Unclassified

NEA/NSC/DOC(2008)7

Organisation de Coopération et de Développement Économiques
Organisation for Economic Co-operation and Development

02-Jun-2008___________________________________________________________________________________________English text only

NUCLEAR ENERGY AGENCY

NUCLEAR SCIENCE COMMITTEENEA/NSC/DOC(2008)7
Unclassified
OECD/NEA-NSC PBMR COUPLED NEUTRONICS/THERMAL HYDRAULICS
TRANSIENT BENCHMARK - THE PBMR-400 CORE DESIGN
Fourth Workshop (PBMRT4)

21-25 January 2008
NEA Headquarters, Issy-les-Moulineaux, France

English text only

JT03246879
Document complet disponible sur OLIS dans son format d'origine
Complete document available on OLIS in its original format

NEA/NSC/DOC(2008)7
NUCLEAR SCIENCE COMMITTEEOECD/NEA-NSC PBMR COUPLED NEUTRONICS/THERMAL HYDRAULICS TRANSIENTBENCHMARK - THE PBMR-400 CORE DESIGN - Fourth Workshop
NEA Headquarters, Issy-les-Moulineaux, France
21-25 January 2008

SUMMARY RECORD
Content:--

Background and Status of the Benchmark
Scope of 4th Workshop
PART I: DIREKT Workshop
PART II: Meeting on OECD Benchmark progress- Session I– General Session- Session II– Feedback by all participants I- Session III– Feedback by all participants II- Session IV– Benchmark Steady State Cases- Sessions V & VI
– Transient Cases Comparisons- Session VII– Transient Cases Discussion and Conclusion- Sessions VII & VIII – Discussion and Closing
Proceedings of the Workshop
Task List and Summary of Actions
Annex I
– Workshop Programme
Annex II
– Workshop Participants

Background and Status of the Benchmark
In 2004 the Nuclear Energy Agency (NEA) of the Organisation for Economic Cooperation andDevelopment (OECD), through the Nuclear Science Committee (NSC), accepted the Pebble-Bed Modular
Reactor (PBMR) coupled neutronics/thermal hydraulics transient benchmark problem for inclusion in its
programme. The PBMR is a High-Temperature Gas-cooled Reactor (HTGR) concept, developed forconstruction in South Africa. The scope of the benchmark is to establish a series of well-defined multidimensional computational benchmark problems with a common given set of cross-sections, to compare
methods and tools in coupled neutronics and thermal hydraulics analysis with a specific focus on transient
events.
Similar efforts of pebble bed reactor transient analysis code–to-code comparisons andbenchmarking include the PBMR 268MW benchmark problem that served as the predecessor to thisexercise, and the work carried out under the IAEA CRP-5 project (TECDOC in preparation). The OECDbenchmark includes additional steady-state and transient cases including reactivity insertion transients.
Furthermore, it makes use of a common set of cross sections (to eliminate uncertainties between different
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codes) and includes specific simplifications to the design to limit the need for participants to introduce
approximations in their models. It has also attracted wide participation.
The first workshop was held on 16-17 June 2005 at the OECD Headquarters, Paris, France(NEA/NSC/DOC(2005)13). The purpose of the first workshop was to introduce participants to thebenchmark exercise, obtain feedback on the benchmark definition and to establish the possible range of
methods and codes to be used in the code-to-code comparisons. The workshop was attended by 24participants from 12 countries and 20 different organizations. It was also important to establish which
experiments might be available to include in later phases of the benchmark effort. Therefore, presentations
on the AVR and on past, current, planned, and potential experiments at the HTR-10 reactor were of greatinterest in identifying possible future test cases with experimental data.
The second workshop took place on 26-27 January 2006 at the OECD/NEA Headquarters. The
details of the meeting are available in NEA/NSC/DOC(2006)29. Presentation on the status of work related
to the PBMR benchmark were presented by ten participants. The information presented varied from detailsof the methods and codes employed to the results obtained for the steady-state cases. The improvements inthe benchmark definition (clarifications and additions) were also discussed. The multi-dimensional crosssection tables and the difficulties experienced with the generation of cross-sections based on MICROX-2(for the range of buckling terms required) were explained. An alternative method, to use the spectrum code
pre-processor of TINTE, was proposed and accepted. The focus of the meeting was a summary of thesteady-state results for Case 1 (stand-alone neutronics) and Case 2 (stand-alone thermal hydraulics).
Comparisons were made by the different participants and some discrepancies were identified, including
mesh effects, differences in k-eff, misinterpretation of definitions (outlet pressure, temperatures) andinterpretations of the requested results (mesh for reporting, power densities, geometrical range used for
averaging). Some of the differences found could be resolved immediately but others required more detailed
analysis or re-evaluation. The workshop was attended by 25 participants from 7 countries representing 16
different organizations.
A special session was organised at the PHYSOR 2006 conference held in Vancouver, Canada
during September 2006. In total five presentations were included in the special session.
The third workshop, held on 1-2 February 2007 (NEA/NSC/DOC(2007)11), finalized all changes
and suggestions on the benchmark specification. The changes or clarifications made to the benchmark
definition were discussed and finalized, and, once implemented, the updated steady-state results werecompared and analysed. It was clear that some discrepancies still remained. To facilitate the resolution ofthese differences a questionnaire was drawn up to be completed by all participants when submitting theirresults. This questionnaire contained specific questions to try and ensure the appropriateness of the results
and included questions on convergence, mesh refinements, coupling schemes and implementation of thecross-section libraries and defined correlations. Any additional assumptions or approximations made mustalso be listed. These exercises led to significant improvements in the results
Scope of the 4th Benchmark Workshop
The fourth workshop was held from 21-25 January 2008, with the following scope:
PART I: Workshop on the DIREKT code system (21-23 January 2008)
A 3-day workshop was presented as Part I of the OECD PBMR400 benchmark meeting. The
DIREKT code, under development at the Research Centre Jülich (FZJ) in Germany, is able to model
steady-state and transient pebble bed reactor thermal hydraulics.

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PART II (24 – 25 January 2008)
The 2-day meeting was held to discuss the OECD PBMR-400 Benchmark transient. The focus
areas were as follows:
1. Steady State results finalization
The final results sent for the steady-state cases were represented and discussed to facilitate the final
comparisons at the meeting. The aim is to publish all the steady-state results in a PHYSOR-2008
summary paper after this meeting.
2. Transient Results
The focus of the workshop was the comparisons of all the transient results. Exercises 1 to 6 results
were be presented and discussed.
The meeting programme is included in Annex I. The workshop was attended by 18 participants from 8
countries representing 11 different organizations with the list of participants in Annex IIPART I: DIREKT Workshop
DIREKT is a computer program for the time-dependent, two-dimensional simulation of thermalhydraulic transients in gas cooled reactors and in particular for pebble bed reactors. The program DIREKT
is divided into two main modules as described below.
1. The solids module calculates the conservation of the energy equation for steady-state or timedependent situations for all solid areas and stationary fluids. Extensive data libraries are included for thethermal conductivity, heat capacity and heat transfer by means of convection. In the model implementation
radiation is considered as part of the effective thermal conductivity in the energy equation. An iterative
single-step procedure is applied as the solution procedure for the resulting solids-temperature field.
2. The coupling is made between the solids module and the convection module via the solid
temperatures field. From this, the further calculation of gas temperatures and heat transfer is made. The
convection module calculates the conservation equations for continuity, momentum and energy for steadystate, quasi-static or transients for a selected fluid flow. A closed solution procedure is used to calculate theresulting fields for relative pressure and fluid temperature by means of a direct matrix solution algorithm.
Examples of the application of the code include(i) Steady-state conditions in pebble bed reactors,(ii) Starting from stationary operating conditions different transients can be modelled,(iii) The program is specifically designed to calculate very quick pressure relief operations in the
primary circuit of gas cooled nuclear reactors and(iv) Calculation of natural convection processes in closed systems, and free convection currents(fire flow), and finally, since extensive expansion of the libraries were made, calculations on
the behaviour of core melts or heavy water cooled reactor concepts can also be investigated.
The workshop focused on the code status and features. Models related to the PBMR 400 OECD
Benchmark problem were set up and analysed during the workshop using a hands-on approach. The
PBMR400 steady-state exercise 2 case was set up and run successfully with refinements still being made to
the model to include these results in the official benchmark set. Discussions also included possible
coupling with other codes. The course material was provided and PC’s were supplied where the software
could be loaded and executed.

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PART II: Meeting on OECD Benchmark Progress
The technical topics presented at this fourth workshop are shown below per session.
Session I – General Session: (Chair F Reitsma)
The meeting chairman welcomed everyone to the second part of the 4th PBMR400 workshop.
Reitsma gave a short overview of the current interest in HTRs and the need and motivation for thebenchmark exercise.
The agenda was approved without any changes (see Annex I, Part II). The participants were
given an opportunity to introduce themselves with a short description of the field in which they are
working and their interest in the benchmark or HTRs in general.
Feedback was then provided on the updates made and progress since the 3rd workshop. The
specification was finalised in June 2007 and placed on the Benchmark web site. It includes all agreed
actions from the 3rd workshop (see NEA/NSC/DOC(2007)11 for details) including a kernel temperatureapproximate model for use during fast reactivity transients. The questionnaires to be completed were also
made available in June 2007.
The next presentation gave a summary of the special session on the OECD PBMR 400MW
benchmark planned for the PHYSOR 2008 meeting in Interlaken, Switzerland to be held from 14-19
September 2008. In total ten abstracts were submitted to the special session but the final number of papers
accepted will only be known later in the year.
During this session, informal feedback was also provided by the OECD/NEA on the efforts madeand status of the preservation of information and experiments in the area of HTRs. The archive on the
DRAGON experience already consists of more than 1000 reports and the scanning and organization of
documents are continuing. The value added by including experiments in the Reactor Physics and Criticality
Handbooks was explained and includes, amongst many others, the quantification of experimental
uncertainties, the provision of a best estimate reference model and details on material impurities. Specificefforts on HTR-10 (already included), the ASTRA facility (and plans to do heat-up experiments in 2009)
and PROTEUS (water ingress and control rod movement) was mentioned.
Session II: Feedback by all participants I (Chair: K Ivanov)
The session was the first of two sessions where participants gave feedback on the work they
performed related to the benchmark exercises.
In the presentation from Penn State University, made by Kostadin Ivanov, the development of
MCNP models, based on the OECD benchmark specification, was described. The models make use of thegiven isotopic distribution of the fuel regions but generate its cross section libraries. Two models were
investigated, the first with only five radial fuel materials (averaged over the axial height) and the second
with the 110 fuel materials as defined. In both cases cross-sections were prepared defining 70 of the 72
isotopes (Np-240 and U-239 not available on basic library used) and assuming 1000K. The k-eff and radial
profiles of the total flux, fission and absorption rates of the two models were compared with the relative
errors provided (see presentation for details).

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NEA/NSC/DOC(2008)7
Brian Boer from TU Delft presented the status of the DALTON-THERMIX(Direkt) work
performed at TU Delft. Results for the steady-state exercises and transient exercises 1, 2, 3 and 6 areavailable. A manual time step size was used for the coupling of the neutronic (DALTON, diffusion, finite
volume) and thermal-hydraulic (THERMIX-DIREKT) codes and was chosen manually depending on theparticular case so that convergence was obtained. Convergence for a time step is not checked and rather,small time steps are taken. The approximation needed, the results and discussion of the DLOFC, PLOFC
and sensitivity of the re-criticality time in the case with no SCRAM were presented. Finally the exercise 6
results for the cold helium inlet scenario were discussed. Future improvements may include a more generaltime stepping procedure and additional validation with the historical AVR experiments.
From Nesca, South Africa, Rian Prinsloo presented updated results with the OSCAR-4 code
system, and further work related to the benchmark. The presentation included an overview of the code
system and work performed at Necsa. Although the official contribution is restricted to the steady-state
exercise 1, related work includes cylindrical nodal code development, model comparisons in cooperation
with PSU and activities in cross section parameterization methodologies based on an automated quasiregression based parameterization.
An update of the TINTE results and related activities was given by Gerhard Strydom. A summaryof the code features and mesh refinements in the models was described, and results for the transient cases
were provided. The effect of the additional pressure built up in Case 3 (PLOFC) due to temperature
increase was quantified and show a difference of 32 °C on the maximum temperature at ~ 40 hours into thetransient. The differences between the newly implemented DIN standard and the TINTE approximate
decay heat model was also quantified to be only 14 °C. Other important sensitivities shown include thecusping effect seen in exercise 5a with different blackness factors applied (to reduce the modelling error)
as well as two specific sensitivity studies of interest on the UO2 temperature (kernel specific model) andDoppler feedback effect. The newly implemented explicit kernel thermal hydraulic model was compared tothe approximate method as proposed in the benchmark definition and the sensitivity of the temperaturesand power excursion to the variation in the kernel material conductivity and specific heat values wasinvestigated. In both cases the transient exercise 5b, which will show the largest sensitivity to the changes,
was selected. The approximate PUEBH model as included in the benchmark specification shows very good
agreement with the explicit model. This illustrates that the results obtained in the benchmark should bereasonable compared to better fuel temperature feedback models. Significant sensitivities to the thermal
properties of the UO2 kernel and its coatings were also shown, emphasizing the importance of theseparameters.
The PARCS-3DTH solutions prepared by the University of Purdue were presented on theirbehalf by Kostadin Ivanov. The neutronic solver is mostly unchanged but a new 2D/3D porous media
thermal hydraulic method was added including the most important phenomena such as a fuel temperaturecorrection in fast reactivity transients and porous media dispersion effects in the azimuthal directions. No
natural convection is currently available. Results for the transient cases using the updated code systemwere presented.
Session III. Feedback by all participants II (Chair: Rian Prinsloo)
Details on the MARS-GCR / CAPP model and transient results were presented by Seung Wook
Lee and included details on the implemented heat conduction and transfer models, coolant flow definitions,heterogeneous pebble models and pebble bed correlations. The explicit coupling methodology was also
explained. Results for the starting steady-state and several transient cases were represented. The results
show good agreement with the expected transient behaviour and were confirmed with preliminary
comparisons with TINTE.
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Further developments of the CAPP code (Core Analyzer for Pebble and Prism) for VHTR’s were
presented by Hyun Chul Lee of KAERI. The FDM and FEM solutions methods are available in the code.
Details of the 2D and different 3D finite elements were shared and described, as well as the linear equation
solvers available. The OECD benchmark was used in the verification of the methods and compared with
FD solutions for different order of shape functions and increase of the number of finite elements. Goodagreement with a reference case and good convergence behaviour were illustrated.
Andreas Pautz, from GRS, presented the transient studies performed jointly with PSU with thecoupled neutron transport / thermal hydraulics code system DORT-TD / THERMIX. The availability of atransport solution of the benchmark adds an important alternative to the otherwise all diffusion suite ofcodes although it should be kept in mind that the cross section library used is restrictive in representing
true transport effects. The background and objectives of the tool’s development were described with thefeatures explained in some detail. Results for the steady state exercise 3 for the diffusion and transport
options, with and without buckling feedback, were presented. The buckling feedback effect was quantified
to be 1300 pcm and the transport effects around 650 pcm. The flux and power profiles were also comparedand the transport solution yielded slightly higher power peaks. The fast control rod ejection (Case 5b)shows good agreement for the maximum power reached between transport and diffusion although a time
shift was noticed, which was smaller than the impact of the correct modelling of fuel feedback
temperatures (Doppler) and thermal conduction properties.
The DORT-TD’s capabilities were further illustrated by the multi-group (beyond 2 groups)
application utilizing higher scattering / quadrature order cross section data. The OECD PBMR400 and an
earlier PBMR268 design were used. Cross-sections in 6-groups were generated independently making useof the MICROX-2 code. For the PBMR268 the k-eff variation for diffusion was smaller at 120 pcm andtransients also showed much better agreement. P1S4 appears to be sufficient and the consistently generated
cross-sections probably add to the good agreement.
In the presentation from PBMR the multi-dimensional cross section table approach used in thisbenchmark was compared to other representations available in TINTE and the new multi-group version of
TINTE called MGT. The standard polynomial representation in TINTE, the tables in MGT but without thecross terms as in the benchmark and the new in-line spectrum calculation option in MGT, were introduced.
Preliminary results were discussed but the explanation for large differences still needs to be investigated.
Gerhard Strydom presented the work of Hikaru Hiruta and co-authors from INL on their updated
steady-state results. The status of the PEBBED coupled code and the transient code CYNOD was also
given.
Session IV. Benchmark Steady State Cases (Chair: G Strydom)
The comparisons were prepared by PSU. A summary of the cases was presented in each case andthen all the results were compared and discussed in the session. For detailed comments, please refer to thepresentations in the proceedings. Only a few remarks will be made here.
In exercise 1 updated results were received from 11 participants mostly after further refinementof meshes or introduction of the correct void treatment. The spread in the k-eff values has improved
compared to the previously reported values, especially if only the updated results are considered, but it isstill larger than expected in this case as the cross section data are provided and differences should be
limited. Participants should revisit their results and ensure that the mesh is fully refined (this was shown toincrease the k-eff in most cases). It was noted that the VSOP k-eff = 1.0 result in the initial generation of7

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the cross-sections increased to 1.00455 with mesh refinement in CITATION. Power and flux profiles allshow similar shapes and trends but larger differences in the 2-D shapes needs further attention and indicate
differences in the effect of void modelling. The outlier results could in most cases be attributed to not
updated earlier submissions.
Also the exercise 2 thermal hydraulics results still show some variations in temperatures. The
definition of fuel, moderator, and maximum fuel temperature was clarified in previous meetings andincluded in the specification and should not be the reason for the differences. The following variations
were identified as needing further investigations. Although the radially averages axial pebble surface
temperatures compares well some differences in the radial profile suggest differences in the helium flow orheat transfer to the coolant in the different radial meshes. Differences in the moderator and fueltemperatures, also noticeable in the axial profiles, suggest differences in the thermal conductivity and orheat capacity of the fuel spheres. Two groups of results, the first from Thermix-Direkt and derivatives andthe second from the Thermix-Konvek family, are visible. Participants have to carefully consider the heattransfer mechanisms implemented in these codes to ensure consistency with the benchmark definition or to
identify and report any differences.
Results for exercise 3 of the steady-state cases were compared and discussed in this session. The
spread in the results had reduced considerably since the previous submissions but some differences are still
too large and need more attention. For example, the two PEBBED k-eff results are significantly higher
than the other results (this was later corrected after the meeting). The other 2-D profiles show goodcorrespondence in general but the detailed maps do show variations close to the void and boundary
condition regions that are to be expected. The feedback effects (due to the coupled neutronics-thermalhydraulics) also tend to smear out some of the differences that were seen in the Case 2 temperature
profiles. It was clear from the discussions that the use of the coupled case with full feedback is morechallenging than the two separated cases but that the feedback effects also reduce certain effects.
It was decided in the session that only results confirmed to be converged and with the supporting
model questionnaire will be included in the official comparisons. Participants will be given a final
opportunity to update results before they are published (see Action list below).

Sessions V & VI: Transient Cases Comparisons (Chair: E Sartori, A Pautz and F Reitsma)
This topic was divided over two session but the activities and results are summarised together.
The Pennsylvania State University prepared the comparisons between all the participant’s contributions for
all the Transient Exercises. The detail can be found in the presentations and in the comparison spreadsheets
available on the website. Only two and, for some cases, three sets of results were available for comparison.
Some general comments are included below.
In Case 1 significant differences in the maximum fuel temperature were seen. A more peakedradial power profile in DALTON is one possible explanation for the difference. An investigation into the
decay heat treatment in TINTE (DIN standard) compared to the specification (based on the DIN standard
total heat) was further suggested. In particular the decay heat relative power profile in TINTE will tend tobe smoother over time while the benchmark definition assumes the same relative power profile before
shutdown (from steady-state solution). Despite this the re-criticality times were similar which suggest thatthe total heat deposited and losses should be similar. Case 2 and 3 show similar results related to decay
heat sources and initial conditions.

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The reactivity transient cases (5a and b) show fair agreement in many power and temperatureshapes throughout the transients. The radial power profile shows similar differences as for the SteadyState 3 case with the MARS-GCR/CAPP more peaked towards the central reflector than the TINTE
results. This could also be the reasons for the higher maximum fuel temperatures. Although the power
excursion shows the same general behaviour the end state power level differs by ~60MW (on 730MW) for
Case 5a. For Case 5b the large differences in the power excursion can be attributed to the absence of akernel model (or correction) that calculate the correct fuel temperature and thus the correct feedback
effects.
In Case 6 the radial temperature and power density differences (also from the starting steady-state
conditions) also introduce differences throughout the transient while the axial profiles compare better. The
increase in the power level after the transient was completed with the associated increase in the averageand maximum fuel temperature in TINTE is not consistent with the other two results and needs to beinvestigated.
The final judgment on the transient case results could not be made on the limited set available atthe meeting. More results should be made available (in total a minimum of 6 and a maximum of 8 sets ofresults could be expected for most transient cases) and better comparisons and conclusion can then be
drawn.

Sessions VII &VIII. Discussion and closing (Chair: F. Reitsma)
During the closing session an action list was drafted (available as a link in the Agenda). The last
benchmark meeting is planned to coinciding with PHYSOR2008 (this was confirmed). The chairman
thanked all the participants and the meeting was adjourned.
Proceedings of the Workshop
Along with this summary participants will receive a CD-ROM containing all papers discussed at
the meetings. The CD-ROM will also include all reports from previous workshops, which discuss thisbenchmark.

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Task list / Outstanding issues – PBMRT4 meeting
•

•

•
•

•
•

•
•
•
•
•
•

PBMRT4 meeting summary with all presentations to be published (also CD) Target 29 February
2008 (Actual May/June 2008)– Official summary, All presentations, All submitted spreadsheets, (updated comparisonpresentations if possible)– Action list with these deadlines and plans
Discussions between current submissions to clarify differences (26 January – end March 2008;
Actual: On-going)– TU Delft, PBMR, KAERI on transients (Action G Strydom)• Differences in Fission Power (Case 6)• Kernel model vs no kernel model• Differences between temperatures although powers are similar– Steady State submissions / updates / converged results (Action F Reitsma)• Plans of all participants• Old results updated or removed (as applicable)
All outstanding code descriptions to be submitted by end of March 2008 (Actual: Ongoing,
deadline 30 June)
All updated results at PSU by 30 April 2008 (Only updated results for Steady State Cases (withrefined mesh) and Transient Cases (since the definition was updated) will be accepted andcompared. (all submissions prior to June 2007 will potentially be disregarded) (Actual: All updates
received till 10 May for Steady State cases included in PHYSOR paper, Further updates deadline
30 June)All outstanding questionnaires to be submitted by 30 April 2008 (Actual: Ongoing)
Updated comparison spreadsheets available end of May / mid June 2008 (Actual: Available results
discussed with Prof. Ivanov till 27 May, Updates possible till 30 June 2008)– Will workshop these at PBMR in May with Prof Ivanov (Status: Done)– (additional questions may be sent to participants to try and understand / quantify
differences)– Updated spreadsheets placed on web
Finalised comparative spreadsheet and statistical analysis (PSU, end June 2008, Actual: mid July
2008)
Draft Benchmark report sent to participants (mid August 2008)– Comments submitted by end August 2008
Draft / Updated Report available at meeting at PHYSOR2008– Meeting on Sunday 14 September 2008 (TBC)– Last meeting to finalise the benchmark
Final report at OECD end November 2008 / end January 2009
Published report, March / April 2009
– Presentations and other data on CD (cleaned version to get rid of inconsistencies )Special Journal issue to be published in 2009

The latest action list with target dates is provided in the table below:

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Summary of Actions and Target Dates (Revised from the dates at the meeting)1

Updates and final submission of:
Code descriptions
Questionnaires
Updates of any results
Updated comparison spreadsheets available to all
Drafted Benchmark Report
Action PBMR/Reitsma
Comments on Benchmark Report
Action: All
5th OECD PBMR 400MW Benchmark meeting

30 June 2008

•
•
•

2
3
4
5

15 July 2008
15 August 2008
30 August 2008
Sunday 14 September 2008
(At PHYSOR 2008 meeting),

6

Final report at OECD
Action PBMR/Reitsma

November 2008
January 2009

/

end

7

Published report

March / April 20098

Special Journal issue to be published in 2009
Action PSU / Ivanov

News at 5th meeting on 14
September* Note that the above contains revised target dates (not the same as the draft in January) The CD
distribution is planned for mid-June 2007.

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NEA/NSC/DOC(2008)7
Annex I
OECD/NEA/NSC
PBMR COUPLED NEUTRONICS/THERMAL HYDRAULICS TRANSIENT BENCHMARK
THE PBMR-400 CORE DESIGN– 4th Workshop
21 – 25 January 2008
FINAL PROGRAMME [P401]([n] indicates paper identification on CD-ROM)PART I: DIREKT Workshop
Day 1: 21 January 2008
I. Theoretical Overview of DIREKT [D01]
II. Input Description and Model Definition [D02]III. Code Layout [D03] and Installation
Day 2: 22 January 2008
IV. Preparation of Steady State Calculations [Example D04]
V. PBMR400 Steady State Case (Stationary run) [Example D05]
Day 3: 23 January 2008
VI. Preparation and execution of a fast depressurization transient [Example D06]
VII. Discussion on use and coupling with other codes

PART II: OECD PBMR400 MeetingDay 4: 24 January 2008
I. General Session (Chair: F. Reitsma)
1. 09:15 – 09:30 Introduction and opening remarks – introduction of participants [P402]
2. 09:30 – 09:35 Adoption of agenda
3. 09:35 – 10:20
3aFeedback on Benchmark Specification updates and PBMRT3.0 meeting [P403]
3b
Feedback on special session planned for PHYSOR2008 [P404]
10:20 – 10:45 Break12

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II. Feedback by all participants I (Chair: K Ivanov)
4. 10:45 – 12:45 Presentations from all participants on progress and results.
4a
Ramatsemela Mphahlele, Dundar Ucar, Kostadin Ivanov, "PBMR-400 Neutronics Modelusing MCNP5" [P405]
4b
B. Boer, D. Lathouwers, J.L. Kloosterman, “DALTON-THERMIX calculation results for thetransient benchmark cases" [P406]
4c
Rian Prinsloo, K Sekhri, “Investigation into steady state result discrepancies” [P407]
4d
Gerhard Strydom, “TINTE OECD PBMR 400MW Benchmark Results” [P408]
4e
V.Seker T Downar "PARCS-3DTH Solutions of the PBMR-400 Benchmark Transients"
Presented by K Ivanov [P409]
Discussions
12:45 – 14:00 Lunch
III. Feedback by all participants II (Chair: R Prinsloo)
5. 14:00 – 16:00 Presentations from all participants on progress and results.
5aSeung Wook Lee “MARS-GCR/CAPP Coupled Calculation for the OECD/NEA PBMR-400
Transient Benchmark Problems” [P410]
5b
Hyun Chul Lee, “Development of CAPP code: Comparison of the FDM and the FEM
solutions to the OECD/NEA PBMR-400 benchmark problem Ex I-1” [P411]
5cAndreas Pautz, “Transient Studies with the Coupled Neutron Transport / Thermal Hydraulics
Code System DORT-TD / THERMIX” [P412]
5d
Ivor Clifford, F Reitsma, G Strydom “Cross Section Representation options for HTR
Transient Analysis tested on the OECD PBMR 400MW Transient Benchmark” [P413]
5eHikaru Hiruta , Abderrafi M. Ougouag, Hans D. Gougar “Summary and Discussion of
Results of Steady State and Transient Analyses by INL” Presented by Gerhard Strydom[P414]
Discussions
16:00 – 16:20 BreakIV. Benchmark Steady State Cases (Chair: G Strydom)
6. 16:20 – 17:30 Steady State Test case 1 & 2 (K Ivanov / F Reitsma)
6a6b

J. Han, P. Mkabela, K. Ivanov, F. Reitsma, "Comparison of Steady State Results of OECD
PBMR-400 Benchmark" [P415]
Discussion

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Day 5: 25 January 2008
V. Transient Cases Comparisons (Chair: E Sartori)
7. 09:00 – 12:30 Transient cases results and comparisons (K Ivanov / F Reitsma)
7a

J. Han, P. Mkabela, K. Ivanov, F. Reitsma, "Comparison of Transient Results of OECD
PBMR-400 Benchmark" [P416]
Discussion

7b.
10:20 – 10:45 BreakVI. Transient Cases Comparisons - Continue (Chair: Andreas Pautz)
12:30 – 13:45 Lunch
VII. Transient cases Discussions and Conclusions (Chair: F Reitsma)
8. 13:45 – 14:30 Transient Cases Discussions and Conclusions (K Ivanov / F Reitsma)
8aDiscussion and summary

14:30 – 15:00 Break
VIII. Discussion and closing (Chair: F. Reitsma)
9. 15:00 – 16:00 Discussion of future actions [P417], Special session at PHYSOR2008 and schedule
10. 16:00 – 16:15 Discussion of next meeting and missing deliverables
11. 16:15 – 16:30 Any other business and closure of meeting

14

NEA/NSC/DOC(2008)7
Annex II
List of Participants
FRANCE:GRIMOD, Maurice, PhD Student, CEA Saclay
SANCHEZ, Richard, Research Director, CEA Saclay
GERMANY:JUEHE, Stephan, Reaktorsicherheit und –technik, RWTH-Aachen
PAUTZ, Andreas, Gesellschaft fuer Anlagen und Reaktorsicherheit, GRS
STRUTH, Stephan, Forschungszentrum Jülich GmbHITALY:MELONI, Paride, ENEA FPN-FISNUC
KOREA ( REPUBLIC OF):LEE, Hyun-Chul, Korea Atomic Energy Research Institute
LEE, Seung Wook, Korea Atomic Energy Research Institute
MEXICO:ALONSO, Gustavo, Instituto Nacional de Investigaciones Nucleares
NETHERLANDS:
BOER, Brian, TU Delft
DING, Ming, TU Delft
SOUTH AFRICA:
DU TOIT, Pieter, Nuclear Engineering Analysis, PBMR Pty Ltd
PRINSLOO, Rian, South African Nuclear Energy Corporation (Necsa)
REITSMA, Frederik, Nuclear Engineering Analysis, PBMR Pty Ltd
SEKHRI, Abdelkrim, South African Nuclear Energy Corporation (Necsa)
STRYDOM, Gerhard, Nuclear Engineering Analysis, PBMR Pty Ltd
UNITED STATES OF AMERICA:IVANOV, Kostadin, Head of RDFMG, Pennsylvania State University
INTERNATIONAL ORGANIZATIONS:SARTORI, Enrico, OECD/NEA Databank15