United States Nuclear Regulatory Commission - Protecting People and the Environment

Rod Bundle Heat Transfer Facility – Steady-State Steam Cooling Experiments (NUREG/CR-7152)

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Publication Information

Manuscript Completed: August 2011
Date Published: May 2014

Prepared by:
L. E. Hochreiter, Principal Investigator
Department of Mechanical and Nuclear Engineering

Fan-Bill Cheung, Co-Principal Investigator
Department of Mechanical and Nuclear Engineering

T. F. Lin, Co-Principal Investigator
Applied Research Laboratory

D. M. McLaughlin, Jr.
J. P. Spring
P. M. Kutzler
S. Ergun

The Pennsylvania State University
University Park, Pennsylvania 16802

K. Tien, NRC Project Manager

NRC Job Code N6154

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

Availability Notice


As part of the Nuclear Regulatory Commission safety analysis computer code development efforts, the Rod Bundle Heat Transfer Test (RBHT) facility has been designed and constructed at The Pennsylvania State University. The test series described in this report is the steam cooling tests. A total of 35 steady-state steam cooling experiments was performed in the RBHT. The purpose of the experiments was to examine the steady-state convective heat transfer from the heater rods to single-phase superheated steam in prototypical rod bundle geometry for computer code model development and validation.

The Rod Bundle Heat Transfer Facility has a full length, 3.66 m (12 ft), 7 by 7 rod array with typical Pressurized Water Reactor rod diameters of 9.49 mm (0.374 in) and a rod pitch of 12.59 mm (0.496 in). The heater rods had a top skewed power shape with a peak to average power of 1.5 at the 2.74 m (9 ft) elevation. The RBHT facility has been designed using prototypical mixing vane spacer grids.

The bundle inlet steam temperature was held at saturation for the given test pressure and the inlet Reynolds number ranged from 1,400 to 30,000 with most of the experiments at the lower Reynolds number range. The facility was instrumented to measure the quantities necessary for determining local convective heat transfer coefficients that reflect the heat transfer enhancement caused by mixing vane grids. The measured quantities include vapor temperatures at sub-channel centerlines, mixing vane grid temperatures, a detailed axial pressure drop along the bundle length, absolute pressure in the upper plenum, rod temperatures upstream and downstream of mixing vane grids, and vapor flow rates in and out of the bundle.

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