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Fusion Engineeringand Design 17 (1991)313-319 313 North-Holland

Summary: Fusion Engineeringand Design 17 (1991)313-319 313
Benefits of natural convection in solid breeder blankets
with poloidal coolant channels under LOFA conditions
Alice Y. Ying, A. Rene Raffray and Mohamed A. Abdou
Mechanical, Aerospaceand NuclearEngineeringDepartment, Universityof California, Los Angeles, CA 90024, USA
This paper analyzesnatural circulation flow in solid breeder blanket designs with poloidal coolant channels under a LOFA
condition. Analyses couple the flow transient behaviors with transient heat transport models. While two-phase natural
circulation exists in the system, a homogenous mixture model is used. The results of example calculations performed for an
ITER solidbreeder design concept indicate that in a 3-loop system with an elevation head (AZ) of 20 m, the removal of the
afterheat (energy stored in the blanket elements and decay heat) depends on two-phase natural circulation flow with a
quasi-equilibriumflowquality of 26% at the outlet of the blanket segment. However,if the available hydrostatic head is about
15 m or less,the amount of natural circulation flowis reduced due to significantincreasesof friction and accelerationlossesin
a two-phasesystem.To relyon natural circulation flow as an afterheat removal mechanism, the design of coolant system with
its flowchannels should be addressed analyticallyand experimentallyto permit stable steady-state operation under conditions
of the presence of vapor in the coolant channels.
1. Introduction
Natural circulation refers to flows driven without the
help of an active mechanical device such as a pump.
The flow is driven by density gradients around the flow


Source: Abdou, Mohamed - Fusion Science and Technology Center, University of California at Los Angeles
Raffray, A. René - Center for Energy Research, University of California at San Diego


Collections: Plasma Physics and Fusion