Download or read book Fuel Element Development Program for the Pebble Bed Reactor written by and published by . This book was released on 1961 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fuel Element Development Program for the Pebble Bed Reactor written by and published by . This book was released on 1959 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fuel Element Development Program for the Pebble Bed Reactor written by Sanderson & Porter, Inc and published by . This book was released on 1959 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerous types of high temperature ceramic fuel elements for the Pebble Bed Reactor are being evaluated. Specimens are 1-1/2 in diameter uranium graphite spheres with external coatings such as silicon carbide or pyrolytically deposited high density graphite and feul particle coatings such as alumina. Low diffusion product leakage rates at high temperatures have been observed for some of these coatings. High level irradiation damage to either the silicon carbide coating or the coating-graphite bond.

Download or read book Fuel Element Development Program for the Pebble Bed Reactor written by and published by . This book was released on 1961 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fuel Element Development Program for the Pebble Bed Reactor written by and published by . This book was released on 1960 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book FUEL ELEMENT DEVELOPMENT PROGRAM FOR THE PEBBLE BED REACTOR Final Report written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The basic fuel element consisted of a uniform dispersion of fuel in a 1 1/2 inch diameter graphite sphere. Ceramic coatings for the retention of fission products were studied. It was found-that molecularly deposited'' ceramics such as alumina, siliconized silicon carbide, and pyrolytic carbon were excellent barriers to fission product leakage. The most advantageous location for ceramic coatings was found to be on the individual fuel particles, where the coating was subject to smaller forces and where a larger thickness-todiameter ratio could be used than if the coating were on the surface of the graphite sphere. Fuel elements were irradiated to burnups ranging up to about 6 at.% U235. In all specimens containing a uniform dispersion of fuel, the graphite spheres were found to retain their structural properties after irradiation. Data are given on fuel particle coatings of A12O3, pyrolytic carbon, and metals: surface coatings of siliconized silicon carbide, pyrolytic carbon, and metal carbides; properties of and the effects of irradiation on graphite spheres; the use of natural graphite in preparing a high-density matrix material; graphite fueling by thorium nitrate infiltration; subsurface metal and metal carbide coatings for graphite; and an in-pile loop program on the behavior of fission products in a recycle helium stream. (auth).

Download or read book FUEL ELEMENT DEVELOPMENT PROGRAM FOR THE PEBBLE BED REACTOR A Topical Report on SUB SURFACE COATINGS FOR FUELED GRAPHITE SPHERES written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: An exploratory program on subsurface coatin8s for graphite fuel elements is summarized. A number of coatings with various melting points which could be located beneath the surface of a fueled graphite sphere were investigated. Of the materials with lower melting points. nickel and a special glass compound appeared to form continuous coatings when a hot-pressing technique was employed. Several materials with high melting points. such as Ti, Cr, and MoSi2, showed some promise, even though present equipment limitations prevented these specimens from being hot-pressed at the melting point of the coating. (W.L.H.).

Download or read book The Pebble Bed Reactor Program Current Fuel Element Developments and Their Effects on the Pebble Bed Reactor Development Program written by and published by . This book was released on 1960 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent fuel element irradiations demonstrated the structural integrity of spherical uranium-graphite fuel elements at burn-ups in excess of the design requirements of a 125 Mw(e) Pebble Bed Reactor (PBR) power plant. Other irradiations indicated the successful development of a coated fuel particle which permits fabrication of fuel elements meeting the PBR design objectives of a fission-product release rate (R/B)? 1°−6. beta plus gamma system activity in a 125 Mw(e) PBR is 490 c, assuming complete release of /sup lO-6/ of all fission products volatile at or below 2500 deg F. The low R/B being obtained from PBR fuel elements indicates that decay during diffusion of the short-lived volatile precursors of nonvolatile daughter products will result in further reduction of this system activity, and an increase in the average half life of the fission products remaining in the system will increase the efficiency of a bypass clean-up system. The method of fabricating coated particles by the hydrolysis of metallic chlorides to produce oxides or pyrolysis of hydrocarbons to produce carbon on a suitable substrate, is described, and preirradiation test results are given. An accelerated coated-fuel-particle program is discussed as well as development work on the Pebble Bed REactor concept as a whole. auth.

Download or read book FUEL ELEMENT DEVELOPMENT PROGRAM FOR THE PEBBLE BED REACTOR PHASE I Progress Report for May 1 1959 to October 31 1959 written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Numerous types of high temperature ceramic fuel elements for the Pebble Bed Reactor are being evaluated. Specimens are 1 1/2 in. diameter uranium graphite spheres with external coatings such as silicon carbide or pyrolytically deposited high density graphite and fuel particle coatings such as alumina. Low fission product leakage rates at high temperatures have been observed for some of these coatings. High-level irradiation has given no visible evidence of radiation damage to either the silicon carbide coating or the coating-graphite bond. (auth).

Download or read book FUEL ELEMENT DEVELOPMENT PROGRAM FOR THE PEBBLE BED REACTOR Quarterly Progress Report for February 1 to April 30 1960 written by and published by . This book was released on 1961 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Emphasis was shifted in the Pebble Bed Reactor (PBR) Fuel Element Development Program from coatings on the sphere surface to coatings on individual fuel particles as the major deterrent to fission-product leakage. In a highlevel irradiation test, cracks developed in the coatings of specimens coated with pyrolytic carbon and siliconized silicon carbide. In another high-level irradiation test, a graphiie sphere fueled with Al2O3-coated UO2 particles is showing excellent fission-product retention. The leakage factors for long-lived volatile flssion products such as Kr/sup 85m/, Kr87, Kr/sup 88/, Xe135 are ranging from 10−9 to 10−6. If this degree of fission-product retention is maintained in a large power reactor, it would result in essentially a "clean" primary loop. A simple crack in a fuelelement surface coating will permit the release of all of the volatile fission products in that specimen except those retained by the fuel particles. In view of the failures in surface-coated specimens tested to date, it appears to be a difficult task to ensure coating integrity in a large number of specimens because of their low thickness-to-diameter ratio and exposure to external loads on the fuel element. The test of a single specimen fueled with coated particles takes on added statistical significance, since about 500,000 "fuel elements" are actually being tested. The acceptability of graphite as a fuel-element matrix material was demonstrated when four types of graphite fueled with UO2 suffered no significant deterioration in structural properties after irradiation to about 6000 kwh which is above the present design objective of the 125 Mw(e) PBR. Thus the incorporation of coated fuel particles, having excellent fission-product retention, into a graphite sphere, having excellent structural properties, offers a simple, rugged fuel element capable of producing high coolant temperatures while retaining most of the fission products. It is this type of fuel element which will receive major emphasis during the remainder of the PBR Fuel Element Development Program. The study of the preparation of graphite blanket elements loaded with ThO2 by the thorium nitrate infiltration process was completed. It was found that graphite densities below 1.45 g/cc and more than five infiltration steps were required to achieve the desired ThO2 loading. A study of the use of natural graphite to produce high-density graphite bodies was started. Densities greater than 2.0 g/cc were produced in a single pressing. The design and construction of an in-pile loop to study fissionproduct behavior in a recycled helium stream were continued. (For preceding period see NYG-9057.) (auth).

Download or read book FUEL ELEMENT DEVELOPMENT PROGRAM FOR THE PEBBLE BED REACTOR Quarterly Progress Report for November 1 1959 to January 31 1960 written by and published by . This book was released on 1960 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: A variety of spherical uranium--graphite fuel elements for the Pebble Bed Reactor (PBR) was fabricated. Poor results with sintered alumina coated UO/ sub 2/ particles led to the development of slumina coating by vspor deposition, for which good results have been obtained. A variety of sub-surface metal, metal carbide, and ceramic coatings located between an unfueled graphite shell and the fueled core of a PBR fuel element was prepared and examined. Most of the materials and processes showed poor results. Excellent metal recoveries were achieved from the metal oxide--graphite system using the grind-leach technique of reprocessing. Test results on Si-- SiC coated fuel elements showed good fission product retention in neutron activation tests, a self-welding tendency between adjacent spheres at 2500 deg F surface temperature, and no evidence of failure when an interanl gas pressure of 300 psi was applied. Fission product release rates from a pyrolytic carbon coated specimen under low-level irradiation were obtained at 150 to 1900 deg F. The design of the in-pile loop to study the behavior of fission products escaping from PBR fuel elements wss established. (C.J.G.).

Download or read book FUEL ELEMENT DEVELOPMENT PROGRAM FOR THE PEBBLE BED REACTOR Phase II Summary Report November 1 1959 to October 31 1960 written by and published by . This book was released on 1961 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Coatings on the fuel element surface and coatings on individual fuel particles are being investigated for retaining fission products in fuel for the Pebble Bed Reacter. Ten fuel element specimens with surface coatings were subjected to varying amounts of high level irradiation. Cracks or pinholes were found in 6 of the coatings. Evidence indicated that the graphite matrix contributed to most of the failures. Release factors of the order of 10−9 for the Si--SiC coating under high-level irradiation existed for a period of about one month, however. The pyrolytic carbon coating showed some promise as a fission product barrier in several neutron activation tests. Fourteen batches of UO2 particles were coated with A12O3 by the vapor deposition process. Tests showed that this coating is an excellent barrier to fission products. In pyrolytic carbon-coated UC2 particles there is no temperature limitation due to reaction between the particle coating and the graphite matrix. (M.C.G.).

Download or read book FUEL ELEMENT DEVELOPMENT PROGRAM FOR THE PEBBLE BED REACTOR Quarterly Progress Report May 1 1960 July 31 1960 written by and published by . This book was released on 1961 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Fabrication of alumina-coated UO2 and pyrolytic carboncoated UC/ sub 2/ particles was studied. Some reaction was noted between alumina and graphite at 2500 deg F. For UC2 particles coated with carbon at 2000 deg F, the coatings were found to crack at temperaturss above 2000 deg F, whereas 2450 deg F deposition gave fewer failures at 3600 deg F, more rapid deposition- ratss, and absence of excess soot formation. A Pebble Bed Reactor fuel element consisting of a 1.5-in. graphite sphere fueled with alumina-coated UO2 particles was irradiated at 1400 deg F to a burrup of 3.3 at.% U235. Up to 2.5 at.% burnup, the fission product leakage factors (rate of release/rate of production) ranged between 10−9 and 10−5 for 10 isotopes and were ascribed to trace amounts of uranium contamination outside the particle coatings. In the latter part of the quarter, ths leakage factor for Xe133 rose to lO/ sup -3/ while several other shorter lived fission products increased to a smaller extent, indicating the beginning of diffusion through the coatings due to radiation damage of the alumina. Carbon-coated UC2 particles coated at 2000 deg F were found to have good fission product retention up to 2000 deg F, and less than 4.5 x 10−6 of the Xen133 was release d in a 4-hr test. Graphite bodies of density>2.0 g/cm3 were prepared using natural graphite powder as filler material, and their crushing strength was on the same order as that of AGOT synthetic graphite. (D.L.C.).

Download or read book Reactor Development Program Progress Report written by and published by . This book was released on 1961-02 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Pebble Bed Reactor Program written by U.S. Atomic Energy Commission and published by . This book was released on 1961 with total page 252 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book In pile Loop Test for the Pebble Bed Reactor Fuel Development Program written by R. C. Koch and published by . This book was released on 1961 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Summaries of Fuels and Materials Development Programs written by and published by . This book was released on 1960 with total page 114 pages. Available in PDF, EPUB and Kindle. Book excerpt: