Measurement of Thermal Neutron Cross Section and Resonance Integral of the Reaction ⁹⁹Tc(n, γ)¹⁰⁰Tc

Abstract

To obtain fundamental data for research on the transmutation of nuclear waste, the thermal neutron cross section and the resonance integral of the reaction ⁹⁹Tc(n, γ)¹⁰⁰Tc have been measured using an activation method.

Four ammonium pertechnetate targets containing 371–375 kBq of ⁹⁹Tc were irradiated for 2 min with reactor neutrons. Activation detectors of Co/Al and Au/Al alloy wires were irradiated for 10 min to monitor the neutron flux and the fraction of the epithermal part (Westcott's epithermal index). The Tc samples and flux monitors were irradiated with and without a Cd capsule. The γ-ray spectra from the irradiated samples were measured using a high purity Ge detector.

The thermal neutron cross section (2,200 m/s neutron cross section) and the resonance integral of the ⁹⁹Tc(n, γ)¹⁰⁰Tc reaction were found to be 22.9±1.3 b and 398±38b, respectively.

The thermal neutron cross section obtained agrees with the previously reported values (20±2b by Lucas, 24.8 by Pattenden, 24±4 by Ovechkin) within the limits of error. On the other hand, the resonance integral is twice the value reported by Lucas (186±16b).

KEYWORDS:

• nuclear transmutation
• incineration
• radioactive waste
• neutron capture
• technetium 99
• technetium 100
• resonance integrals
• thermal neutrons
• cross sections
• half-life
• gamma spectra
• activation method
• fission products
• experimental data