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Title:
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Fission product retention in the ACACIA reactor primary system
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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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1-3-1999
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ECN report number:
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Document type:
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ECN-R--98-019
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Other
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Number of pages:
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Full text:
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37
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Download PDF
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Abstract:
The transport and deposition of fission products in the ACACIA (AdvanCedAtomic Cogenerator for Industrial Applications) high temperature reactor
primary system are investigated. The study focuses on the behaviour
calculated with the MELCOR computer code of 4 nuclides: Cs-137, Sr-90,
Ag-110m, and I-131. After a ten-year operation period, the total activity of
the released nuclides in the primary system is about 58 GBq. The highest
activity is produced by Cs-137 (52 GBq), followed by I-131 (4 GBq), and
Ag-110m (1.8 GBq). The contribution of Sr-90 is very low (1600 Bq). The
highest activity is found in the precooler (56 GBq). The main reason is the
condensation of the volatile species CsOH and CsI in this component. Other
components with high activities are the recuperator (1.4 GBq) and the
compressor (0.007 GBq). These components are contaminated by Ag-110m. The gas
ducts in the energy conversion unit are contaminated by Ag-110m (0.043 GBq)
and I-131 (0.011 GBq). Contamination as a consequence of a Loss Of Coolant
Accident (LOCA) or a Loss of Flow Accident (LOFA) is difficult to estimate,
because it depends on a number of phenomena. Under the assumption that 10
fuels elements are damaged, the activity is about 44 GBq. In this accident,
Ag-110m produces most of the activity (31 GBq), followed by Cs-137 (12 GBq),
and I-131 (1.4 GBq). Although the activity of Sr-90 is high (0.023 GBq), it
is negligible compared to the activity of the other nuclides. Obviously, the
activity is proportional to the number of damaged fuel elements. The
distribution of the nuclides over the components is not considered in view of
the large number of uncertainties. 9 refs.
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