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Title:
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Post-test analysis of PANDA test P4 [ECN-C--98-104 ; INNO-TEPSS(98)-D19]
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Author(s):
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Published by:
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Publication date:
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ECN
NUC
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1999
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ECN report number:
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Document type:
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ECN-C--98-104
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ECN publication
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Number of pages:
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Full text:
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88
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Download PDF
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Abstract:
The results of a post-test analysis of the integral system test P4, whichhas been executed in the PANDA facility at PSI in Switzerland within the
framework of Work Package 2 of the TEPSS project are presented. The post-test
analysis comprises an evaluation of the PANDA test P4 and a comparison of the
test results with the results of simulations using the RELAPS/MOD3.2,
TRAC-BF1, and MELCOR 1.8.4 codes. The PANDA test P4 has provided data about
how trapped air released from the drywell later in the transient affects PCCS
performance in an adequate manner. The well-defined measurements can serve as
an important database for the assessment of thermal hydraulic system analysis
codes, especially for conditions that could be met in passively operated
advanced reactors, i.e. low pressure and small driving forces. Based on the
analysis of the test data, the test acceptance criteria have been met. The
test P4 has been successfully completed and the instrument readings were with
the permitted ranges. The PCCs showed a favorable and robust performance and
a wide margin for decay heat removal from the containment. The PANDA P4 test
demonstrated that trapped air, released from the drywell later in the
transient, only temporarily and only slightly affected the performance of the
passive containment cooling system. The analysis of the results of the RELAPS
code showed that the overall behaviour of the test has been calculated quite
well with regards to pressure, mass flow rates, and pool boil-down. This
accounts both for the pre-test and the post-test simulations. However, due to
the one-dimensional, stacked-volume modeling of the PANDA DW, WW, and GDCS
vessels, 3D-effects such as in-vessel mixing and recirculation could not be
calculated. The post-test MELCOR simulation showed an overall behaviour that
is comparable to RELAPS. However, MELCOR calculated almost no air trapping in
the PCC tubes that could hinder the steam condensation rate. This resulted in
lower calculated pressure values, i.e. an overestimation of the actual PCC
performance. Any stratification of the DW and WW gas space and the WW pool
was not calculated by MELCOR since these volumes have been represented by a
single node. The TRAC-BF1 calculations show a reasonable agreement with the
P4 test, but only a part of the transient as well as part of the system have
been analyzed with the code. Because of numerical problems, the wetwells were
not included in the TRAC-BF1 model, but were replaced by BREAK components
using tabulated pressure values that were based on the experimental results.
21 refs.
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