N. L. Singh

Measurement of 232Th and 238U neutron capture cross-sections in the energy range 5 to 17 MeV

The neutron capture cross sections of 232Th and 238U at the average neutron energies of 5.08 ± 0.17, 8.96 ± 0.77, 12.47 ± 0.83, and 16.63 ± 0.95 MeV have been measured by using the activation technique and off-line γ-ray spectroscopy. The 232Th and 238U were irradiated with neutrons produced from the 7Li(p, n) reaction using the proton energies of 7, 11, 15 and 18.8 MeV from the 14UD BARC-TIFR Pelletron facility in Mumbai, India. Detailed covariance analysis was also performed to evaluate the uncertainties in the measured cross-sections. The excitation function of the 232Th(n, γ) and 238U(n, γ) reactions were calculated using the theoretical model code TALYS-1.9. The experimental and theoretical results from the present work were compared with the ENDF/B-VII-1 and JENDL-4.0 nuclear data libraries and were found to be in good agreement.

Investigation of (n, p), (n, 2n) reaction cross sections for Sn isotopes for fusion reactor applications

The compound Nb3Sn possess superconductivity at suitable temperatures, therefore, it is best suited to be used in the toroidal coils of superconducting magnets which holds the fusion plasma and confine it inside the reactor core. The neutron induced reaction cross-sections are required from threshold to 20MeV for different isotopes of Tin (Sn). Since limited data is available for the reactions with the Sn isotopes. Therefore, we have optimized the (n, p) and (n, 2n) reaction cross-sections for all possible Sn isotopes from threshold to 20MeV with modified input parameters in the nuclear reaction modular codes EMPIRE-3.2.2 and TALYS-1.8. These codes account for the major nuclear reaction mechanisms, including direct, pre-equilibrium, and compound nucleus contributions. The present results from 116Sn(n,p)116mIn, , 117Sn(n,p)117mIn, 118Sn(n,2n)117mSn,120Sn(n,2n)119mSn and 124Sn(n,2n)123mSn reactions calculated with nuclear modular codes: TALYS - 1.8, EMPIRE - 3.2.2 were compared with EXFOR data, systematics proposed by several authors and with the existing evaluated nuclear data library ENDF/B-VII.1, as well. The results from the present study can be used for the future development of ITER devices as well as to upgrade the nuclear model codes.

Measurement of (n, p) cross section for some structural materials at 14.2 MeV

The (n, p) reaction cross section for some structural materials such as 75As, 66Zn, 64Zn, 55Mn, 51V and 58Ni was measured at 14.2±0.2 MeV using activation and off line gamma ray spectroscopic technique. For the purpose of safe and economical design of reactors, the neutron cross section data for structural materials are required with high precession and accuracy. The neutron cross section data for important structural materials are collected and evaluated systematically and data files are prepared for the reactor design. However, considerably large discrepancies exist among different evaluated nuclear data files. Hence there is a need to study these reactions with better accuracy. The results were compared with existing data available in EXFOR data base. The measured cross sections were also estimated theoretically using nuclear modular codes: TALYS-1.6 and EMPIRE-3.2.2.

Investigation of (n,2n) cross sections for some structural materials at 14.0 MeV

Activation technique was used to measure ⁵²Cr(n,2n)⁵¹Cr, ⁵⁵Mn(n,2n)⁵⁴Mn, ⁷⁵As(n,2n)⁷⁴As, ⁹³Nb(n,2n)^92mNb, and ¹²⁴Sn(n,2n)^123mSn reactions at around 14.0 MeV neutron energy. These elements are being used as structural materials in reactor technology. The correction due to the self scattering and self absorption in the samples and pile up effects in the detector was measured experimentally by simulation technique. This technique provides an exact magnitude of corrections experimentally. The experimental cross sections are compared with latest literature data taken from EXFOR database and also with theoretical predictions accounting for nucleon evaporation and preequilibrium emission using hybrid model (ALICE/90) and TALYS-1.4 code over neutron energies from 12 to 16 MeV.

Transmission Electron Microscopy of Longitudinal Double Submerged Arc Weld (LDSAW) of X-120M Steel Line Pipe

This paper deals with the development of submerged arc welding wires for longitudinal double submerged arc welded (LDSAW) line pipe weld through transmission electron microscopy (TEM). The experimental procedure in the paper describes the test coupons preparation for submerged arc welding (SAW) with various combinations of wire and flux with varying level of alloying element. Microstructural characterization by transmission electron microscopy has been carried out to establish the desired microstructure in the weld of LDSAW for manufacturing the API-5L X-120M line pipes. The TEM micrographs for shows the lath type ferrite and bainitic type ferrite with high dislocation density. The lath type ferrite and bainitic type ferrite with high dislocation density also have fine precipitates in the ferrite matrix having orientation relationship. The weld metal suitable for X-120M have the microstructure of mainly bainitic and martensitic with high dislocation density and coarse precipitates in the matrix. The bainitic and martensitic microstructure have excellent fracture toughness down to -20 °C at this strength level (X-120M).