Average Neutron Gross Section Measurements in U-235 Fission Spectrum for Some Threshold Reactions

Abstract

Integral cross section / Activation technique / Fission spectrum / Threshold reactions / Fast neutron dosimetry / Neutron spectrum unfolding AbstractFission neutron spectrum averaged cross sections have been measured for the threshold reactions "Ni(n, 2n)"Ni, 2n)'"I, "Mn(n, 2n)='^Mn, "Cu(n, a)®»Co and "P(n, p)3'Si, by the activation technique using high-resolution y-ray spectroscopy. The fast neutron spectrum at the Irradiation position has been characterized by using an additional set of activation foils. The results are presented with a complete uncertainty covariance matrix and are compared with evaluated values and previous measurements.

Measurements of U-235 Fission Neutron Spectrum Averaged Cross Sections for Threshold Reactions

“…The irradiations have been performed near the core of the IEA-R1 reactor, very close (~4 mm) to the fuel element. According to the previous study [1], the fast neutron spectrum in this position is similar to the 235 U fission spectrum. However, a new neutron spectrum characterization was performed applying the same methodology, i.e., multiple foil activation techniques in combination with a package of computer codes called SAIPS [6] for data analysis.…”

“…The experimental procedure employed in the present study has been described in detail previously [1], Therefore only a summary will be presented here. The irradiations have been performed near the core of the IEA-R1 reactor, very close (~4 mm) to the fuel element.…”

“…A systematic investigation of fast neutron threshold reactions has been undertaken [1] in this laboratory using the fission spectrum obtained at IEA-R1 2 MW pool-type research reactor. In the first part of the experiment [1] attention was paid to install an adequate irradiation device near the reactor core, to characterize the neutron spectrum at the irradiation position and to measure averaged neutron cross sections for a particular set of threshold reactions.…”

“…In the first part of the experiment [1] attention was paid to install an adequate irradiation device near the reactor core, to characterize the neutron spectrum at the irradiation position and to measure averaged neutron cross sections for a particular set of threshold reactions. In the present paper, another important set of threshold reactions, listed in Table 1, was investigated as an effort to establish the origin of some discrepancies between calculated and measured values of σ (see for example references [2,3] and [4]) and to provide new experimental information on these parameters with lower overall uncertainties than those reported in the literature.…”

Preparation of31Si-labelled silicate: a radiotracer for silicon studies in biosystems

“…It can also be produced by fast neutron irradiation of phosphorus or its compounds by the 31 P(n,p) 31 Si nuclear reaction having a threshold energy of 0.7328 MeV and a s for fast neutrons of 0.034 barn. 7,8,17,18 Preparation of 31 Si from 31 P using the (n,p) route is accompanied by the simultaneous production of 32 P (t 1/2 =14.26 d) due to the presence of thermal neutrons. The involved nuclear reaction 31 P(n,g) 32 P has a s of 0.16 barn.…”