Study on Effective Average (γ, n) Cross Section for 89Y, 90Zr, 93Nb, and 133Cs and (γ, 3n) Cross Section for 99Tc

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A nondestructive detection technique was proposed for the easy assessment of long-lived radionuclides by the use of bremsstrahlung photons. The nuclide of 99Tc was considered for the assessment over an effective average 99Tc (γ, 3n) 96Tc cross section. For validating the experimental method on 99Tc, photonuclear (γ, n) cross sections of 89Y, 90Zr, 93Nb, and 133Cs were measured. Continuous-energy bremsstralung photons were generated from a platinum target bombarded by an electron beam of 32/36 MeV from an electron linac. The photonuclear (γ, n) cross sections were previously measured by Saclay (France) and Livermore (USA) laboratories for 89Y, 90Zr, 93Nb, and 133Cs nuclides. For 89Y, 90Zr, and 133Cs, the present results were in good agreement, within 9% deviation with Saclay and an acceptable deviation of 14–36% from Livermore. In the case of 93Nb, the contribution for 93Nb (γ, n) 92Nb* in the metastable state was 55.2% of the total (γ, n) cross section of Saclay in an averaged form. The present experimental method was thus confirmed to show a good accuracy. The effective average cross section of 99Tc (γ, 3n) 96Tc was obtained as 2.30 mb in the energy range of 25.723–36 MeV.