Mixing phenomena of interest to boron dilution during small break LOCAs in PWRs. Revision 7/95

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This paper presents the results of a study of mixing phenomena related to boron dilution during small break loss of coolant accidents (LOCAs) in pressurized water reactors (PWRs). Boron free condensate can accumulate in the cold leg loop seals when the reactor is operating in a reflux/boiler-condenser mode. A problem may occur when subsequent change in flow conditions such as loop seal clearing or re-establishment of natural circulation flow drive the diluted water in the loop seals into the reactor core without sufficient mixing with the highly borated water in the reactor downcomer and lower plenum. The resulting low boron ... continued below

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10 p.

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Nourbakhsh, H.P. & Cheng, Z. July 1, 1995.

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Description

This paper presents the results of a study of mixing phenomena related to boron dilution during small break loss of coolant accidents (LOCAs) in pressurized water reactors (PWRs). Boron free condensate can accumulate in the cold leg loop seals when the reactor is operating in a reflux/boiler-condenser mode. A problem may occur when subsequent change in flow conditions such as loop seal clearing or re-establishment of natural circulation flow drive the diluted water in the loop seals into the reactor core without sufficient mixing with the highly borated water in the reactor downcomer and lower plenum. The resulting low boron concentration coolant entering the core may cause a power excursion leading to fuel failure. The mixing processes associated with a slow moving stream of diluted water through the loop seal to the core are examined in this paper. Bounding calculations for boron concentration of coolant entering the core during a small break LOCA in a typical Westinghouse-designed four-loop plant are also presented.

Physical Description

10 p.

Notes

INIS; OSTI as DE95016509

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  • 7. international topical meeting on nuclear reactor thermal-hydraulics (Nureth-7), Saratoga Springs, NY (United States), 10-15 Sep 1995

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  • Other: DE95016509
  • Report No.: BNL-NUREG--60573-(Rev.7/95)
  • Report No.: CONF-950904--5-Rev.7/95
  • Grant Number: AC02-76CH00016
  • DOI: 10.2172/102204 | External Link
  • Office of Scientific & Technical Information Report Number: 102204
  • Archival Resource Key: ark:/67531/metadc618583

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  • July 1, 1995

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  • June 16, 2015, 7:43 a.m.

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  • April 7, 2016, 8:19 p.m.

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Nourbakhsh, H.P. & Cheng, Z. Mixing phenomena of interest to boron dilution during small break LOCAs in PWRs. Revision 7/95, report, July 1, 1995; Upton, New York. (digital.library.unt.edu/ark:/67531/metadc618583/: accessed September 22, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.