Search

The objective of this paper is to present the main results of the keff inter-comparison exercise performed in 2019-2022 by LANL, LLNL, ORNL and IRSN on a set of common benchmarks. The paper includes a description of the methodology to make the inter-comparison, presents the set of selected cases along with the main tendencies that could be at-tributed to nuclear data. In addition, it identifies some issues on the processing and interpretation of nuclear data done by the various codes of the intercomparison.

University administrators must realize that past management styles they used to acquire their positions of campus power often become the future incarnations of their failure as administrators. The conundrum of power is that the less power a leader grants to people, the less powerful the leader becomes in the eyes of the people. Individuals have a need for power though they tend to deny the need's existence; acknowledgement of the power motive must precede any mastery of the conundrum making up the power-complex of leadership. Power has multiple descriptions as leaders utilize several power bases, including raw power, person power, legitimate power, coercion power, reward power, expert power, information power, and referent power. Power's scope and scale can be configured as a representation of x-axis and y-axis intercepts. The scope of power refers to the purpose or motive for which it is being employed, ranging from low to high congruence of one individual's motives with another individual's needs. The scale of power gauges the degree to which the resources of a position are brought to bear on the followers as the leader attempts to carry out his or her power motive. Includes 59 references. (JDD)

To demonstrate that nuclear reactors can be built faster and more economically than they have been in the past, the US Department of Energy Office of Nuclear Energy is sponsoring the development of a small nuclear reactor called the Transformational Challenge Reactor (TCR) [1–2]. An important part of the design and licencing process of a new reactor is validation of the software used to analyze the reactor using established reactor physics benchmarks. This paper discusses validation of the neutronics software used to model four preliminary designs of the TCR core [2]. Because the TCR core design uses innovative technology and methods, comparable established benchmarks are limited or do not exist. For this effort, established benchmarks from the International Handbook of Evaluated Criticality Safety Benchmark Experiments (ICSBEP) [3] were considered to be suitable for this design based on analysis using the SCALE/TSUNAMI-computed similarity indices to determine the amount of shared uncertainty between the design and each selected benchmark experiment. This paper addresses the challenges faced in benchmarking a unique reactor for licensing and construction, a task that will become more common as a new generation of innovative nuclear reactors are designed and built.

Many universities have changed their policies regarding the nature of on-campus housing--shifting from gender-specific to coed dorms. This study examines the scope of that transition in the United States. From a sampling of 100 universities in the United States, including the nation's 50 largest universities, it was found that the vast majority of on-campus housing is currently coed in nature. Anecdotal information provided by the housing offices at these universities suggests that this transition is largely driven by student demand and financial considerations. Implications for future research and university policy making are discussed.

The identification and analysis of reaction paths leading to palladium catalyst deactivation during cyanation of haloarenes are described. The studies have shown that in this case C-N activation has occurred via an [S.sub.N]2-type displacement of amine and has ruled out alternative 3-center C-N oxidative addition or Hofmann elimination processes.

The fluoride congener of Wilkinson's catalyst, [(Ph3P)3RhF] is synthesized and fully characterized. It is found that in sharp contrast with Wilkinson's catalyst, [(Ph3P)3RhF] easily cleaves the inert C-Cl bond of nonactivated chloroarenes under mild conditions to produce trans-[(Ph3P)2Rh(Ph2PF)(Cl)] as a result of C-Cl, Rh-F, and P-C bond cleavage and C-C, Rh-Cl, and P-F bond formation.

The synthesis and structural peculiarities of iridium complexes exhibiting a novel eta(super 1)-N,eta(super 2)-C,C-binding interaction between the pyridinyl-functionalized fulvene ligand and the metal center are described. The efforts to prepare cyclometalated Ir and Pt complexes with ligands containing smaller pi systems than those of the phenyl-pyridines are still underway.

Activation of the C--Cl bond of chlorbenzene with [[(COD).sub.2]Ni] and a bidentate N,N-ligand such as N,N,N',N'-tetramethylethylenediamine (tmeda) and 2,2'-bipyridyl (bipy) has been reported to produce [sigma]-phenyl complexes [(tmeda)Ni(Ph)C1] (1) and [(bipy)Ni(Ph)Cl], respectively. However, in sharp contrast, we found that similar reactions involving almost the identical ligands N,N,N',N'-tetraethylethylenediamine (teeda) and 6,6'-dimethyl-2,2'bipyridyl (6,6'-[Me.sub.2]bipy) resulted in homocoupling and the formation of non-organometallic dichlorocomplexes [(teeda)Ni[Cl.sub.2]] and [(6,6'-[Me.sub.2]bipy)Ni[Cl.sub.2]]. The latter two compounds and 1 were characterized by single-crystal X-ray diffraction data. The remarkable change in the reaction outcome points to its extremely high sensitivity to minor alterations in the structure of the stabilizing N,N-ligand. In contrast, analogous reactions of [[Pd(dba).sub.2]] with PhI in the presence of teeda or 1,2-dipiperidinoethane (dpe) produced the expected [sigma]-phenyl complexes [(teeda)Pd(Ph)I] and [(dpe)Pd(Ph)I], much like the previously reported reaction with tmeda. Key words: C-Cl activation, zerovalent nickel complexes, N,N-ligands, oxidative addition, homocoupling, X-ray analysis. Il a ete rapporte anterieurement que l'activation de la liaison C--Cl du chlorobenzene a l'aide de [[(COD).sub.2]Ni] et d'un ligand N,N bidentate, tel la N,N,N',N'-tetramethylethylenediamine (tmeda) ou le 2,2'-bipyridyle (bipy), conduit a la formation de complexes [sigma]-phenyles, tels le [(tmeda)Ni(Ph)Cl] (1) et le [(bipy)Ni(Ph)Cl] respectivement. Les observations faites dans ce travail contrastent fortement avec ces resultats alors que des reactions semblables impliquant les ligands tres semblables N,N,N',N'-tetraethylethylenediamine (teeda) et 6,6'-dimethyl-2,2'-bipyridyle (6,6'-[Me.sub.2]bipy) conduisent a un homocouplage et a la formation des dichlorocomplexes non-organometalliques [(teeda)Ni[Cl.sub.2]] et [(6,6'-[Me.sub.2]bipy)Ni[Cl.sub.2]]. Ces deux derniers complexes et le compose 1 ont ete examines par diffraction des rayons X sur un cristal unique. Les changements remarquables observes dans les resultats de ces reactions indiquent qu'ils sont extremement sensibles a des changements mineurs dans la structure du ligand N,N stabilisateur. Au contraire, les reactions analogues du [[Pd(dba).sub.2]] avec le Phi en presence de teeda ou de 1,2-dipiperidinoethane (dpe) ont conduit aux complexes [sigma]-phenyles attendus [(teeda)Pd(Ph)I] et [(dpe)Pd(Ph)I], tel qu'il avait ete observe anterieurement dans les reactions avec le tmeda. Mots cles : activation de la liaison C-Cl, complexes zerovalent du nickel, ligands N,N, addition oxydante, homocouplage, analyse de diffraction des rayons X. [Traduit par la Redaction]

This work presents an assessment of the applicability of existing benchmark critical experiments to the criticality safety code validation for a large-capacity high-assay low-enriched uranium (HALEU) transportation package concept. Numerous next-generation nuclear reactor designs require HALEU fuel, which is characterized by an enrichment between 5 and 20 wt% 235U. The U.S. Department of Energy (DOE) has proposed to recover and downblend highly enriched uranium from DOE-owned used nuclear fuel to accelerate the demonstration of commercially viable microreactor technologies. One element of the infrastructure needed to demonstrate HALEU-fueled reactors is the ability to safely transport enriched product to be used for fuel fabrication. There is uncertainty as to whether existing critical benchmark experiment data are sufficient to support criticality safety code validation for HALEU transportation applications. The anticipated chemical form of the HALEU in the proposed transportation concept is UO2 with 20 wt% 235U/U. The concept uses a combination of an existing transportation packaging design and a novel basket design, including borated aluminum flux traps. The basket provides space for 18 reusable, stainless steel canisters that contain the HALEU. In 10 CFR 71, normal conditions of transport (NCTs) and hypothetical accident conditions (HACs) are defined for fissile material transportation packages. NCT and HAC KENO-VI models of the transportation package were developed using the Standardized Computer Analyses for Licensing Evaluation (SCALE) 6.2.3 computer code package, and optimum moderation conditions were determined using the SCALE SAMPLER sequence. The SCALE Tools for Sensitivity and Uncertainty Analysis Methodology Implementation (TSUNAMI) sequences were then used to compare the neutronic characteristics of 1584 International Criticality Safety Benchmark Evaluation Project benchmark critical experiments with the NCT and HAC HALEU transportation models. The TSUNAMI integral correlation coefficient ck was the criterion used to rank neutronic similarity. Thirty-four experiments were identified as similar (ck ≥ 0.9) to the NCT model, and 55 experiments were identified as similar to the HAC model. Hundreds of experiments were also identified as at least marginally similar (ck ≥ 0.8) to both models. The results indicate that additional critical experiments are unlikely to be needed to support HALEU transportation criticality safety analyses for package concepts similar to the concept package analyzed. [ABSTRACT FROM AUTHOR]