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Title: Independent Safety Assessment of the TOPAZ-II space nuclear reactor power system (Revised)

Abstract

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.

Publication Date:
Research Org.:
USDOE Assistant Secretary for Nuclear Energy, Washington, DC (United States)
Sponsoring Org.:
USDOE, Washington, DC (United States)
OSTI Identifier:
140934
Report Number(s):
DOE/NE-0001P
ON: DE94008653; TRN: 94:006526
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: Sep 1993
Country of Publication:
United States
Language:
English
Subject:
22 NUCLEAR REACTOR TECHNOLOGY; 21 NUCLEAR POWER REACTORS AND ASSOCIATED PLANTS; TOPAZ REACTOR; LAUNCHING; SAFETY ANALYSIS; POWER SYSTEMS

Citation Formats

NONE. Independent Safety Assessment of the TOPAZ-II space nuclear reactor power system (Revised). United States: N. p., 1993. Web. doi:10.2172/140934.
NONE. Independent Safety Assessment of the TOPAZ-II space nuclear reactor power system (Revised). United States. doi:10.2172/140934.
NONE. Wed . "Independent Safety Assessment of the TOPAZ-II space nuclear reactor power system (Revised)". United States. doi:10.2172/140934. https://www.osti.gov/servlets/purl/140934.
@article{osti_140934,
title = {Independent Safety Assessment of the TOPAZ-II space nuclear reactor power system (Revised)},
author = {NONE},
abstractNote = {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.},
doi = {10.2172/140934},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Wed Sep 01 00:00:00 EDT 1993},
month = {Wed Sep 01 00:00:00 EDT 1993}
}

Technical Report:

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  • 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 ofmore » the core configuration. Core configuration constraints were therefore not established for radiologically cold reentry accidents.« less
  • Models based on the TDS thermionic diode model were developed for the TOPAZ II and SPACE-R nuclear power systems. Due to computer code limitations inherent in the TDS model, only the TOPAZ II system model ran successfully. Several parameter studies were conducted on the TOPAZ II model. These studies determined system performance and efficiency while varying the following: (1) the coolant flow inlet temperatures; (2) the rate of coolant temperature change; (3) the power profile of the core; and (4) the cesium reservoir temperature. Analysis of the results indicate that the model accurately represented the TOPAZ II system, underestimating publishedmore » data by 10%. Coolant flow parameter studies indicate that raising coolant flow temperatures up to 100 K higher increases system power by put to 5%. Additional increases in temperature result in gradual performance degradation. Varying the axial power profile of the core from the actual peaked profile to a flat profile results in a negligible 0.3% change in total system performance. The peaked profile used in TOPAZ II produces the highest system efficiency of all the profiles modeled. The cesium pressure study indicates that the system is operating above optimum cesium pressure and that system performance is strongly dependent on cesium pressure. Increasing cesium reservoir temperature above design temperature by 30 K decreases system efficiency by 30%.« less
  • Models based on the TDS thermionic diode model were developed for TOPAZ II and SPACER nuclear power systems. Several parameter studies were conducted with the TOPAZ II model. These determined system performance and efficiency while varying the following: (1) Coolant flow inlet temperatures. (2) Rate of coolant temperature change. (3) Power profile of the core. (4) Cesium reservoir temperature. Analysis of results indicate the model accurately represented the TOPAZ II system, underestimating published data by 10%. Coolant flow studies indicate that raising coolant temperatures up to 100 K higher increases system power by up to 5%. Additional increases in temperaturemore » result in gradual performance degradation. Varying the axial power profile of the core from the actual peaked profile to a flat profile results in a negligible 0.3% change in system performance. The peaked profile used in TOPAZ II produces the highest system efficiency of all the profiles modeled. The cesium pressure study indicates the system is operating above optimum cesium pressure and system performance is strongly dependent on cesium pressure. Increasing cesium reservoir temperature above design temperature by 30 K decreases system efficiency by 30%.« less
  • The United States (US) Strategic Defense Initiative Organization (SDIO) decided to investigate the possibility of launching a Russian Topaz II space nuclear power system. A preliminary nuclear safety assessment was conducted to determine whether or not a space mission could be conducted safely and within budget constraints. As part of this assessment, a safety policy and safety functional requirements were developed to guide both the safety assessment and future Topaz II activities. A review of the Russian flight safety program was conducted and documented. Our preliminary nuclear safety assessment included a number of deterministic analyses, such as; neutronic analysis ofmore » normal and accident configurations, an evaluation of temperature coefficients of reactivity, a reentry and disposal analysis, an analysis of postulated launch abort impact accidents, and an analysis of postulated propellant fire and explosion accidents. Based on the assessment to date, it appears that it will be possible to safely launch the Topaz II system in the US with a modification to preclude water flooded criticality. A full scale safety program is now underway.« less
  • The feasibility of upgrading the power of the Heat Pipe Space Nuclear Reactor (HPSNR) system design was investigated. This report discusses the four primary methods for power upgrading: increasing the thermal power output to the reactor core, pulse-mode operation, improving the heat rejection, and improving the thermal-to-electric energy conversion.