Mitglied in der Helmholtz-Gemeinschaft
The calculational tools and software at FZJ
A. Xhonneux
IEK-6, Forschungszentrum Jülich
TM Re-evaluation of Maximum Operating Temperatures and Accident Conditions for High
Temperature Reactor (HTR) Fuel and Structural Materials
IAEA Vienna, 12-15 January 2015
Overview
I. Legacy codes
II. HCP Code Package (HCP) Prototype
1. Introduction
2. Examples for new features
3. First results
III. Summary and conclusion
IV. TECDOC
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
Folie 2
Overview
I. Legacy codes
II. HCP Code Package (HCP) Prototype
1. Introduction
2. Examples for new features
3. First results
III. Summary and conclusion
IV. TECDOC
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
Folie 3
HTR-Research at University Aachen / FZJ

Over 40 years of research

Developed HTR-Codes are worth thousands of person-months:
A. Xhonneux
•
since 1969: VSOP
•
since 1983: FRESCO-II (Freisetzung aus dem Core)
•
since 1985: PANAMA
(Partikelbruch Nabielek Martin)
•
since 1987: DIREKT
(Thermohydraulik schneller Druckentlastungen)
•
since 1987: TINTE
(Time Dependent Neutronics and Temperatures)
•
since 2007: MGT
(Multi Group TINTE)
•
since 2010: MGT-3D
•
since 2010: HCP
(Very Superior Old Programs)
(HTR Code Package)
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
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Overview of HTR-Codes
Primary loop multi-physics codes
Fission product release
non local heat sources
VSOP
MGT
core
design
reactor
dynamics
nuclide densities, FE history, decay
heat
2D power
density,
temperature
neutron dose
DIREKT
Thermohydraulics &
Dust
Transport
A. Xhonneux
temperature,
burnup,
fast neutron
fluence
PANAMA
FRESCO-II
TRISO fuel
Performance
FP diffusion
in CP and
FE
damage information
temperatures,
geomerty,
materials
SPATRA
FP
deposition
on metallic
surfaces
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
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VSOP - Features

Core design and simulation of normal operation (optimized for HTR)

Stationary neutronics (2-D and 3-D, CITATION)

Fluid mechanics, stationary and time depending (2-D, THERMIX)

Depletion calculation (based on ORIGEN)

Pebble flow simulation

Calculation of decay power according to German DIN standard

Calculation of fuel cycle costs

Results can serve as input for MGT
H.-J. Rütten, K.A. Haas, Ch. Pohl
VSOP (99/11) Computer Code System
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
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VSOP - Verification and Validation
 Critical Experiments
• CESAR-II (CEA, Cadarache, France)
• KAHTER
(FZJ, Jülich, Germany)
• PROTEUS (PSI, Villigen, Switserland)
 Benchmarks and Code-to-Code Validation
• IAEA CRP-I for Small Pebble Bed Facilities
• IAEA CRP-I for Small Block-Type Facilities
• IAEA CRP-5 for Special Block-Type Assemblies (HTTR)
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
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VSOP - Verification and Validation
 First criticality of HTR
• HTR-10 Pebble-Bed Reactor
• HTTR Block-Type Reactor
(INET, China)
(JAEA, Japan)
 As a part of the licensing process of the HTR-MODUL
• Code-to-Code comparison against the
SIEMENS-INTERATOM ZIRKUS Code System
• Used by TÜV Hannover to check the validity of the ZIRKUS
Code System
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
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MGT-3D - Features

Simulation of shorts transients and accidents (optimized for HTR)

Typical use-cases: DBA (TWCR, DLOF-C, TECR, water and air ingress)

MGT-3D is precursor of TINTE (TIme Dependent Neutronics
and Temperatures)

Neutron diffusion in r/z7phi-geometry coupled with fluid dynamics

0-D spectrum code (based on MUPO) with up to 43 energy groups

Space- and time depending Xenon-Iodine dynamics

Cross-sections for approximately isotopes based on ENDF/B-VII
K. Nünighoff, J.Li, C.Druska, H.-J. Allelein,
Status of updating the cross section library of the juelich reactor dynamics codes
TINTE / MGT to ENDF-B-VII, PHYSOR 2010, Pittsburgh, Pennsylvania, USA, May 9-14, 2010
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
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MGT-3D - Features

Nuclear and non-nuclear (external) heat sources

Heat transport by conduction, convection and radiation

Calculation of temperature profiles in fuel elements

Calculation of gas flow and gas mixtures including diffusion

Simulation of chemical processes in case of air/water ingress

Fortran 95
C. Druska, St. Kasselmann, A. Lauer, Investigations of space-dependent safety-related
parameters of a PBMR-like HTR in transient operating conditions applying a multi-group diffusion
code, Nuclear Engineering and Design, Volume 239, Issue 3, March 2009, Pages 508-520,
ISSN 0029-5493
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
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MGT-3D - Verification and Validation
 Used in many benchmark calculations
 Simulation of several short transients performed at AVR by
using precursor TINTE (results in very good agreement)
•
Blower speed rise/reduction (see figure)
•
Control rod withdrawal
•
Xe-I dynamics
•
…
 HTTR LOFC
 Ongoing: fast depressurizations
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
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Overview of Fission Product Codes at FZJ
FP release rate from one FE
(NOC and accident Conditions)
Fickean diffusion of FPs
in defective and intact
CPs / FEs
Recoil
SiC-Layer thinning
Release from FEs and
transport under
accident conditions
FP-Transport in core
due to convection
Deposition on reflector
surfaces
Fuel Performance
 CP damage fractions
 SiC-Layer thinning
due to thermal
decomposition
Deposition / penetration
metallic surfaces
(primary loop)
STACY: Source Term Analysis Code System
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
Folie 12
FRESCO / PANAMA - Verification and Validation
 Used in many benchmark calculations (amongst others CRP-6)
 Validated by many heat-up (KüFA) tests of spheres/single
coated particles
 SPATRA: First steps with respect to V&V by VAMPYR
experiments in AVR
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
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Overview
I. Legacy codes
II. HCP Code Package (HCP) Prototype
1. Introduction
2. Examples for new features
3. First results
III. Summary and conclusion
IV. TECDOC
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
Folie 14
HTR Code Package (HCP) - Overview
Data Library
(e.g. nuclide properties)
Data
Input
ASCII, XML,
Binary
(user control, program flow, post processing, visualization, I/O)
Validated
XML
A. Xhonneux
Data Output
HCP Backbone
MGT-FD
MGT-N
TRISHA
TNT
SHUFLE
STACY
STAR
Multi-Group
TINTE Fluid
Dynamics
Multi-Group
TINTE Neutronics
Spectrum
Calc. and
Resonance
Treatment
Topological
Nuclide
Transmutation
Softw are for
Handling
Universal
Fuel
Elements
Source
Term
Analysis
Code
System
Source Term
Aerosol
Resuspension
3-D Fluid
Dynamics
3-D
Neutronics
Spectrum /
Resonances
Burn Up
Fuel
FP Release
Management
Dust Issues
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
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Physics Modules - Overview
Physics Model
Former Code
HCP Module
MGT-N
3D Neutronics
MGT-3D
SPEC
3D Fluid Dynamics
MGT-FD
Graphite Corrosion by Air and Water
Depletion and Energy Release
Fuel Management
FP Release / Fuel Performance
Graphite Dust Deposition and
Resuspension
A. Xhonneux
VSOP, Origen-Juel,
NAKURE
TNT
VSOP
SHUFLE
FRESCO I/II
PANAMA
STACY
N.A.
STAR
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
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Overview
I. Legacy codes
II. HCP Code Package (HCP) Prototype
1. Introduction
2. Examples for new features
3. First results
III. Summary and conclusion
IV. TECDOC
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
Folie 17
Examples for Newly Available Features
 New 0D / 1D / 2D spectrum calculation code (TRISHA)
 New CP kernel model (extending MGT-3D)
 Simulation of HTR with prismatic fuel (extending fluid dynamics in MGT-3D)
 Decay heat code using HCP data model (re-implementation of NAKURE)
 Spatially resolved fission product release and transport calculation
(combining several legacy codes w.r.t. fission products to STACY module)
…
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
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TRISHA - New Spectrum Code

Different methods for different core
regions

Better treatment of special zones
(e.g. reflector/core, burnable poison)

different methods for different time
points (e.g. normal operating
conditions, transients)

New Spectrum
Code
2-D cartesian transport
(collision probability method)
Applicable to both LWR and HTR 1-D transport (spher./cyl./cart.)
(collision probability method)
0-D transport
(Bn method)
0-D diffusion
(„Mupo“ approach)
Work in progress (PhD F. Tantillo, RWTH Aachen)
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
Folie 19
TRISHA - 0D solvers (flux calculation)


A. Xhonneux
One cell calculation, T=900 K, σ0 = 10+10 barn, mix of graphite/U-235
Work in progress (PhD F. Tantillo, RWTH Aachen)
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
Folie 20
TRISHA - 1D transport solvers (keff)


A. Xhonneux
Analytical criticality benchmarks (data from LANL)
Work in progress (PhD F. Tantillo, RWTH Aachen)
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
Folie 21
TRISHA - 2D transport solver (flux calculation)
Φthermal
Serpent


PWR fuel element (17x17)
Master thesis F. Tantillo, RWTH Aachen
New solver
for SPEC
Φfast
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
Folie 22
MGT - New CP Kernel Model
 Kernel temperature is needed to consider feedback from fluid dynamics to
neutronics (resonance treatment)
 Up to now, a linear extrapolation was used to determine the temperature
difference between the kernel and the surrounding graphite matrix during
transients (based on value PUEBH for steady-state conditions)
 New Kernel model solves heat transport equation numerically
 More precise solution
 Solution requires less engineering judgement
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
Folie 23
MGT - Influence of new Kernel Model
PMBR-400, Rapid Control Rod Ejection Accident
No calculation of convection
Power (w.r.t. nominal
power)
60
Kernel model
50
PUEBH = 1
PUEBH = 1,8
40
PUEBH = 3
30
20
10
0 0
1
2
3
4
5
6
Time (s)
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
Folie 24
MGT - Verification of Temperature Calculation
 Heat transport equation is
solved in 2D to calculate
temperature distribution in
unit cell of block type
reactor (both Japanese
and US fuel)
 Verification has been
conducted (comparison
with CFX)
 Block type reactor
calculation with MGT-3D
has been performed within
HTTR LOFC project
A. Xhonneux
Fig: Comparison of temperature profile (unit cell calculation of GT-MHR)
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
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 NAKURE has been
re-implemented in C++ to
couple it to the HCP
 Verification with original
NAKURE has been
performed
3000
100
2500
2000
10
1500
1000
1
500
0
Decay power of interval [W]
 NAKURE calculates decay
heat after DIN standard
based on operating history
Power during normal operation [W]
TNT - Decay Heat Calculation
0.1
Operating time [h]
Normal operation
A. Xhonneux
Decay power
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
Folie 26
TNT - DIN versus TNT for single fuel element
Depleted fuel element,
end of core pass
Fresh fuel element,
start of core pass
160
8
Nakure++
140
Nakure++
TNT
7
TNT
6
Power (W)
Power (W)
120
100
80
5
4
60
3
40
2
20
1
0
0
Time (s)
Time (s)
OTTO, burn up target = 100 MWd/kg (Benchmark case documented in DIN standard)
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
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STACY - Release Calculation of Compacts
 New options in STACY:
• Diffusion calculation
for cylindrical
compacts
• Spatially resolved
fission product release
calculation based on
Serpent calculation
HT-Phase
1.0E-01
Relative Cs-137 release
 By using same calculation
approach FRESCO-II
results are reproduced by
STACY
1.0E-02
1.0E-03
1.0E-04
1.0E-05
1.0E-06
0
110
220
330
440
550
660
Operating time [efpd]
FRESCO-II, Layer1
FRESCO-II, Layer2
FRESCO-II, Layer5
STACY, Layer 1
STACY, Layer 2
STACY, Layer 5
Fig: Cs-137 release fraction in 1th, 2nd and 5th layer of HTTR
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
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STACY - Cs-137 Release of HTTR
mol/s
 Exemplary result of
spatially resolved fission
product release calculation
 Releases differ <10 % due
to solving 1D diffusion
equation in cylindrical
coordinates
 Releases differ 10-20 %
due to spatial resolved
calculation
Fig: Cs-137 release distribution in third layer at 660 days
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
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Overview
I. Legacy codes
II. HCP Code Package (HCP) Prototype
1. Introduction
2. Examples for new features
3. First results
III. Summary and conclusion
IV. TECDOC
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
Folie 30
HCP Prototype
 HCP Prototype couples
MGT-3D, SPEC and TNT
 Sequence of steady-state
calculations can be
performed
 First step towards fully
integrated prototype
 HCP Prototype-II: Simulation of sequence of steady state and accidents
conditions with one integrated code (combining MGT-3D / SPEC / TNT /
SHUFLE, replacing capabilities of VSOP)
A. Xhonneux
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IAEA Vienna, 12-15 January 2015
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HCP Prototype - Data Flow
 HCP Prototype:
• Sequence of steady state calculations with MGT-3D making use of burn up
calculation by TNT, spectrum calculation by new SPEC code
• Equilibrium core generated by VSOP, because fuel shuffling is not fully coupled yet
 Next steps:
• Finalization of coupling SHUFLE to the backbone
• Generating the equilibrium core with the HCP Prototype instead of VSOP
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
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Overview
I. Legacy codes
II. HCP Code Package (HCP) Prototype
1. Introduction
2. Examples for new features
3. First results
III. Summary and conclusion
IV. TECDOC
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
Folie 33
Conclusions
 Objectives for HCP
• to increase the simulation capabilities to the present LWR level
• to decrease the forecast uncertainties
• to reduce conservatisms
• to reduce the effort for future model extensions
• to increase the quality of documentation
 HCP is the repository for the Jülich/Aachen knowledge in HTRs
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
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Conclusions, cont’
 Status
• necessary effort is high
• the prototype will be supplemented step by step until full HCP
operation capability is reached
• As documentation is weak at present, effort will be increased
considerably
 Future
HCP concept and main parts will be used for the simulation of
other reactor types (main focus on small and medium types of
LWR)
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
Folie 35
Overview
I. Legacy codes
II. HCP Code Package (HCP) Prototype
1. Introduction
2. Examples for new features
3. First results
III. Summary and conclusion
IV. TECDOC
A. Xhonneux
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
IAEA Vienna, 12-15 January 2015
Folie 36
TECDOC
 Make legacy codes available
 Not all modelling aspects have been fully validated:
A. Xhonneux
•
Further V&V of legacy codes/HCP
•
Perform calculations for new upcoming experiments
(melt-wire experiments to determine max. temperatures?)
•
Validation of full-core STACY calculations?
Re-evaluation of Maximum Operating Temperatures and Accident Conditions
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