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November 30–December 3, 2021
Washington, DC|Washington Hilton
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Nuclear Science and Engineering
Fusion Science and Technology
The U.S. Army’s Deactivated Nuclear Power Plant Program
The U.S. Army Corps of Engineers (USACE), Baltimore District, is home to the North Atlantic Division’s Radiological Health Physics Regional (RHPR) Center of Expertise, which is leading the decommissioning of Army reactors.
From 1956 to 1976, the Army’s nuclear power program operated several small nuclear reactors to confirm the feasibility of their meeting military power needs on land. Three Army reactors were deactivated in the 1970s and placed into safe storage awaiting future decommissioning.
Sooyoung Choi, Chidong Kong, Deokjung Lee, Mark L. Williams
Nuclear Science and Engineering | Volume 180 | Number 1 | May 2015 | Pages 41-57
Technical Paper | dx.doi.org/10.13182/NSE14-72
Articles are hosted by Taylor and Francis Online.
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. 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. The 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.