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An assessment of the methods for determining defect or failure fractions in HTGR coated particle fuels and their relationship to particle microstructure

Description: The methods for determining the fraction of defective or failed coatings in high-temperature gas-cooled reactor (HTGR) fuel particles, the burn-leach and acid leach methods, are critically analyzed. Evaluation of the method reveals that (1) the efficacy of the methods is limited by access, for leaching and oxidizing fluids, to the interior of defective or failed coatings; (2) the coating defects can be characterized in terms of pores by a distribution of effective pore radii; (3) effective pore radii significantly less than several, hundred nanometers cannot be detected; and (4) pore radii less than the latter limit may contribute significantly to fission product release from the defective or failed particles. The currently used methods are thus inadequate for detecting defective or failed fuel particle coatings. The development of better methods is recommended; the intrusion method, by which a portion of the distribution of effective pore radii was determined in the analysis from limited previous measurements, is suggested as one suitable basis for the development. 32 refs., 10 figs., 11 tabs.
Date: April 1989
Creator: Meyers, B. F.
Partner: UNT Libraries Government Documents Department

Core refueling subsystem design description. Revision 1

Description: The Core Refueling Subsystem of the Fuel Handling and Storage System provides the mechanisms and tools necessary for the removal and replacement of the hexagonal elements which comprise the reactor core. The Core Refueling Subsystem is not "safety-related." The Core Refueling Subsystem equipment is used to prepare the plant for element removal and replacement, install the machines which handle the elements, maintain control of air inleakage and radiation release, transport the elements between the core and storage, and control the automatic and manual operations of the machines. Much of the element handling is performed inside the vessel, and the entire exchange of elements between storage and core is performed with the elements in a helium atmosphere. The core refueling operations are conducted with the reactor module shutdown and the primary coolant pressure slightly subatmospheric. The subsystem is capable of accomplishing the refueling in a reliable manner commensurate with the plant availability requirements.
Date: July 1, 1987
Creator: Anderson, J.K. & Harvey, E.C.
Partner: UNT Libraries Government Documents Department

Proceedings of the Third International Workshop on the implementation of ALARA at nuclear power plants

Description: This report contains the papers presented and the discussions that took place at the Third International Workshop on ALARA Implementation at Nuclear Power Plants, held in Hauppauge, Long Island, New York from May 8--11, 1994. The purpose of the workshop was to bring together scientists, engineers, health physicists, regulators, managers and other persons who are involved with occupational dose control and ALARA issues. The countries represented were: Canada, Finland, France, Germany, Japan, Korea, Mexico, the Netherlands, Spain, Sweden, the United Kingdom and the United States. The workshop was organized into twelve sessions and three panel discussions. Individual papers have been cataloged separately.
Date: March 1995
Creator: Khan, T. A. & Roecklein, A. K.
Partner: UNT Libraries Government Documents Department

New concept of small power reactor without on-site refueling for non-proliferation

Description: Energy demand in developing countries is increasing to support growing populations and economies. This demand is expected to continue growing at a rapid pace well into the next century. Because current power sources, including fossil, renewable, and nuclear, cannot meet energy demands, many developing countries are interested in building a new generation of small reactor systems to help meet their needs. The U.S. recognizes the need for energy in the developing countries. In its 1998 Comprehensive Energy Strategy, the Department of Energy calls for research into low-cost, proliferation- resistant, nuclear reactor technologies to ensure that this demand can be met in a manner consistent with U.S. non-proliferation goals and policies. This research has two primary thrusts: first, the development of a small proliferation-resistant nuclear system (i.e., a technology focus); second, the continuation of open communication with the international community through early engagement and cooperation on small reactor development. A system that meets developing country requirements must: (1) achieve reliably safe operation with a minimum of maintenance and supporting infrastructure; (2) offer economic competitiveness with alternative energy sources available to the candidate sites; and (3) demonstrate significant improvements in proliferation resistance relative to existing reactor systems. These challenges are the most significant driving forces behind the LLNL proposed program for development of a new, small nuclear reactor system. This report describes a technical approach for developing small nuclear power systems for use in developing countries. The approach being proposed will establish a preliminary set of requirements that, if met, will cause new innovative approaches to system design to be used. The proposed approach will borrow from experience gained over the past forty years with four types of nuclear reactor technologies (LWR, LMR, HTGR, and MSR) to develop four or more pre-conceptual designs. The pre-conceptual designs will be used to confirm the ...
Date: July 13, 1998
Creator: Brown, N.W., LLNL
Partner: UNT Libraries Government Documents Department

Formulation of a possible advanced reactor legislative strategy and proposal

Description: A number of initiatives have been taken to date regarding the formulation of legislation to support in various ways the DOE advanced nuclear reactor program. Among the more prominent of these are bills that have been introduced by Sen. Johnston (D-La) and Rep. Udall (D-Az) as well as a draft bill put together by the nuclear industry and that could be introduced by Rep. Stallings (D-Id). These legislative initiatives are presented in this paper.
Date: December 31, 1994
Partner: UNT Libraries Government Documents Department

Validation of NESTLE against static reactor benchmark problems

Description: The NESTLE advanced modal code was developed at North Carolina State University with support from Los Alamos National Laboratory and Idaho National Engineering Laboratory. It recently has been benchmarked successfully against measured data from pressurized water reactors (PWRs). However, NESTLE`s geometric capabilities are very flexible, and it can be applied to a variety of other types of reactors. This study presents comparisons of NESTLE results with those from other codes for static benchmark problems for PWRs, boiling water reactors (BWRs), high-temperature gas-cooled reactors (HTGRs) and CANDU heavy- water reactors (HWRs).
Date: February 1, 1996
Creator: Mosteller, R.D.
Partner: UNT Libraries Government Documents Department

A Gas-Cooled Reactor Surface Power System

Description: A human outpost on Mars requires plentiful power to assure survival of the astronauts. Anywhere from 50 to 500 kW of electric power (kWe) will be needed, depending on the number of astronauts, level of scientific activity, and life- cycle closure desired. This paper describes a 250-kWe power system based on a gas-cooled nuclear reactor with a recuperated closed Brayton cycle conversion system. The design draws upon the extensive data and engineering experience developed under the various high-temperature gas cooled reactor programs and under the SP-100 program. The reactor core is similar in power and size to the research reactors found on numerous university campuses. The fuel is uranium nitide clad in Nb 1 %Zr, which has been extensively tested under the SP-I 00 program The fiel rods are arranged in a hexagonal array within a BeO block. The BeO softens the spectrum, allowing better use of the fbel and stabilizing the geometty against deformation during impact or other loadings. The system has a negative temperature feedback coefficient so that the power level will automatically follow a variable load without the need for continuous adjustment of control elements. Waste heat is removed by an air-cooled heat exchanger using cold Martian air. The amount of radioactivity in the reactor at launch is very small (less than a Curie, and about equal to a truckload of uranium ore). The system will need to be engineered so that criticality cannot occur for any launch accident. This system is also adaptable for electric propulsion or life-support during transit to and from Mars.
Date: November 9, 1998
Creator: Harms, G.A.; Lenard, R.X.; Lipinski, R.J. & Wright, S.A.
Partner: UNT Libraries Government Documents Department

The effect of water vapor on the release of fission gas from the fuel elements of high temperature, gas-cooled reactors: A preliminary assessment of experiments HRB-17, HFR-B1, HFR-K6 and KORA

Description: The effect of water vapor on the release of fission gas from the fuel elements of high temperature, gas-cooled reactors has been measured in different laboratories under both irradiation and post irradiation conditions. The data from experiments HRB-17, HFR-B1, HFR-K6, and in the KORA facility are compared to assess their consistency and complimentarily. The experiments are consistent under comparable experimental conditions and reveal two general mechanisms involving exposed fuel kernels embedded in carbonaceous materials. One is manifest as a strong dependence of fission gas release on the partial pressure of water vapor below 1 kPa and the other, as a weak dependence above 1 kPa.
Date: September 1, 1995
Creator: Myers, B.F.
Partner: UNT Libraries Government Documents Department

Licensed operating reactors: Status summary report data as of December 31, 1991. Volume 16

Description: The Nuclear Regulatory Commission`s annual summary of licensed nuclear power reactor data is based primarily on the report of operating data submitted by licensees for each unit for the month of December because that report contains data for the month of December, the year to date (in this case calendar year 1991) and cumulative data, usually from the date of commercial operation. The data is not independently verified, but various computer checks are made. The report is divided into two sections. The first contains summary highlights and the second contains data on each individual unit in commercial operation. Section 1 capacity and availability factors are simple arithmetic averages. Section 2 items in the cumulative column are generally as reported by the licensee and notes as to the use of weighted averages and starting dates other than commercial operation are provided.
Date: March 1, 1992
Partner: UNT Libraries Government Documents Department

On the benefits of an integrated nuclear complex for Nevada

Description: An integrated nuclear complex is proposed for location at the Nevada Test Site. In addition to solving the nuclear waste disposal problem, this complex would tremendously enhance the southern Nevada economy, and it would provide low cost electricity to each resident and business in the affected counties. Nuclear industry and the national economy would benefit because the complex would demonstrate the new generation of safer nuclear power plants and revitalize the industry. Many spin-offs of the complex would be possible, including research into nuclear fusion and a world class medical facility for southern Nevada. For such a complex to become a reality, the cycle of distrust between the federal government and the State of Nevada must be broken. The paper concludes with a discussion of implementation through a public process led by state officials and culminating in a voter referendum.
Date: January 1, 1994
Creator: Blink, J.A. & Halsey, W.G.
Partner: UNT Libraries Government Documents Department