Download or read book On the Impact of the New Decay Constants of Delayed Neutron Groups on Reactor Pulse Experiments written by Ingrid Švajger and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Delayed Neutron Reduced Groups by Least Squares written by Thomas E. Springer and published by . This book was released on 1964 with total page 42 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Reduced Delayed Neutron Group Representations written by R. E. Skinner and published by . This book was released on 1959 with total page 40 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Seven Surrogate Precursors for Modeling Delayed Neutron Decay and Predicting Reactivity written by and published by . This book was released on 1997 with total page 6 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of a different set of group decay constants for each fissionable nuclide complicates analysis of the dynamic behavior of fast reactors. A fast reactor containing six principal fissioning nuclides of uranium and plutonium must, in effect, be described by 36 delayed neutron groups. Additionally, the use of group decay constants that depend on the neutron energy spectrum makes it difficult to select values that describe the dynamic response of epithermal systems because virtually all delayed neutron activity measurements have been performed for fast or thermal-neutron-induced fission. Clearly, it would be desirable to have a single set of group decay constants that could be applied to all fissionable nuclides. A set of seven fixed decay constants is proposed herein. Each of the proposed decay constants is associated with a specific, dominant delayed neutron precursor. In effect, each group is represented by a single surrogate precursor. Using recently measured delayed neutron activities for U-235 and Np-237, the proposed set of decay constants actually improved the goodness of fit to the data. For other fissionable nuclides lacking experimental data, a method has been devised to obtain yields consistent with the proposed set of decay constants from the traditional six-group parameters. This transformation is accomplished without altering the traditional inferred reactivity scale.
Download or read book Measurements of Delayed Neutron Emission from Np 237 Am 241 and Am 243 written by and published by . This book was released on 1995 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Delayed Neutrons from Fissionable Isotopes of Uranium Plutonium and Thorium written by George Robert Keepin and published by . This book was released on 1957 with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An Investigation of the Delayed Neutron Decay Curves Resulting from Uranium and Plutonium Fission written by C. Redman and published by . This book was released on 1944 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Measurements of Delayed Neutron Parameters for U 235 and Np 237 written by and published by . This book was released on 1997 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: Delayed neutrons are emitted by excited nuclei formed in beta decay of fission products called delayed neutron precursors. About 1% of the total neutrons released in fission are delayed neutrons; however, this small fraction plays an important role in nuclear reactor control. The delayed neutrons determine the time-dependent behavior of reactors, and knowledge of parameters used to predict neutron emission rate is essential for establishing reactivity worths. The delayed neutron yields, decay constants, and the absolute yield for the six-group delayed neutrons have been measured for U-235 and Np-237. This experiment has been called for in the forecast of experiments needed to support operations in the US. The bare U-235 metal assembly Godiva IV at the Los Alamos Critical Experiment Facility (LACEF) provided the source of neutrons. Godiva IV generated about 107 total fissions in the samples for the infinite and instantaneous irradiation needed to accentuate the shorter and longer-lived groups of delayed neutrons. The detection system used in the experiment consisted of 20 He-3 tubes embedded in a polyethylene cylinder. The delayed neutron activity resulting from the fast neutron-induced fission has been measured. The measured absolute yield for U-235 was determined to be 0.0163 " 0.009 neutrons/fission. This value compares very well with the well-established Keepin absolute yield of 0.0165 " 0.0005. The newly measured absolute yield value for Np-237 was 0.0126 " 0.0007, which compares well to the recently reported value of 0.0129 " 0.0004 by Saleh and Parish. The measured values for U-235 are corroborated with period (e-folding time) versus reactivity calculations.
Download or read book A New Experimental Design and Method for Improved Delayed Neutron Data of Group Abundances written by Heejun Chung and published by . This book was released on 2014 with total page 150 pages. Available in PDF, EPUB and Kindle. Book excerpt: The nuclear data on the physics of delayed neutrons coming from fission events are of key importance in reactor kinetics and safeguards applications. The accuracy of reactor kinetics calculations, reactor physics validation studies and techniques for non-destructive assay of special nuclear material are all limited by the quality of these data. The uncertainties on the delayed neutron group abundances of the longest-lived delayed neutron groups are particularly large - up to 13 % for thermal fissions of 235U, 16 % for fast fissions of 238U, and 38 % for fast fissions of 239Pu [1]. There are also several competing data sets with significant variation in values. Recent work indicates that these already large uncertainties are underestimated due to numerical instabilities in the parametric fitting methods [2]. A novel approach to experimentally measure delayed neutron group yields has been proposed by Jordan and Perret [3]. This approach combines gamma-ray scanning and delayed neutron fission rate measurement techniques. With two independent estimates of the same fission rate, a higher uncertainty delayed neutron parameters can be linked to lower uncertainty delayed gamma parameters. An experimental apparatus implementing these techniques has been designed, optimized, and built. The apparatus consists of a D-D neutron generator, a detector bundle, a sample handler, and related electronics.
Download or read book Few Group Constants for Delayed Neutrons written by Lionel Friedman and published by . This book was released on 1956 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Uncertainty Evaluation of Delayed Neutron Decay Parameters written by Jinkai Wang and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In a nuclear reactor, delayed neutrons play a critical role in sustaining a controllable chain reaction. Delayed neutron's relative yields and decay constants are very important for modeling reactivity control and have been studied for decades. Researchers have tried different experimental and numerical methods to assess these delayed neutron parameters. The reported parameter values vary widely, much more than the small statistical errors reported with these parameters. Interestingly, the reported parameters fit their individual measurement data well in spite of these differences. This dissertation focuses on evaluation of the errors and methods of delayed neutron relative yields and decay constants for thermal fission of U-235. Various numerical methods used to extract the delayed neutron parameter from the measured data, including Matrix Inverse, Levenberg-Marquardt, and Quasi-Newton methods, were studied extensively using simulated delayed neutron data. This simulated data was Poisson distributed around Keepin's theoretical data. The extraction methods produced totally different results for the same data set, and some of the above numerical methods could not even find solutions for some data sets. Further investigation found that ill-conditioned matrices in the objective function were the reason for the inconsistent results. To find a reasonable solution with small variation, a regularization parameter was introduced using a numerical method called Ridge Regression. The results from the Ridge Regression method, in terms of goodness of fit to the data, were good and often better than the other methods. Due to the introduction of a regularization number in the algorithm, the fitted result contains a small additional bias, but this method can guarantee convergence no matter how large the coefficient matrix condition number. Both saturation and pulse modes were simulated to focus on different groups. Some of the factors that affect the solution stability were investigated including initial count rate, sample flight time, initial guess values. Finally, because comparing reported delayed neutron parameters among different experiments is useless to determine if their data actually differs, methods are proposed that can be used to compare the delayed neutron data sets.
Download or read book Delayed Neutrons from U235 After Short Irradiation written by and published by . This book was released on 1949 with total page 24 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1976-06 with total page 1216 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1969 with total page 1502 pages. Available in PDF, EPUB and Kindle. Book excerpt: Lists citations with abstracts for aerospace related reports obtained from world wide sources and announces documents that have recently been entered into the NASA Scientific and Technical Information Database.
Download or read book Reactor Physics Constants written by Reactor Physics Constants Center (U.S.) and published by . This book was released on 1963 with total page 880 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Obdachlosigkeit written by and published by . This book was released on 1971 with total page 70 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Statistical Determination of the Reduced Prompt Neutron Generation Time lambda beta in the SPERT IV Reactor written by Roger Lee Johnson and published by . This book was released on 1963 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt:
