United States Nuclear Regulatory Commission - Protecting People and the Environment

Post-Test Calculations on Steam Cool-Down Test QUENCH-04 with RELAP5, SCDAP/RELAP5, and TRACE (NUREG/IA-0406)

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Publication Information

Manuscript Completed: July 2011
Date Published: December 2011

Prepared by:
Ch. Homann, W. Hering

Karlsruhe Institute of Technology (KIT)
Institute for Neutron Physics and Reactor Technology (INR)
76344 Eggenstein-Leopoldshafen, Germany

A. Calvo, NRC Project Manager

Prepared for:
Division of Systems Analysis
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

Prepared as part of:
The Agreement on Research Participation and Technical Exchange
Under the Thermal-Hydraulic Code Applications and Maintenance Program (CAMP)

Published by:
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001

Availability Notice


In this report, the capabilities of RELAP5, SCDAP/RELAP5, and TRACE to describe oxidation of fuel elements by steam and related hydrogen production are assessed. This work is performed on the background of out-of-pile experiments on the reflood of overheated fuel rod simulators in the QUENCH facility and related numerical investigations at the Karlsruhe Institute of Technology. It is found that oxidation effects play a role even below 1500 K, i.e. for a temperature range that is covered by all of these three codes. The present work relies on the detailed representation of the experimental facility as used for many years for pre- and post-test calculations for the various QUENCH tests with SCDAP/RELAP5. The experimental basis is test QUENCH-04 that consisted mainly of a heat-up and a steam cool-down phase as a relatively simple case, but the present work is also a code to code comparison. As a first step, investigations were concentrated on transients before the reflood phase. Code or modeling errors were identified in both RELAP5 and TRACE that impede reliable predictions for such situations.

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