Amelioration du modele de fuites de neutrons dans le schema de calcul des conditions critiques et des parametres homogeneises d'un reacteur nucleaire

The new theoretical method, implemented in APOLLO-2 code as the TIBERE procedure, allows to take into account, the influence of assembly heterogeneity on neutron leakage This method lies on the heterogeneous B1 procedure; however this formalism, in its exact form, should lead to very complex calculations; but, assuming a small number of approximations, it is possible to reduce it to a formalism using only calculation tools very close to those existing in APOLLO-2 It is the purpose of the TIBERE model, which allows to define the leakage cross-sections as additional absorption cross-sections having a space and energy dependence, thus cell-consistent leakage rates can be defined in order to perform the whole core calculation The study of this refined heterogeneous leakage treatment was undertaken because of the insufficiency of the homogeneous leakage model, especially in cases when an assembly contains voided or almost voided zones, so that the streaming effect may become important The fission rate comparisons between the experimental results obtained from the series of experiments EPICURE where the water was substituted, in the central part of reactor, by aluminium in order to simulate void and the results of the whole reactor calculations were accomplished, where leakages were calculated by the classical (homogeneous) procedure and by the TIBERE (heterogeneous) procedure of APOLLO-2 code They prove that the heterogeneous treatment of leakage give results which lie on the whole closer to the experimental values In other words, the classical leakage procedure underestimates the depression in the zone with aluminium, due to streaming This new model could be used, of course, for PWR's with other types of fuel, and also for other types of reactors. (Author

Monte Carlo Simulation of Proton Transport at Therapeutic Energies

Physical and biological characteristics of protons as well as technical requirements on proton beams are reviewed in order to illustrate the need for accurate proton transport simulations for therapeutic applications. Certain Monte Carlo proton transport simulation codes that have been used at therapeutic energies are briefly discussed. A general insight into two proton transport simulation schemes is presented; one including the generation and transport of secondary protons and the other comprising the generation and transport of secondary electrons. Based on different experiences gained, an analysis of the role of secondary particle is given

The application of the finite element method to the multigroup two-dimensional neutron diffusion equation on the KONEL code

The application of finite element method in space dependent neutron diffusion equation is shown in this paper The diffusion equation is first discretized using rectangular elements Applying piecewise polynomials in a variational form of the diffusion equation a system of linear algebraic equations is obtained Choleski decomposition is used to factorise the global matrix and numeration of nodes and finite elements is performed by line dissection The multigroup two-dimensional diffusion code KONEL was written based on this method (author)Society for Electronics,Telecommunications, Automation, and Nuclear Engineering; Belgrade (Yugoslavia); ETAN '86: 30. Conference; 30. Konferencija za ETAN; Herceg Novi (Yugoslavia); 2-6 Jun 1986

Verifikacija raspolozivih racunarskih programa za proracun efekta sigurnosnih sipki eksperimentima na reaktoru RB

Safety rod calculations performed by computation codes for global reactor core analysis were verified on experimental results obtained by measurements on RB reactor Three-dimensional code TRITON and two-dimensional codes VAMPIR and KONEL were applied In the first two codes finite difference method is used for the space discretization of the diffusion equation and in the third finite element method Calculation errors were analyzed for X-Y-Z, X-Y and R-Z geometries The obtained results are on the frame of the expected calculational errors (author)31. Conference - ETAN'87: Society for Electronics, Telecommunications, Automation, and Nuclear Engineering; ETAN'87: 31. Konferencija za elektroniku, telekomunikacije, automatiku i nuklearnu tehniku; Bled (Yugoslavia); 1-5 Jun 1987

The application of the finite element method to the multigroup two-dimensional neutron diffusion equation on the KONEL code

The application of finite element method in space dependent neutron diffusion equation is shown in this paper The diffusion equation is first discretized using rectangular elements Applying piecewise polynomials in a variational form of the diffusion equation a system of linear algebraic equations is obtained Choleski decomposition is used to factorise the global matrix and numeration of nodes and finite elements is performed by line dissection The multigroup two-dimensional diffusion code KONEL was written based on this method (author)Society for Electronics,Telecommunications, Automation, and Nuclear Engineering; Belgrade (Yugoslavia); ETAN '86: 30. Conference; 30. Konferencija za ETAN; Herceg Novi (Yugoslavia); 2-6 Jun 1986

Proliferation capacity and p53 expression of HTB140 cells after proton irradiation

Human HTB140 melanoma cells were used to investigate different responses to single irradiation with protons, regarding cell proliferation, induction of apoptosis and expression of p53. Exponentially growing cells were irradiated close to the Bragg peak maximum of the unmodulated 62 MeV proton beam. Doses applied ranged from 8 to 24 Gy at the dose rate of 15 Gy/min. Cell proliferation, measured 6 and 48 h postirradiation, has shown highly significant dose and time dependent decrease. Protons induced apoptosis, 6 and 48 h after irradiation, decreasing with the increase of postirradiation incubation time. The largest number of apoptotic cells was at 6 h after irradiation with 16 Gy protons. High level of p53 expression was detected in all irradiated samples, as well as in controls and was independent of dose applied and postirradiation incubation time.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

VAMPIR - A two-group two-dimensional diffusion computer code for burnup calculation

VAMPIR is a computer code which simulates the burnup within a reactor coe It computes the neutron flux, power distribution and burnup taking into account spatial variations of temperature and xenon poisoning Its overall reactor calculation uses diffusion theory with finite differences approximation in X-Y or R-Z geometry Two-group macroscopic cross section data are prepared by the lattice cell code WIMS-D4 and stored in the library form of multi entry tabulation against the various parameters that significantly affect the physical conditions in the reactor core herein, the main features of the program are presented (author)29. Conference - ETAN '85: Society for Electronics, Telecommunications, Computers, Automation and Nuclear Engineering; 29. Konferencija ETAN-a; Niš (Yugoslavia); 3-7 Jun 1985

Present status of the NET IBK computer code package for in-core fuel management and related core parameter calculations

This paper presents and discusses the current status of the NET IBK (Nuclear Engineering Department of the Boris Kidric Institute of Nuclear Sciences) computer code package for nuclear analysis of power reactors and in-core fuel management The standard scheme for reactor fuel burnup analysis comprises the WIMS code and several 2 D (RZ or XY) and 3 D (XYZ) codes for overall reactor core calculations and criticality search They are coupled and modified to compute neutron flux, power density distribution and burnup taking into account spatial variations of temperature and xenon poisoning, as well as the reactivity changes due to xenon transients during the start-up and shut-down Presently, codes for overall reactor calculations are based on finite difference solution of group diffusion equations Efforts are being made to improve reactor cell and fuel assembly parameters calculations, and to develop advanced methods for solving diffusion equations Also, an optimization model, based on coarse zonal discretization of a reactor core is being developed for optimal fuel loading pattern search The NET IBK computer code package has been extensively used to study advanced fuel utilization schemes in different types of power reactors, as well as for solving in-core fuel management problems of the own research reactors Particular attention has been paid to experimental verification of the calculational procedures In this paper, a number of interesting results is presented and discussed 15 refs, 6 figs, 7 tabsINIS record: [http://inis.iaea.org/search/search.aspx?orig_q=RN:22023261

Effects of short time exposure of HTB140 melanoma cells to fotemustine and dacarbazine

Different experimental set-ups were designed to study cytotoxic and cytoststic effects on HTB140 melanoma cells after 1 h treatment with fotemustine (FM) or dacarbazine (DTIC). FM induced dose dependent cell inactivation, boosted by its toxicity, particularly for higher doses. DTIC treatment for 1 h was insufficient to provoke almost any effect on melanoma cells. Good correlation between viability and proliferation assays applied was detected for both drugs.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200

Sensitivity of HTB140 cell exposed to protons and alkylating agents

Malignant melanoma is a highly aggressive cancer with a poor prognosis due to resistance to radiotherapy and chemotherapy regimens. The mainstay of treatment remains DNA-alkylatingagent dacarbazine (DTIC). Fotemustine (FM), chloroethylnitrosourea agent, also has demonstrated significant antitumoral effects in malignantmelanoma. However, the resistance of melanoma cells limits their clinical application. In order to enhance the inhibition of melanoma cell growth, in this study, combined treatment of FM and DTIC with proton irradiation, was investigated. We analyzed the effects of combined treatment on HTB140 melanoma cell viability and proliferation. Significant inhibition of cell growth, especially cell proliferation, was obtained after treatment with protons and FM compare to single irradiation or drug treatment. Treatment with protons and DTIC has shown improved growth inhibition compare to appropriate single drug treatment, but not compare to irradiation as a single treatment.Physical chemistry 2006 : 8th international conference on fundamental and applied aspects of physical chemistry; Belgrade (Serbia); 26-29 September 200