art.inl.gov
• Advanced Reactor Technologies• Idaho National Laboratory
Gas-Cooled ReactorFuels and Methods Program Review
June 18-19, 2019
Status of the IAEA CRP on HTGR UAM and OECD/NEA MHTGR-350
Benchmarks
Gerhard Strydom ART-GCR: National Technical Director
Program Goals and Objectives
• Pre-2012: development of tools; support NGNP for DOE and NRC (PEBBED, PEBBLES, CYNOD, THETRIS, COMBINE7, HEXPEDITE)
• 2012-2018: mature tools with minor developmental work (PEBBED, PHISICS/RELAP5-3D, XS generation with DRAGON, HELIOS, SERPENT and SCALE), support private HTGR efforts (X-Energy, Kairos Power, Framatome)
• 2019+: all code development now under NEAMS; ART limited to V&V with NEAMS-tools and maintaining a low/high option to vendors and DOE.
• Methods activity is split between Experimental Validation (Jim Wolf – HTTF, NEUPs) and Simulation
• The two tasks active under the FY-19 GCR Methods Simulation activity are both code-to-code verification benchmarks:§ OECD/NEA MHTGR-350: best-estimate core neutronics & thermal fluids; lattice
physics§ IAEA CRP on HTGR Uncertainties in Modeling (UAM): uncertainty and sensitivity
assessment of cross section & material input uncertainties on lattice; core stand-alone and coupled steady state and transients.
2
IAEA CRP on HTGR Reactor Physics, Thermal-Hydraulics and Depletion Uncertainty Analysis
• The IAEA use Coordinated Research Projects to establish international co-operative research programs (more than 1,600 institutions were involved in ~100 CRPs in 2018).
• Typically 3-6 years project duration. The current IAEA Coordinated Research Project (CRP) on HTGR UAM was started in 2012 and ends June 2019.
• The objective of the CRP is § To contribute new knowledge towards improving the fidelity of calculation
models § in the design and safety analysis of high temperature gas-cooled reactors§ by fully accounting for all sources of uncertainties in calculations.
3
Participation• China – INET
• China – Harbin Engineering University
• Germany – GRS
• Korea – KAERI
• Poland – AGH University of Science and Technology
• Russian Federation – Kurchatov Institute
• South Africa – North West University
• USA – North Carolina State University
• USA – Idaho National Laboratory
4
IAEA CRP on HTGR UAM – Phases and ExercisesExercise I-1 and I-2: Cell neutronics
Exercise I-3 and I-4: Cell thermal fluids
Phase I (Local)
Exercise II-1: Core depletion
Exercise II-2: Stand-alone core neutronics
Phase II(Global)
Exercise III-1: Coupled core neutronics + thermal fluids steady-state
Phase III(Design)
Exercise III-3: Stand-alone core kinetics
Exercise IV-1: Coupled core transient (CRW)Phase IV(Safety)
Exercise III-4: Stand-alone core thermal fluids
5
Reference Designs
250 MW Pebble Bed Prismatic MHTGR-3506
HTR-10 Fuel Pebble Model Options (Harbin Univ. & INET)
7
HTR-10: Single Fuel Pebble
Module type kinf ± σRelative
uncertainty (%Δk/k)
Relative difference (%)
TRISO stochastic model 1.70534 ± 0.00013 0.4757 ± 0.00021 --Lattice random model 1.70609 ± 0.00014 0.4798 ± 0.00022 0.86Lattice jiggled model 1.70539 ± 0.00013 0.4776 ± 0.00021 0.40Zone jiggled model 1.70450 ± 0.00015 0.4768 ± 0.00021 0.23
TRISOS stochastic model with TC algorithm
1.70585 ± 0.00017 0.4751 ± 0.00021 -0.13
Regular lattice model 1.70468 ± 0.00015 0.4774 ± 0.00021 0.36RPT model 1.70481 ± 0.00013 0.4764 ± 0.00020 0.15
Homogenized model 1.59431 ±0.00016 0.4909 ± 0.00025 3.2Total homogenized model 1.57253 ± 0.00017 0.4940 ± 0.00025 3.8
• Uncertainty propagated from nuclear cross-sections
8
INET (China) recent activities related to IAEA CRP on HTGR UAM• Work related to PBR-250 benchmark exercises§ NCSU: UQ&SA results for PBR-250 Ex. I-1 (pebble model), I-2 (assembly
model) and PBR-250 (full-core explicit model) at cold zero power state with SCALE/TSUNAMI-3D
§ INL MOOSE: Exercise I-3 (single pebble T/H benchmark)
• Code development for HTGR uncertainty analysis based on VSOP99 code§ Stochastic sampling method based
§ Nuclear cross section uncertainty analysis
§ Fission yield uncertainty analysis
§ UQ&SA for HTGR depletion calculation
9
PBR-250 Fully Explicit core model
n CE TSUNAMI-3D (CLUTCH)• HTR-PM at cold initial critical state
n Criticality calculation verified• 3D CE KENO-VI vs. Serpent-2
n Uncertainty: 0.68221±0.00081%
10
Phase II Lattice Building Blocks: Single Block and Super Cell
Cross sections are generated for the central fuel block in a 7-block “super” cell. This method accounts for the spectral environment changes caused by the surrounding depleted fuel and graphite blocks.
11
Phase II Ex. II-2 Definitions
Ex. II-2a: model option 1Fuel region loaded with single fresh block XS library.
Ex. II-2a: model option 2Fuel center ring loaded with fresh fuel XS library. Core periphery constructed using XS derived from cell L.
Ex. II-2b: model option 1Fuel region loaded with single fresh and depleted blocks
Ex. II-2b: model option 2Fuel region loaded with fresh and depleted blocks, and cell L on periphery.
12
Ex. II-2a: K-eff Mean and Uncertainty (INL)
• The core keff mean values vary significantly (more than 4%) between the depleted (2b-r) and fresh cores (2a-r).
• In contrast to these large keff differences, the standard deviations only vary between 0.44%-0.51%.
• This is a relatively tight uncertainty band for cores containing different fuel loading patterns, rodded and unrodded reflector blocks, and a peripheral super cell cross-section libraries.
13
Ex.II-2b – Core Stand-alone (KAERI)
Problem 3D CoreSuper Cell
for Fresh FuelSuper Cell
for Burnt Fuel
Code DeCART/MUSAD/CAPP DeCART/MUSAD
Parameter keff Axial Offset (%) CRW(pcm) kinf kinf
Value 1.04104 -0.108 81 1.05621 1.04503
Uncert.(%) 0.69 1.53 1.19 0.78 0.58
• No. XS sets: 600
• Multi-Group XS: 190 group based on ENDF/B-VII.1
• Covar. data: 190 group from ENDF/B-VII.1
• Few-Group XS: 10 group
Rel.Power 1.001Std.Dev(%)
0.8190.384
1.3530.327
0.974
0.3300.764
0.271
1.2900.339
0.930
0.3090.833
0.292
1.1010.327
1.105
1.2920.272
0.8570.343
1.3550.311
0.8360.320
1.0110.332
0.7680.313
1.057
0.2760.823
0.3390.997
0.395
0.8250.342
0.9310.266
0.3161.080
0.292
0.342
14
Experimental Data• HTGR operational and experimental data base is very limited.
• Older facilities typically did not include well-characterized uncertainty data.
IEU-COMP-THERM-008(ASTRA)
VHTRC-GCR-EXP-001/CRIT-COEF
15
VHTRC – Impact of Manufacturing Uncertainties (NCSU)
VHTRC manufacturing uncertainties: experiment vs RAVEN/PHISICS (both ~300-380 pcm)
16
CRP on HTGR UAM – Summary• The CRP has been extended from May 2018 to June 2019 to allow
uncertainty propagation to the coupled transient phase.
• IAEA TECDOC will be drafted in 2020; possibly issued in 2021-2050.
• The CRP has already produced more than 16 conference and journal publications since 2016.
• 2 MSc and 3 PhDs completed or nearing completion
• Several codes further developed to be able to do this work (e.g.):§ PHISICS + RELAP5-3D + RAVEN @ INL § MUSAD + DeCart/McCard (KAERI)§ TSUNAMI-MG-DH (GRS)§ VSOP99 Uncertainty module (INET)§ Double Heterogeneity treatment in SCALE improved (ORNL)
17
OECD/NEA MHTGR-350 Benchmark• FY-19 status and FY-20 outlook§ Phase I Ex. 1 (core neutronics) and Phase III (lattice) reports finalized by
participants (see 2018 presentation by J. Ortensi). Currently being prepared for publication by OECD/NEA.§ Phase I Ex. 2 (core thermal fluids):
• First draft comparison report in Dec. 2017 showed significant differences in certain reflector regions for case without bypass flows. INL RELAP5-3D results updated in Dec. 2018 based on model refinements.
• U-Michigan (AGREE) and KAERI (GAMMA+) launched independent verification of their models until convergence with CFD code CFX was reached on a series of simpler exercises (Annals of Nuclear Energy publication to follow).
• Updated results will be compared by Dec. 2019.§ Phase I Ex. 3 (coupled neutronics/thermal fluids):
• Temperature differences carried over into coupled models.• INL (PHISICS/R5) results updated in 2018.• Unknown if UNIST (MCS/GAMMA+) plans to update their results.• Updated U-Michigan (PARCS/AGREE) results expected by end 2019.
18
FY-2019 Level 2 and 3 Milestone Status• L3 on IAEA CRP results for Phases II-IV (due Sept. 15th, 2019)
19
Path Forward • Since 2012, the HTGR Methods & Simulation activity has been under
increasing funding pressure.
• In FY-19, DOE formalized the mandate of HTGR Methods: § Focus only on V&V of existing and new codes that are/will be used to support
vendor & NRC HTGR development and licensing§ No new code development in ART – all code development must be under
NEAMS§ Only minimal code maintenance + documentation of existing tools
(PHISICS/R5, PEBBED); justified by ad hoc interest (e.g. TCF with Framatome). § The final reports for the two international benchmarks will be completed in FY-
20 (only $50k in new funding requested). § DOE deliverable: L3 report on IAEA CRP results for Phases II-IV (due Sept.
15th, 2019)
20
Path Forward • For FY-20, the focus shifts to V&V of HTGRs using the latest
NEAMS/NRC supported tools (MAMMOTH, PRONGHORN, etc.).§ Pebble shuffling/depletion capability for pebble bed HTGRs (on MOOSE)§ Fast nodal solver for prismatic HTGRs (on MOOSE)
• These activities will be supported through NEAMS funding under Reactor Product Line (RPL). This effort remains small (<$500k in FY-20).
• Development of any new tools is funded through separate NEAMS+NRC funding lines outside ART. The focus is different for developers and users, so we see this division of roles as a positive development going forward.
21
References
• IAEA CRP on HTGR UAM:§ INL reports § PBR-250 data from Fu Li (INET)§ MHTGR-350 data from Tae-Young Lee (KAERI), Pascal Rouxelin (NCSU)
• OECD/NEA MHTGR-350: § INL reports § Status updates from Volkan Seker (U-Mich), Javier Ortensi (INL)
22