[en] Topaz stone irradiation is one of the targets of interest from foreign stakeholders, while the irradiation position available in the RSG-GAS reactor is the Irradiation Position (IP) position (B-6, D-9, E-4, G-7) and outcore, but the outcore position results are not satisfactory. To meet the safety limits of reactivity disturbances, a safety analysis of topaz irradiation reactivity in 4 Irradiation Position positions with variations in topaz capsule height from 15 cm to 100 cm height is needed. Thermalhydraulic interference is neglected because topaz stone is irradiated with an open capsule which immediately gets a coolant flow from the reactor coolant water. This study is a follow-up study that has been done before. The methodology used was to analyze topaz irradiation reactivity at 4 IP positions with high variation from 15 cm to 100 cm which were included with the U-235 low enrichment target of 3 grams in the position of Central Irradiation Position (CIP) D-6 and E-7. Irradiated topaz target modeling is divided into 3 parts, namely capsule guide, topaz capsules and topaz target stone with high variation every 15 cm. The diffusion group constants from modeling use the WIMSD-5B program and the results are used to calculate the reactivity with the BATAN -2DIFF program. From the results of calculating the reactivity of topaz stone with a high variation of up to 100 cm, the optimum is at the height of 60 cm topaz capsules or equivalent to 14862.6 grams of topaz stone and obtained a reactivity of 1.5175 % Δk/k and the peak radial power factor are 1.2765, it still meets the operational safety limit requirements. (author)

[en] The Independent Safety Assessment described in this study report was performed to assess the safety of the design and launch plans anticipated by the U.S. Department of Defense (DOD) in 1993 for a Russian-built, U.S.-modified, TOPAZ-II space nuclear reactor power system. Its conclusions, and the bases for them, were intended to provide guidance for the U.S. Department of Energy (DOE) management in the event that the DOD requested authorization under section 91b. of the Atomic Energy Act of 1954, as amended, for possession and use (including ground testing and launch) of a nuclear-fueled, modified TOPAZ-II. The scientists and engineers who were engaged to perform this assessment are nationally-known nuclear safety experts in various disciplines. They met with participants in the TOPAZ-II program during the spring and summer of 1993 and produced a report based on their analysis of the proposed TOPAZ-II mission. Their conclusions were confined to the potential impact on public safety and did not include budgetary, reliability, or risk-benefit analyses

[en] An analysis was performed to investigate the effect of disassembling the radial reflector of the TOPAZ-II space nuclear reactor following a postulated reactivity initiated accident (RIA). In this RIA, the control drums, starting in the full-in position, are assumed to run out at their maximum speed of 1.4 degrees/s to their full-out position and remain out. This noncredible event occurs because of a malfunction in the drive mechanism of the control drums. Results indicate that the disassembly of only 3 of 12 radial reflector panels would successfully shut down the reactor with little overheating of the fuel and the moderator. 16 refs., 15 figs

[en] In December 1991, the Strategic Defense Initiative Organization decided to investigate the possibility of launching a Russian Topaz-2 space nuclear power system. Functional safety requirements developed for the Topaz mission mandated that the reactor remain subcritical when flooded and immersed in water. Initial experiments and analyses performed in Russia and the United States indicated that the reactor could potentially become supercritical in several water- or sand-immersion scenarios. Consequently, a series of critical experiments was performed on the Narciss M-II facility at the Kurchatov Institute to measure the reactivity effects of water and sand immersion, to quantify the effectiveness of reactor modifications proposed to preclude criticality, and to benchmark the calculational methods and nuclear data used in the Topaz-2 safety analyses. In this paper we describe the Narciss M-II experimental configurations along with the associated calculational models and methods. We also present and compare the measured and calculated results for the dry experimental configurations

[en] Some applications of orbit transfer with Topaz-type reactors are discussed (AIP)

No abstract available

[en] This paper presents the results of a design calculation to compute the 3-dimensional geometry of the TOPAZ reactor. Emphasis was given to the calculation of the temperature effects and temperature reactivity coefficients. Performance of the control and safety systems, spectral and dynamic characteristics were also evaluated

[en] The main purpose of the demonstration flight tests of two prototype Space Nuclear Power Systems (SNPSs) carried out on the COSMOS series spacecraft in 1987-88 in the TOPAZ program was to prove the working capacity of thermionic SNPSs in the space flight environment. The achieving of long lifetime was not an objective of the flight tests. The working orbit altitude guarantees the spacecraft orbital lifetime of not less than 350 years; enough for nuclear fission products decay to safe level in case of any failure in SNPS and spacecraft systems. The first prototype operated for 143 days, the second for 342 days. The cause of termination for both tests was the planned exhaustion of cesium in the vapor generator. The comparison of flight test data with ground SNPS test results leads to the conclusion that the space environment did not influence the SNPS basic processes and its performance. The flight tests confirmed the validity of basic structural decisions and control algorithm, and demonstrated that the thermionic SNPS is a viable electrical power source for spacecraft. 2 refs

[en] This report documents the reentry safety analyses conducted for the TOPAZ II Nuclear Electric Propulsion Space Test Program (NEPSTP). Scoping calculations were performed on the reentry aerothermal breakup and ground footprint of reactor core debris. The calculations were used to assess the risks associated with radiologically cold reentry accidents and to determine if constraints should be placed on the core configuration for such accidents. Three risk factors were considered: inadvertent criticality upon reentry impact, atmospheric dispersal of U-235 fuel, and the Special Nuclear Material Safeguards risks. Results indicate that the risks associated with cold reentry are very low regardless of the core configuration. Core configuration constraints were therefore not established for radiologically cold reentry accidents

[en] TOPAZ-II is a small-scale reactor which has compact design and high heterogeneity, and all these features make the deterministic codes unsuitable for this type of reactor. The burn-up calculation of TOPAZ-II was carried out using Monte Carlo code MVP-BURN which was developed by Japan Atomic Energy Agency (JAEA). And the detailed results were presented in this paper after a comprehensive calculation based on an applicable calculation scheme. The burn-up calculation scheme proposed in this paper can be used as a reference for the burn-up calculation of other similar reactors as well. (authors)