TITLE:
A Review of the Scaling Study of the CANDU-6 Moderator Circulation Test Facility
AUTHORS:
Bo Wook Rhee, Hyoung Tae Kim
KEYWORDS:
CANDU-6, Thermal-Hydraulic Phenomena, Moderator Tank, Experimental Test Facility, Scaling Analysis
JOURNAL NAME:
Journal of Power and Energy Engineering,
Vol.2 No.9,
September
15,
2014
ABSTRACT: Following the previous relevant works [1]-[3],
a scaling analysis is performed to derive a set of scaling criteria which were
thought to be suitable for reproducing the major thermal-hydraulic phenomena in
a scaled-down CANDU moderator tank similar to that in a prototype power plant
during a full power steady state condition. The objective of building a
scaled-down moderator tank is to generate the experimental data necessary to
validate the computer codes which are used to analyze the accident analysis of
CANDU-6 plants. The major variables of interests in this paper are moderator
flow velocity and temperature of the moderator which is D2O inside the
moderator tank during a steady state and transient conditions. The reason is
that the local subcooling of the moderator is found to be a critical parameter
determining whether the stable film boiling can sustain on the outer surface of
the calandria tube if the contact of overheated pressure tube and cold
calandria tube should occur due to pressure tube ballooning during LBLOCA with
ECC injection failure [4]. The key phenomena involved include the inlet jet development
and impingement, buoyancy force driven by the moderator temperature gradient
caused by non-uniform direct heating of the moderator, and the pressure drop
due to viscous friction of the flow across the calandria tube array. In this
paper, the previous researches are reviewed, some concerns or potential
problems associated with them implied by comparing CFD analyses results between
the CANDU-6 moderator tank and 1/4 scaled-down test facility are described, and
as a way to examine the assumption of the scaling analysis is true an
order-of-magnitude analyses are performed. Based on the results of these
analyses the assumption of neglecting
and
terms cannot be
justified for the power of 0.5 MW and 1.566 MW for the 1/4 scaled-down
facility. Further investigation is thought to be necessary to confirm this
result, i.e. if the scaling of the previous work1 is justifiable by some other
independent analyses.