K. Devan

Effects of cross section sets and quadrature orders on neutron fluxes and on secondary 24Na activation rate of a pool type 500 MWe FBR

In the early stages of shield design for the 500 MWe pool type Prototype Fast Breeder Reactor (PFBR), the DLC-37 coupled (100n, 21 γ) cross section set, extended to include data for the plutonium isotopes, only was used for the transport calculations. Several limitations were recognised in this set. Two new sets IGC-S2 (100n, 21 γ) and IGC-S3 (175n, 42 γ) have been created and validated at IGCAR, based on ENDF/B-VI (5). Comparison of the results of two-dimensional transport calculations using DLC-37, IGC-S2 and IGC-S3 is presented in this paper, for PFBR. Since the activation of secondary sodium in the Intermediate Heat Exchanger (IHX) depends significantly but differently on the axial and radial neutron fluxes leaking from the core, 2-D transport calculations with reasonable orders for the anisotropy and angular quadrature are necessary. The effects of anisotropy in the scattering cross sections and the SN order, on the shield parameters are studied with IGC-S2. It is found that 175-group calculations clearly predict the finer details of the neutron spectrum in the sodium pool and would facilitate more accurate shield design of PFBR.

Generation and validation of a new 121 group coupled (n, γ) cross section library for fast reactor applications

Abstract A new 121 group (100 neutron group, 21 gamma group) coupled cross section library with anisotropic scattering has been generated at IGCAR for 25 nuclides by using the 1985 version of NJOY code system. The basic data used are ENDF/B-IV for neutrons and DLC-99 for photons. A set of six neutron source benchmarks, one gamma source benchmark and one gamma production benchmark has been used in validating this new library. Of these, the first six are computational benchmarks and the last two are experimental benchmarks. Reasonably good predictions have been obtained with this new set relative to the reference solutions. Thus, capability has been developed at IGCAR for generating new multigroup cross section libraries for shielding applications.

Extension of rational approximation method to p-wave collision amplitudes in Reich–Moore resonance formalism

Abstract Rational approximation method developed to calculate s-wave collision matrix for non-fissile nuclides in Reich–Moore (RM) resonance formalism is extended to the p-wave part of the RM collision amplitudes.

A rational approximation to Reich–Moore collision matrix of non-fissile nuclides

The cross sections of many important nuclides are represented in Reich–Moore (RM) formalism in the recent American Evaluated Nuclear Data file, ENDF/B-VI. Processing of cross sections with RM resonance parameters is much more difficult than the other multilevel formalisms such as MLBW and Adler–Adler. In this paper, we derive a rational approximation to the RM collision matrix in the vicinity of a resonance. This simplifies the cross section processing. The energy range of the validity of this approximation in the vicinity of a resonance is also derived. Choosing Ni58 as an example, results of our approximation for a non-fissile nuclide are given for two typical s-wave resonances. Our rational approximation method is found to work with good accuracies in the vicinity of resonances.

Preparation of multigroup lumped fission product cross-sections from ENDF/B-VI for FBRs

Abstract Multigroup pseudo fission product cross-sections were computed from the American evaluated nuclear data library ENDF/B-VI, corresponding to various burnups of the proposed 500 MWe prototype fast breeder reactor (PFBR), in India. The data were derived from the cross-sections of 111 selected fission products that account for almost complete capture of fission products in an FBR. The dependence of burnup on the pseudo fission product cross-sections, and comparison with other data sets, viz. JNDC, ENDF/B-IV and ABBN, are discussed.