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Analysis of Steam-Entry Experiments in the Phase-I GCFR Critical Assembly

Technical Report ·
DOI:https://doi.org/10.2172/5010459· OSTI ID:5010459
 [1];  [1];  [1]
  1. General Atomic Co., San Diego, CA (United States)
The initial three-phase program of critical experiments conducted in behalf of design and safety evaluations for the 300-MW(e) GCFR demonstration plant included extensive studies of steam-entry effects. This report presents results of a General Atomic analysis of the simulated steam ingress experiments in a central 47-liter region of the 3150-liter-core Phase-I GCFR assembly. Investigations of differences in calculated steam worth due to variations in analytical technique are reported, including methods for cross-section generation, adjustments for heterogeneity, neutron-streaming effects, group structure, and the use of various stages of perturbation theory. For each of the densities of steam simulated by CI2 (up to the equivalent of 45 g/liter H2O in the "coolant" channels), the regeneration of cross-section sets for the zone fuel materials with the hydrogen-degraded spectra was found essential for obtaining reasonable agreement of calculated and measured flooding worths. Also, it was necessary to use exact perturbation theory methods, since first-order perturbation was found to be completely inappropriate with the 10- and 28-group structures employed.
Research Organization:
General Atomic Co., San Diego, CA (United States)
Sponsoring Organization:
USDOE National Nuclear Security Administration (NNSA), Nuclear Criticality Safety Program (NCSP)
DOE Contract Number:
EY-76-C-03-0167-023
OSTI ID:
5010459
Report Number(s):
GA-A--14798
Country of Publication:
United States
Language:
English