A New Equivalence Theory Method for Treating Doubly Heterogeneous Fuel - II. Verifications

Journal Article · Mon Mar 09 00:00:00 EDT 2015 · Nuclear Science and Engineering

DOI:https://doi.org/10.13182/NSE14-72· OSTI ID:1223635

Choi, Sooyoung ^[1]; Kong, Chidong ^[1]; Lee, Deokjung ^[1]; Williams, Mark L. ^[2]

---

1. Ulsan National Institute of Science and Technology (UNIST), Ulju-gun (Korea)
2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

A new methodology has been developed recently to treat resonance self-shielding in systems for which the fuel compact region of a reactor lattice consists of small fuel grains dispersed in a graphite matrix. The theoretical development adopts equivalence theory in both micro- and macro-level heterogeneities to provide approximate analytical expressions for the shielded cross sections, which may be interpolated from a table of resonance integrals or Bondarenko factors using a modified background cross section as the interpolation parameter. This paper describes the first implementation of the theoretical equations in a reactor analysis code. In order to reduce discrepancies caused by use of the rational approximation for collision probabilities in the original derivation, a new formulation for a doubly heterogeneous Bell factor is developed in this paper to improve the accuracy of doubly heterogeneous expressions. This methodology is applied to a wide range of pin cell and assembly test problems with varying geometry parameters, material compositions, and temperatures, and the results are compared with continuous-energy Monte Carlo simulations to establish the accuracy and range of applicability of the new approach. It is shown that the new doubly heterogeneous self-shielding method including the Bell factor correction gives good agreement with reference Monte Carlo results.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC05-00OR22725
• OSTI ID: 1223635
• Journal Information: Nuclear Science and Engineering, Vol. 180, Issue 1; ISSN 0029-5639
• Publisher: American Nuclear Society - Taylor & Francis
• Country of Publication: United States
• Language: English

Related Subjects

22 GENERAL STUDIES OF NUCLEAR REACTORS