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Title: TRANSPORT CHARACTERISTICS OF SELECTED PWR LOCA GENERATED DEBRIS.

Abstract

In the unlikely event of a Loss of Coolant Accident (LOCA) in a pressurized water reactor (PWR), break jet impingement would dislodge thermal insulation from nearby piping, as well as other materials within the containment, such as paint chips, concrete dust, and fire barrier materials. Steam/water flows induced by the break and by the containment sprays would transport debris to the containment floor. Subsequently, debris would likely transport to and accumulate on the suction sump screens of the emergency core cooling system (ECCS) pumps, thereby potentially degrading ECCS performance and possibly even failing the ECCS. In 1998, the U. S. Nuclear Regulatory Commission (NRC) initiated a generic study (Generic Safety Issue-191) to evaluate the potential for the accumulation of LOCA related debris on the PWR sump screen and the consequent loss of ECCS pump net positive suction head (NPSH). Los Alamos National Laboratory (LANL), supporting the resolution of GSI-191, was tasked with developing a method for estimating debris transport in PWR containments to estimate the quantity of debris that would accumulate on the sump screen for use in plant specific evaluations. The analytical method proposed by LANL, to predict debris transport within the water that would accumulate on the containmentmore » floor, is to use computational fluid dynamics (CFD) combined with experimental debris transport data to predict debris transport and accumulation on the screen. CFD simulations of actual plant containment designs would provide flow data for a postulated accident in that plant, e.g., three-dimensional patterns of flow velocities and flow turbulence. Small-scale experiments would determine parameters defining the debris transport characteristics for each type of debris. The containment floor transport methodology will merge debris transport characteristics with CFD results to provide a reasonable and conservative estimate of debris transport within the containment floor pool and subsequent accumulation of debris on the sump screen. The complete methodology will, of course, include a means of estimating debris generation, transport to the containment floor, transport to the sump screen, and the resulting loss of NPSH.« less

Authors:
; ;
Publication Date:
Research Org.:
Los Alamos National Lab., NM (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
765635
Report Number(s):
LA-UR-00-4998
TRN: US0303031
DOE Contract Number:
W-7405-ENG-36
Resource Type:
Conference
Resource Relation:
Conference: Conference title not supplied, Conference location not supplied, Conference dates not supplied; Other Information: PBD: 1 Oct 2000
Country of Publication:
United States
Language:
English
Subject:
21 SPECIFIC NUCLEAR REACTORS AND ASSOCIATED PLANTS; 22 GENERAL STUDIES OF NUCLEAR REACTORS; ACCIDENTS; CONTAINMENT; ECCS; FLOORS; IMPINGEMENT; LOSS OF COOLANT; PWR TYPE REACTORS; RESOLUTION; SAFETY; SCREENS; THERMAL INSULATION; TRANSPORT; TURBULENCE; WATER

Citation Formats

A. K. MAJI, B. MARSHALL, and ET AL. TRANSPORT CHARACTERISTICS OF SELECTED PWR LOCA GENERATED DEBRIS.. United States: N. p., 2000. Web.
A. K. MAJI, B. MARSHALL, & ET AL. TRANSPORT CHARACTERISTICS OF SELECTED PWR LOCA GENERATED DEBRIS.. United States.
A. K. MAJI, B. MARSHALL, and ET AL. Sun . "TRANSPORT CHARACTERISTICS OF SELECTED PWR LOCA GENERATED DEBRIS.". United States. doi:. https://www.osti.gov/servlets/purl/765635.
@article{osti_765635,
title = {TRANSPORT CHARACTERISTICS OF SELECTED PWR LOCA GENERATED DEBRIS.},
author = {A. K. MAJI and B. MARSHALL and ET AL},
abstractNote = {In the unlikely event of a Loss of Coolant Accident (LOCA) in a pressurized water reactor (PWR), break jet impingement would dislodge thermal insulation from nearby piping, as well as other materials within the containment, such as paint chips, concrete dust, and fire barrier materials. Steam/water flows induced by the break and by the containment sprays would transport debris to the containment floor. Subsequently, debris would likely transport to and accumulate on the suction sump screens of the emergency core cooling system (ECCS) pumps, thereby potentially degrading ECCS performance and possibly even failing the ECCS. In 1998, the U. S. Nuclear Regulatory Commission (NRC) initiated a generic study (Generic Safety Issue-191) to evaluate the potential for the accumulation of LOCA related debris on the PWR sump screen and the consequent loss of ECCS pump net positive suction head (NPSH). Los Alamos National Laboratory (LANL), supporting the resolution of GSI-191, was tasked with developing a method for estimating debris transport in PWR containments to estimate the quantity of debris that would accumulate on the sump screen for use in plant specific evaluations. The analytical method proposed by LANL, to predict debris transport within the water that would accumulate on the containment floor, is to use computational fluid dynamics (CFD) combined with experimental debris transport data to predict debris transport and accumulation on the screen. CFD simulations of actual plant containment designs would provide flow data for a postulated accident in that plant, e.g., three-dimensional patterns of flow velocities and flow turbulence. Small-scale experiments would determine parameters defining the debris transport characteristics for each type of debris. The containment floor transport methodology will merge debris transport characteristics with CFD results to provide a reasonable and conservative estimate of debris transport within the containment floor pool and subsequent accumulation of debris on the sump screen. The complete methodology will, of course, include a means of estimating debris generation, transport to the containment floor, transport to the sump screen, and the resulting loss of NPSH.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Sun Oct 01 00:00:00 EDT 2000},
month = {Sun Oct 01 00:00:00 EDT 2000}
}

Conference:
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  • In the unlikely event of a loss-of-coolant accident (LOCA) in a pressurized water reactor, break jet impingement would dislodge thermal insulation from nearby piping, as well as other materials within the containment, such as paint chips, concrete dust, and fire barrier materials. Steam/water flows induced by the break and by the containment sprays would transport debris to the containment floor. Subsequently, debris would likely transport to and accumulate on the suction sump screens of the emergency core cooling system (ECCS) pumps, thereby potentially degrading ECCS performance and possibly even failing the ECCS.A systematic study was conducted on various types ofmore » fibrous and metallic foil debris to determine their transport in water. Test results reported include incipient movement, bulk movement, accumulation on a screen, the ability of debris to jump over 5-cm (2-in.) and 15-cm (6-in.) curbs, and the effects of accelerating flow and turbulence. These data are currently being used in conjunction with computational fluid dynamics modeling to determine the potential for each debris type to reach the suction screen.« less
  • This paper presents a comparison between computational fluid dynamics (CFD) analysis and experiments in order to help pressurized water reactor (PWR) plants develop a methodology for estimating the amount of insulation debris that may transport to the sump screens of an emergency core cooling system (ECCS). This information is essential for the resolution of Generic Safety Issue-191 on the safety margins of the ECCS systems subsequent to debris accumulation and head loss at the screen.Tests were carried out on a simulated containment floor in the laboratory to determine the flow velocities in which different types of objects including insulation debrismore » would move along the floor. CFD analyses were independently carried out to determine the flow velocities in the containment under different flow rates and break locations. It was shown that the flow regimes predicted by the CFD analyses compare well with the experimentally observed movement along the floor. Based on this observation the transport fraction of different types of insulation debris can be estimated specific to any PWR plant.« less
  • No abstract prepared.
  • A seven Ohm Blumlein has been used to generate a proton beam in an induction linac using a single magnetically insulated accelerating gap. The proton beam generated has an energy of up to 1.3 MeV at 4.0 kA and a pulse duration of 50 nsec. In this paper the authors report measurements of the beam characteristics and beam transport. Lack of complete neutralization was apparent and a modified system which relies on collective focusing of the ion beam by an electron cloud in an axial magnetic field has been developed. First results obtained using the collective focusing show evidence ofmore » improved transport over, at least, short distances. Further measurements are needed to confirm the adequacy of the present system for transport over the scale lengths needed for a multi-gap accelerator.« less