Jerzy Janczyszyn

Determination of Al, Si and O in isolated steel inclusions by 14 MeV neutron activation analysis

The method of non-destructive analysis for Al, Si and O in non-metallic inclusions isolated from steel is presented. The small powdered samples varying in mass from 2 mg to 40 mg were analysed, thus making the development of a proper technique of sample preparation necessary. The specific activation geometry and rotation of samples during irradiation were chosen to improve the accuracy and precision. Lower limits of determination for Al, Si, and O were: 1.4 mg, 0.3 mg, and 0.8 mg, respectively.

Precise measurement of the integral cross section for the reaction 24Mg(n,p)24Na between 13.5 and 18.0 MeV

Abstract Activation technique has been used to measure the cross-section ratio for 24Mg(n,p)24Na and 27Al(n,a)24Na reactions, the last being a reference one. The reaction T(d,n)4 He was used to produce the neutrons. Countings of γ-spectra were performed with a 75 × 75-mm NaI (T1) detector. The new cross-section values for 24Mg were calculated based on the best values of the 27Al-reaction cross-sections for respective neutron energies. In general, the obtained total error is 1.5–2 times smaller than previously.

System of programs for activation analysis calculations: (SPAAC)

A system of programs performing calculations for relative instrumental neutron activation analysis with germanium detectors was developed. It can be used if standards and unknowns are irradiated together and measured at the same counting geometry. Experimental and library data are evaluated by five programs. The final result is a table of concentrations. The whole system works automatically, without the intervention of an operator and runs on an IBM-PC.

Role of covariances in calibration and determination in activation analysis

Abstract When more then one measured signal is used in activation analysis or more then one sample of a material is analysed in the same batch, there is a problem of correlation. Algorithms are derived and tested for the calculation of calibration coefficients and their covariance matrix and for the calculation of the final result from the analysis of several subsamples. The results compare favourably with the results of other computational procedures in use.

Non-destructive determination of aluminium, silicon and oxygen in steel by 14 MeV neutron activation analysis

Analysis of steel for aluminium, silicon and oxygen is presented. The use of a Ge(Li) detector and the technique of precise photopeak integration enabled to attain a detection limit of 0.04% for Al. A method of the evaluation of the iron interference in silicon determinations is proposed.

Assessment of the control rods shadow effect in the VENUS-F core

Abstract The partitioning and transmutation (P&T) of spent nuclear fuel is an important field of present development of nuclear energy technologies. One of the possible ways to carry out the P&T process is to use the accelerator driven systems (ADS). This technology has been developed within the EURATOM Framework Programmes for several years now. Current research in this field is carried out within the scope of 7th FP project FREYA. Important parts of the project are experiments performed in the GUINEVERE facility devoted to characterising the subcritical core kinetics and development of reactivity monitoring techniques. The present paper considers the effects of control rods use on the core reactivity. In order to carry out the evaluation of the experimental results, it is important to have detailed core characteristics at hand and to take into consideration the differences in the effect of control rods acting separately or together (the so-called shadow effect) on both the reactivity value and the measured neutron flux. Also any core asymmetry should be revealed. This goal was achieved by both MCNP simulations and the experimental results. However, in the case of experimental results, the need for calculating respective correction factors was unavoidable.

Geochemical studies of natural graphites by INAA determined trace element concentrations

Abstract An attempt to characterize natural graphites by their trace element content is reported. Ten samples of graphite of known deposits over the world are classified by their graphitization indices, ranging from 0.26 to 1.00, and analyzed for trace elements content. Results of neutron activation analysis of 28 evaluated elements, i.e. Na, Rb, Cs, Th, U, Cr, Fe, Co, As, Sb, Ag, Au, Se, Te, Zn, Hg, Zr, Hf, Ta, Sc, La, Ce, Nd, Sm, Eu, Tb,Yb and Lu, are presented and briefly discussed.

Measurement of cross-section for 24Na production from magnesium isotopes by 13.5–18.0 MeV neutrons

Abstract Activation technique has been used to measure cross-sections for 25Mg(n,np + d + pn)24Na and to evaluate their upper limits for 26Mg(n,2np + npn + nd + t + dn + p2n)24Na reactions, respectively. The 27Al(n,α)24Na reaction has been used as reference. The obtained results allowed for correction of the previously determined cross sections for 24Mg(n,p)24Na reaction.