Post on 27-May-2019
TRIGA Burnup CalculationsUsing SERPENT
Anže Pungerčič, Dušan Ćalić, Luka Snoj(anze.pungercic@ijs.si)
Jožef Stean Institute, Reactor Physics Department, Slovenia
8th International Serpent User Group MeetingEspoo, Finland, May 29 – June 1, 2018
Outline
• Introduction
• Complete operational history analysis• Steady-State operation
• Pulse mode operation (Pulse experimental database)
• Serpent model and burnup methodology• STRIGA computer tool
• Results of burnup analysis
• Plans for the future
Introduction• TRIGA Mark II research reactor at the „Jožef Stefan“
Institute started operation in 1966.
• Reconstruction in 1991 enabled pulse mode operation.
• Initiated activities to analyse complete operationalhistory of the JSI TRIGA research reactor:
• Steady-State operation
• Pulse mode operation
Reactor core• Fuel type: Cylindrical fuel elements
• Fresh fuel composition: U mixed with ZrH
• 91 Positions
• Six concentric rings
• 4 Control rods
• JSI TRIGA utilization (398 JSI TRIGA related articles1966-2018).
• 15 articles regarding burnup calculation (only usingdeterministic TRIGLAV)
• Large discrepancies (> 500 pcm ) for calculations withburned fuel
• Experimental validation of reactor simulation codeswith excess reactivity measurements.
Burnup analysis vital for:
• Optimization of fuel management
• Decommissioning of the research reactor
Motivation
Operational history analysis• Every operation made with the JSI TRIGA reactor
documented in reactor logbooks.
50 logbooks
20 000 pages
Steady-State: Extracted information• Operational parameters
• Reactor power (changes)
• Operation time
• Core configuration changes (fuel element positions)
• Weekly excess reactivity measurements
Pulse experimental database
• Fuel isotopic composition (Future)• Provides the needed information to simulate or analyse each
pulse separately.
• Publicly available at http://trigapulse.ijs.si
Insertedreactivity
Power andtemperature
signals
Pmax, Etot, FWHM, Tmax
Control rod calibration and
position
Serpent TRIGA model validated on core configuration No. 132 (benchmark) and compared to MCNP
D. Ćalić, G. Žerovnik, A. Trkov, L. Snoj “Validation of the Serpent 2 code on TRIGA Mark II benchmark experiments” Applied Radiation and Isotopes, 107 (2016) 165-170.
STRIGA: Computer tool for TRIGA researchreactors
•Development•Fortran 77
•Purpose•Monte Carlo calculation for TRIGA research reactor•Burnup calculations•Typical steady state calculations
•Goal•Increase the accuracy of TRIGA benchmark usingburned fuel
Cycle 1
Dimension and material data
Serpent input filesTRIGLAV input
files
STRIGA procedure 1/3
• Triglav.inp
• elem.inp
STRIGA
TRIGA.dim TRIGA.lib
materials.inp
3D pins.inp
triga.i
Serpent burnupcalculations
burnup.inp
Serpent output file forcycle 1
STRIGA procedure 2/3
SLIB = utility code that converts Serpentoutput file to ISO library format for
TRIGA reactor
triga.i_dep.mTRIGA.iso
Fuel isotopic library with atomicnumber densities and burnup for
each fuel element
Cycle 2
Dimension, material data and isotopic composition of burned fuel
Serpent input files
TRIGLAV inputfiles
STRIGA procedure 3/3
• Triglav.inp
• elem.inp
STRIGA
TRIGA.dim TRIGA.lib
materials.inp
3D pins.inp
triga.i
Serpent burnupcalculations
TRIGA.iso
burnup.inp
•History after 1991 simulated in 2000 CPU hours(σ𝒌𝒆𝒇𝒇 ≈ 𝟏𝟓 𝒑𝒄𝒎)
•Complete history in ≈ 10000 CPU hours
Different fuel element types.
Goal: Analyse the effects of differentfuel element types.• Fuel element properties:
• Aluminium-LEU
o Low enriched uranium (20 %)
o Without Zr rod
o Aluminium cladding
o 8.5 wt% uranium
• FLIP-HEU (Absorber erbium)
o High enriched uranium (70 %)
o Stainless Steel cladding
o 8.5 wt% uranium
• SS-LEU 8.5 wt% U
o Stainless Steel cladding
• SS-LEU 12 wt% U
Fuel region
Absorbers
SerpentModel
Graphite
Uppercladding
Bottomcladding
TRIGLAV (in-house developed 2D diffusion approximationcode)
Reduction of excess reactivity Cycle No. 69 Cycle No. 218
Measured 𝑝𝑐𝑚 𝑘𝑔𝑈
𝑀𝑊𝑑-94.4 ± 12.8 -292.4 ± 67.3
Calculated with TRIGLAV 𝑝𝑐𝑚 𝑘𝑔𝑈
𝑀𝑊𝑑-78.4 ± 3.9 -216.0 ±10.8
Core 69 Core 218
• Operational history of the JSI TRIGA research reactoranalysed.
• Constructed a publicly available pulse experimental database (http://trigapulse.ijs.si)
• The validated Serpent TRIGA model used for completehistory simulation with the help of the STRIGA computer tool.
• Noticeable differences between different types ofTRIGA fuel elements
• Good agreement between in-house developedTRIGLAV and Serpent for burnup changes in excessreactivity.
Summary
Future work (discussion)• Uncertainties in final fuel el. burnup and its isotopic
composition.
• Effect of the choice in reactor power P and time t on that power.