Fundamentals of Nuclear Reactor Physics-

…, 2007

Since the beginning of the Nuclear Power industry, numerous experiments concerned with nuclear energy and technology have been performed at different research laboratories, worldwide. These experiments required a large investment in terms of infrastructure, expertise, and cost; however, many were performed without a high degree of attention to archival of results for future use. The degree and quality of documentation varies greatly. There is an urgent need to preserve integral reactor physics experimental data, including measurement methods, techniques, and separate or special effects data for nuclear energy and technology applications and the knowledge and competence contained therein. If the data are compromised, it is unlikely that any of these experiments will be repeated again in the future. The International Reactor Physics Evaluation Project (IRPhEP) was initiated, as a pilot activity in 1999 by the by the Organization of Economic Cooperation and Development (OECD) Nuclear Energy Agency (NEA) Nuclear Science Committee (NSC). The project was endorsed as an official activity of the NSC in June of 2003. The purpose of the IRPhEP is to provide an extensively peer reviewed set of reactor physics related integral benchmark data that can be used by reactor designers and safety analysts to validate the analytical tools used to design next generation reactors and establish the safety basis for operation of these reactors. A short history of the IRPhEP is presented and its purposes are discussed in this paper. Accomplishments of the IRPhEP, including the first publication of the IRPhEP Handbook, are highlighted and the future of the project outlined.

nuclear reactors

IEEE Transactions on Plasma Science, 1975

2010

has received his Ph.D. degree in applied physics and nuclear engineering from Columbia University, New York, in . His career has bridged activities in the academia and multidisciplinary national research centers. His teaching and research experience as a full professor at leading academic institutions includes appointments (tenured, part-time, visiting, or adjunct

Nuclear Science & Engineering, 2025

This work proposes a paradigm shift in nuclear safety. Its NCV Method (Neutronics / Calorimetrics / Verification Procedures) integrates nuclear power's motive force-neutron flux-within Second Law exergy analysis, coupled with a corrected First Law conservation of energy flows, both descriptive of the entire system. These descriptions with two satellite equations result in a verifiable understanding of the nuclear engine: neutron flux [or neutronic terms f (Φ)], useful power produced and system heat rejection, all coupled to reactor vessel coolant mass flow. Key to NCV is its assumption that all nuclear phenomena are inertial processes, devoid of terrestrial reference. This approach demands reinterpretation of Einstein's ΔE = c 2 Δm by describing his ΔE as an exergetic potential, an ultimate Free Exergy. For fission, Free Exergy consists of both recoverable and irreversible portions of the MeV release. In transference to the coolant, the recoverable release produces an exergetic increase (ṁΔg) in the fluid; its T Ref derives from an Inertial Conversation Factor (Ξ). Importantly, Ξ also transforms this recoverable release to an explicit Core Thermal Power (ṁΔh). This paper asserts that traditional nuclear engineering has lacked direct linkage between neutron flux and system fluid thermodynamics. With NCV, nuclear power's motive force is directly related to extensive properties, thus allowing reconciliation of principal system parameters of the nuclear engine (neutron flux, power out, heat rejection and main system flow). Principal verification is accomplished by comparing the computed useful power to that which is directly measured, correcting for losses. The NCV Method has the potential to reduce uncertainty in computed Core Thermal Power from its commonly accepted ±2% by an order of magnitude. Its ability to improve plant safety becomes intrinsic, for example: • Tracking changes in verifiable flux vs. reactor vessel coolant flow; • Tracking changes in the axial position where saturation may be approached and the position of the average coolant temperature, thus early warning of the core becoming uncovered; • Monitoring instantaneous computed flux vs. reactor vessel pump current and its reactive load; • Detecting changes in the important Δλ GEN and Δλ EQ82 verification parameters which compare the computed shaft power delivered to the generator, to the measured plus losses; • Surveilling component irreversible losses using Fission Consumption Indices; etc.

2016

Monte-Carlo simulations were used to study the radiolysis of liquid water at 25-325 ο C when subjected to low linear energy transfer (LET) of 60 Co γ-ray radiation and fast neutrons of 2 and 0.8 MeV. The energy deposited in the early stage of 60 Co γ-ray irradiation was approximated by considering short segments (~150 µm) of 300 MeV proton tracks, corresponding to an average LET of ~0.3 keV/µm. In case of 2 MeV fast neutrons, the energy deposited was considered by using short segments (~5 µm) of energy at 1.264, 0.465, 0.171, 0.063 and 0.24 MeV. 0.8 MeV fast neutrons were approximated by 0.505, 0.186, 0.069 and 0.025 MeV protons. The effect of 0.4 M H 2 SO 4 solution on radiolysis was also studied by this method for both 60 Co γ-rays and 0.8 MeV fast neutrons. The simulated results at the time of 10-7 s after irradiation were obtained and compared with the available experimental results published by other researchers to be in excellent agreement with them over the entire temperature ranges and radiation sources studied. Except for g(H 2) that increase with temperature rises, the general behaviors of higher radical products and lower molecular products at higher temperatures were obtained. The LET effect is also validated by this study, showing that the increase in LET would yield higher molecular and lower radical products. Studies on 0.4 M H 2 SO 4 solutions also show good agreement between the computed and experimental data for γ-ray irrradiation: the presence of 0.4 M H + , except for g(H 2) that gives lower value at 25 ο C and higher value at 325 ο C, gives the higher values for radicals and g(H 2 O 2) at 25 ο C and lower values at 325 ο C, compared with that for neutral water. The computed data show good agreement with the experimental data for 0.4 M H 2 SO 4 solutions induced by 0.8 MeV fast neutrons, except for g(H 2) and g(H •) that gives good agreement up to 50 ο C, then the opposite tendencies with the further temperature rises. However, the simulated fast neutron radiolysis on acidic demonstrates similar tendencies on temperature dependence with that for simulated 60 Co γ-radiolysis, but in different magnitude. For better understanding, more experimental data for fast neutrons are needed, especially under the acidic conditions.

The purpose of a nuclear power plant is not to produce or release "Nuclear Power." The purpose of a nuclear power plant is to produce electricity. It should not be surprising, then, that a nuclear power plant has many similarities to other electrical generating facilities. It should also be obvious that nuclear power plants have some significant differences from other plants.

2002

2005

The International Reactor Physics Experiments Evaluation Project (IRPhEP) was initiated by the Organization for Economic Cooperation and Development (OECD) Nuclear Energy Agency's (NEA) Nuclear Science Committee (NSC) in June of 2002. The IRPhEP focus is on the derivation of internationally peer reviewed benchmark models for several types of integral measurements, in addition to the critical configuration. While the benchmarks produced by the IRPhEP are of primary interest to the Reactor Physics Community, many of the benchmarks can be of significant value to the Criticality Safety and Nuclear Data Communities. Benchmarks that support the Next Generation Nuclear Plant (NGNP), for example, also support fuel manufacture, handling, transportation, and storage activities and could challenge current analytical methods. The IRPhEP is patterned after the International Criticality Safety Benchmark Evaluation Project (ICSBEP) and is closely coordinated with the ICSBEP. This paper highlights the benchmarks that are currently being prepared by the IRPhEP that are also of interest to the Criticality Safety Community. The different types of measurements and associated benchmarks that can be expected in the first publication and beyond are described. The protocol for inclusion of IRPhEP benchmarks as ICSBEP benchmarks and for inclusion of ICSBEP benchmarks as IRPhEP benchmarks is detailed. The format for IRPhEP benchmark evaluations is described as an extension of the ICSBEP format. Benchmarks produced by the IRPhEP add new dimension to criticality safety benchmarking efforts and expand the collection of available integral benchmarks for nuclear data testing. The first publication of the "International Handbook of Evaluated Reactor Physics Benchmark Experiments" is scheduled for January of 2006.