PowerPointPrsentation

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IP EUROTRANS DM1
Transient Analysis for the EFIT 3-Zone Core
P. Liu, X.-N. Chen, A. Rineiski, S. Wang, M.
Flad, W. Maschek Forschungszentrum Karlsruhe,
IKET Postfach 3640, D-76021 Karlsruhe
IP EUROTRANS DM1 WP1.5 Mtg. Bologna, 28-30 May
2008
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Contents

• Design base and Some former work
• (ULOF, Beam trip, UTOP, UBA already
  presented in last meeting)
• SIMMER-III new model
• (with a new implemented pump model)
• ULOF (under new pressure drop conditions)
• Beam Trip (short term beam trip1second)
• Unprotected Blockage (first fuel ring totally
  blocked)
• Summaries

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ENEA 384MWth 3Zone Core Design
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Former work-SIMMER-III simulation of the steady
state
SIMMER-III
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Former work-SIMMER-III simulation of the steady
state
SIMMER-III Calculated Peak Fuel
Temperature 1352.1 ? Peak Clad Temperature
521.1 ?
Limit temperatures at nominal conditions Fuel
1380 ?, Clad 550 ? (From ENEA Files)
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New geometrical model of EFIT core in SIMMER-III
Coolant inlet
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ULOF analysis

• Assumptions and conditions
• Core - SG midplane distance 3.7 m
• The transient starts at 60 s from a well
  established steady-state
• Total pressure drop in the primary system
• 1.1 bar
• 1.37 bar (two cases)
• 1.87 bar
• Pump head becomes zero in 10 s halving time 2
  s (Main)
• Pump head becomes zero in 5s, halving time 2 s
• (for the 2nd case of 1.37bar)

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ULOF analysis -1.1 bar pressure drop
Pump head becomes zero in 10 s,
halving time 2 s
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ULOF analysis -1.37 bar pressure drop (1st case)
Pump head becomes zero in 10 s,
halving time 2 s
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ULOF analysis -1.37 bar pressure drop (1st case)
Simple view of the Coolant Movement in the system
during the pump coast down process.
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ULOF analysis -1.37 bar pressure drop (2nd case)
Pump head becomes zero in 5 s, halving time 2
s Pump coast down data needed!!
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ULOF analysis -1.87 bar pressure drop
Pump head becomes zero in 10 s,
halving time 2 s
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ULOF-Comparison
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Beam trip analysis
Assumption External beam amplitude being zero
for 1 second.

• Fuel temp. at core mid-plane
• Coolant and clad temp. at core outlet

• Maximum fuel temp. decrease about 554 K
• Maximum clad temperature decrease
• about 14 K
• Maximum coolant temperature decrease about 12 K.

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Unprotected blockage

• Assumptions/Conditions/Parameters
• Innermost ring totally blocked
• Transient starts at 30 s from a well established
  steady-state
• He fission gas pressure (1MPa BOC initial at
  gas plenum)
• Radial heat exchange between SA rings is taken
  into account
• Clad failure and gas release at 1280K
• Clad weakening and start of fuel movement at 1513
  K
• Hexcan crack at 1280K
• Hexcan weakening at 1513K
• Fuel particle size volumetrically equals to one
  pellet r 4.555mm
• Steel particle size r 2.0mm
• No-removable upper pin structure
• No damage propagation to Target facility

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Unprotected blockage-Continued

• Power increased to a maximum of 655 MW
• Fuel pin damage propagation happens, damage
  spreads to the third fuel ring.

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Summaries

• ULOF Analysis
• New SIMMER modeling on the ULOF has been
  performed with a pump and heat exchange region
  and in turn, the three free surface well modeled
  with the implemented pump model in SIMMER-III
• Under the 1.37 bar total pressure drop and the
  assumed pump coast down conditions, the current
  core can survive the ULOF transient
• Pump coast down data should be well established

• Beam Trip Analysis
• With a 1 seconds beam-off, the maximum fuel
  temperature decreases about 554 K, the maximum
  clad temperature transiently decreases 14 K, the
  maximum coolant temperature decreases 12 K

• UBA Analysis
• Fuel damage could happen and spread to the third
  fuel ring if the first fuel ring is completely
  blocked
• The power can arrive as high as 655 MW
• The power finally decreases due to the inherent
  fuel sweep-out mechanism.