Simulation of Westinghouse G1 and G2 Low Pressure Boil-Off Experiments Using WCOBRA/TRAC
- Westinghouse Electric Company, Nuclear Services Division, P.O. Box 355, Pittsburgh, PA 15230-0355 (United States)
During the 1970's Westinghouse performed full scale core uncover tests to determine the core level swell behavior of a PWR core region under thermal-hydraulic conditions typical of a Small Break LOCA. In the G1 and G2 boil-off test series, prototypical PWR rod bundles were used to simulate core uncover or boil-off conditions over a wide range of power and pressure. Historically, thermal-hydraulic codes used to simulate SBLOCA transients have been validated against these or similar boil-off tests to assess the codes' models for interfacial drag and heat transfer under transient boil-off conditions. Generally, most of the work concentrated on the intermediate to high pressure range (from 500 to 1200 psia), and less attention was paid to near atmospheric conditions. For advanced plants such as the AP1000, following a postulated SBLOCA transient, boil-off condition may occur in the core even in the low pressure range. This has required further code validation, to ensure that the void fraction distribution in the core can be predicted with confidence. In this paper the interfacial drag model of WCOBRA/TRAC computer code was assessed against low pressure data from the G1 and G2 test series, where the pressure was extended down to the near atmospheric pressure. Preliminary results indicated the tendency of the nominal interfacial drag model of the code to over-predict the level swell. When a multiplier of a modest magnitude (0.8) was applied to the interfacial drag coefficient, the code results improved where most of the test data was captured within {+-}20%. (authors)
- Research Organization:
- American Nuclear Society, 555 North Kensington Avenue, La Grange Park, IL 60526 (United States)
- OSTI ID:
- 21160703
- Resource Relation:
- Conference: ICAPP'04: 2004 international congress on advances in nuclear power plants, Pittsburgh, PA (United States), 13-17 Jun 2004; Other Information: Country of input: France; 18 refs; Related Information: In: Proceedings of the 2004 international congress on advances in nuclear power plants - ICAPP'04, 2338 pages.
- Country of Publication:
- United States
- Language:
- English
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