Pretest Analysis of a 1:4-Scale Prestressed Concrete Containment Vessel Model (NUREG/CR-6685)
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Manuscript Completed: August 2000
Date Published: October 2000
R- A. Dameron,* L. Zhang,*
Y. R. Rashid,* M. S. Vargas*
Sandia National Laboratories, Principal Contractor
P.O. Box 5800
Albuquerque, NM 87185-0744
5435 Oberlin Drive
San Diego, CA 92121
J. F. Costello, NRC Project Manager
Division of Engineering Technology
Office of Nuclear Regulatory Research
U.S. Nuclear Regulatory Commission
Washington, DC 20555-0001
NRC Job Code W6290
The Nuclear Power Engineering Corporation of Japan and the U.S. Nuclear Regulatory Commission, Office of Nuclear Regulatory Research, are co-sponsoring and jointly funding a Cooperative Containment Research Program at Sandia National Laboratories in Albuquerque, New Mexico. As a part of the program, a prestressed concrete containment vessel model will be tested to failure at Sandia in September 2000. The model, uniformly scaled at 1:4, is representative of the containment structure of an actual pressurized-water reactor plan (OHI-3) in Japan. The objectives of the internal pressurization test are to obtain measurement data of the structural response of the model to pressure loading beyond design basis accident in order to validate analytical modeling, to find pressure capacity of the model, and to observe its failure mechanisms.
This report describes results of pretest analytical studies of the prestressed concrete containment vessel model performed by ANATECH Corp. under contract with Sandia National Laboratories. Construction is being commissioned by the Nuclear Power Engineering Corporation in Japan. The pretest analysis represents the second phase of a comprehensive analysis effort. The first phase consisted of preliminary analyses to determine what finite element models would be necessary for the pretest prediction analyses.
The principal objectives of the pretest analyses are to (1) obtain validation of analytical methods for predicting the structural response and failure modes of a prestressed concrete containment and (2) provide information useful for planning test procedures and instrumentation.
In addition to documenting the predicted behavior of the liner, concrete, rebar, and tendons, a variety of failure modes and locations have been investigated. Global analysis was used to help identify possible failure modes; other analyses investigated localized failure modes or modes specifically associated with 3D behavior. Liner-tearing failure at the cylinder's midheight near penetrations and a shear/bending failure at the base of the cylinder wall were found to be competing failure modes. More detailed modeling of these locations placed a higher likelihood of failure on the liner tearing mode at the cylinder midheight near a major penetration. The most likely location for the liner-tearing failure was found to be near the equipment hatch at the ending point of a vertical T-anchor, near where the liner is attached to the thickened liner insert plate. Using a strain-based failure criteria that considers the triaxiality of stress and a reduction in ductility in the vicinity of a weld, the failure strain was 0.162. The failure pressure at which the local analysis computed strain that reached the failure strain, is 3.2 times the design pressure of 0.4 MPa, or 1.28 MPa.
The pretest analyses, which were completed one year prior to completion of model construction and testing, did not include certain as-built features, actual prestress losses, creep and temperature conditions that may affect the PCCV model behavior during the test. An assessment of the possible uncertainties these as-built conditions may introduce and an approximate analysis of temperature and creep effects are described in the closing chapters of this report.