylindrical part and 10 mm bottom, strength is secured, in case of no breach in the metal structure, 2) the actual voltages are very close to the maximum and needs to be done additional non-destructive testing in several areas, 3) because of the hot chamber is relatively new (less than 5 years), detailed calculations or further inquiries are not required