505) 845-7977 MICHAEL TODOSOW BROOKHAVEN NATIONAL LABORATORY BLDG 701 UPTON, NY 11973 (516) 282-2445 ^ -S B o jj J* o i t^ B6 P e efl O *--*3» -^ ai 9 « O --60 (5 « rt 5 o fi S •a -S > ^ op ea 2 >^ •S ? -o ^ « " g <5 dp » S
Nuclear Thermal Propulsion (NTP) has been identified as a critical technology in support of the NASA Space Exploration Initiative (SEI). In order to safely develop a reliable, reusable, long-lived flight engine, facilities are required that will support ground tests to qualify the nuclear rocket engine design. Initial nuclear fuel element testing will need to be performed in a facility that supports a realistic thermal and neutronic environment in which the fuel elements will operate at a fraction of the power of a flight weight reactor/engine. Ground testing of nuclear rocket engines is not new. New restrictions mandated by the National Environmental Protection Act of 1970, however, now require major changes to be made in the manner in which reactor engines are now tested. These new restrictions now preclude the types of nuclear rocket engine tests that were performed in the past from being done today. A major attribute of a safely operating ground test facility is its ability to prevent fission products from being released in appreciable amounts to the environment. Details of the intricacies and complications involved with the design of a fuel element ground test facility are presented in this report with a strong emphasis on safety and economy.
A variety of approaches for handling effluent from nuclear thermal propulsion system ground tests in an environmentally acceptable manner are discussed. The functional requirements of effluent treatment are defined and concept options are presented within the framework of these requirements. System concepts diflfer primarily in the choice of fission-product retention and waste handUng concepts. TTie concept options considered range from closed cycle (venting the exhaust to a closed volume or recirculating the hydrogen in a closed loop) to open cycle (real time processing and venting of the effluent). This paper reviews the strengths and weaknesses of different methods to handle effluent from nuclear thermal propulsion system ground tests.
In this study we extend previous stochastic analyses of contaminant transport in geologic media for a single species to a chain of two species. Our particular application is the quantification of uncertainties due to lack of characterization of the spatial variability of hydrologic parameters on transport of radionuclides from a high‐level waste repository to the biosphere. Radionuclide chains can have a significant impact on demonstrating compliance (or violation) of standards regulating the release to the environment accessible to humans. Two approaches for determining the cross‐covariance terms in the mean concentration equations are presented. One uses a Taylor expansion to obtain the cross‐covariance between the velocity and concentration fluctuations, while the other is based on a Fourier‐Laplace double transform method. For the conditions of interest here, the differences between these two approaches are expected to be small. In addition, the variances are calculated in a unique way by solving another associated partial differential equation. A parametric study is carried out to examine the sensitivity of the mean concentration of the two species and their corresponding variances and cross‐covariance on the parameters associated with the structure of the stochastic velocity field. It is found that the dependent variables are most sensitive to the intensity and correlation length of the velocity fluctuations. The magnitude of the variances and cross‐covariance of the concentrations are proportional to the magnitude of the mean concentrations which depend on inlet concentration boundary conditions.
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