[en] Setting limits on human exposure to space-related radiation involves two very different processes - the appropriate hard science, and certain emotional aspects and expectations of the groups involved. These groups include the general public and their elected politicians, the astronauts and flight crews, and NASA managers, each group with different expectations and concerns. Public and political views of human space flight and human radiation exposures are often poorly informed and are often based on emotional reactions to current events which may be distorted by 'experts' and the media. Career astronauts' and cosmonauts' views are much more realistic about the risks involved and there is a willingness on their part to accept increased necessary risks. However, there is a concern on their part about career-threatening dose limits, the potential for overexposures, and the health effects from all sources of radiation. There is special concern over radiation from medical studies. This last concern continues to raise the question of 'voluntary' participation in studies involving radiation exposure. There is greatly diversity in spaceflight crews and their expectations; and 'official' Astronaut Office positions will reflect strong management direction. NASA management has its own priorities and concerns and this fact will be reflected in their crucial influence on radiation limits. NASA, and especially spaceflight crews, might be best served by exposure limits which address all sources of spaceflight radiation and all potential effects from such exposure. radiation and all potential effects from such exposure

[en] The objective of this project is to develop a software tool for use by personnel who must select a surface decontamination technique. The software will incorporate performance data for available surface decontamination techniques. The major activities in the project are broken down as follows: Task 1 - Complete decision tree development. Task 2 - Literature search for surface decontamination reports. Task 3 - Compilation of database from literature data. Task 4 - Sensitivity analysis and model design. Task 5 - Design of model data structures. Task 6 - PC software design and coding

[en] With help of Glauber-Sitenko's theory of multiplicity diffraction scattering a calculation of differential cross section of elastic scattering of hadrons on ⁹ Be nucleus in 2αN model under intermediate energies is carried out. It is shown a principal possibility of exactly analytical calculation of matrix elements for elastic π ⁹ Be scattering amplitude in general form

[en] A methodology for obtaining high resolution crystal structure potential distribution from electron microscope images of defects is presented. The technique is based on the inversion multislice procedure when extended to non-periodic wavefields. The sensitivity of the method to the defect model and position in the crystal is examined briefly. This investigation suggests that if a defect similar to the ones modelled here actually exists and is sufficiently immobile, then it could be detected in HRTEM images and its structure could be deduced by the methods of wavefield retrieval and inversion as presented here. Further the recovered structure should enable the configuration of the object to be distinguished from amongst feasible contenders. A major shortcoming of this study is that it requires a good estimate of the crystal thickness and of the position of the defect; also the effects of diffuse-diffuse couplings between diffuse-scattered beams that would be present in defects that are less localised than that modelled here, and are extended in the direction of the electron beam, may need to be considered in future investigations. (authors)

[en] Annual report of VATESI - Lithuanian Nuclear Safety Authority's activity in 1997 is presented. According to the prescribed responsibilities by the Law on Nuclear Energy and by the statute, VATESI's main fields of activities in 1997 were evaluation of the safety of Ignalina NPP, supervision of Ignalina NPP's operational safety, control of the implementation of safety improvement program SIP-2 in Ignalina NPP, preparation for the licensing of the unit No.1 of Ignalina NPP, accountancy and control of nuclear materials, regulation of radioactive waste management. Detailed description of all these activities is provided in the report. Important role of international assistance and cooperation is emphasized also. Year 1997 was safe for the operation of Ignalina NPP: there were no safety significant events according to the INES scale, only three events received qualification as level 1 events. In 1997 there was completed SAR of Ignalina NPP, its review report RSR and those were presented to the authorities. Taking into account all recommendations of SAR and RSR a new safety improvement program SIP-2 was made and started implemented

[en] A study of irradiation creep in vanadium-base alloys is underway with experiments in the Advanced Test Reactor (ATR) and the High Flux Isotope Reactor (HFIR) in the United States. Test specimens are thin-wall sealed tubes with internal pressure loading. The results from the initial ATR irradiation at low temperature (200--300 C) to a neutron damage level of 4.7 dpa show creep rates ranging from ∼0 to 1.2 x 10^-5/dpa/MPa for a 500-kg heat of V-4Cr-4Ti alloy. These rates were generally lower than reported from a previous experiment in BR-10. Because both the attained neutron damage levels and the creep strains were low in the present study, however, these creep rates should be regarded as only preliminary. Substantially more testing is required before a data base on irradiation creep of vanadium alloys can be developed and used with confidence

[en] Before the parametric dependencies of irradiation creep can be confidently determined, analysis of creep data requires that the various creep and non-creep strains be separated, as well as separating the transient, steady-state, and swelling-driven components of creep. When such separation is attained, it appears that the steady-state creep compliance, B_o, is not a function of displacement rate, as has been previously assumed. It also appears that the formation and growth of helium bubbles under high helium generation conditions can lead to a significant enhancement of the irradiation creep coefficient. This is a transient influence that disappears as void swelling begins to dominate the total strain, but this transient can increase the apparent creep compliance by 100--200% at relatively low (≤20) dpa levels

[en] Neutron dosimetry measurements have been conducted for various positions of the High Flux Beam Reactor (HFBR) at Brookhaven National Laboratory (BNL) in order to measure the neutron flux and energy spectra. Neutron dosimetry results and radiation damage calculations are presented for positions V10, V14, and V15

[en] The US specimen matrix for the collaborative DOE/Monbusho HFIR 13J varying temperature irradiation capsule contains two ceramics and 29 different metals, including vanadium alloys, ferritic/martensitic steels, pure iron, austenitic stainless steels, nickel alloys, and copper alloys. This experiment is designed to provide fundamental information on the effects of brief low-temperature excursions on the tensile properties and microstructural evolution of a wide range of materials irradiated at nominal temperatures of 350 and 500 C to a dose of ∼5 dpa. A total of 340 miniature sheet tensile specimens and 274 TEM disks are included in the US-supplied matrix for the irradiation capsule

[en] Two studies were conducted in the peri-urban area of Dakar to collect baseline information on feeding, milk production, reproduction, body weight and body condition (Phase I), and to examine the influence of supplementation with local by-products on productive and reproductive parameters of indigenous cattle in traditional smallholder farms (Phase II). Baseline data collected from smallholder farms between 1994 and 1996 indicated delayed first calving, long calving intervals, decreasing body condition score (BCS) and body weight and low milk yields as major problems associated with cattle productivity in the region. Fertility was related to forage availability; animals showed high fertility after the rainy season and low fertility during the dry season. Supplementation during the critical period of the dry season using agro-industrial by-products (brewer's grains, molasses, groundnut cake, oyster shell and salt) had beneficial effects on productivity. Supplementation reduced loss in body weight and body condition, maintained milk yield and growth rate of the calves during the dry season and reduced length of 'days open' and the calving interval. (author)