ISSN:0550-3043    

DOI:10.13182/NT70-A28667

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

Small, high-temperature, fast-spectrum reactors, of the type proposed for auxiliary space-power applications, cannot be conveniently controlled by fuel or control-rod motion in the CORe. Consequently, the reflector (which may be a moderator) must provide the needed reactivity control. Critical experiment measurements employing conventional as well as pulsed-neutron techniques on various reflector control methods show that at least 5%Δk control worth is easily achieved, and full shutdown of over 12%Δk can be achieved by complete reflector removal. Though pulsed-neutron techniques are convenient for evaluating large changes in system reactivity, the interpretation of such measurements is far from straightforward, particularly on fast reactors with moderating reflectors.

ISSN:0550-3043    

DOI:10.13182/NT70-A28669

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

The N-Reactor complex, which was started up early in 1964 and modified to permit use of the by-product steam for electrical generation in April of 1966, has now operated for almost three years as a dual-purpose reactor. N Reactor has demonstrated itself as a versatile production reactor in the U.S. Atomic Energy Commission complex by operating at thermal power levels up to 4800 MW and operating under a coproduct mode of operation (plutonium - tritium production) in conjunction with providing steam to Washington Public Power Supply System (WPPSS) for electrical generation.This paper identifies N-management's solution to a few of its problems. A program of retubing the N-Reactor steam generators is now being completed without an extended shutdown of the reactor. The exposure to personnel when doing charge-discharge and maintenance work on the reactor is being minimized by decontaminating portions of the primary-system piping prior to extended maintenance.

ISSN:0550-3043    

DOI:10.13182/NT70-A28670

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

The time- and space-dependent temperature distribution within a TRIGA Mark II fuel element has been measured during a series of power excursions. The temperatures were obtained from 14 thermocouples welded to the uranium-zirconium hydride fuel at various radial locations. The experimental temperatures were used to solve the radial time-dependent heat conduction equation for the local heat generation rate (power density) as a function of radius and time during each pulse. Within the accuracy of the measurement, the radial power profile was found to be independent of the fuel temperature.

ISSN:0550-3043    

DOI:10.13182/NT70-A28671

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

Exact equations for the experimental analysis of fission-gas holdup beds are developed by the method of statistical moments. The mean retention time, given by the first moment, is independent of the factors which affect mass transfer. This independence emphasizes the important fact, sometimes overlooked in the analysis of fission-gas holdup beds, that the true dynamic adsorption coefficient for a stable fission-gas isotope is identical to the static adsorption coefficient. The second moment, used in combination with the first moment, describes the spreading of the input after it has passed through the holdup bed. The meaning of these equations is examined in detail, and by their correct use the factors needed for the design of fission-gas holdup beds can be determined rapidly from laboratory experiments. This method of analysis is applied to data obtained from fronts of dilute85Kr passed through charcoal beds.

ISSN:0550-3043    

DOI:10.13182/NT70-A28672

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

Experiments were conducted to determine the behavior of stationary gas bubbles in narrow liquid-filled gaps. The work was carried out to help answer the question of how fission gas bubbles may behave in the sodium bond of oxide and carbide fueled rods. The hydraulic data obtained with uncracked pellets indicate that stagnant bubbles may exist even when the simulated fuel rod was vibrated. These stagnant bubbles are large enough to cause calculated hot spots in the bond. The location under an overhanging ledge formed by axial eccentric pellets was a common place for bubbles to stagnate. Possible differences between the actual fuel-rod behavior in the reactor and the test conditions may be caused by heating effects which influence bubble motion, cracked pellets which prevent accumulation of fission gas in the bonding, and the release of significant amounts of fission gas only when the reactor is shut down. Equations are presented for the maximum bubble size, and the length and width of bubbles stagnated at the lips (overhang) of fuel pellets.

ISSN:0550-3043    

DOI:10.13182/NT70-A28673

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

For engineering applications of underground nuclear explosions it is necessary to know the properties of the material in which the explosion takes place. Many organizations provide measurements of the properties of interest, but their techniques are not always fully suited to the specific needs of Lawrence Radiation Laboratory. Core data are often unavailable or, if available, are not useful. Therefore, a number of systems have been developed at this Laboratory to measure, in place and under especially difficult conditions, such properties of earch materials as density and acoustic velocity. We have also developed some techniques for increasing the usefulness to us of measurements made by others, generally by providing calibrations more suited to the rock types in which we work.

ISSN:0550-3043    

DOI:10.13182/NT70-A28674

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

The void space in a variety of objects can be obtained by a neutron activation method utilizing the normal argon content in the air filling the pores and voids of such samples. The activation reaction used is40Ar(n,γ)41Ar which has a cross section of 0.63 b. Argon-41 decays by beta emission with a half-life of 1.85 h to the stable isotope of potassium,41K.If the quantity of air in a sealed container is known, the air can be used as an activation“foil”to estimate the total flux seen by the sample while in the reactor. After standard air volumes have been evaluated, porous solids containing air can be analyzed for void space if placed under the same conditions of geometry and efficiency and the activity acquired used as a measure of the total air present relative to a standard. It is possible to use this technique with substances for which the porosity (void space/bulk volume) is difficult to measure in other ways.

ISSN:0550-3043    

DOI:10.13182/NT70-A28675

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

Using neutron activation analysis (NAA), the sodium-to-potassium ratio as well as the sodium concentration has been determined for both normal and CF patients. The ratio results correlate with those based on the accepted sodium concentration analysis in the diagnosis of CF and the results also confirm calculations that the sensitivity of the NAA ratio method is a function of neutron energy with the optimum neutron energy being∼1.2 MeV.The coupling of the ratio technique with NAA greatly increases the possibility of performing a successful“sweat test”on an infant and offers the following benefits:Reduction in required sample volume by at least a factor of 3 due to the increased sensitivity of NAAElimination of the necessity to know the amount of sweat, again allowing the use of a smaller sampleElimination of the errors inherent in the present concentration analysis method such as evaporation, electrolytes present from previous perspiration, and variation of electrolyte concentration with sweat rate.

ISSN:0550-3043    

DOI:10.13182/NT70-A28676

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor

摘要:

The differential fast-neutron flux above 0.5 MeV at one spatial position in the High Flux Isotope Reactor was determined experimentally using several threshold activation detectors. The series expansion technique utilizing the concept of least squares was used to obtain an approximate solution to the set of integral equations which are defined by the experimentally determined activation data. Good agreement was achieved between the integrated flux (i.e., the differential flux integrated above 0.5 MeV) determined in this work and the integrated flux determined independently using one-dimensional, multigroup diffusion theory.

ISSN:0550-3043    

DOI:10.13182/NT70-A28677

出版商:Taylor&Francis    

年代:1970

数据来源: Taylor