A1 Journal article (refereed), original research

System code analysis of accumulator nitrogen discharge during LOCA experiment at PWR PACTEL test facility

Open Access publication

Publication Details
Authors: Kauppinen Otso-Pekka, Kouhia Virpi, Riikonen Vesa, Hyvärinen Juhani
Publisher: Elsevier
Publication year: 2019
Language: English
Related Journal or Series Information: Nuclear Engineering and Design
Volume number: 353
ISSN: 0029-5493
eISSN: 1872-759X
JUFO-Level of this publication: 3
Open Access: Open Access publication
Location of the parallel saved publication: http://urn.fi/URN:NBN:fi-fe2019101532803


The hydroaccumulators
in pressurized water reactors can inject nitrogen into the reactor system. In
the primary system, nitrogen affects core cooling and accident management, both
adversely and beneficially. The PWR PACTEL experiment NCG-13 have shown that during
a hot leg SB LOCA, nitrogen in the primary side can block the primary to
secondary heat transfer and thereby prevent the primary depressurization to the
point needed for the long-term accident management. This paper presents the APROS
and TRACE calculations of the PWR PACTEL NCG-13 experiment. Both codes
calculate the transient progression and the timing of the main events
satisfactorily, once the suitable options are selected and adjustments made.
There is, however, one big discrepancy between the code simulations and the
experiment: in the simulations, much more nitrogen is needed to get
qualitatively the same behaviour. The difference is a factor of 2.5 by mass for
stopping the depressurization and 4-6 to cause a core heat-up. This is of
concern regarding the confidence in the codes, as the simulations underestimate
the adverse effect of nitrogen on the core coolability.

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Last updated on 2020-20-03 at 10:03