Download or read book Importance of Delayed Neutrons in Nuclear Research written by S. Das and published by . This book was released on 1993 with total page 114 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 Energies of the Delayed Neutrons from U235 Fission Products written by and published by . This book was released on 1946 with total page 34 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 Analytical Applications for Delayed Neutrons written by and published by . This book was released on 1983 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Analytical formulations that describe the time dependence of neutron populations in nuclear materials contain delayed-neutron dependent terms. These terms are important because the delayed neutrons, even though their yields in fission are small, permit control of the fission chain reaction process. Analytical applications that use delayed neutrons range from simple problems that can be solved with the point reactor kinetics equations to complex problems that can only be solved with large codes that couple fluid calculations with the neutron dynamics. Reactor safety codes, such as SIMMER, model transients of the entire reactor core using coupled space-time neutronics and comprehensive thermal-fluid dynamics. Nondestructive delayed-neutron assay instruments are designed and modeled using a three-dimensional continuous-energy Monte Carlo code. Calculations on high-burnup spent fuels and other materials that contain a mix of uranium and plutonium isotopes require accurate and complete information on the delayed-neutron periods, yields, and energy spectra. A continuing need exists for delayed-neutron parameters for all the fissioning isotopes.
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 written by George Robert Keepin and published by . This book was released on 1955 with total page 56 pages. Available in PDF, EPUB and Kindle. Book excerpt: A comprehensive review is given of existing measurements as of October 1955 on the properties of delayed neutrons from various fissionable isotopes. The relation of these measurements to current theory and practice is discussed.
Download or read book Effect of Delayed Neutrons on the Spectrum of the Transport Operator written by Janusz Roman Mika and published by . This book was released on 1966 with total page 21 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Delayed Neutrons Pt II written by Beno Gilbert and published by . This book was released on 1967 with total page 104 pages. Available in PDF, EPUB and Kindle. Book excerpt:
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 Measurement of the Delayed Neutron Emission Probability of 86As and 91Br written by Aczel Regino García Ríos and published by . This book was released on 2020 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Nuclear technology developments and nuclear astrophysics studies impose high data requirements on neutron-rich nuclei in terms of amount and quality. Radioactive decay data on -delayed neutron emitters are of particular relevance given the important role delayed neutrons play in both fields. In 2013, the International Atomic Energy Agency (IAEA) started Coordinated Research Project (CRP) on a reference database for beta-delayed neutron emission evaluation [170]. The database, which is in the process of publication [168], includes -delayed neutron emission probabilities for 309 nuclei, about a hundred more than Evaluated Nuclear Structure Data File (ENSDF) to date (as of July, 2020) [7,8]. But there is a long road ahead to meet the delayed neutron data requirements of nowadays nuclear science and technology. The recent large-scale theoretical evaluation by Marketinet al. [6] on 5409 neutron-rich nuclei predicts that 90% of them are -delayed neutron emitters...
Download or read book Neutrons Nuclei and Matter written by James Byrne and published by CRC Press. This book was released on 1996-01-01 with total page 181 pages. Available in PDF, EPUB and Kindle. Book excerpt: Neutrons, Nuclei and Matter is an encyclopedic work of reference covering almost every conceivable aspect of neutron physics. This is a major compilation of fundamental properties and interactions, detailing both the neutron's role as a major element in tests of the Standard Model of astro-particle physics and its use in nuclear energy generation and the study of condensed matter systems. * Comprehensible and accessible treatment of all areas of neutron physics * Overview of the current theoretical and experimental status of the whole of neutron physics * Comprehensive reference list and bibliography with over 1500 entries summarising important papers on neutron physics * Comprehensive index, making the book very accessible The author, inventor of the Penning trap method for determining neutron lifetime, has produced a book that will interest anyone who uses the neutron as a research tool or who attempts to investigate its nature either experimentally or theoretically. Jim Byrne has worked in neutron physics and allied areas for over thirty years and is a world authority in the field. Books written on neutron physics traditionally fall into two classes. Either they deal mainly with the interactions of neutrons with nuclei, covering subjects such as slow scattering, Breit-Wigner resonance theory, nuclear fission and energy production, or they devote themselves to the applications of neutron scattering in studies of condensed matter and magnetic systems. In both cases, the neutron is viewed as a tool but is not itself the main topic of interest. Neutrons, Nuclei and Matter is different; in particular it includes a detailed treatment of the strong, weak and electromagnetic properties of neutrons, which in recent years have provided major areas of research for the testing of the predictions of the Standard Model of particle physics. Parallel developments in cosmology and astrophysics are also explored. The book looks at the growth in interest in the wave properties of neutrons following the development of the perfect crystal interferometer, and the way that this instrument has made it possible to demonstrate quantum behaviour very directly. Around a fifth of the material in Neutrons, Nuclei and Matter is about the generation of nuclear energy from fission and fusion sources, which is treated from an analytical rather than a technological viewpoint. The middle section gives an extended discussion of neutron optics, concluding with a review of the applications of elastic and inelastic neutron scattering in materials technology. The final fifth of the volume is devoted entirely to the fundamental role the neutron plays in today's particle physics, stressing its potential for bringing to light new phenomena beyond the Standard Model. Everything has been placed in context within science as a whole, with discussion of the origins of different ideas and considerable attention to historical detail. Neutrons, Nuclei and Matter is a reference work that every physics department and main library should have in its collection.
Download or read book The Role of Delayed Neutrons in the Gamma process written by Teruaki Ohnishi and published by . This book was released on 1972 with total page 11 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dynamics and Control of Nuclear Reactors written by Thomas W. Kerlin and published by Academic Press. This book was released on 2019-10-05 with total page 402 pages. Available in PDF, EPUB and Kindle. Book excerpt: Dynamics and Control of Nuclear Reactors presents the latest knowledge and research in reactor dynamics, control and instrumentation; important factors in ensuring the safe and economic operation of nuclear power plants. This book provides current and future engineers with a single resource containing all relevant information, including detailed treatments on the modeling, simulation, operational features and dynamic characteristics of pressurized light-water reactors, boiling light-water reactors, pressurized heavy-water reactors and molten-salt reactors. It also provides pertinent, but less detailed information on small modular reactors, sodium fast reactors, and gas-cooled reactors. Provides case studies and examples to demonstrate learning through problem solving, including an analysis of accidents at Three Mile Island, Chernobyl and Fukushima Daiichi Includes MATLAB codes to enable the reader to apply the knowledge gained to their own projects and research Features examples and problems that illustrate the principles of dynamic analysis as well as the mathematical tools necessary to understand and apply the analysis Publishers Note: Table 3.1 has been revised and will be included in future printings of the book with the following data: Group Decay Constant, li (sec-1) Delayed Neutron Fraction (bi) 1 0.0124 0.000221 2 0.0305 0.001467 3 0.111 0.001313 4 0.301 0.002647 5 1.14 0.000771 6 3.01 0.000281 Total delayed neutron fraction: 0.0067
Download or read book Analysis of Delayed Neutrons and Development of a Laser based Technique for Nuclear Forensics written by Stacey Vanessa Lastra and published by . This book was released on 2012 with total page 54 pages. Available in PDF, EPUB and Kindle. Book excerpt: Bearing in mind the aims and goals of nuclear forensics and national non-proliferation mission, a delayed neutron detection method was developed for the purpose of detecting and quantifying fissile material commonly used in the production of nuclear weapons. This method involves the irradiation of solutions of various concentrations of special nuclear material uranium and plutonium in the University of California, Irvine's TRIGA® nuclear reactor. Delayed neutrons emitted from the samples post-irradiation are then detected and counted using the delayed neutron system. Decay spectra of the emission and detection of delayed neutrons from these samples were constructed and analyzed in an effort to observe similarities and differences in decay behavior of uranium and plutonium. The correlation of decay spectra from ranging concentrations was also noted. Based on the patterns and trends found, characterization and quantification of the special nuclear material were possible. This method can potentially one day be implemented for the improvement of current safeguards of nuclear material. At Sandia National Laboratories, scientists are also making advancements in nuclear forensics. Researchers are currently working on developing a portable and time-efficient laser-based method of detection of noble gases released from a clandestine nuclear test. This method will help to verify compliance with the Comprehensive Test Ban Treaty which bans all nuclear testing. This trace noble gas detection platform is an ongoing project at Sandia and will hopefully be implemented in the near future.
Download or read book Delayed Neutrons from Fission written by and published by . This book was released on 1972 with total page 27 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Passive Nondestructive Assay of Nuclear Materials written by Doug Reilly and published by . This book was released on 1991 with total page 700 pages. Available in PDF, EPUB and Kindle. Book excerpt:
