MELCOR ex-vessel LOCA simulations for ITER{sup +} Page: 1 of 5
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Qc;jJpq5A%5'-MELCOR Ex-Vessel LOCA Simulations for ITER+
Michael J. Gaeta and Brad J. Merrill
Idaho National Engineering Laboratory
Lockheed Martin Idaho Technologies Company
Idaho Falls, ID 83415-3885Hans-Werner Bartels and Leonid Topilski
ITER San Diego Joint Work Site
11025 N. Torrey Pines Road
La Jolla, CA 92037ABSTRACT
Ex-vessel Loss-of-Coolant-Accident (LOCA) simulations for
the International Thermonuclear Experimental Reactor
(ITER) were performed using the MELCOR code. The main
goals of this work were to estimate the ultimate pressurization
of the heat transport system (HTS) vault in order to gauge the
potential for stack releases and to estimate the total amount of
hydrogen generated during a design basis ex-vessel LOCA.
Simulation results indicated that the amount of hydrogen
produced in each transient was below the flammability limit
for the plasma chamber. In addition, only moderate
pressurization of the HTS vault indicated a very small
potential for releases through the stack.
INTRODUCTION
The content of this paper is a subset of the work performed to
support the Early Safety and Environmental Characterization
Study (ESECS) as part of the ITER project. Previous studies
[1,2] were performed to examine ex-vessel LOCAs for one and
two loop variations of the first wall (FW) and shield/blanket
(SB) design issued in November 1994 and described in [3].
This design is referred to as the November Garching design in
this paper.First Wall
o Shield/BlanketFig. 1 The two loop MELCOR FW/
These postulated ex-vessel failures are of concern for two
reasons. First, an in-vessel breach following an ex-vessel
LOCA in the FW or SB cooling system would allow a path
way to release any tritium retained by the plasma facing
components within the vacuum vessel. Second, the resulting
elevated FW temperatures allow for the possibility of
hydrogen generation by beryllium-steam chemical reactions.
In the following, the MELCOR model of the November
Garching ITER FW/SB design is presented followed by the
results obtained for ex-vessel LOCA simulations.
MODEL DESCRIPTION AND GEOMETRY
The basic two loop cooling configuration modeled in this
study is shown in Fig. 1. The FW is adjacent to the plasma
chamber, which is followed by the SB, and both are
surrounded by a toroidal vacuum vessel. Coolant piping
connects these components within the torus to the pump,
pressurizer and heat exchanger within the HTS vault. Both
the plasma chamber and the HTS vault are connected to a
suppression system through rupture disks that open at
specified pressure differentials. The suppression tank is
vented and filtered to a stack. MELCOR volumes and
connections between these volumes were constructed to
model these systems.C)c
0-'This work was funded by the U.S. Department of Energy, Office of Fusion Energy, under contract No. DE-AC07-941D13223.
DOCUMENT - T
D I Si ONMASTER
First Wall Vault Boundary__' Shield/Blanket
HX HX
Pressurizer Cold Plenum --0- Pressurizer
Pump
Hot PlenumCod. -----Rupture Cl
Vacuum v Dsk
Vessel
Suppression Tank FILTER
SB model of the November Garching design.1 11 s
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Gaeta, M. J.; Merrill, B. J. & Bartels, H. W. MELCOR ex-vessel LOCA simulations for ITER{sup +}, article, November 1, 1995; Idaho Falls, Idaho. (https://digital.library.unt.edu/ark:/67531/metadc621386/m1/1/: accessed April 24, 2024), University of North Texas Libraries, UNT Digital Library, https://digital.library.unt.edu; crediting UNT Libraries Government Documents Department.