Sponsored by the U.S. Nuclear Regulatory Commission
Volume 13 / Number 1 / December 2013
Fall 2013 CAMP Meeting
he Fall 2013 CAMP Meeting was held from
November 6 through 8 at the Hotel Palomar in the
historic Dupont Circle neighborhood of Washington,
DC. It was one of the most well attended Fall meetings
with a total of fifty-six participants from seventeen
countries participating in the meeting. Countries
represented included Brazil, Canada, China, Croatia,
Czech Republic, Germany, Italy, Japan, Korea, Poland,
Slovenia, Sweden, Switzerland, Spain, Taiwan, United
Arab Emirates and the United States. The CAMP
members were welcomed to the meeting by Ms. Kathy
Gibson, Director of the Division of Systems Analysis in
the NRC Office of Nuclear Regulatory Research.
Following introductory remarks Ms. Gibson informed the
CAMP members of Antony Calvo’s reassignment to
another NRC division, and indicated that Carl Thurston
and Dr. Kirk Tien will be sharing Antony’s duties under
the direction of Dr. Chris Hoxie. She thanked the CAMP
members for their hard work which contributes to the
success of the CAMP program. The work that CAMP
T
(Continued on page 2)
TRACE User Problems
his is a report on TRACE user problems and
resolutions. Open trouble reports identified in the
previous newsletters with no new progress are not
discussed, but can be found in the TRACE trouble report
system (TRACEZilla) on the NRC Codes website
(https://www.nrccodes.com).
been resolved or closed or duplicates.
T
A resolved trouble report indicates that it has been
addressed with an update or documentation change that
is pending. A closed trouble report indicates that it has
either been addressed by successfully re-running the
test problem(s) of interest with a current version of
TRACE or it has been closed by incorporating a pending
update into the NRC developmental version of TRACE.
A pending update implies that it has been tested,
documented, reviewed, and submitted to the NRC, but
has not been included in the developmental version of
For the time period between January 1, 2013 and
December 31, 2013, 31 new trouble reports were
submitted to TRACEzilla. 69 trouble reports were either
resolved or closed during this same time period. As of
December 31, 2013, there are 672 trouble reports in the
TRACE bug reporting system; 21 of those are open, with
the remainder resolved, closed, or duplicates. This
implies that ~97% of the TRACE trouble reports have
(Continued on page 4)
Contents:

Fall CAMP Meeting

TRACE User Problems

Recent RELAP5 User Problems

Items of Interest
Thermal-Hydraulic
Code News
Committed to the support of the
T/H Codes User Community
Website:
https://www.nrccodes.com
1
Thermal-Hydraulic Codes News
December 2013
Dr. Hoxie described the major elements of the “Reactor
Core and System Analysis Code Suite”. The codes
included in this suite include SNAP (platform/graphical
user interface), Triton/Helios/CASMO and GenPMAXS
(cross section library generation), PARCS & PATHS
(core physics and steady state thermal hydraulics) and
TRACE (reactor system thermal hydraulic analysis).
Fall 2013 CAMP Meeting …continued
from page 1
members are performing is a very high priority for NRC
in providing oversight of reactor licensees and applicants,
and helping the NRC accomplish its safety mission. Ms.
Gibson discussed how the CAMP program benefits both
the NRC and CAMP members.
Dr. Hoxie provided an overview of NRC/ISL
presentations at this meeting. In addition, he provided a
brief overview of recent TRACE development, PARCS /
PATHS / GenPMAXS development and SNAP
development, along with a brief status summary for
RELAP5.
Member contributions have leveraged NRC resources,
improved the codes, and improved modeling. Examples
include areas such as identifying code errors and plant
modeling for new applications. Programs have provided
a venue for members to develop and share knowledge
about thermal-hydraulic safety analysis. The user
community and the quality of the analysis codes benefit
through the network effect of the program.
Dr. Hoxie presented information on the PWR TRACE
modeling guidelines. The modeling guidelines are a
document that presents a complete set of
recommendations for inputs specific to PWR plant
models for Westinghouse, Combustion Engineering, and
Babcock & Wilcox type designs currently operating in the
U.S. The modeling guidelines are being developed to
(1) codify “best practices” for PWR modeling, (2) serve
as a training tool, and (3) help highlight areas of need or
guide future investigation. The modeling guidelines will
be used to (1) form a consensus on how specific PWR
plant models are to be built, and (2) potentially provide
assistance in modeling other PWR designs, though the
strict applicability of the guidelines is currently limited.
The guidelines will ultimately be translated to test facility
modeling to ensure that all modeling details are
consistent between plant and assessment models. The
PWR TRACE modeling guidelines are available now on
the
NRCCodes
Sharepoint
site
(https://www.nrccodes.com).
The NRC is seeking
CAMP member feedback for these guidelines. Dr. Hoxie
also mentioned that there is ongoing work to develop
BWR Modeling Guidelines.
As TRACE matures, CAMP will be an important
contributor to its future development and assessment,
and CAMP membership is expected to continue to
expand based on increased nuclear activities worldwide.
As evidence, two new CAMP members were
announced: Netherlands and Vietnam.
Carl Thurston then welcomed the CAMP members and
thanked them for supporting the CAMP program. Of the
56 attendees at this meeting,
there were 35 international
members and 20 NRC staff. 33
presentations were provided at
this meeting.
Carl motioned to accept the
meeting minutes from the Spring
2013 CAMP meeting. Chester
Gingrich seconded the motion,
and the minutes were accepted.
TRACE is used at the NRC for licensing support and
design certification activities: ESBWR, US-EPR, US
APWR, AP1000, ABWR, Integrated PWR pre-application
phase, power uprates for operating reactors and Generic
Safety Issue (GSI) support.
Carl introduced Marlin Strand and thanked him for
supporting the Fall 2013 CAMP Meeting.
Marlin
introduced the evening activities for the CAMP meeting,
and welcomed everyone to Washington, DC.
The first technical presentation was given by Dr. Chris
Hoxie of the USNRC. Dr. Hoxie gave a presentation on
the Status of NRC Code Development. CAMP related
contacts at the NRC were provided as follows:







Dr. Hoxie presented the release dates for TRACE V5.0
Patch 02 and 03, and indicated that Patch 04 is being
finalized and should be ready for release in early 2014,
less than two years after the Patch 03 release. It is
strongly recommended that CAMP members upgrade to
Patch 03, which is more robust and has better CPU
performance. Dr. Hoxie showed a graph of CPU
performance for a SBLOCA transient, and the
improvement with Patch 03 was quite significant.
CAMP Program: [email protected]
NUREG/IA: [email protected]
CAMP Code Distribution:
[email protected]
TRACE: [email protected]
SNAP: [email protected]
PARCS: [email protected]
RELAP5: [email protected]
Lastly, Dr. Hoxie reminded CAMP members that TRACE
is the future of NRC safety systems thermal hydraulic
analysis. The NRC would like CAMP members to focus
their assessments on TRACE, and suggested the
2
Thermal-Hydraulic Codes News
December 2013
following areas: fuel rod models, grid spacer models,
pre-CHF droplet field void fraction predictions and
additional integral tests.
Since 1998, 417 user problems have been reported: 298
are resolved, 30 are in work, 28 are on hold and three
are not resolvable. A complete list of user problems
from 1998 to date is posted on the NRCCodes
Sharepoint site (https://www.nrccodes/com). RELAP5
priorities from the Spring 2013 TPC meeting were
presented and briefly discussed.
Next, Chris Murray (USNRC) gave a presentation on
TRACE Code Development Status. TRACE follows a
system of releasing major versions followed by periodic
numbered patch releases. Patch release history is as
follows:




V5.0 Patch Release 01 (10/17/2008)
V5.0 Patch Release 02 (06/02/2010)
V5.0 Patch Release 03 (05/11/2012)
V5.0 Patch Release 04 (early 2014)
Focus for TRACE is on making the code more robust as
well as key modeling improvements.
Presently there are 650 total trouble reports in our
tracking system (as of 10/24/2013). 578 trouble reports
are closed out, 56 trouble reports are considered
resolved, but not yet closed out, and 16 trouble reports
are open. Since the last CAMP meeting 30 new
developmental code versions have been created, 24
new unique trouble reports were submitted, 44 trouble
reports have been resolved or closed out.
Additional presentations included:
Chris Murray then described some of the more
significant changes that have gone into TRACE since
the last CAMP Meeting (from V5.750 to V5.823). The
major changes include fuel rod model improvements,
usability enhancements, uncertainty quantification,
CONTAN improvements and other bug fixes. In addition,
the PARCS source in TRACE was updated to v32m11,
which went into TRACE V5.771.
Users can see a snapshot of the recent TRACE
development activity on https://www.nrccodes.com using
the Build page. Planned fixes or updates are listed in the
Holding Bin. TRACE V5.0 Patch 4 is planned to be
released in March 2014.
Doug Barber then reported on the RELAP5/MOD3.3
status.
The
latest
full
release
is
RELAP5/MOD3.3Patch04, which is Version 3.3iy,
October 2010. The most recent developmental version
is 3.3js. A table showing the code names, version
numbers and release dates for all RELAP5/MOD3.3
releases was provided.
Resolution for one user problem was reported and
discussed. UPN 2013-05 from Wojtek Baltyn dealt with
code indexing errors when processing input from the
radiation enclosure cards. In addition, there were
several bugs related to compilation with the g77 compiler
that were addressed. The features implemented as fixes
to resolve this user problem were made Version 3.3js.
User problems continuing to be worked and on hold
were also briefly discussed.
3

Dr. Nathanael Hudson, US NRC, “PARCS Status
and Updates”

Chester Gingrich, US NRC, “SNAP Status and
Updates”

Dr. Jennifer Uhle (presented by Dr. Joseph
Staudenmeier), US NRC, “Regulatory Use of
Thermal Hydraulic Systems Analysis Codes”

Chester Gingrich & Dr. Steve Bajorek, US NRC,
“TRACE
Uncertainty
Quantification
Demonstration”

Ilijana Ivekovic, ENCONET, “CAMP Activities in
Croatia”

Dr. Andrej Prosek, Josef Stefan Institute, “Status
of CAMP Activities in Slovenia”

Dr. Ernest Staron, National Atomic Energy Agency
of Poland (PAA), “CAMP Related Activities in
Poland 2013”

Dr. Aeju Cheong, Korea Institute of Nuclear Safety
(KINS), “Status of CAMP Activities in Korea”

Yu Chiang, Institute of Nuclear Engineering and
Science, “Status of CAMP Activities in Taiwan”

Sean Roshan, Royal Institute of Technology, KTH,
“Status Report of CAMP Activities in Sweden”

Markus T. Schlenker, Karlsruhe Institute of
Technology, “Determination of Equilibrium Cycles
for Reduced Moderation BWR with PARCS and
Assessment of Reactivity Coefficients”
Thermal-Hydraulic Codes News

December 2013
Dr. Stephanie P. Bush-Goddard, US NRC, “The
Radiation
Protection
Code
Analysis and
Maintenance Program (RAMP)”

Dr. Fulvio Mascari, ENEA (Remote Presentation),
“Analyses of Natural Circulation Phenomena
Typical of the MASLWR by using the TRACE V5
Code”

Dr. Victor Sanchez, Karlsruhe Institute of
Technology (KIT), “Extension of GenPMAXS to
Support the Monte Carlo Lattice Code SERPENT2
Beta”

Dr. Patrick Raynaud, US NRC, “Core-Wide
Estimates of Fuel Dispersal During a LOCA with
FRAPCON/ FRAPTRAN and TRACE”


page 1
TRACE. Inclusion of a pending update into TRACE
typically requires additional review and testing by the
NRC staff.
Dr. Yong Jin Cho, Korea Institute of Nuclear
Safety, “Progress Report - TRACE Assessment for
PASCAL Local Condensation Experiment”
Pavel Kral, UJV Rez, “Analysis on Condensation
Models in RELAP and TRACE”

Dr. Aaron Epiney, Paul-Scherrer Institute, “PSI
TRACE/PARCS Methodology for Steady-State
BWR Analyses”

Dr. Konstantin Nikitin, KKM, Switzerland, “Minimal
Requirements
to
the
ThermalHydraulics/Neutronics Mapping for BWR/6 ATWS”

Joshua Whitman, US NRC, “New TRACE Feature:
Adaptive
User-Independent
Time-Step
Optimization (AUTO)”

Joshua Whitman, US NRC, “Changes to TRACE
Error and Warning Messages”

Tetsuhiro Ozaki, Nuclear Fuel Industries, Ltd.,
“Validation of TRAC-BF1 Code and Estimation of
Interfacial Shear Uncertainty”

Dr. Nathanael Hudson, US NRC,
Updates, Assessments, and Status”

Haejung Sung, KEPCO, “TRACE Assessment
using VAPER Tests”

Dr. Suk K. Sim, Environment & Energy
Technology, Inc., “Investigation of the Loop Seal
Clearing Phenomena for the ATLAS DVI /CL
SBLOCA Tests using MARS-KS”

TRACE User Problems …continued from
Petr Heralecky, TES s.r.o., “Post-Test Analysis of
Upper Plenum Break 11% at PSB VVER Facility
using TRACE V5.0 and RELAP5 MOD3.3”


Social activities during the CAMP Meeting included a
social hour on Wednesday evening and a wine tasting
followed by a tour of the
Phillips
Collection
on
Thursday evening. The
Spring
2014
CAMP
Meeting will be held at the
University of Zagreb in
Croatia.
The most current developmental version of TRACE is
Version 5.831 as of December 31, 2013. Updates
included in Version 5.831 can be found on the TRACE
user support web site (https://www.nrccodes.com).
New Trouble Reports Still Open
The following new trouble reports are still open and have
not been resolved or closed.
Trouble Reports 653 – Power weighting of reactivity
feedback parameters.
A developer while reviewing the FxBoronReact update
noted some inconsistencies in the power weighting for
the core reactivity feedback parameters. In general, the
intent of the power weighting is to increase the
importance for a given reactivity feedback parameters in
the region where the neutron flux or local power is
relatively large. The specific problem identified was the
power weighting factors were not normalized correctly
when the core bypass and water rod regions of the core
were included. In addition, the power weighting factor
for the water rods and core bypass for BWRs was set to
1.0 and the power weighting factor should be
approximated with the lower fuel power factor. This
trouble report is still under investigation.
“PATHS:
Trouble Reports 658 – PARCS bug for ADF rotation
when there is more than 1 mesh in 1 fuel assemble.
Dr. Masahiro Furuya, CRIEPI, “Code Validation for
Rapid Flow-Decrease Event in SIRIUS-F Facility
which Simulates ABWR”
A user reported that when PARCS V3.1m07 was used to
simulate a PWR core in steady-state the code crashed.
The neutronic mesh for each fuel assembly is 2x2 and
the ADF option was set to true in the tree_xs input. The
ADF rotation option in ROT_ADF was also set to true.
Dr. Masahiro Furuya, CRIEPI, “Investigation of
Fukushima Daiichi Accident with TRACE Code”
4
Thermal-Hydraulic Codes News
December 2013
User reported that outside reflector lattices are rotated
according to their positions and macro cross-sections
were input a PMAX files. This trouble report is still under
investigation.
more information concerning why the calculation could
not continue and what needed to be done to correct the
error. This approach reduces the number of warning
and error messages written before TRACE would
normally stop at the end of input processing. The user
had a difficult time determining which messages were
fatal input errors and which messages were warnings or
information messages. With the new methodology in the
newErr update input error messages are easily identified,
since the code stops for the first input error encountered
and all other user messages are clearly labeled as
warnings, information, etc. This update closes this
trouble report.
Trouble Reports Closed
During the time period from September 26, 2012 to
December 18, 2012 the following trouble reports have
been closed with updates included into the NRC
developmental version of TRACE. In some instances,
these trouble reports have been closed by rerunning the
test problems of interest with the most current version of
TRACE and/or by modifying TRACE documentation to
address the issue.
Trouble Report 355 – Recovery from a Time-Warp.
Update AUTO went into version 5.770 and closed this
trouble report. Update AUTO adds to TRACE the
capability to backup more than one time step if TRACE
fails with time step cannot reduce below user input for
DTMIN. When TRACE repeats the last time step over
and over with smaller and smaller time step sizes, this
indicates that TRACE cannot resolve this numerical
problem with a smaller time step. For earlier versions of
TRACE this required a rerun or restarting with a smaller
DTMAX in attempt to solve through this numerical
problem. With AUTO TRACE has the capability to
backup more than one time step and rerun through the
problem time period with smaller time step size. With
this update the robustness of the code is significantly
improved. Note this AUTO backup logic does not
currently work with PARCS coupled or CONTAN
coupled TRACE calculations.
Trouble Report 287 – Inconsistencies in reactivity
feedback models in TRACE.
Update R5fdbkFix went into version 5.793 of TRACE.
Update R5fdbkFix added RELAP5 reactivity feedback
model capability into the BWR reactivity feedback
models in TRACE. This closes this trouble report.
Trouble Report 299 – Error in mass flow rates used in
HTC calculations when 1D PIPE is deadend.
The MIT pressurizer test problems were rerun with
version 5.765 and the 1D and 3D models of these tests
gave consistent results. The Clean1Ddrag update went
into version 5.750 and closed this trouble report. The
Clean1Ddrag update moved the 1D interfacial and wall
drag from a component based method to a global data
structure method. With this change the stratified flow
weighting factor (i.e., wfhf) was calculated consistently
for 1D and 3D deadend fluid cells (i.e., inlet but no
outlet).
Trouble Report 398 – Accumulation of round-off error in
the shifting of tables relative to a trip.
Update unShiftTables when into version 5.763 and
closed this trouble report. The original logic in TRACE
shifted tables each time step relative to when a
controlling trip status had last changed. This continuous
shifting and adjustment of tables relative to trip status
changes could result in significant accumulation of
round-off error in a given table depending upon how
many time steps the table was shifted.
Update
unShiftTable replaced this logic so that the time when a
controlling trip status changed could be saved with the
table and used to determine the correct independent
variable values to be used to evaluate the table. This
eliminated the accumulation of round-off error, since the
tables are no longer shifted.
Trouble Report 325 – Typical velocity error for restart
with components replaced with ASCII input.
Update FxRstVels went into version 5.721. With this
update if there is a relatively small inconsistency for a
given cell edge between the fluid velocity in the ASCII as
compared to the fluid velocity in the restart file a user
warning is written and restart file velocity is used for that
cell edge in the ASCII input file. If the velocity difference
is significant, then input error is thrown the calculation is
stopped. This trouble report is closed.
Trouble Report 354 – Excessive warning messages.
Trouble Report 400 – Getting a -0 for Diff->statName.
Update newErr went into version 5.780. This update
changed the TRACE input error processing logic so that
the first input error encountered results in the calculation
stopping after writing an input error message for the
users. In addition, an effort was made to improve the
error messages and attempt to provide the user with
When two TRACE output files are the same the TRACE
perl testing scripts compare them using the diff program
and result should be a diff file with 0 length. However,
sometimes on the RedHat LINUX operating system the
file length would be -0. This would indicate that results
5
Thermal-Hydraulic Codes News
December 2013
for this test problem changed or were different, when in
fact they were the same. Using the most current perl
scripts and with Lahey compiler on the LINUX 64 bit OS
with version 5.820 this behavior was no longer observed
and this trouble report was closed.
pipeType option 9 to the PIPE component. PIPEs with
pipeType option 9 have all of the PRIZER component
modeling capability included into the PIPE component.
This allows side junctions to be included into a PIPE
component with pipeType equal to 9.
Trouble Report 403 – Signal variables for CONTAN
component.
Trouble Report 585 – Enhancements to built-in heater
model in PRIZER component.
Update CONTANCTRL went into version 5.670 and
update CONTANSV went into version 5.651 and closed
this trouble report. These two updates added signal
variables and control block capability to the TRACE
CONTAN component.
Update FxPRIZERSJ went into version 5.680 and closed
this trouble report.
Update FxPRIZERSJ added
pipeType equal to 9 to the PIPE component, which
implies PIPE components can be used to simulate
pressurizers. PIPE component power to fluid table and
trips input can be used to trip off pressurizer heaters
when pipeType is 9.
Trouble Report 468 – APEX1000 small break modeling
guidelines.
Trouble Report 591 – Potential error with direct
moderator heating.
Application of NRC small break modeling guidelines to
APEX1000 indicate that when there is an orifice in the
cold leg pipe wall critical flow model should be turned on
there and if controlling choking is not expected
downstream from this location, then this can be the only
critical flow location simulated. For example, SJC
connected from cold leg to an atmospheric break.
However, long runs of relative small piping from the cold
leg to the break flow tank with valves between the cold
leg and the break flow tank may result in the controlling
critical flow moving from the cold leg break orifice to the
VALVE component. Therefore, the complete critical flow
discharge line including VALVE components may need
to be simulated for these types of tests. In a plant small
break accident with a hole or split in the side of a cold
leg or hot leg, there is not discharge piping to be
simulated. An SJC connected to a BREAK component
is the appropriate model. This trouble report is closed.
Update FxDirModHEat went into version 5.783 and
closed this trouble report.
This update adds the
capability to TRACE for the user to specify as functions
of time the fraction of the fission heat and/or decay heat
that is direct moderator heating. Direct moderator
heating associated with the fission power is due mainly
to neutron slowing down or interacting with the
moderator water. Direct moderator heating associated
with decay heat power is due mainly to gamma ray
interaction with the moderator water. Fraction of these
two sources of power that is direct moderator heating
would not normally be the same value. Note that fission
and decay heat power levels are only calculated by
TRACE when the TRACE point kinetics model is turned
on. If the point kinetics model is turned off and the
power is specified by the user, then the fission power
direct moderator heating input fraction is used for the
total power specified and the decay power direct
moderator heating fraction input is ignored.
Trouble Report 536 – Test problem manopipe02.i results
in erroneous amplitude decay.
Trouble Report 596 – Behavior of ISNOTB in point
kinetics model turns off all boron reactivity feedback.
Update FxLevelBackup went into version 5.610 and
closed this trouble report. This update changed the logic
when the level tracking model would force a backup.
With this update and with the initial conditions in
equilibrium and dtmin = 0.001 the manometer
oscillations amplitude does not decay. As the time step
is increased, the manometer oscillations amplitude will
decay. Initial conditions in equilibrium are important to
minimize the impact of phase change as the level moves
up and down in the vertical flow paths. If phase change
is turned off, then initial conditions in equilibrium are not
important, however current versions of TRACE do not
include a user input to turn off phase change.
Update FxDirModHeat went into version 5.783 and
closed trouble report. This update removed all of the
ISNOTB logic from TRACE. The ISNOTB input is still
read in so that old input decks still run, but the ISNOTB
input is ignored. The ISNOTB input was associated with
using burnable poisons in then boron reactivity feedback.
If at a future date a user need is identified for reactivity
feedback due to changes in burnable poison
concentrations this model can be revisited.
Trouble Report 597 – Suggestion to add core avg
parameters in reactivity feedback model to XTV graphics.
Trouble Report 584 – Enable side junctions for
PRIZERS.
The FxDirModHeat update went into version 5.783
added the core average parmeters used in the reactivity
feedback model to the XTV graphics variables. There
Update FxPRIZERSJ went into version 5.680 and closed
this trouble report.
Update FxPRIZERSJ added
6
Thermal-Hydraulic Codes News
December 2013
would some SI to English units conversion problems for
when the reactivity feedback coefficient for Doppler was
based on the square root of the core average fuel
temperature. These last concerns associated with this
trouble report were addressed with the FxNameListUnits
update that went into version 5.821. This trouble report
is closed.
Update GapEdits went into verison 5.690 and closed this
trouble report. With the GapEdits negative gap width are
not allowed. A negative gap width could be calculated
when the fuel pin outer radius expands beyond the inner
radius of the cladding. A negative gap width maybe
used in the future to estimate the contact pressure
between the fuel pin and cladding. With version 5.690
and larger gap widths are not allowed to be smaller than
the roughness of the fuel pin and cladding surfaces.
Trouble Report 600 – Error in energy source term for
water coming from TRACE BREAK component and
flashing in CONTAN compartment.
Trouble Report 608 – Add more gap heat transfer
parameters to the output/graphics files.
The energy source term error was fixed in version 5.541.
This fix was also included in an update FxContanFlash
along with two other fixes for the CONTAN component.
The modified version of the FxContanFlash update went
into version 5.701 and closes this trouble report. The
two other fixes were associated with mass and energy
source term for FILL components connected to a
CONTAN compartment and logic associated with
flashing in the liquid pool in an CONTAN compartment.
Update GapEdits went into verison 5.690 and closed this
trouble report. The GapEdits update adds a number of
gap heat transfer parameters to the output and graphics
files.
Trouble Report 609 – Implement a fuel swelling model.
Update GapEdits went into version 5.690 and
implemented FRAPCON 3.4 fuel swelling model into the
TRACE gap conductance model. FRAPCON has been
compared favorable to experimental data for the steadystate fuel rod center line temperature and is used as a
benchmark for the TRACE fuel rod models. Update
FxFCModels went into verison 5.761 and closed this
trouble report. This update implemented the following
fuel rod modeling recommendations based on
comparison to FRAPCON models:
1) Consistent with FRAPCON gap conductance
model, surface roughness factors are not
included in open gap HTC calculations.
2) Consistent with FRAPCON gap conductance
model, closed gap modes are applied when gap
thickness < (roughness of the fuel and cladding).
When the gap is closed then the roughness of
the fuel and cladding is included in the closed
gap HTC calculation.
3) The factor of 1.8 in the temperature jump
correlation in the FRAPCON documentation was
not supported by other references and was
removed from the TRACE temperature jump
model.
4) Consistent with the FRAPCON conductance
model coding that b factor is only included in the
closed gap conductance model.
5) The minimum allowed for the characteristic
dimension across the gap was set to 0.025 mils.
Trouble Report 601 – SJC pump has small flow when it
should be zero.
Update FxErrMess went into version 5.690 and closed
this trouble report. This update allows velocities in SJC
pump cell edges to go to zero and stay at zero if
boundary condition velocities are zero. All other active
cell edges if at zero velocity are reset to small velocities
(i.e., 1.2e-10 m/s) in the direction of the pressure
gradient so that donor cell logic can anticipate when the
flow starts to move again. For SJC PUMPs the flow are
boundary conditions are not solved for from the TRACE
momentum equations and therefore should not be reset.
Trouble Report 603 – AMNCSS and AMXCSS for CSS
input applies to what parameters?
Modified documentation was included into the
FxErrMess update and documentation in the NRC
TRACE repository was changed and closed this trouble
report.
The constrained steady-state (CSS) input
documentation was modified so that it is clear which
parameters have a minimum and maximum specified by
the user input AMNCSS and AMXCSS. In addition, the
units for these parameters was clearly identified.
Trouble Report 605 and 606 – Hoop stress and axial
stress in gap models
Trouble Report 610 – Possible bug in contact resistance
model.
The FxErrMess update went into version 5.690 and
closed this trouble report. This update includes logic
changes so that heat structure gap model hoop and axial
stresses can be plotted. Trouble report 606 is a
duplicate of this trouble report 605.
Update GapEdits went into version 5.690 and closed this
trouble report. With the GapEdits update, user can input
separate roughness for the fuel outer surface and the
cladding inner surface. With separate roughness, then
the contact resistance model can be evaluated correctly.
Trouble Report 607 – Negative gap width reported in
output.
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December 2013
Trouble Report 613 – Implement actual FRAPCON fuel
relocation model.
In addition, the fuel gap model documentation was
updated to reflect that the contact pressure is estimated
from the cladding yield stress. The implied assumptions
is as the gap closes the cladding stress is sufficient to
deform the cladding to the expanded radius of the fuel
and that cladding stress is at or close to the cladding
yield stress.
This appears to be a reasonable
assumption and relatively easy to implement. If this
assumption is found to be significantly inaccurate, then a
detailed multi-dimensional mechanical deformation
model may be required.
Update FxFCModels went into version 5.761 and closed
this trouble report.
This update implemented the
FRAPCON 3.4 fuel relocation model.
Trouble Report 614 – Determination of interface
pressure in contact resistance model.
With update GapEdits going into version 5.690 this
trouble report is closed. The interface pressure for a
closed gap is calculated based on assuming that the
cladding stress is at the cladding yield stress. If this
assumption proves to be inaccurate, then a more
mechanistic model can be implemented at a future date.
Trouble Report 611 – Investigate use of 1.27e-07 m as
default for RFCLAD.
With update FxFCModels into version 5.761 and FxNFCI
into version 5.762 this trouble report is closed. In
general the gap conductance goes as Kg / drg + contact
conductance + radiation heat transfer.
Kg is the
conductivity of the gas in the gap and drg is the
characteristic gap width dimension. drg will typically
include any temperature jump corrections due to the
dimension of the gap approaching molecular mean free
path distance and surface roughness if the gap is
considered closed. In addition, the FRAPCON closed
gap model includes a b factor that is correlation factor
based on fuel rod experimental data. The minimum that
drg is allowed to go will have a direct impact on the
closed gap conductance. The initial minimum allowed
for drg was based on the FRAPTRAN coding (i.e.,
1.27e-07 m). As the TRACE models moved toward to
FRAPCON (i.e., including the b factor in the closed gap
conductance model in TRACE), then the minimum as
implemented in the updates listed above is consistent
with FRAPCON (i.e., 0.025 mils = 6.35e-07 m). If
TRACE moves toward the FRAPTRAN models, then this
minimum allowed for the drg and for the fuel and
cladding roughness should be revisited. Based on
implementation of the FRAPCON models into TRACE,
then this minimum should be consistent with the
FRAPCON models.
Trouble Report 619 – Large component number fails for
CHAN component grouped view factors and path length
files when TRACE attempts to open these files.
The logic in generation of file names for grouped view
factor and path length files used to store data as CHAN
component input is processed assumed CHAN
component numbers no larger than 9999. With the
GapEdits update this logic was modified to handle
CHAN component numbers as larger as 999999. These
grouped view factor and path length files are written out
for user convenience since significant cpu time may be
spent calculating these grouped view factors and path
lengths. Once calculated if the geometry does not
change then these input files can be pasted into CHAN
component inputs and TRACE calculation for these view
factors and path lengths can be skipped. For relatively
simple geometry analytical formulas are used to
determine the view factors and typically do not require
significant cpu time. However as the geometry becomes
more complicated the view factors may be calculated
using Monte Carlo methods, which may require
significant cpu time depending upon the number of
CHAN components, the number fuel rods and water rods
in each CHAN component, whether the geometry varies
axially or is constant and how many view traces are
used per surface segment within the fuel assembly.
Under these conditions the user may only want to
calculate the grouped view factors and path lengths
once.
Trouble Report 612 – Possible gap model improvements.
Update FxNFCI went into version 5.762 and closed this
trouble report. This update removes the old TRAC-P
dynamic gap model and the RELAP5 fuel slumping
model. The TRACE dynamic gap model currently in
TRACE is considered a best estimate model and is
based on FRAPCON 3.4. The available input options for
NFCI for the TRACE heat structure component has been
reduced from a large number of possibilities to three
values (i.e., = 0 implies constant gap conductance, =1
implies best estimate models for cladding thermal and
mechanical deformation but not including plastic
deformation and/or rupture, = 2 same as 1, except
includes plastic deformation and cladding rupture).
Trouble Report 620 – Slight difference in PCT for restart
for CHAN nfciTest-13.Rev.FE.
Update GapEdits went into version 5.690 and closed this
trouble report. Determined that heat structures radiation
heat fluxes were not included in the TRACE TPR library
dump/restart files.
Update GapEdits include heat
structure radiation heat fluxes in the TRACE
dump/restart files and resolves this difference in PCT at
restart.
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December 2013
Trouble Report 627 – RELAP5 reactivity feedback
models in TRACE not working for transient restart.
Update FxErrMess went into version 5.890 and update
newErr went into version 5.780 and closed this trouble
report. With the newErr update it is clear whether or not
a user message is an input error, warning, information,
etc. In addition, any fatal input error results in TRACE
stopping immediately.
Multiple fatal input error
messages are no longer possible. These updates
significantly reduce the confusion level for input error
messages.
For earlier versions of TRACE the RELAP5 reactivity
feedback models were not available for TRACE models
of BWR. Update R5fdbkFix went into version 5.793 and
closed this trouble report. Trouble report 287 is similar
to this trouble report and with update R5fdbkFix in
version 5.793 both of these trouble reports are closed.
Trouble Report 628 – Choking problem with V5.0 Patch
3.
Trouble Report 633 – TRACE V5.0 Patch 3 does not
read data curve.
TRACE calculations were compared to a ROSA-2
intermediate side break test. TRACE results were not
consistent with expectations until choking was turned at
both the break orifice in the cold leg and on at the
VALVE components in the discharge line. There are
periods during the transient where choking may occur at
both the break orifice and at the VALVE components. If
the discharge is long enough and has sufficient flow loss
and relatively small areas, then as the two phase mixture
expands in the discharge line the minimum break flow
may occur at the two-phase choking at VALVE rather
than at the break orifice, even though the flow area at
the break orifice is smaller than the flow area through the
valve. With the choking model turned at the correct
multiple locations the results look reasonable and
consistent and this trouble report is closed.
Update ContBrkFix went into version 5.820 and closed
this trouble report. This update fixes the logic error that
was writing over the BREAK component solute table.
Trouble Report 637 – Power component’s maximum rate
of change programmed reactivity (i.e., RRPWMX) affects
also the maximum programmed reactivity.
Update FxCladRupEdit went into version 5.672 and
closed this trouble report. This update fixes a logic error
in the application of the maximum allowed change in
reactivity in the POWER component. With this fix the
user input for RRPWMX is used correctly with the
programmed reactivity.
Trouble Report 638 – Initialization errors flagged by
Regression Test Problem Set on LINUX 64 bit OS with
Lahey compiler.
Trouble Report 629 – Warning message about 1D level
tracking with SEPD components no longer needed.
Update LaheyFix went into version 5.772 and closed this
trouble report. This update fixes the run time errors and
initialization errors identified by the Lahey compiler on
the LINUX operating system.
Update R5fdbkFix went into version 5.793 and this
trouble report is closed. Logic was added to update
R5fdbkFix to remove this user warning message that is
no longer needed or useful.
Trouble Report 639 – Cladding rupture fine mesh index
may be off by one.
Trouble Report 630 – DirectCoolantHeating in the
Regression test problem suite for PARCS does not with
TRACE since version 5.540.
Update FxCladRupEdit went into version 5.672 and
closed this trouble report. This update improves logic for
determination of the fine mesh node index at the
cladding rupture location.
Update ExMappingFix went into version 5.673 and this
trouble report is closed. Logic errors in heat structure
input processing was causing these test problems to fail
and testing scripts were not picking up that these test
problems were all failing. The ExMappingFix resolves
this input processing error
Trouble Report 642 – Version 5.80 results in compiler
errors for Lahey compiler on LINUX OS.
Trouble Report 631 – Heat transfer rates from HS to fluid
cells not backed up correctly.
Update FxFCModels went into version 5.761 and closed
this trouble report. This update includes fixes for the
compiler errors identified by Lahey compiler on LINUX
OS.
Update PowerBackupFix went into version 5.764 and
closed this trouble report. This update fixes the HS
backup logic so that heat transfer rates are backed up
correctly.
Trouble Report 643 – lenNamelist in NamlistDat module
should be 123 for version 5.690.
Trouble Report 632 – Input error messages confusing.
The fix for this trouble report went into version 5.701 and
closed this trouble report. The variable lenNamelist
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Thermal-Hydraulic Codes News
December 2013
needs to be consistent with the number of name list
variables initialized in the NamlistDat module.
lenNamelist was 124 and it should have been 123.
When lenNamelist is too large then there will undefined
entries in the namelist data structure.
stub connected to the RPV is short, then going back to
an SJC PIPE connected to the BREAK is a reasonable
approach. With the SJC PIPE the upstream choked flow
plane fluid conditions are in the RPV fluid cell and will
typically result in larger critical flow rates as compared to
a short pipe where flashing and phase change may
occur upstream from the choking plane. For very short
pipe stub, no significant flashing will be expected. If
larger critical flow is conservative for the transient of
interest then lean toward to the SJC PIPE and BREAK
combination.
Trouble Report 645 – Potential error in indiex used in
NCG mixture property evaluation fluids model.
Update FxMixNCGTP went into version 5.773 and
closed this trouble report. This update fixes some index
errors in the non-condensable gas (NCG) mixture
thermal and fluid properties model. The NCG mixture
properties model is based on the FRAPCON 3.4 model
and is used in the gap conductance model and in the
fluids component models when mixtures of NCG are
present.
Trouble Report 649 – Not clear which form of the
reactivity feedback coefficients and units used when
R5fdbk = 1.
Update FxBoronReact went into version 5.791 and
FxMWRXAppK into version 5.800 and closed this trouble
report. Documentation was update and logic errors
corrected so that it should be obvious to the user which
reactivity feedback coefficients and the units are used
with the TRACE point kinetics reactivity feedback
models.
Trouble Report 646 – Restart problem for models with
iGas > 10 and VESSEL component.
The FxMixNCGTP update went into version 5.773 and
closed this trouble report.
This update fixes
restart/dump problems for the VESSEL component when
there are more than one NCG present.
Trouble Report 650 – Table driven POWER component
does not work during steady-state.
Trouble Report 647 – Error in the 3” axial renode logic
when fine mesh, cladding rupture, and metal-water
reaction model are turned on.
The default behavior for a TRACE table or tripped table
is during steady-state a constant initial value is used.
The typical TRACE table is not evaluated until the
transient starts. In this case the user wanted to use
control systems during steady-state to determine
pressurizer power and pump power as the steady-state
is approached. Using PIPE with pipeType 9 could use
the existing pressurizer models to control the pressurizer
heater during the approach to steady-state and then at
the start of the transient trip off the TRACE internal
pressurizer models and trip on powered HS components
that will be used to simulate the transient pressurizer
behavior. PUMP models will turn on the pump friction
heating models. If a user need for steady-state controls
for POWER component is identified it can added at a
future date. This trouble report is closed.
FxMWRXReNode update went into version 5.784 and
FxMWRXAppK update went into version 5.800 and
these updates close this trouble report. With these
updates the user has the option to run with the inside
surface of 3 inches zone at the cladding rupture location
for the inside surface metal-water reaction to be forced
or relaxed. If the 3 inch zone is forced and the axial
noding is too small for 3 inch renode around the cladding
rupture location, then the calculation stops. If the 3 inch
zone is not forced, then the calculation will continue if
the axial coarse mesh noding is too small for a 3 inch
renode around the cladding rupture location.
Trouble Report 648 – Critical flow at SJC edges may not
be correct.
Trouble Report 651 – Version 5.780 has a USE
ErrorInterface, ONLY: error missing in TestForBackup.
Based on the resolution of trouble report 628 and
investigation of the results for this trouble report, this
trouble report was also resolved and closed. Results are
consistent with expectations for the models used. For a
split in the side of a reactor pressure vessel (RPV) an
SJC PIPE connected to an atmospheric break is the best
representation of this geometry. If the break is a small
pipe connected to the RPV and there is non-zero length
of pipe between the break and the RPV, then a PIPE
component connected to the RPV and then to the
atmospheric break may be the best approach. The
intent is to provide the best estimate for the fluid
conditions upstream from the choking plane. If the pipe
Update FxMWRXReNode went into version 5.784 and
closed this trouble report.
The newErr update
implemented optional arguments into the error routine.
This implies that an error routine interface must be
defined in any modules where error is called. In a few
cases the newErr update missed where USE
ErrorInterface, ONLY: error needed to be added to
TRACE source files.
Trouble Report 652 – Input deck failures for version
5.780.
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Thermal-Hydraulic Codes News
December 2013
With the newErr update some test problems that did run
were now failing. The failure was due to the change in
some input error testing logic that changed e character
missing from the ASCII input from a warning to a fatal
input error. The e character in the TRACE array input
implies that the array input is finished. A few input
models have the e character in column 81 and therefore
does not get included into the fixed format input in
the .echo file. When the array input is read from
the .echo file it finds the e character missing and throws
a fatal input error. This is the expected behavior for
TRACE input processing and this trouble report is closed.
Trouble Report 659 – Negative pressure calculated in
some CONTAN test problems.
Update NegPresFix went into version 5.812 and closed
this trouble report.
This update modified logic in
PredictVoid routine so that the estimated new time NCG
partial pressure did not go negative even though the
total pressure was approaching the triple point pressure.
Trouble Report 660 – Divide by zero error for CONTAN
test problem CVTR_T3.rev7sv.
Trouble Report 654 – HS fatal input errors called from
CountingCoup.
Update NegPresFix went into version 5.812 and update
ContBrkFix went into version 5.820 and closed this
trouble report. The divide by zero occurred during
initialization of the CONTAN component and was
associated with certain condensation film parameters not
correctly initialized. The updates listed above modifies
logic so that the CONTAN component parameters are
correct initialized during initialization.
Update FxMWRXAppK went into version 5.800 and
closed this trouble report. The CountingCoup module in
TRACE scans the ASCII and restart file input to
determine the total number of fluid, heat structure, etc.
components in the TRACE input model and the total for
each type of component. This information is needed to
allocate arrays and data structures. The HS component
is scanned using the HS input routines, but during the
scanning the component number, etc is not saved. So if
an input error is detected then with the newErr update
that went into 5.780 will cause the calculation to stop,
but the error message itself will not be complete since it
was called from the input scan initiated by CountingCoup.
Logic was added to the HS input processing routines to
skip input error checks during an input scan initiated by
CountingCoup.
Trouble Report 661 – Divide by zero when non-ideal
helium is used.
Non-ideal helium does not appear to be used anymore in
TRACE. This model was removed from version 5.801 of
TRACE. This closes this trouble report.
Trouble Report 662 – Floating point overflow when
TRACE attempts to write to XTV file.
The steady-state pressurizer models in TRACE use a
scaling factor of 1.0e+35 times the pressurizer volume
and flow area to ensure that the pressurizer pressure
stays constant during a steady-state calculation. This
implies that the interfacial heat transfer coefficients
written to the graphics file (i.e., XTV file) will include this
scaling factor.
Given that the graphics file data
structures are mostly single precision this results in a
floating point overflow. The scaling factor was changed
to 1.0e+15 in version 5.801. This closes this trouble
report.
Trouble Report 655 – Appears to be backup problem
with version 5.784.
Update FxBackupMB went into version 5.811 and closed
this trouble report. Certain time integrated mass and
energy flow rate parameters were not included into the
TVar data structures used to save solution variables at
selected potential backup times as the calculation
proceeds. This time integrated parameters are part the
TRACE edited mass and energy balances. Without
these parameters in the TVar data structures a backup
would appear to result in a mass error. With these
parameters added to the TVar data structures, then a
backup would not add to the mass error.
Trouble Report 663 – Divide by zero error for higher
order numerics test problem.
The NegPresFix update went into version 5.812 and
closed this trouble report. This update changed in the
logic in StbVel1D routine so that for a mixed numerics
calculation with a PUMP component, SETS is turned off
and diagonal terms in the vvt and vlt coefficient matrix
are set to 1.0 and the off-diagonals are set to zero. This
eliminates the divide by zero in the TriSolve routine for
the vvt and vlt velocities. In addition, logic was added to
catch zero diagonal terms and throw a run time error.
Trouble Report 657 – Version 5.792 compiled on LINUX
64 bit with Lahey compiler uncovered coding errors.
Update FxErrCalledBy went into version 5.822 and
closed this trouble report. This update fixes compiler
errors uncovered with the Lahey compiler on a LINUX 65
bit OS. It also adds calledBy argument to the error
routine so that calls to error can pass the name of the
subroutine that is calling error. This information will be
useful to developers when users provide them with the
error message of interest.
Trouble Report 664 – Divide by zero error in heat
structure logic.
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December 2013
This fix for this problem was change the minimum
pressure at the choking plane to be the triple point
pressure. Properties at the triple point pressure are
reasonable and consistent and eliminates the possibility
for zero velocities at the choking plane.
The fprop routine was not getting called for PLENUM
components during initialization. The fprop routines
calculates fluid viscosities and other fluid properties.
The fluid viscosities are transferred to any HS
component connected to these PLENUM components.
However, since viscosities were calculated during
initialization the first time heat transfer coefficient
calculations need a Reynolds number a divide by zero
error occurs. The fix is to all a call to fprop for the
PLENUM component during initialization. This fix was
added to version 5.801 and closed this trouble report.
Trouble Reports
Pending
Resolved
with
Updates
During the time period from January 1, 2013 to
December 31, 2013 the following Trouble Reports have
been resolved with updates or documentation
modifications pending. These Trouble Reports are
awaiting NRC review and a decision to implement or not
to implement the associated code updates or document
modifications into TRACE.
Trouble Report 665 – “floating invalid” error reported in
the HtStrShared module.
Run time error occurred in the heat structure fuel pin
dish volume calculation when the fuel pin was not dished.
Logic was added to skip the fuel pin dish volume
calculation if the fuel pin is flat (i.e., no dish). This logic
change was made in version 5.801 and closed this
trouble report.
Trouble Report 402 – Incorrect vapor internal energy fit
between 1 bar and 20 bars.
During external independent review of TRACE, Marv
Thurgood identified the saturated vapor internal energy
fits from the TRAC-P computer code as inadequate in
the range between 1 and 20 bars. The derivative of
internal energy with respect to pressure and temperature
are of the wrong sign. These errors for the saturated
vapor phase also impact the superheated steam internal
energy calculation. The TRAC-P EOS fits are not
recommended for use and are currently only maintained
for old input decks that use these EOS fits. Starting with
version 5.600 the default EOS model for TRACE is the
IAPWS steam tables. This trouble report is marked as
resolved. There will be no attempt to fix these fits since
they are no longer recommended and are maintained
only for backward compatibility.
Trouble Report 667 – Input description for PGAPT and
GMLES are confusing and needs to be reworked.
Update ChanGMLES went into version 5.824 and closed
this trouble report. New input was added to the CHAN
component so that when name list inpu legacyFRM is
FALSE then GMLES input for the CHAN is expected. In
general, if the fuel rods simulated by the HTSTR or
CHAN input is fresh fuel, then PGAPT can be used to
calculate the number gram-moles of fill gas in the fuel
rod gap and plenum. The user input for PGAPT is for
cold conditions and the cold condition gas volume will be
used to determine the number of gram-moles of fill gas.
If the fuel rods have burnup, then a code like FRAPCON
or something similar would be run to determine the
number of gram-moles of gas in the gap and fuel rod
plenum and the composition of this gas, since it will
contain not only fill gas but also fission product gases.
For this case GMLES input should be used for the
HTSTR or CHAN input. If the user inputs non-zero input
for GMLES, then PGAPT input must be zero. If the
PGAPT input is non-zero, then GMLES must be input as
zero. Input descriptions for PGAPT and GMLES were
modified to be consist with the ChanGMLES update and
describe when which input should be used.
Trouble Report 604 – Inaccurate interfacial heat/mass
transfer as 3D vessel level crosses nodal boundary
using 3D level tracking.
A user reported that TRACE 3D model of the MASLWR
test facility predicted a pressure spike when the mixture
level in the pressurizer region of the reactor pressure
vessel dropped from level 27 to 26. These results were
observed with verison 5.540. These calculations were
repeated with version 5.680 and the pressure spike went
away. There were a number of level tracking fixes
between versions 5.540 and 5.680 that may have been
the reason for these improved results. This trouble
report is marked as resolved.
Trouble Report 668 – Found a case where the choked
flow critical liquid phase velocity was zero.
Trouble Report 618 – Removal of unnecessary units
definitions in the VarLabels array.
Update FxNegChoke went into version 5.823 and closed
this trouble report. The lower limit for the pressure at the
choking plane was 1.0e-06 Pa and under certain
conditions as the correct critical flow search is going it
was possible pressure at the choking plane to go so low
that the fluid properties were negative. This resulted in
negative critical flow velocities that were limited to zero.
The FxCleanupUnits update is pending for NRC review.
This update removes 217 unused units definitions from
the VarLabels array. The VarLabels array defines the
units for a given TRACE variable or parameter that
would be in TRACE input or output or graphics. This
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Thermal-Hydraulic Codes News
December 2013
units definition is used for converting the parameter
between SI and English units. As models changes and
input and output changes and graphics variables change
units definitions that were needed in older versions of
TRACE are no longer needed. For version 5.831 the
length of the VarLabels array is 1465 and removal of 217
elements from this array would reduce it’s size by ~15%.
calculation. For the 5.791 restart the user included
name list input closest = .TRUE., which turns on TRACE
logic to restart to the dump closest to the user requested
dump given by user input DSTEP. The steady-state
wrote two restarts dump (i.e., one at time step 0 and one
at time step ~25520). For the 5.791 restart with closest
= .TRUE. and DSTEP = 2552, TRACE restarted from
time step 0 dump. TRACE reported which dump it
restarted from, but this was not immediately noticed in
the TRACE output files. With DSTEP changed to 24000
TRACE restart from the final steady-state dump and
calculations were consistent with the version 5.0 Patch 3
results. This trouble report is resolved.
Trouble Report 636 – Motor torque curves no accurately
used by TRACE.
The motor torque curves in TRACE were not correctly
converted from English to SI units. This problem was
fixed with the FxCladRupEdit update that went into
version 5.672. The final issue for this trouble report was
resolved with the FxIPMPTY3 update which contains
documentation updates to address the name list input
PUMPFRICQ input associated with pump friction heat
loss model. The update is pending.
Recent RELAP5 User Problems
R
ELAP5 user problems reported or resolved are
summarized in each issue of the newsletter. If
you encounter a problem with RELAP5, please
report it to [email protected] complete
list of RELAP5 user problems, including a description of
the problem, status (resolved, in work, on hold or
unresolvable) and, if resolved, the manner of resolution,
is available on the https://www.nrccodes.com web site.
Trouble Report 644 – Logical function calls in an IF (…)
or DO WHILE (…) relative to Fortran 90/95 standard.
There were a number of places in the TRACE source
that included within IF (…) tests and DO WHILE (…)
coding where a logical function used in the IF or DO
WHILE that may have secondary effects. For example,
IF (FUN1(x, y) .AND. FUN2(w, z)) THEN there is no
requirement that both FUN1 and FUN2 will be called or
which one is called first. Therefore if FUN1 and/or FUN2
have secondary results, then there is no guarantee that
the function will be evaluated. The PURE update was
developed to address this trouble report and resolves
this trouble report. The PURE update forces all logical
functions in TRACE to be PURE Fortran 95 functions
(i.e., no side effects). Functions that could not be made
to be pure were modified to be subroutine and the logical
result returned through the argument list. This update is
pending.
Since the last TH newsletter was published nine new
user problems were submitted. Six of these problems
were resolved and two were placed on hold.
A
description of these user problems is provided below in
chronological order.
No. 2012-08 (10/1/2012)
Code Versions Affected: RELAP5/Mod3.3 Patch04
The user reported an execution error when
RELAP5/Mod3.3Patch4 was coupled with PARCS. This
error occurred regardless of the PARCS version (v2.7,
v3.0, v3.2). However, this error was nonexistent in
earlier versions of RELAP5, i.e., Mod3.3Patch3, using
the same input deck. The coupled RELAP5/PARCS was
simulating an operational transient at Ringhals-3 nuclear
power plant. During the steady state calculation, after
several time steps, the calculation terminated and
RELAP5 produced an error indicating bad void fractions.
Checking the output files did not reveal any suspicious /
unphysical parameters. Moreover, comparing with those
obtained from a successful simulation (Patch3) did not
show any significant differences up to the time step the
code crashed.
Trouble Report 656 – Description of NFAX is insufficient
in Volume 1 of the TRACE Users Guide.
Documentation modifications in the FxNameListUnits
update identify and explain the input requirements for
the NFAX array for both the CHAN and HTSTR
components. The NFAX input requirements are
enforced by TRACE but were not documented for the
user. This update is pending.
Trouble Report 672 – Differences between 5.0 Patch 3
and 5.791.
Resolution (10-08-12): The input decks were received
from the user, and upon further examination, the void
fractions were becoming slightly negative (-1.0e-20),
which caused the error checking logic in the RDMR to be
tripped. Logic was added to the RDMR to include an
epsilon of +/-1.0e-6 in the void fraction evaluation. This
TRACE version 5.791 was not restarting from the restart
that user expected. Given this difference in restarts
between 5.0 Patch 3 and 5.791 the calculated results
were significantly different. For the 5.0 Patch 3 restart
the user use ASCII input so that the calculation started
from the last restart dump for the steady-state
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Thermal-Hydraulic Codes News
December 2013
eliminated the problem and the coupled code ran
successfully to the specified end time.
minimal impact, but ultimately, the oscillations were not
mitigated. Some further study is needed to make the
flow regime map more consistent across flow boundaries.
No. 2012-09 (10/1/2012)
Code Versions Affected: RELAP5/Mod3.3 Patch04
No. 2012-11 (12/3/2012)
Code Versions Affected: RELAP5/Mod3.3 Patch04
Under certain conditions, discontinuities in the mass flow
rate of a two-phase fluid could be observed in a RELAP5
model of Forsmark 1 system 323 sub 2.
The
discontinuities appeared in a junction, modeling a
reducer (diameter 300 mm to 200 mm) in a vertical pipe.
During a 5 ms long time interval the mass flow rate
oscillates at almost every major time step with
approximately 15 kg/s, i.e. 0.08 g of water moves back
and forth through the junction during one oscillation.
When building the code with the “-map” configure option,
the compilation of stateq.ff failed. There were numerous
failures including variables not declared and endif’s out
of place.
Resolution (12-04-12): The undeclared variables were
addressed by adding the sparms.hh header file along
with declaring the spropstat(:) array. In addition, several
array indices were changed from ivx to ix and a
misplaced endif was replaced with an appropriate if-test.
The code now compiles stateq.ff without errors.
Following initial observation, the cause of the problem
was likely due to level tracking turned on in a couple of
pipes. Gas surge that propagates through the pipes
causes activation of level tracking when it shouldn’t be
on. The user was advised to turn off level tracking. In
addition, modifications to the level detection logic that
would work for the user's calculation scenario could be
explored.
No. 2013-01 (1/7/2013)
Code Versions Affected: RELAP5/Mod3.3 Patch04
The user reported difficulty building the code with
Cygwin on Windows 7 64bit SP1 Pro using the IFC
compiler. The issue was that some scripts had the ^M
end of line character which should have been stripped
off. The configure and bldhh scripts called ‘d2u’ to
convert these files, but that alias is no longer available in
Cygwin.
On Hold (04-09-13): Have not heard any feedback from
the user on this issue.
No. 2012-10 (10/8/2012)
Code Versions Affected: RELAP5/Mod3.3je
Resolution (01-07-13): The ‘d2u’ calls were replaced
with ‘dos2unix’. This resolved the user problem and the
build process completed successfully.
The user reported problems with a model containing a
relief valve opening. Two input files were provided that
are the same except that the size of the orifice
representing the relief valve is smaller in one case. In
the model, there are four relief valves going to one of
two tanks. In these input files, the opening relief valve is
component 2 while the flow is going to the tank at
component 57. The problem was that while the 900
case ran very smoothly, the 475 case was quite unstable.
In the 475 case there were a number of pipes (volume
1903 for instance) where things were smooth for the first
ten seconds or so, but then when voidf reached a low
point of near 0.2, the solution became unstable. It
appeared as though the flow regime was switching from
slug flow to stratified flow at a high frequency. This was
causing all sorts of disturbances in the flow as seen in
velocities, densities, etc throughout the rest of the pipe.
In the 900 case, the liquid void fraction never dropped
below around 0.4 and the flow regimes were steady.
Similar behavior has been seen with this instability in
several other models; it always seems to happen when
voidf approaches 0.2 to 0.3.
No. 2013-02 (1/7/2013)
Code Versions Affected: RELAP5/Mod3.3 Patch04
The user reported liquid appearing in a model that only
contained non-condensable. The user needed to be
setting Word 5 on Card 120 to “2”, indicating a pure noncondensable case. However, after setting this value, the
case failed early on.
Resolution (01-07-13): A change to eqfinl in version
3.3ik
broke
the
code
when
running
pure
noncondensables. The logic that was added to version
3.3ik needed to include a test that the case was not pure
noncondensables. This if-test was added to the code
and pure noncondensable cases now run.
No. 2013-03 (3/19/2013)
Code Versions Affected: RELAP5/Mod3.3 Patch04
The user reported the following error: “******** number
of words on a card or total number of words on cards too
large, processing terminated.” The error is due to a limit
in inp.ff that restricts the number of available words to
2^19. The user has requested extending this to 2^21.
However, when it was previously extended from 2^17 to
On Hold (11-14-2012): Several attempts were made to
relax the transition between slug / horizontal stratification,
and between bubbly / slug and slug / annular mist. In
addition, attempts were made to relax the interfacial drag
and interfacial heat transfer directly. There was some
14
Thermal-Hydraulic Codes News
December 2013
2^19 (3.3hi), there were only two additional bits available.
Now, there are no more available bits in the mask to
extend the limit to 2^21, so a more complicated fix is
required. This user problem remains “in work”.
Regarding the g77 compiler issues, the cnv32.f and
stgd2o.ff routines didn’t compile because intrinsic
function ‘trim’ is not recognized by g77. The
‘action=read’ item in the open function also was not
recognized by g77. Envrl subroutine psatd2o.ff did not
compile because common block declarations were
placed after data statements. Relap subroutine rvalve.ff
did not compile because a comma was missing in format
statement 3140. All of these items were corrected in this
update.
No. 2013-04 (4/1/2013)
Code Versions Affected: RELAP5/Mod3.3 Patch04
The user reported difficulty getting an input model to run
after converting from a Mod3.1.1 input deck. The issue
seems related to the modeling of cross flow junctions.
Resolved (04-09-13): The user's input model was fixed
to work with Mod3.3Patch04. The fix consisted of three
things. First, junction 3 of component 200 (crossflow
junction) was changed to connect to the side of
component 200 rather than the top. This fixed the input
processing issue. Second, the problem failed at about
1.4 second due to a high pressure in the CST. The
resolution was to make the area of the TDV connected
to the top of the CST large (it was very small compared
to the CST area). Third, changed the time step control
flage for tt = 2 to tt = 3. This allowed the code to
complete its calculation rather than fail at about 40 s.
Items of Interest
T
he Spring 2014 CAMP Meeting will be held at the
Faculty of Electrical Engineering and Computing
(FER) in Zagreb, Croatia. The meeting will be
May 7 – 9, and additional information, including the
registration form, can be found on the NRCCodes
Sharepoint site (https://www.nrccodes.com).
TRACE V5.0 Patch 4 is currently scheduled for release
in March 2014. The focus for Patch 4 has been to make
the code more robust and to make key modeling
improvements. This version will include the following
major features:
There were some follow-on questions concerning valve
operations and trip logic that were also resolved.
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No. 2013-05 (5/8/2013)
Code Versions Affected: RELAP5/Mod3.3 Patch04
The user had problems when reading cards 6SS00000.
Error messages like these below appear:
0******** too many numbers on cards 60100000 through
60100000
0******** Delete expected but not found on card
0******** too many numbers on cards 60200000 through
60200000
0******** Delete expected but not found on card
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In addition, some problems were discovered when
building the code with the g77 compiler.
Resolution (05-10-13): The problem with the radiation
enclosure model was a bad indexing location in the ‘a’
array. Using the debugger it was noted that at the
beginning of the rradht.ff subroutine, the index number
n3 was 486. In this logic, the code searches for card
60000000. If found, the input processing moves forward.
It then looks for card number 6SS00000 by calling inplnk.
inplnk bumps the index number (n3) by 2. If the card
number is found, it then checks to see if the 1st word in
6SS00000 is an integer or a delete card by calling
impmod. However, the location to start the check was in
the wrong spot, therefore an error resulted. The solution
to fix the problem was to reset the index number before
calling impmod.
Make the IAPWS tables the default EOS algorithm
Generic working fluids (NIST database)
Refactored interfacial heat transfer logic
Mechanistic CONTAN models for sprays and films
on walls and improved CONTAN/TRACE
communication (signal variables, trips)
PIPE-based pressurizer modeling
Higher order methods, with component-bycomponent selection of numerical method
Multi-step backup capability
Fuel rod model improvements
Metal-water reaction improvements
Helical coil & cross flow heat transfer models
AUTO multistep backup capability
Improved error message behavior
Implicit wall heat transfer modeling option
This work has been driven by user needs, which
includes adding features needed to model small modular
reactors (integral PWRs). Considerable effort is also
being spent on making code modifications and
improvements to support NRC staff who are using
TRACE/PARCS
to
simulate
transients
where
neutronics/thermal-hydraulics coupling is important. As
such, TRACE V5.0 Patch 4 will include PARCS v32m11,
which contains the following upgrades:
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15
Changes Wielandt shift with adaptive parameter
Adds limiters for the ADF adjusting factor in CMFD
based on GET
Thermal-Hydraulic Codes News
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December 2013
Adds I and Pm densities, and core average beta,
output to dep file
Implements of z-direction discontinuity factors
Adds Xe/Sm density calculation at shutdown
cooling period
Allows user to directly input incremental core
average burnup
Adds termination logic for control rod critical
position search when neutronics have reached
maximum iterations but TH solution is not
converged
Rewrites detector response, and enable detector
edit output for each depletion point
Adds more Xe/Sm options
Adds option for starting transient from subcritical
state
Adds prediction of reactivity worth of each control
rod by bilinear weighting
Limits time step size increasing to 2 times at one
step unless user requires sudden larger increment
Rewrites critical control rod position searching
Adds a user input option for linear or quadratic
precursor approximation
The exponential integration is approximated with
3rd order Taylor expansion when lambda* delt
<0.001 which is more reliable than direct
evaluation
Future improvements of TRACE will continue to focus on
enhancing capabilities related to the simulation of new
and advanced reactor designs. In addition, the focus will
continue to be on improving the robustness and
accuracy of the code.
You are encouraged to visit the SharePoint site,
https://www.nrccodes.com. You can join in discussions,
download relevant documents, access TRACE (Bugzilla)
and RELAP5 User Problem descriptions and, for CAMP
members, access information on the CAMP program
including status of proposed and active in-kind
contributions, announcements and a calendar of
upcoming events. The discussions area supports asking
questions and sharing experiences.
Chris Murray is the contact point for the SharePoint site.
If you have any problems accessing the site, or if you
have any questions or would like additional information
on the NRC TH codes, please contact Chris Murray at
[email protected] or 301-251-7513.
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