48 research outputs found
An Integrated Software Platform for Best Estimate Safety Analyses of Nuclear Power Plants
Nuclear power plant safety is granted through the demonstration that regulatory acceptance
criteria are fulfilled by the provided (calculated) analyses of the NPP performances and sufficient safety
margins are respected during normal operation, anticipated transients and postulated accident conditions.
Safety margins are very hard to determine in absolute terms, numerical calculations are used to assess
their values. Over the last 30 years an extensive effort has been carried out aiming to improve the
knowledge of the nuclear power plant behaviour under transient scenarios. The development of Best
Estimate (BE) computer codes are the direct consequence of these noteworthy efforts.
The availability of more sophisticated and specialized computer codes gives the analyst the possibility to
perform very detailed analysis in all the fields involved in the safety of a NPP: thermal-hydraulics, CFD,
3D neutron kinetics etc. The possibility to create a software environment where a multidisciplinary
problem can be solved adopting different specialized codes able to exchange data among them is a fruitful
approach to the problem aiming to improve the results.
The computational tools, adopted in best-estimate approach in licensing, include a) the best estimate
computer codes; b) the nodalizations together with the procedures for the development and the
qualification; c) the uncertainty methodology.
The Nuclear Research Group of San Piero a Grado of the University of Pisa has developed a software
platform with 15 interacting computer codes. Such platform covers the reactor simulation multidisciplinary
problem from generation of neutron cross-sections, through system thermal-hydraulic analyses, up to
detailed structural and fuel mechanics studies and it embeds software procedures for automatized data
transfer between codes. Together with methodological procedures for nodalizations development and
qualification the platform leads to a great decrease of the human induced error in the results. The
developed platform has been tested and successfully applied to perform the safety analyses required by the
Chapter 15 of the Final Safety Analysis Report of the CNA-2 nuclear power plant in Argentina
Recent Applications of RELAP5-3D at GRNSPG
CNA2 : FSAR activities
Standard Consolidated Reference Experimental Database
MASLWR benchmark
OECD benchmarks
CHF calculation in low mass flux condition
Turbulence effects in Relap5-3
TP53 mutations confer resistance to hypomethylating agents and BCL-2 inhibition in myeloid neoplasms
Synthesis and properties of the heterospin (S1 = S2 = 1/2) radical-ion salt bis(mesitylene)molybdenum(I) [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazolidyl
The authors are grateful to the Presidium of the Russian Academy of Sciences (Project 8.14), the Royal Society (RS International Joint Project 2010/R3), the Leverhulme Trust (Project IN-2012-094), the Siberian Branch of the Russian Academy of Sciences (Project 13), the Ministry of Education and Science of the Russian Federation (Project of Joint Laboratories of Siberian Branch of the Russian Academy of Sciences and National Research Universities), and the Russian Foundation for Basic Research (Projects 13-03-00072 and 15-03-03242) for financial support of various parts of this work. N.A.S. thanks the Council for Grants of the President of Russian Federation for postdoctoral scholarship (grant MK-4411.2015.3). B.E.B. is grateful for an EaStCHEM Hirst Academic Fellowship. A.V.Z. thanks the Foundation named after D. I. Mendeleev, Tomsk State University, for support of his work.Low-temperature interaction of [1,2,5]thiadiazolo[3,4-c][1,2,5]thiadiazole (1) with MoMes2 (Mes = mesitylene / 1,3,5-trimethylbenzene) in tetrahydrofuran gave the heterospin (S1 = S2 = 1/2) radical-ion salt [MoMes2]+[1]– (2) whose structure was confirmed by single-crystal X-ray diffraction (XRD). The structure revealed alternating layers of the cations and anions with the Mes ligands perpendicular, and the anions tilted by 45°, to the layer plane. At 300 K the effective magnetic moment of 2 is equal to 2.40 μB (theoretically expected 2.45 μB) and monotonically decreases with lowering of the temperature. In the temperature range 2−300 K, the molar magnetic susceptibility of 2 is well-described by the Curie-Weiss law with parameters C and θ equal to 0.78 cm3⋅K⋅mol–1 and −31.2 K, respectively. Overall, the magnetic behavior of 2 is similar to that of [CrTol2]+[1]– and [CrCp*2]+[1]–, i.e. changing the cation [MAr2]+ 3d atom M = Cr (Z = 24) with weak spin-orbit coupling (SOC) to a 4d atom M = Mo (Z = 42) with stronger SOC does not affect macroscopic magnetic properties of the salts. For the XRD structure of salt 2, parameters of the Heisenberg spin-Hamiltonian were calculated using the broken-symmetry DFT and CASSCF approaches, and the complex 3D magnetic structure with both the ferromagnetic (FM) and antiferromagnetic (AF) exchange interactions was revealed with the latter as dominating. Salt 2 is thermally unstable and slowly loses the Mes ligands upon storage at ambient temperature. Under the same reaction conditions, interaction of 1 with MoTol2 (Tol = toluene) proceeded with partial loss of the Tol ligands to afford diamagnetic product.PostprintPostprintPeer reviewe