Published by De Gruyter

Volume 78 Issue 3

Issue of Kerntechnik

Contents
Journal Overview

Contents/Inhalt

September 9, 2013

Page range: 151-153

Summaries/Kurzfassungen

September 9, 2013

Technical Contributions/Fachbeiträge

September 9, 2013

Chemistry aspects of the source term formation for a severe accident in a CANDU type reactor

A. Constantin, M. Constantin

Page range: 158-166

Abstract

The progression of a severe accident in a CANDU type reactor is slow because the core is surrounded by a large quantity of heavy and light water which acts as a heat sink to remove the decay heat. Therefore, the source term formation is a complex and long process involving fission products transport and releasing in the fuel matrix, thermal hydraulics of the transport fluid in the primary heat system and containment, deposition and transport of fission products, chemistry including the interaction with the dousing system, structural materials and paints, etc. The source term is strongly dependent on initial conditions and accident type. The paper presents chemistry aspects for a severe accident in a CANDU type reactor, in terms of the retention in the primary heat system. After releasing from the fuel elements, the fission products suffer a multitude of phenomena before they are partly transferred into the containment region. The most important species involved in the deposition were identified. At the same time, the influence of the break position in the transfer fractions from the primary heat system to the containment was investigated.

September 9, 2013

Analytical study on degraded core quenching

O. S. Gokhale, B. P. Puranik, A. K. Ghosh

Page range: 167-180

Abstract

Severe accident analysis of a reactor helps in emergency planning and evolution of Severe Accident Management Guidelines (SAMG). Actions recommended in the SAMG aim at arresting accident progression and limiting significant radioactive release. However, success of these SAMG actions needs to be assessed with respect to the evolution of accident. Analysis of consequences of injection of water into the reactor pressure vessel from bottom only as a SAMG action has been carried out for VVER-1000 (V320) reactor. The analysis shows that the success of this SAMG action depends not only on the state of core degradation at the time of injection, but also on the highest temperature reached in the reactor core at the time of injection as well as the availability of steam in the RPV.

September 9, 2013

Experimental investigations on control of flow instability in single-phase natural circulation loop

K. Bodkha, N. Kumar, P. K. Vijayan

Page range: 181-192

Abstract

Natural circulation systems offer simplicity, enhanced safety and reliability and thus are advantageous over their forced circulation counterpart. However, natural circulation is susceptible to flow instabilities. These instabilities are undesirable for various reasons. Literature suggests the use of orifices at the inlet to suppress instability. However, orificing introduces pressure drop which limits the flow rate and hence the heat carrying capacity of the fluid. In the present study, investigations have been carried out with different mechanical gadgets to control the natural circulation flow instabilities. Extensive experiments have been carried out in a single-phase rectangular natural circulation loop to study the effect of these mechanical gadgets on instability. The paper brings out the results of experimental investigations carried out on the role of mechanical gadgets in controlling instability.

September 9, 2013

Burnup calculations using serpent code in accelerator driven thorium reactors

M. E. Korkmaz, M. Yiğit, O. Ağar

Page range: 193-197

Abstract

In this study, burnup calculations have been performed for a sodium cooled Accelerator Driven Thorium Reactor (ADTR) using the Serpent 1.1.16 Monte Carlo code. The ADTR has been designed for burning minor actinides, mixed 232 Th and mixed 233 U fuels. A solid Pb-Bi spallation target in the center of the core is used and sodium as coolant. The system is designed for a heating power of 2000 MW and for an operation time of 600 days. For burnup calculations the Advanced Matrix Exponential Method CRAM (Chebyshev Rational Approximation Method) and different nuclear data libraries (ENDF7, JEF2.2, JEFF3.1.1) were used. The effective multiplication factor change from 0.93 to 0.97 for different nuclear data libraries during the reactor operation period.

September 9, 2013

Investigation of neutronic effects in structural material of a hybrid reactor by using the MCNPX Monte Carlo transport code

M. Günay

Page range: 198-203

Abstract

In this study, 98–90% Li 2 BeF 4 -2–10% ThF 4 , 98–90% Li 2 BeF 4 -2–10% UF 4 , 98–90% Li 2 BeF 4 -2–10% UO 2 and 100% Li 2 BeF 4 molten salt-heavy metal was used as fluid. The fluids were used in the liquid first wall, liquid second wall and shield zones of the designed hybrid reactor system. A steel wall of 4 cm thickness is used as structural material. Proton, deuterium, tritium, He-3 and He-4 gas production rates are the parameters of radiation damage. In the study, the effect of liquid second wall thicknesses (20 cm, 30 cm, 40 cm, 50 cm) on the neutron flux distribution and the parameters of radiation damage according to neutron energy spectrum in the structural material were investigated for the selected fluids. A three-dimensional analysis was done by using the most recent version of the MCNPX-2.7.0 Monte Carlo code and the nuclear data library ENDF/B-VII.

September 9, 2013

Nuclear aspects and cyclotron production of the positron emitter ⁵⁵Co

M. Talebi, T. Kakavand, M. Mirzaii

Page range: 204-208

Abstract

The radionuclide 55 Co (T 1/2 = 17.5 h, E β+ = 1.5 MeV, 76% β + decay) is an important β + emitting radioisotope. For production of 55 Co via nat Fe( p, xn ) 55 Co reaction, an iron layer was deposited on a copper substrate by means of electro-deposition method which could be irradiated by 29.5 MeV protons at 100 μA. No-carrier-added (n.c.a.) 55 Co was separated from the iron target via an anion exchange column (Dowex 1 · 8). The achieved production yield was 31.25 MBq/μAh. Also, excitation functions for the 55 Co radionuclide via nat Fe(p, xn) 55 Co, 56 Fe(p, 2n) 55 Co and 54 Fe(d, n) 55 Co reactions were calculated by TALYS-1.4 code and TENDL-2011 database and compared with previous published data.

September 9, 2013

Calculation of age-dependent effective doses for external exposure using the MCNP code

Tran Van Hung

Page range: 209-213

Abstract

Age-dependent effective dose for external exposure to photons uniformly distributed in air were calculated. Firstly, organ doses were calculated with a series of age-specific MIRD-5 type phantoms using the Monte Carlo code MCNP. The calculations were performed for mono-energetic photon sources with source energies from 10 keV to 5 MeV and for phantoms of newborn, 1, 5, 10, and 15 years-old and adult. Then, the effective doses to the different age-phantoms from the mono-energetic photon sources were estimated based on the obtained organ doses. From the calculated results, it is shown that the effective doses depend on the body size; the effective doses in younger phantoms are higher than those in the older phantoms, especially below 100 keV.

September 9, 2013

Effect of Cu²⁺/Al³⁺ mole ratio on structure of Cu – Al bimetallic nanoparticles prepared by radiation induced method

A. Abedini, F. Larki, E. Saion, M. Noroozi

Page range: 214-219

Abstract

Cu–Al bimetallic nanoparticles were synthesized by gamma irradiation technique in aqueous solutions containing metal chlorides as precursors, polyvinyl alcohol (PVA) as a capping agent, isopropanol as a radical scavenger, and distilled water as a solvent. The Cu–Al bimetallic nanoparticles were characterized by transmission electron microscopy (TEM), UV-visible absorption spectrometry, powder X-ray diffractometer (XRD), and Energy-dispersive X-ray spectroscopy (EDX). The TEM, XRD, EDX, and absorption analyses confirmed the formation of core-shell structure of Cu–Al bimetallic nanoparticles at lower Cu 2+ /Al 3+ mole ratio, and the formation of Cu–Al alloy nanoparticles at higher Cu 2+ /Al 3+ mole ratio. The TEM analysis for particle size and size distribution revealed that the average particle size of Cu–Al bimetallic nanoparticles decreased with the increase of absorbed dose. It may be explained due to the competition between nucleation and aggregation processes in the formation of metallic nanoparticles under irradiation.

September 9, 2013

A numerical method for resonance integral calculations

T. Tanbay, B. Ozgener

Page range: 220-228

Abstract

A numerical method has been proposed for resonance integral calculations and a cubic fit based on least squares approximation to compute the optimum Bell factor is given. The numerical method is based on the discretization of the neutron slowing down equation. The scattering integral is approximated by taking into account the location of the upper limit in energy domain. The accuracy of the method has been tested by performing computations of resonance integrals for uranium dioxide isolated rods and comparing the results with empirical values.

September 9, 2013

Computational modeling of monoenergetic neutral particle inverse transport problems in slab geometry

R. R. Gomes, R. C. Barros

Page range: 229-232

Abstract

An analytical numerical method applied to three different types of monoenergetic neutral particle inverse transport problems in the discrete ordinates (S N ) formulation is presented: (a) boundary condition estimation; (b) interior source estimation; and (c) effective slab length estimation. These three types of inverse problems governed by the linear integrodifferential transport equation in S N formulation are related respectively to medical physics; nuclear waste storage; and non-destructive testing in industry. Numerical results and a brief discussion are given to conclude the paper.

September 9, 2013

Effects on criticality of selected scattering phase functions in neutron transport equation using the Chebyshev approximation

A. Kara, F. Anlı

Page range: 233-237

Abstract

Criticality and diffusion problems have been widely studied in neutron transport theory using polynomial expansion techniques in different geometries. In this study, instead of conventional scattering functions, two different phase function will be used in slab geometry transport equation by using the T N approximation and Marshak boundary conditions. Critical half thicknesses of the slab will be calculated. The numerical results obtained will be presented in tables.

September 9, 2013

U₁ and P₁ approximations to neutron transport equation for diffusion length calculation

A. Bülbül, H. Öztürk

Page range: 238-240

Abstract

U 1 and P 1 approximations are used for the calculation of asymptotic relaxation length in one-dimensional neutron transport equation. The approximation methods are applied to anisotropic neutron transport equation with backward and forward scattering. The methods are based on the series expansion of the neutron angular flux in terms of the Chebyshev polynomials of second kind and Legendre polynomials. By applying the first order approximation to the transport equation, asymptotic relaxation lengths are calculated. Numerical results obtained from both methods are compared with each other.

Technical Notes/Technische Mitteilungen

September 9, 2013

T_N approximation for the critical size of one-speed neutrons in a slab with anisotropic scattering

H. Öztürk

Page range: 241-244

Abstract

The critical thickness for one-speed neutrons in a uniform finite slab with anisotropic scattering is investigated using Marshak boundary condition. The angular part of the neutron angular flux is expanded in terms of the Chebyshev polynomials of first kind. Numerical results for the critical thickness of the slab are calculated for various values of the collision and the anisotropy parameters and they are given in the tables together with the ones obtained by Legendre polynomials approximation and the ones available in literature for comparison. The results obtained by the present method are in good accordance with the literature values.

September 9, 2013

Albedo and constant source problems for extremely anisotropic scattering

M. A. Koçmen, A. Teğmen, D. Türeci, M. Ç. Güleçyüz, R. G. Türeci

Page range: 245-249

Abstract

The half-space albedo problem and the constant source problem have been solved for a combination of the linearly anisotropic scattering and İnönü’s scattering functions. The linear transport equation for extremely anisotropic scattering kernel can be converted into an equivalent equation with a linearly anisotropic scattering kernel and the modified F N method can be used for albedo calculations.

About this journal

Kerntechnik is an independent journal for nuclear engineering (including design, operation, safety and economics of nuclear power stations, research reactors and simulators), energy systems, radiation (ionizing radiation in industry, medicine and research) and radiological protection (biological effects of ionizing radiation, the system of protection for occupational, medical and public exposures, the assessment of doses, operational protection and safety programs, management of radioactive wastes, decommissioning and regulatory requirements). For more than 75 years Kerntechnik offers original scientific and technical contributions, review papers and conference reports.
All articles are subject to thorough, independent peer review.

Volume 78 Issue 3

Issue of Kerntechnik

Contents

Summaries

Chemistry aspects of the source term formation for a severe accident in a CANDU type reactor

Abstract

Analytical study on degraded core quenching

Abstract

Experimental investigations on control of flow instability in single-phase natural circulation loop

Abstract

Burnup calculations using serpent code in accelerator driven thorium reactors

Abstract

Investigation of neutronic effects in structural material of a hybrid reactor by using the MCNPX Monte Carlo transport code

Abstract

Nuclear aspects and cyclotron production of the positron emitter 55Co

Abstract

Calculation of age-dependent effective doses for external exposure using the MCNP code

Abstract

Effect of Cu2+/Al3+ mole ratio on structure of Cu – Al bimetallic nanoparticles prepared by radiation induced method

Abstract

A numerical method for resonance integral calculations

Abstract

Computational modeling of monoenergetic neutral particle inverse transport problems in slab geometry

Abstract

Effects on criticality of selected scattering phase functions in neutron transport equation using the Chebyshev approximation

Abstract

U1 and P1 approximations to neutron transport equation for diffusion length calculation

Abstract

TN approximation for the critical size of one-speed neutrons in a slab with anisotropic scattering

Abstract

Albedo and constant source problems for extremely anisotropic scattering

Abstract

Nuclear aspects and cyclotron production of the positron emitter ⁵⁵Co

Effect of Cu²⁺/Al³⁺ mole ratio on structure of Cu – Al bimetallic nanoparticles prepared by radiation induced method

U₁ and P₁ approximations to neutron transport equation for diffusion length calculation

T_N approximation for the critical size of one-speed neutrons in a slab with anisotropic scattering