Status of the RELAP modelling of XT-ADS at SCK?CEN

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Status of the RELAP modelling of XT-ADS at SCK?CEN

• B. Arien, S. Heusdains

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SCK?CEN design
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XT-ADS RELAP MODEL
SCK design (present status)
Input deck
Separate input deck
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From SCK design to Ansaldo design
?
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Differences between the SCK and Ansaldo designs
for the primary circuit
SCK Ansaldo
Primary system
Vessel diameter 5.3 6.11
Core diameter Number of fuel sub-assembly (SA) positions Lower level of the core barrel 1.425 171 Above SA inlet level 1.48 183 Same SA inlet level
Core barrel hole diameter Total cross section Level of the free surface 0.200 m 2.55 m² 3.995 m 0.100 m 1.319 m² 0.5 m underneath vessel top ? (to be confirmed)
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Ansaldo design
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XT-ADS RELAP MODEL
Ansaldo design (present status)
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Lower plenum modelling (I)

• To respect the LBE inlet level in the core
  storage, it is necessary to divide the lower
  plenum into 2 parts
• One LBE volume between the vessel bottom and the
  core storage inlet level (vol. 10)
• One LBE volume (core collector) between the core
  storage inlet and core inlet levels (vol. 12)
• The medium plenum (MP) is defined in such a way
  that
• its top level (inlet) primary pump outlet level
  
• its bottom level (outlet) core bottom level
• Present solution the MP outlet directly linked
  to the core collector and the LBE flow in the
  core collector is separated into 2 parts
• One flow going directly to the core inlet (via
  core collector)
• One flow going to the core storage via volume 10
• Alternative solution prolongation of the MP by
  an annular volume (vol. X) corresponding to the
  LBE volume located between the MP bottom and the
  core storage inlet level vol. X is linked to
  vol. 10 and LBE flow in vol. 10 is separated into
  2 parts
• One flow going to the core via vol. 12
• One flow going to the core storage
• The choice between both solutions depends on the
  real LBE path in the lower plenum (CFD modelling).

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Lower plenum modelling (II)
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Lower plenum modelling CFD results for MYRRHA
Draft2 design (1)
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Lower plenum modelling CFD results for MYRRHA
Draft2 design (2)
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Primary heat exchangers
? Same geometry but other dimensions
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Spallation loop
Spallation loop new design target
?
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Primary system calibration

• Steady-state calibration of the nominal flows
• (by section and pressure drop calibration)
• in the fuel (62.754 kg/s per assembly 4518 kg/s
  in the core
• in the assembly-by-pass "inter-wrapper" flow
  (183 wrappers) 296 kg/s
• in the core by-pass (leaks between spallation
  loop and diaphragm, and others...medium plenum)
  631 kg/s
• in the core storage 90 kg/s
• in the dummy assemblies 1258 kg/s
• cooling spallation loop 206 kg/s
• total flow for 2 pumps 7000 kg/s
• Pump modelling
• Axial pumps characteristic curves from Ansaldo

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Present status of the work
design SCK model design Ansaldo model
PRIMARY SYSTEM - table of data - input deck - calibration at zero power and with centrifuge pumps table of data (draft) new pump model (Ansaldo) - input deck in preparation
SECONDARY SYSTEM table of data input deck test in stand alone - table of data
TERTIARY SYSTEM input deck (old model) calibration -Tractebel data expected
SPALLATION LOOP table of data input deck - calibration at zero power - new target design updating
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In progress

• Primary system calibration
• Secondary system updating and calibration
• Spallation loop input deck and calibration
• Tertiary system model..
• Calibration of the complete model
• Reporting on the model