Photoneutrons from a beryllium reflector: a potential source of problems with Zr-Au flux monitors in k standardization based neutron activation analysis

Koster-Ammerlaan, M.; Bode, P.; Winkelman, A.
February 2012
Journal of Radioanalytical & Nuclear Chemistry;Feb2012, Vol. 291 Issue 2, p569
Academic Journal
The assumption that the shape of the epithermal neutron spectrum can be described, in any research reactor, by the 1/ E function is a fundamental starting point of the k standardization. This assumption may be questioned from a reactor physics viewpoint. The type of moderator, the existence of neutron reflectors, the additional production of (γ, n) neutrons and resonance capture by construction materials may be different for each reactor, with consequences for the shape of the neutron spectrum. This dependency may explain that various practitioners reported contradicting experiences with the use of Zr-Au flux monitors for the determination of the α-parameter. An objective view on the influence of the design of the reactor and irradiation facility on the shape of the neutron spectrum can be obtained by modeling. This has been applied in the Reactor Institute Delft for reactor configurations in which the irradiation facilities face the fuel elements with the presence of beryllium reflector elements. The Monte Carlo calculations indicate a distortion of the 1/ E relationship at the higher energy edge of the epithermal neutron spectrum. This distortion is attributed to the formation and thermalisation of both photoneutrons and ( n, 2 n) produced fast neutrons in the beryllium, and has a direct impact on the resonance activation of Zr, other than represented by the 1/ E function. The obtained relationship between neutron flux and neutron energy was also used for estimating the f-value and compared with the value obtained by the Delft Cr-Mo-Au flux monitor.


Related Articles

  • Trace Element Levels in Terrestrial and Aquatic Environments Near the Nigeria Research Reactor. Ewa, I. O. B.; Oladipo, M. O. A.; Umar, I. M. // Journal of Environmental Systems;2005-2006, Vol. 32 Issue 1, p17 

    Soils and river sediments sampled around the vicinity of the Nigeria Research Reactor-1 (NIRR-1) were investigated for their physical properties, morphology, and trace element levels as part of a the reactor pre-operational environmental monitoring campaign. Neutron Activation Analysis (NAA),...

  • Inconsistencies of neutron flux parameters for k standardization in neutron activation analysis determined with the use of Au+Zr and Au+Mo+Cr monitor sets at the LVR-15 reactor in Řež. Kubešová, Marie; Kučera, Jan // Journal of Radioanalytical & Nuclear Chemistry;Aug2012, Vol. 293 Issue 2, p665 

    Multipurpose research reactors require monitoring of neutron flux parameters ( α, f, F or Φ) during every irradiation of samples when k standardization in neutron activation analysis is to be used, because the above parameters may change quite frequently and unpredictably. We tested two...

  • Instrumental neutron activation analysis of hafnium in zirconium metal using internal standardization. Miura, Tsutomu; Matsue, Hideaki; Kuroiwa, Takayoshi // Journal of Radioanalytical & Nuclear Chemistry;Oct2009, Vol. 282 Issue 1, p49 

    Instrumental neutron activation analysis with the internal standard correction was applied to determination Hf in high purity Zr metal. Zirconium, which was a matrix element, was used as an internal standard to compensate for inhomogeneity of the neutron flux through an irradiation capsule and...

  • DETERMINATION OF NEUTRON FLUX PARAMETERS AFTER INSTALLATION OF CD-LINED FOR IMPLEMENTATIONS OF FNAA AND FNAA WITH NIRR-1. Limen, Njinga Raymond; Ibrahim, Y. V.; Adeleye, M. O.; Jonah, S. A. // Indian Journal of Scientific Research;Dec2011, Vol. 2 Issue 4, p1 

    A permanent Cd-lined irradiation channel has been installed in one of the large outer channel of NIRR-1 for use in epithermal and fast NAA procedures. Measurements performed with Cu-wires and (0.1)%Au-Al foils to characterize the thermal, epithermal column and check its effect on the neutrou...

  • Correlations between admixtures and color centers created upon irradiation of natural beryl crystals. Ibragimova, E.; Mukhamedshina, N.; Islamov, A. // Inorganic Materials;Feb2009, Vol. 45 Issue 2, p162 

    Colorless samples of natural beryl which are of little value were irradiated by a neutron flux from a reactor, gamma rays from a shutdown reactor, and gamma rays from a 60Co source to impart gem color to them. As a result of selection of irradiation conditions for samples of pale aquamarines and...

  • Characterization of pneumatic fast transfer system irradiation position of KAMINI reactor for k-based NAA. Rao, J.; Senthilvadivu, E.; Seshadreesan, N.; Acharya, R.; Venkatasubramani, C.; Reddy, A. // Journal of Radioanalytical & Nuclear Chemistry;Oct2012, Vol. 294 Issue 1, p137 

    The pneumatic fast transfer system position at KAMINI reactor, Indira Gandhi Centre for Atomic Research, India was characterized by determining the epithermal neutron flux shape factor (α) and the sub-cadmium to epithermal neutron flux ratio ( f) for k-based Neutron Activation Analysis (...

  • The new PGAA and PGAI facility at the research reactor FRM II in Garching near Munich. Kudejova, P.; Meierhofer, G.; Zeitelhack, K.; Jolie, J.; Schulze, R.; Türler, A.; Materna, T. // Journal of Radioanalytical & Nuclear Chemistry;Dec2008, Vol. 278 Issue 3, p691 

    In April 2007, first cold neutrons flew through the new neutron guide dedicated to prompt gamma activation analysis at the research reactor FRM II. The cold neutron flux intensity of 6.0·109 cm−2·s−1 with mean neutron energy of 1.8 meV was measured at the exit window of the...

  • Automatic activation analysis. Westphal, G. P.; Grass, F.; Lemmel, H.; Sterba, J.; Schröder, P.; Bloch, Ch. // Journal of Radioanalytical & Nuclear Chemistry;Jan2007, Vol. 271 Issue 1, p145 

    Automatic activation analysis (AAA) is rendered possible by a unique neutron activation analysis facility for short-lived isomeric transitions based on a fast rabbit system with sample changer and sample separation, and an adaptive digital gamma-spectrometer for very high counting rates of up to...

  • Installation of Kayzero-INAA standardization in the TNRC and its applications for trace elements determination in different materials. Abugassa, I. O.; Khrbish, Y. S.; Abugassa, S. O.; Ben Faid, N.; Bashir, A. T.; Sarmani, S. // Journal of Radioanalytical & Nuclear Chemistry;Jan2007, Vol. 271 Issue 1, p27 

    The paper focuses on the validation of the k 0-method of instrumental neutron activation analysis ( k 0-INAA) in the Tajura Nuclear Research Center (TNRC) via the analysis of several certified reference materials. The selected reference materials were: SRM 1572 Citrus Leaves, SRM 1575 Pine...


Read the Article


Sorry, but this item is not currently available from your library.

Try another library?
Sign out of this library

Other Topics