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[en] The derivation of a method to calculate the transient diffusion response in one-dimensional slab geometry is presented. The model developed is used to represent the fission-product diffusion process in the graphite moderator of an HTGR core. (U.S.)

[en] As part of technical assistance to the US Nuclear Regulatory Commission (NRC, 1), a systematic format for seismic equipment qualification (EQ) was initiated. This format consists of thirty issues associated with seismic EQ. Each issue was considered as a Category of Possible Seismic EQ Requirements and Criteria. That is, seismic EQ standards might be (but presently are not formulated in terms of requirements and criteria that address each of the thirty issues. Each of the thirty issues was ranked and a minimum set identified. The current requirements in existing NRC and national standards were also evaluated against this common set of issues, and they were estimated to score 60 out of 100 overall. It is believed that the systematic format exhibited in this paper can be of assistance in obtaining a broader and more complete perspective on seismic EQ issues. This format (but especially the technique) may also be of interest in non-seismic EQ since many of the issues are common

[en] A special purpose computer program, TRAFIC, is presented for calculating the release of metallic fission products from an HTGR core. The program is based upon Fick's law of diffusion for radioactive species. One-dimensional transient diffusion calculations are performed for the coated fuel particles and for the structural graphite web. A quasi steady-state calculation is performed for the fuel rod matrix material. The model accounts for nonlinear adsorption behavior in the fuel rod gap and on the coolant hole boundary. The TRAFIC program is designed to operate in a core survey mode; that is, it performs many repetitive calculations for a large number of spatial locations in the core. This is necessary in order to obtain an accurate volume integrated release. For this reason the program has been designed with calculational efficiency as one of its main objectives. A highly efficient numerical method is used in the solution. The method makes use of the Duhamel superposition principle to eliminate interior spatial solutions from consideration. Linear response functions relating the concentrations and mass fluxes on the boundaries of a homogeneous region are derived. Multiple regions are numerically coupled through interface conditions. Algebraic elimination is used to reduce the equations as far as possible. The problem reduces to two nonlinear equations in two unknowns, which are solved using a Newton Raphson technique

[en] A general purpose algorithm for integrating nonlinear systems of ordinary differential equations is presented. A number of specific applications are discussed, such as mixed linear/nonlinear problems, mixed transient/steady-state problems, and substructuring. The problem of integrating past singularities is briefly discussed. It is concluded that while the algorithm is easily derived in an elementary form, its efficient use in some of the more complicated problems requires a number of special considerations in the derivation and in the programming. Each specific application can probably benefit from custom treatment. Nevertheless, each application ultimately distills to the following essence: (1) The incremental predictor and corrector phases employ substantially the same steps. (2) The predictor phase is a modified implicit extrapolation of the current rates. (3) The corrector phase is a modified Newton's method based on the residual of a vector function. (4) In partially linear problems one can save steps by matrix partitioning. (5) The frequency of updates of the tangent matrix is arbitrary, and the calculational efficiency can be optimized by simultaneously varying the size of the time step and the frequency of the matrix updates

[en] The Automated Transportation Management System (ATMS) Software User Guide (SUG) constitutes the user procedures for the ATMS System. Information in this document will be used by the user to operate the automated system. It is intended to be used as a reference manual to guide and direct the user(s) through the ATMS software product and its environment. The objectives of ATMS are as follows: to better support the Procurement function with freight rate information; to free Transportation Logistics personnel from routine activities such as the auditing and input of freight billing information; to comply with Headquarters Department of Energy-Inspector General (DOE-IG) audit findings to automate transportation management functions; to reduce the keying of data into the Shipment Mobility Accountability Collection (SMAC) database; and to provide automation for the preparing of Bill of Lading, Declaration of Dangerous Goods, Emergency Response Guide and shipping Labels using HM181 Retrieval of hazardous material table text information

[en] The one-dimensional computer program PADLOC is designed to analyze steady-state and time-dependent plateout of fission products in an arbitrary network of pipes. The problem solved is one of mass transport of impurities in a fluid, including the effects of sources in the fluid and in the plateout surfaces, convection along the flow paths, decay, adsorption on surfaces (plateout), and desorption from surfaces. These phenomena are governed by a system of coupled, nonlinear partial differential equations. The solution is achieved by (a) linearizing the equations about an approximate solution, employing a Newton Raphson iteration technique, (b) employing a finite difference solution method with an implicit time integration, and (c) employing a substructuring technique to logically organize the systems of equations for an arbitrary flow network

[en] A study on the feasibility of using experience data on the performance of equipment in nonnuclear facilities during earthquakes found that such data would be quite useful, if they were developed, in addressing issues concerning the seismic qualification of equipment in operating nuclear power plants located in the eastern United States. Guidelines and criteria for the use of these data were also developed. Thirty possible issues associated with seismic qualification of equipment were identified and ranked, and the current seismic equipment qualification requirements evaluated against each of these issues. These results and this technique are also believed to be of use in areas beyond experience data and seismic issues such as in general EQ

[en] Two constitutive models for concrete are discussed. For short-term loads, the orthotropic variable modulus model is described, and for long-term loads a viscoelastic model utilizing a Dirichlet series approximation for the creep compliance function is summarized. The orthotropic variable modulus model is demonstrated in an analysis of a PCRV head with penetrations. The viscoelastic model is illustrated with a simulation of a prestressed concrete cylinder subject to non-uniform temperatures

[en] A study of transient stress wave propagation in graphite HTGR fuel elements has been undertaken as a step toward developing techniques for the evaluation of seismic impact loads. The objectives of the study were to identify appropriate numerical methods, to understand the influence of the geometry and the multiple holes on the response, and to determine the relative importance of high frequency response and lower mode vibrations. A general review is made of the dynamic contact problem, and the methods available to model impact phenomena and stress wave propagation are evaluated