[en] Assembly homogenized cross sections are computed in a reference situation where approximated boundary conditions are introduced to emulate the effect of the assembly environment in the reactor core, and leakage is used to achieve criticality. The leakage model is an essential part in this approach to assembly homogenization for reactor core calculations. This note discusses leakage models that are presently available in the transport codes APOLLO2 and ECCO. In both codes, the concept of Laplacian has been used to develop homogeneous as well as heterogeneous leakage models. In the homogeneous approach, critically is achieved via an absorption term proportional to the scalar flux, and the corresponding leakage coefficients are computed in an equivalent homogeneous medium. On the other hand, in a heterogeneous model critically is obtained with a leakage term produced by a macroscopic current that is defined per region and per group. In the heterogeneous models the scalar flux and the macroscopic current obey a system of coupled integral equations, and the corresponding numerical values must be simultaneously determined by external iterations. (author)

[en] This thesis deals with three different fields of plasma physics. In the first part, we studied free expansion of an ionised uranium vapour generated in an electron beam evaporator. The electron temperature and the electron density of the expanding plasma have been measured by a Langmuir probe. The experimental results have been compared with the ones obtained by numerical simulation using a fluid code. The calculated points are in the error bars. We observe that there are two electron populations with different temperatures, which undergo a mixing during the plasma expansion. The neutral density influence on the electron temperature by collisional relaxation is also studied. The second part deals with a plasma diagnostic which can replace Langmuir probe in the case of a cold magnetized plasma: the resonance cone phenomenon. After recalling the wave propagation theory in a cold plasma, we introduce a new calculation of the potential radiated by an antenna in a collisional magnetized plasma. The domain where the resonance cone exists in considerably reduced because of collisions. More of that, the cone angle is reduced by this phenomenon too. The experiments performed show that we must take into account a wave turbulence phenomenon to explain the High collision frequency that we observe. The third part is about the study of the expansion of a plasma into another one. We solve this problem with fluid codes and Particle-In-Cell (PIC) code. THe electron families have a counter stream motion locally. Then, we study the electrostatic extraction of two plasmas-one pulsed, one continuous-in which we observe electron unfurling. (author)

[en] The collision dynamics of He single ionization by 3.6 MeV/u Se²⁸⁺ impact was explored using the GSI-reaction microscope, a high resolution integrated multi electron - recoil-ion momentum spectrometer. The complete three particle final state momentum distribution (9 cartesian components p_i) was imaged with a resolution of Δp_i ∼ ±0.1 a.u. by measuring the three momentum components of the emitted electron and the recoiling target-ion in coincidence. The projectile energy loss has been determined on a level of ΔE_p/E_p ∼ 10^-7 and projectile scattering angles as small as Δθ ∼ 10^-7rad became accessible. The experimental data which are compared with results of classical trajectory Monte-Carlo (CTMC) calculations reveal an unprecedented insight into the details of the electron emission and the collision dynamics for ionization of helium by fast heavy-ion impact. (orig.)

[en] The document reproduces the text of a letter dated 19 June 1997 received by the Director General of the IAEA from the Resident Representative of the People's Republic of China, regarding the continued participation of the Hong Kong Special Administrative Region of the People's Republic of China in the activities of the IAEA as from 1 July 1997

[en] Radioecological situation on the Kara-Zhira coal deposit is examined. The control and auxiliary measuring characteristics of situation in the Balapan site's district are carried out. A comparison of fission products activity with source activity of spent on fission substance making is conducted. The fission products activity has ben became less if the time of endurance is more than 200 years. The general description of radioecological situation characteristics is given. The existing fields of the contamination are not large by absolute density of contamination

[en] The Republican Scientific and Technical Program is developed for the study of radioecological situation on territory of the Semipalatinsk test site (STS) and carrying out of nature protecting measures on contaminated territories. The number of specific measures are undertaken. According this program 4500 sq.km of Abralj district is examined. It is noted, that the intensive economic activity has being conducted on hazardous zones of former Semipalatinsk test site territory. The population constantly complains on diseases, unemployment, and great mortality. There is extremely necessity of ban of the use of the territory of former STS for national economy without preliminary expertise. Ministry of public health, Ministry of finances and local state bodies must find means for opening rehabilitative centers and providing of existing hospitals with new apparatus and equipment

[en] The results of medical surveillance of 83 myocardial infraction sicks long time living in Kurchatov are given. Many of the sicks directly worked at the Semipalatinsk test site. Total there were 62 - man and 21 - women, with average age - 51,5 years old. It was established, that myocardial infraction has been developed at man of young and mature age and twice more exceed indexes of same age groups living in outside zone of radiation risk. The large-centre and transmural myocardial infraction form with hard course and protracted restoration is primly developed in Kurchatov

[en] The problem of ecological influence on health level, including dentistry is extremely actual. In this connection the attempt of study of Semipalatinsk region population's mouth status was undertaken. For assessment of dentistry status have been 9779 inhabitants of Abaj, Beskargaj, Zhana-Semej, Borodulikhinskij districts and Semipalatinsk city were examined. The 3289 inhabitants of Kokpekty district according WHO recommendations with use methodic of definition of dentistry level of health were examined also. The insensitivity of paradonta diseases by CPITN indexes is given. Diseases of mouth mucous most diagnose are adduced

[en] This report provides data on federal offshore operations for 1995. Information is included for leasing activities, development, petroleum and natural gas production, sales and royalties, revenue from federal offshore leasing, disbursement of federal revenues, reserves and resource estimates, and oil pollution in U.S. and international waters

[en] Materials Protection, Control, and Accounting (MPC ampersand A) upgrades have begun at the Institute of Theoretical and Experimental Physics (ITEP), a site that has significant quantities of direct-use nuclear materials. Cooperative work was initiated at this Moscow facility as a part of the U.S.-Russian Government-to-Government program to upgrade MPC ampersand A systems. An initial site visit and assessment was conducted in September 1996 to establish communication between ITEP and the U.S. Department of Energy (DOE) and the participating U.S. national laboratories. Subsequently, the parties reached an agreement to develop two master plans for MPC ampersand A upgrades. Los Alamos National Laboratory (LANL) and Oak Ridge National Laboratory (ORNL) would assist in developing a plan for Material Control and Accounting (MC ampersand A) upgrades, and Sandia National Laboratories (SNL) would assist in developing a plan for Physical Protection (PP) upgrades. The MC ampersand A plan included MC ampersand A training, a mass measurement program, nondestructive assay instrumentation, item identification (bar coding), physical inventory taking, and a nuclear materials accounting system. The PP plan included basic PP system design training, Central Alarm Station (CAS) location and equipment upgrades, site and critical-building access control system, intrusion detection alarm assessment, and guard force communications