Report a Safety Concern
Search

The U.S. Nuclear Regulatory Commission is in the process of rescinding or revising guidance and policies posted on this webpage in accordance with Executive Order 14151 Ending Radical and Wasteful Government DEI Programs and Preferencing, and Executive Order 14168 Defending Women From Gender Ideology Extremism and Restoring Biological Truth to the Federal Government. In the interim, any previously issued diversity, equity, inclusion, or gender-related guidance on this webpage should be considered rescinded that is inconsistent with these Executive Orders.

Home NRC Library Document Collections NUREG-Series Publications Publications Resulting from International Agreements

Improvement of RELAP5/MOD3.3 Reflood Model Based on the Assessments against FLECHT-SEASET Tests (NUREG/IA-0251)

On this page:

Download complete document

Publication Information

Date Published: February 2011

Prepared by:
Tong-Soo Choi, Chang-Hwan Ban
KEPCO Nuclear Fuel
Daejeon, Korea

Dong-Gu Kang, Seung-Hoon Ahn
Korea Institute of Nuclear Safety
Daejeon, Korea

A. Calvo, NRC Project Manager

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:
U.S. Nuclear Regulatory Commission

Availability Notice

Abstract

The reflood model of RELAP5/MOD3.3 was assessed against eight selected FLECHT-SEASET tests. Comparisons of predicted and measured peak cladding temperatures and quench times indicated that the code predicts peak cladding temperatures relatively well. However, rod quenches were predicted to occur too early. To improve the predictability for quench times, we carefully reviewed and modified the wall-to-fluid heat transfer models for the film boiling regime. After the modifications, the same set of eight FLECHT-SEASET tests was simulated again to show that the modifications made in this study improve the code’s predictability not only for quench times but also for peak clad temperatures. The modifications reduced the RMS error in the prediction of peak clad temperatures and quench times from 48.3 to 36.7 K and 85.9 to 32.1 seconds, respectively.

Page Last Reviewed/Updated Tuesday, March 09, 2021