INL/OSU LDRD

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INL/OSU LDRD Developing Core Flow Analysis
Methods for the VHTR and GFR Designs

• Theron Marshall, INL
• J.N. Reyes, Jr., Brian Woods, Qiao Wu, OSU
• ACE Workshop
• September 19-20, 2005

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TABLE OF CONTENTS

• Introduction
• Research Objectives
• Research Plan
• Gas Reactor Test Section (Preliminary)
• Towards a Large Scale GRTF at INL

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INTRODUCTION

• The Idaho National Laboratory (INL), through its
  LDRD program, has established a research project
  at Oregon State University (OSU) to investigate
  the flow behavior in the VHTR and GFR during a
  LOCA.
• OSU will conduct LOCA experiments and participate
  in a joint modeling and analysis effort to
  validate ATHENA modeling for the GFR and VHTR.

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RESEARCH OBJECTIVES

• The principal objective is the experimental
  validation and optimization of RELAP5/ATHENA
  thermal hydraulics modeling of a Loss of Coolant
  Accident (LOCA) for both the thermal and fast
  gas-cooled next-generation nuclear reactors.
• Design, construct, and operate a small scale Gas
  Reactor Vessel Test Section (GRTS).
• Provide LOCA core flow data to benchmark
  RELAP5/ATHENA predictions.
• Develop and assess Computational Fluid Dynamics
  (CFD) models for the LOCA.
• Provide the INL with a technological basis for
  seeking funding for a national, large-scale gas
  reactor thermal fluids test facility at INL.

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Research Plan
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Flow Directions in VHTR and GFR
GFR with concentric inlet/outlet and upward flow
through core
NGNP with concentric inlet/outlet and downward
flow through core
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Flow Behavior During a LCOA in VHTR and GFR
Figure 1 Helium mass flow through the VHTR core
following the LOCA initiation. Onset of natural
circulation occurs after 200 hours (Moore, 2002).
Figure 2 Helium mass flow through the GFR core
following the LOCA initiation. Onset of natural
circulation occurs within one minute.
(Marshall, 2005).
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Scaling Analysis

• Fluid Properties Scaling
• Top-Down System Scaling
• Natural Circulation
• Bottom-Up Phenomena Scaling
• Local Transport Phenomena
• Air Ingress by Diffusion
• Lower Plenum Turbulent Mixing

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Description of GRTS Normal Flow Path for VHTR
Configuration
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Air Ingress Flow Path for VHTR Configuration
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GRTS Preliminary Design
Drawing by Jim Nylander, Harris Thermal
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GTRS Proposed Operating Conditions

• Pressure Vessel Wall Rated to operate at 550oC
  (1022oF) and 1 MPa (155 psia).
• Ceramic lined shroud and upper head can operate
  above 1000oC
• Hexagonal Ceramic Heaters to simulate the
  prismatic core.
• Matches VHTR Temperature Conditions
• Inlet Temperature 490oC (914oF)
• Outlet Temperature 1000oC( 1832oF)

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GRTS Benchmark Tests

• OSU will conduct tests for upward and downward
  flow through the core under reduced circulation
  pump flow conditions.
• Core flow stability assessment
• LOCA (air ingress study)
• Future Proposal
• Thermal mixing in the hot duct
• Thermal mixing in the lower plenum

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GRTS Benchmark Calculations

• INL will use RELAP5/ATHENA to predict GRTS core
  flow data.
• OSU will use the computational fluid dynamics
  code FLUENT to predict GRTS thermal mixing
  behavior.
• Ph.D. Graduate Student to support INL code
  development effort.

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Significance of LDRD Results

• Provide INL with a technological basis for
  seeking funding for a national, large-scale gas
  reactor thermal fluids test facility
• Scaling Analysis Methods
• Reduced Scale Benchmark Data
• Benchmarked Analysis Tools
• Support Basis for INL Design and Certification of
  the NGNP

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Conclusions

• OSU/INL LDRD project Developing Core Flow
  Analysis Methods for the VHTR and GFR Designs is
  underway.
• Scaling Analysis Methods
• Reduced Scale GRTS
• Reduced Scale Benchmark Data
• Benchmarked Analysis Tools