ML20006F504
| ML20006F504 | |
| Person / Time | |
|---|---|
| Issue date: | 12/11/1989 |
| From: | Advisory Committee on Reactor Safeguards |
| To: | Advisory Committee on Reactor Safeguards |
| References | |
| ACRS-2677, NUDOCS 9002280099 | |
| Download: ML20006F504 (38) | |
Text
7
{ y y '.
gg3-g,77
>o M*I*ijQ fpA */b&
fD j i
j Jjbh DATE ISSUED: 12/11/89 l
/2/1t} fi I
ADVISORY COFVIITTEE ON REACTOR SAFEGUARDS THERMAL HYDRAULIC PHENOMENA SUBCOMMITTEE HEETING MINUTES STATUS OF NRC-RES T/H RESEARCH PROGRAM NOVEMBER 14, 1989 BETHESDA, MARYLAND p0Rp0SE:
The purpose of the meeting was to discuss selected topics related to the NRC-RES thermal hydraulic research program, including l
future research needs and the recent ACRS letter commenting on thermal hydraulic research.
ATTENDEES:
Principle neeting attendees include:
ACRS NRC I. Catton, Chairman L. Shotkin, RES D. Ward, Member B. Sheron, RES H. Plesset, Consultant G. Hsii, NRR V. Schrock, Consultant D. Bessette, RES N. Zuber, RES B&W R. Lee, RES D. Birmingham G. Geissler Duke Power Co.
L S. Nesbit MEETING HIGHLIGHTS. AGREEMENTS, AND REQUESTS l
1.
Dr. Catton noted the following comments:
l
- T/H is the discipline needed to assure core heat removal and l
subsequent plant safety. Good T/H research requires enough l
l experience to develop a feeling for the processes and their relationship to available experimental data, as well as the
)
glue that binds it all together: the computer code-combined with a great deal of coninon sense.
- He has great concern about the level of funding for NRC T/H research and what appears to be a substitution of code use for research.
Code use is not research.
DESIC HTED ORIGINAL 9002280099 991211 h
\\
g-7 g acas p
certifica or
,c
L3
('
4 i
T/H Phenomena Meeting Minutes November 14, 1989 t
- ARC speaks of " closure" of research for T/H.
Closure is counterproductive here. Trying to do so will result in NRC 3
loosing its capability to address future problems. Such j
issues as: a CE request to revise their CHF correlation for the St. Lucie Plant, a recent concern regarding loss of i
thermal margin due to channel box bowing in GE plants, and the on-going research regarding the ability of codes to calculate l
BWR instability all argue for a balanced approach to T/H research.
He said he was trying to make a case int balance.
There needs to be more of the type of research that develops the judgement needed to use the tools NRC has paid so dearly to develop.
Mr. Ward said he agreed with the above points.
2.
Dr. B. Sheron began the RES presentations.
In response to Dr.
Catton's remarks above, he said RES does not see a need for a
+
further major code development effort.
RES will maintain T/H expertise via a cadre of experts in order to meet the T/H research needs of the Commission. Dr. Catton indicated that he is seeing a disintegration of the RES cadre and a lack of good planning. Dr.
Sheron indicated that the ACRS should consider what the future role of RES should be and discuss this issue with the Connission. Dr.
Sheron said NRR, due to resource constraints, is not maintaining a technical expertise in T/H. Thus, RES has the joint burden of maintaining this expertise and conducting the research.
Dr. Catton indicated he is concerned that research work is falling into the hands of individuals who lack necessary expertise in the physics of T/H.
I e *,.
?
{
1 i
T/H Phenomena Meeting Minutes November 14, 1989 i
l Turning to discussion of the budget reduction process, Dr. Sheron indicated that, at this time, RES sees no major T/H issues for i
resolution.
Key points noted by Dr. Sheron included.
- RES has taken two major cuts for FY 90 totaling v $31M, which leaves a total allotment of $77.1M.
- Considerations involved in allocating research cuts include:
(1) continue research for specific user needs, high priority research on the Commission's agenda, and research that signif-o icantly reduces risk uncertainty; (2) maintain stability at the National Laboratories; and (3) avoid jeopardizing previous commitments.
In response to Dr. Catton, Dr. Sheron said RES is directing some of the code assessment effort for severe accident work to the T/H Branch. A cooperative experimental program with the FRG is under consideration here. Dr. Catton requested RES 1
discuss this with the Subcommittee at a future meeting.
- Discussing the allocation of the cuts, Dr. Sheron noted, in response to Mr. Ward, that there is little latitude for reallocations of money once a cut is made. Dr. Sheron indicated that the Commission has not shown a strong inclination to lobby the Congress for additional funding for research and/or reallocate the Agency's funds.
Dr. Catton indicated that DOE should be contributing funding to developmer.* of the codes, as they're using them.
Dr. Plesset asked if RES could contract with the reactor vendors to aid the resource crunch. RES indicated that its difficult to do, since a joint need must exist and conflict of interest must be
- avoided, a
?..
4 T/H Phenomena Meeting Minutes November 14, 1989 It was noted that RES has provided a grant to Penn State University to develop a 3-D kinetics model for TRAC. As the results of the program are uncertain, RES is relying on the RAMONA code at this time.
Figures 1 and 2 shows the allocation of the FY 90 Grahm Rudman (G-R)cutsinRESatboththeprogramelementlevelandfortheT/H related work (Figure 2).
Messrs. Catton and Schrock noted they have seen disturbing in-stances of a lack of coordination in T/H research which has re-sulted in people doing work for which they are not qualified. What is needed, they believe, is o broader view of what constitutes "T/H research." Dr. Sheron indicated he is aware of the problem, and RES is taking steps to address the concern.
3.
L. Shotkin detailed the specific cuts impacting T/H research.
Figure 3 shows the T/H programs affected by the above cuts.
Programs that were " zeroed out" for FY 90 include: university test loops, ROSA-II, and " analysis of events" (LaSalle, etc.).
Dr. Catton indicated that the OTSG follow-on program deserved some work vis-a-vis severe accident considerations.
He didn't see why the degree of. interest should go from a $4 to zero (i.e., a residueofconcernremainsthatshouldbeexamined).
In response to Mr. Ward, Dr. Catton indicated that LANL's review of the ORNL steam tube evaporation data for applicability to the OTSG follow-on was inadequate. Mr. Ward indicated that the proposed OTSG follow-on program seems to have been eliminated due 4
to legal concerns.
Dr. Sheron said the combination of legal concerns, budget, cuts, and lack of NRR support combined to end the
l'l',..
,a l
t n
T/H Phenomena Heeting Minutes
-5 November 14, 1969 OTSG follow-on effort. He also said RES has contributed funds to maintain the MIST facility in a " ready" state for at least three years, if its needed.
Dr. Catton suggested that he ROSA-IV facility should be useful for tests of accident management strategies.
RES may well fund additional tests at ROSA IV if the need is seen, in any event, NRC's access to ROSA-IV data is assured until 1992.
j Dr. Catton suggested RES evaluate the need for additional research on the suppression pool T/H's for the ABWR containment.
The future funding plans, including the impact of the above budget i
cut,werediscusse6(Figure 4).
RES intends to restore the deleted FY 90 funding for ROSA 11, university loop, etc., in FY 91.
l Addressing the RES provisions to retain T/H test data, Dr. Shotkin said final reports will be provided for the MIST, 2D/3D, and UMCP (B&W facility) projects. Also, synthesis reports (e.g., Feed and Bleed Cooling) and accident management strategy reports will also be provided.
The Subcommittee expressed interest in the synthesis report program and encouraged RES in this effort.
RES is updating their T/H research plan in February 1990.
Input from the ACRS, Commission, NRC management, etc., will be considered in developing this plan.
Dr. Shotkin suggested that RES meet with the ACRS when the Plan is complete.
9 The focus of future research will be in the areas of:
- Maintainirg Expertise i
,.p f 3F 3.
- - ~
+
T/H Phenomena Meeting Minutes November 14, 1989
- 600 MW ALWRs
- PIUS, CANDU
' Thermal Sciences
- Severe Accident Management Strategies..
4.
G. Hsii (NRR) commented on the scope and adequacy of the future (RES)T/Hresearchprogram. He indicated that RES needs indepen-dent expertise and assessed codes to perform licensing reviews.
NRR endorses the scope of the RES T/H research program.
Dr. Catton
-cited the issue of CE's request to modify their CHF correlation as an example.of NRR's apparent lack of expertise in T/H. Mr. Hsii indicated that NRR relies on Battelle PNL for expertise in this j
area.
l
- 5..
D.'Bessette-(RES) discussed the status of the RES T/H code develop-ment effort for TRAC-PF1/ MOD 2 and RELAPS/ MOD 3.
The history of the development of the codes is given in Figure 5.
I Key points noted were:
i
- For RELAP5/ MOD 3, a number of modifications were made (Figures 6-8).
Concerning the " pipe offtake model" in MOD 3, Mr.
j Schrock asked if the model has been revised in accordance with the Berkley research data.
He maintained that the model has not been properly fixed. Mr. Bessette said he has been assured the model has been appropriately revised. Dr. Shotkin said RES will examine this issue and report back to the Subconinittee.
In response to Dr. Catton, Dr. Shotkin said most of the concerns raised by himself and others have been addressed in i
the new code versions.
Dr. Catton asked that RES provide a list of the criticisms made for the codes and how they were addressed.
He also asked for information on the convergence
G.,
8 b
-4 T/H Phenomena Meeting Minutes November 14, 1989 testing done on the above codes.
Dr. Catton also suggested that a-2-D downcomer model be used in the codes.
Further discussion resulted in a proposal that tht< T/H Phenomena Subcommittee hold meetings with the INEL and LANL represente-tives to review the above code changes in detail.
- MOD 3 of RELAPS is scheduled for release in January 1990; draft documentation should be available in May 1990.
- TRAC PF1/M002 is scheduled for a March 1990 release date.
Documentation will be available in June 1990. As with RELAP5 MOD 3, ICAP will assess the code during 1990-91.
Figures 9-14 detail the improvements made to TRAC PF1/M002.
6.
N. Zuber discussed the lessons learned from the CSAU methodology exercise for the LB LOCA case. These lessons learned will be documented in NUREG/CR-5249. The' key lesson learned is that a cost-effective and timely resolution of safety issues requires a close integration of experimental and analytical activities (code and/ormodeldevelopmentapplications). Dr. Zuber said CSAU is being applied to the SB LOCA and the severe accident issue resolutionprogram(Figure 15).
7.
G. Hsii (NRR) discussed the impact on NRR licensing activities of the OTSG program termination. NRR said there are no effects on currently approved codes or safety analyses.
There is a lack of data for quantifying overall OTSG model conservatism. Future code applications will continue to require a conservative bounding approach through sensitivity studies.
In response to Dr. Catton, Mr. Hsii indicted that if a B&W licensee wants relief for an area where the associated code model is lacking, NRR will insist that the licensee upgrade the code as necessary. Dr. Catton asked NRR to provide information on how they will deal with the case wtere the code has a non-physical SG model.
~
p z, ;
, e y
q g
V
'~
T/H Phenomena Meeting Minutes November 14, 1989 The status of the NRR review of the W BE ECCS/LOCA model was discussed by G. Hsii. W will use the COBRA / TRAC code. The BE model will be applied to both 3-loop (Nortn Anna) and 4-loop (Sequoyah) lead plants.
For the treatment of uncertainties, the response surface method and CSAU process will be used.
Figure 16 details the code qualification process and Figure 17 shows the proposed method for uncertainty quantification.
The W schedule calls for submitting the quantification document for the three loop lead plant application in April 1990.
Dr. Catton suggested that the documentation for the new code models contain information on code convergence and stability.
8.
D. Bessette provided RES response to the ACRS June 1989 letter on T/H research and the Commission SRM on same. The RES response to the five points in the ACRS letter included:
i
' RES will solicit universities for projects in T/H such as L
erosion / corrosion, FIV, thermal stratification, etc.
In l-response to Mr. Ward, Mr. Bessette said the FY 90 funding cuts will not eliminate this effort, just postpone it.
- Regarding data analysis, RES has no plans to " resurrect" data from closed facilities (e.g., Semiscale, LOFT, etc.).
1; l
- RES is exploring research in the thermal sciences. To date, i
they have focused on fire-related research.
Dr. Catton cited a number of other topics / items for consideration under this 1
- .0 t ',
1 T/H Phenomena Meeting Minutes November 14, 1989 aegis. RES requested a list of priority research items from the Subcommittee for their consideration.
Mr. Ward indicated that a number of disparate safety issues are not being treated in a scientific manner; they are being compart-l mentalized within the Agency's organizational structure. He said the agency needs to treat these issues in an-interdisciplinary manner.
Further discussion resulted in a suggestion that the ACRS I
' clarify its opinion here via another letter to the Comission.
l Mr. Ward indicted that the ACRS had recommended that RES develop a fast running T/H systems code.- He said it is not feasible to run sensitivity analyses because the current codes are so big and cumbersome. RES had investigated establishing a consortium to develop a fast running PWR systems code, but sufficient funding could not be obtained.
l Figures 18-19 detail the RES response to the Comission staff
]
requirements memorandum, j
9.
R. Lee (RES) provided discussion on'the RES T/H program in fire research.
He reviewed the fire codes now in use-and their limita-tions.
RES will develop a position paper on the analytical tool needed for fire propagation modelling in nuclear power plants.
i 10.
R. Lee overviewed the status of the MIST program. Points noted included:
k
- There were four Phases to the program. All Phases are com-plete. The cooperative program contract will terminate in February 1990.
Figure 20 shows the list of Phase III and IV tests. A 11-Volume set of test reports will be issued in the near future.
{).
- 'i-t 4-T/H Phenomena Meeting' Minutes November 14, 1989 11.
D. Birmingham (B&W) reviewed the Phase IV program test matrix.
The l
objectives of Phase IV tests were:
- Explore current operating procedures and possible alternative strategies for mitigating various accident conditions.
- Obtain insight on scaling compromises known to exist in the test facility.
Extend the database beyond that obtained during Phase III.
The test matrix for Phase IV included:
(1) risk dominant transient;(2)steamgeneratorperformance;(3)scalingtests;(4) increased break size; and (5) natural circulation. tests. Risk dominant transients simulated were:
SB LOCA without HPI, SB LOCA with lack of auxiliary equipment or control systems, and station blackout. Dr. Catton indicated that in spite of his initial misgivings, the B&W design of the downcomer appears to have worked n
well.
In response to Dr. Catton, Dr. Lee noted that separate effects tests of the flow regimes for a full size U-bend pipe were run at ANL by Dr. M. Ishii. These results were incorporated into M003 of the RELAPS code. B&W is using a M002 version of RELAPS.
~12.
G; Geissler (B&W) overviewed the results of the MIST Phase IV
. tests.
Key results noted for the specific tests cited t,elow included:
- Nominal Transient with Distorted Core Power - The major post SB LOCA phenomena (depressurization, intermittent and inter-rupted loop flow, BCM, refill, post refill cooldown) were experienced. The timing of these phenomena was altered
0..
L.y N
a e
c.
1 T/H Phenomena Meeting Minutes November 14, 1989 slightly, however, the transient response was similar to the MIST Phase III tests.
2
- 10CM SB LOCA without HPI Steam Generator Blowdown - With HPI-unavailable, all four cold leg discharge pipes voided and the primary system repressurized early in the transient. The system continued to be depressurized/repressurized as pressure slowly decreased (Figure 21),
i Station Blackout Transient (SBO) - Small leak si:e resvited in a reduced depressurization rate, single phase natural circu-lation maintained for 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
Intermittent primary loop flow, steam generator heat transfer occurred and resulting steam generator pressure excusions seen exceeded the facility design limit; the test was terminated.
- Scaling tests simulating the Crystal River and Rancho Seco transients showed that the MIST facility response differed significantly from what was seen at the plant.
In response to Mr. Ward, Mr. Geissler said he believes the reason for the anomalous response of MIST was due to errors. in simulation of the test boundary conditions vis-a-vis actual plant conditions.
13.
S. Nesbit (B&WOG) discussed the B&WOG analysis program.
Key points noted included:
- The goals of the analysis program include:
- Demonstrate the ability of RELAP5 to predict the thermal-hydraulic behavior of scaled B&W integral system test facilities.
+
1 T/H Phenomena Meeting Hinutes November 14, 1989 l
- Verify the nodalization detail required to model the key phenomena of small break LOCA and related transients at a B&W plant.
- Gain enhanced understanding of the phenomena and inter-actions during such transients.
- Satisfy the $1M benchmarking commitment which was part of the NRC/EPRI/B&WOG/B&W Integral System Test Program agreement.
- Figure 21-A shows the list of tests to be benchmarked by the OG using RELAP-5/M002.
In response to Dr. Catton, B&W said they will have documented that all major T/H phenomena.of concern are " hit" at least once in the code calculations.
In response to Mr. Ward, Mr. Nesbit indicated that the code will not be exercised against the depressurization/repressurization phenomena. Dr. Catton indicated that the code benchmark program is not addressing modeling of multidimensional phenomena. He urged the 0G to exercise their code against full scale tests.
G. Geissler reviewed the results of the MIST natural circulation (NC) tests. The intent of this phase of the MIST test program was to determine if the MIST facility exhibits phenomena similar to those observed during actual plant natural circulation events (e.g.
TMI-1 NC test - Figure 22).
)-
Highlights of the results of the NC tests were:
The Natural Circulation Simulation Test - Showed that flow interruption occurred in one loop and RCP heat loss and establishment of secondary flow path via reactor vessel vent v
m i
T.
s L
)
T/H Phenomena Meeting Minutes
- November 14, 1989
.J i
valves resulted in backflow in one cold leg. - This " cold leg temperature anomaly" observed in plant transients'(e.g. TMI-1)
-was also observed in MIST facility (occurs in cold leg that experiencesbackflow).
l
- Tests simulating both closed RVV's (using controlled power re-ductions)andfacilityheat-losses,demonstratedthecoldleg anomaly is reproducible and is caused by excessive heat losses from the RCP at low power conditions.
- MIST operator actions were exercised at various times during the natural circulation tests.
Preliminary results indicate that the RCP operation and core power increase resulted in the establishment of sustained natural circulation. conditions.
i RCP starts, however, can result in primary and secondary pressure increases.
S. Nesbit discussed the analysis program for simulation of the NC tests. The B&WOG has decided to focus on use of this information to aid operator training and NC operation at the plant.
I:
14.
R. Lee nnted the following aspects of the plans for use of the MIST data. This program includes:
L l-
- NRC is funding analysis of MIST tests with the frozen code h
versions of RELAP5 and TRAC-PF1.
4
- Analysis of counterpart tests to assure the code's scale-up capability.
- Test data will be stored on tapes at INEL, and will be added to the NRC Reactor Safety Data Bank, pending funding availability.
l I
l-
,l' ' "
4
..h T/H Phenomena Meeting Minutes November 14, 1989
- 15. The> following comments were noted~ during the Subcommittee's dis.
cussion of.the above topics.
Dr. Plesset - Somewhat disappointed with the MIST program.
It was not well organized for qualifying the codes against MIST data. He suggested that transient tests be run at full scale plants to obtain the desired data.
Dr. Catton - Had initial reservations with the MIST test program, but it-appears the test results are good and a lot of quality test data was generated for use in exercising the codes. The program's cost appears excessive though.
All in all, B&W accomplished their charter for the program.
Mr. Ward - Agrees the MIST Program has been successful.
Believes the Subcommittee should hear more information on the code bench-marking effort, as there may be a shortfall here. The CSAU SB LOCA exercise now underway may help address his concern.
Concerning the RES T/H research program, he felt it was a mistake for the ACRS to stop writing the yearly " Report to Congress" on NRC's research program. This report made it easier to address the issue of the RES Office's viability vis-a-vis spending for the other NRC Offices. The current policy of having RES take the brunt of all. agency budget cuts is resulting in the loss of key technical competence in some areas. The Commission seems to be wandering
=.
down this road without much thought as to the consequences.
Mr. Schrock - He agrees with Mr. Ward. He's less critical of the
[
B&W MIST effort then is Dr. Plesset. He does believe that NRC L
should have elected to upgrade the MIST facility to full (decay) l power capability. This would have prevented the hole in the test data we have vis-a-vis OTSG T/H performance.
FJ
... ~.
.v T/H Phenomena Meeting Minutes November 14, 1989
- 16. The meeting was adjourned at 4:45 p.m.
FUTURE SUBCOMMITTEE ACTIONS The Subcommittee will hold meetings with NRC RES, and INEL and LANL representatives to review in detail the changes / improvements make to the latest versions of the RELAP5 and TRAC-PF1 codes.
Dr. Catton will report to the ACRS during its November Meeting.
He will
-suggest that the Committee discuss with the Commission the issue of RES T/H research funding in lieu of the recent budget cuts.
NOTE:
Additional meeting details can be obtained from a transcript of this meeting available in the NRC Public Document Room, 2120 L Street, NW, Washingtnn, DC 20006,(202)634-3273,or can be purchased from Ann Riley and Associates, Ltd., 1612 K Street, NW, Suite 300, Washington, DC 20006, (202) 293-3950.
)
I L
~
/'
f,. '.,
~
ALLOCATION OF G-R CUTS IN RES BY-PROGRAM ELEMENT FY 1990 Gramm-Rudman Mark ($ in millions)
FY 90 Budoet G-R Reduction Final FY 90 Integrity of Reactor Components
$27,655 DE ($1,855)
$25,000 Preventing Damage to
$16,050 DSR ($2,850)
$13,200 Reactor Cores Reactor Containment
$22,325 DSR ($2,625)
$19,500 Performance DE
($200)
Low Level Waste Disposal
$1,670 DE
($270)
$1,400 Safety Issues and
$15,700 DSIR($1,370)
$13,100 Developing Regs.
DRA ($1,015)
DSR
($145)
D0
($70)
High Level Waste
$4,600 DE (1500)
$4,100 P
Total Reduction by Division:
$2,825*
DSR
$5,620 DSIR $1,370 DRA
$1,015 00
$70
- $500K must be reduced from the HLW budget
/PM.)
4,'
q'. -
~I ALLOCATION OF G-R CUTS IN DSR G-R Procram Cateaory FY90 Budaet Reduction Allocation Preventing Damage to 16,050 2,850 Accident Management 1.5M Reactor Cores Thermal-Hydraulics
.5M Human Factors
.85M t
l Reactor Containment 20,525 2,625 SARP l.975 Performance PRA 650K Safety. Issues and 800 145 HFB-r Div. Regs.
gfg g l
l l
i l-4 l
l 1
- h
~
._ f PROGRAMS IMPACTED BY FY90 : BUDGET CUTS T
, [
RES BUDGET REDUCTION -
T/H PROGRAMS AFFECTED 108M -=88M B&W OTSG TESTING 1450 -300 (RPSB:
8850 - 3850 '= 5000*)
UNIVERSITY LOOPS 250-> 0
- TOTAL = 5000
^~
+ 1650 B&W FY89 6650 ANAL. OF EVENTS 500 + 0 88M- -77M 690 MW ALWR 900 - 560 (RPSB:
5000 - 4500 = 500)
ANALYSES e
2
n v
F
- c..
~
FUNDING OF ACTlVITIES
~
FISCAL YEAR
~
1989 1990 1991 1992 1993 1994 3350 yosa 32aa PLANT PERFORMANCE 7500 5200 4900- 4-1B0- 3000-3000 300 3 00 Q
B&W TESTING 2870 1450 1150-900 0
0 ivoo i
EXPT'S & ANALYSIS 1930 2100 1550 1500 1500 1500 l
i MODELING 2700 1650 2200 1700 1500 1500.
2900 i
REACTOR APPLICATIONS 2330 5300 4300 3750 3750 3750 1950 OPERATING REACTORS 1025 2500 2000 1750 1750 1750 4
3 56o LWR SYSTEMS STUDIES 95 1500-1700 1750 1750 1750 l
ANALYSIS FOR OPERATING soo REACTOR EVENTS 1210 1300 600 250 250 250
-% suaaovs is so B h)
F t'F'/
CA gri Y o tt in
~y Recent History of the Codes 1984:
RELAP5/ MOD 2 and TRAC-PF1/ MOD 1 frozen in December.
1985-87:
Independent assessment under ICAP provided a common understanding of capabilities and limitations.
1987:
Development plan agreed to by ICAP participants in December.
1988-89:
RELAP5/ MOD 3 and TRAC-PF1/ MOD 2 development carried out according to plan.
1990-91:
Independent assessment of RELAP5/ MOD 3 and TRAC-L PF1/ MOD 2 under ICAP.
I hNk
O-C.1 RELAP5/ MOD 3 Status o
Objectives:
Utilize code development expertise of ICAP members to Fix known MOD 2 deficiencies.
l Extend range of applicability of RELAP5 to large break LOCA.
e MOD 3 modifications:
g Critical heat flux Critical flow Vertical stratification criterion 2
lM4 6)
...;[,'
C.1 RELAP5/ MOD 3 Status (continued) o MOD 3 modifications: (continued)
ECCS jet condensation in large l
horizontal pipes Horizontal stratification inception criterion (JAERI)
Pipe offtake model (UKAEA)
Metal-water reaction (Studsvik)
Fuel model (Studsvik)-
Radiation heat transfer model 4
(Studsvik)
Non-condensible gas model
)
Junction based interfacial drag 3
t
/.Vid if
+
.C.1 RELAP5/ MOD 3 Status.(continued) o MOD 3 modifications: (continued)
CCFL Downcomer penetration Upper plenum deentrainment L
Bubbly-slug to drop-annular flow regime transition (CEGB)
L Interfacial shear in bubbly and slug flow regimes (CEGB)
Code portability Y
4
[ht. t]
=
. j\\, 4 TRAC-PF1/ MOD 2 J
-,-[
MODEL AND FEATUREIMPROVEMENTS That are made in MOD 2 and are not available in MOD 1
- 1. 3 D 2 Step Numerics The 1 D 2 Step numerics have been applied to the 3 D
-VESSEL hydro solution. This allows the 3 D VESSEL component to take larger time steps that exceed the material Courant limit during a relatively slow trans-lent such as a small break or operational transient.
- 2. Partial Vectorization of the VESSEL Component This recoding improvement allows MOD 2 to take advan-L tage of the vectorization capability of the CRAY or L
CRAY-like machines. Preliminary testing indicated a l.
10% to 20% speed up for a LBLOCA calculation due to vectorization.
l-l
- 3. Inversion of the VESSEL Component Data Base inversion of the VESSEL component data base results in coding that is easier to read and maintain. It also i
results in arrays that can be vectorized on CRAY or CR AY-like machines for the axial direction.
L
- 4. Generalized Heat Structures L
.The development of a generalized heat structure com-ponent allows the user to couple through a heat-transfer path any hydro cell in the MOD 2 input model with any other hydro cell. This component results in increased accuracy and flexibility in modeling steam generators, vessel internal structures, etc.
L
- 5. Consistent Wall Shear Model Between 1-D & 3 D As part of the MOD 1 O/A document research,the 1-D and 3-D wall-shear models were found to be inconsist ent and inaccurate. The MOD 2 wall-shear models were made consistent and the following improvements were L
made: fixed laminar flow errors, included the surface roughness effect in the turbulent regime, and improved the accuracy cf the two-phase pressure drop model.
/
pa.1[
L
\\
TRAC-PF1/ MOD 2 v
i MODEL AND FEATUREIMPROVEMENTS That are made in MOD 2 and are not available in MOD 1 (Cont'd)
- 6. Improved Valve Model The MOD 1 valve model for flow resistance through a partially closed valve was not based on theory or experimental data. The MOD 2 valve model was -
developed based on experimental data for partially closed globe valves.
- 7. Capacitance Matrix Method Replaces the l
Direct and Gauss Seldeliterative Vessel-Matrix Solution Algorithms in MOD 1, VESSEL component mass errors where caused by not converging tightly the Gauss Seldel interative solution of the vessel matrix equation. The altama-tive was to solve the vessel-matrix equation by direct
- matrix inversion, but the calculational effort went up significantly for VESSEL components with more than 100 mesh cells. The capacitance Matrix method was-cho:sen to replace both methods because it provided the efficiency of a banded-matrix solver and the -
accuracy of a direct-inversion algorithm.
- 8. General Orientation of the VESSEL Component With Respect to Gravity This input-data option was developed to provide horizontal-vessel modeling for the N Reactor.
- 9. - Calculate With Rotational Symmetry of 60,120, or 180 Degrees in the VESSEL Component
~
)
This feature allows for flexible and efficient VESSEL f
component noding when rotational symmetry exists in the vessel region.
- 10. Implementation of ANS 79 Decay Heat Standard The ANS 1979 decay-heat standard was implemented in the MOD 2 code.
$}
n y'.. '. '
TRAC-PF1/ MOD 2 I
+'
N MODEL AND FEATURE IMPROVEMENTS That are made in MOD 2 and are not available in MOD 1 (Cont'd) n
- 11. Improved Models for interfacial Shear and Heat Transfer The interfacial shear and heat transfer models have been improved in the following areas:
. Downcomer penetration
. Upper plenum deentrainment
. Hot / cold leg ECC injection High mass-fitx conditions
. Vertical stratification in the VESSEL component
. Condensation and evaporation in the presence i
of non condensibles L
. Flow-regime dependent interfacial heat transfer
- 12. Branching Flow at TEES & Improved Critical Flow The UK recommended model for branching flow at TEES was programmed in the MOD 2 TEE component. The model determines the amount of vapor pull through or liquid entrainment that occurs in a horizontal pipe L
that has a smaller pipe or break located on its top, bottom, or side.
l-
- 14. Improved Accumulator Model Several test cases have been set up for the LOFT
)-
accumulator and the ROSA-IV separate effects accumulator tests. Calculations are being preformed with MOD 2 to determine whether the new models in MOD 2 still result in oscillations and excessive vapor entrainment..
. _ _. ~. _ _ _ _ _ _ _ _
f.
TRAC-PF1/ MOD 2 MODEL AND FEATURE IMPROVEMENTS That are made in MOD 2 and are not available in MOD 1 l
(Cont'd) f 15.-Improved Subcooled Bolling Model An improved subcooled bolling model has been imple-mented in MOD 2. The modelincludes Lahey's mechan-o
- istic model for partitioning the wall heat transfer l
between liquid flashing to steam and subcooled liquid heating up and Saha-Zuber's model for determining i
L
. the liquid enthalpy at bubble departure.
- 16. Momentum-flux Conservation At A Flow-Area Change t
The momentum-convection term in MOD 2 has been modified to include flow-area ratio factors which accurately evaluate the Bernoulli equation at a p
flow area change. Now the MOD 2 user must expil-citly account for irreversible form losses through l
the input data and not from the differencing error of the approximated momentum convection term.
L
- 17. Irreversible form loss evaluation by TRAC Expanded for 1-D and Extended to 3-D The NFF.it.0 input option for 1 D components, where TR AC internally evaluates an abrupt area-change irreversible form loss, has been extended to also evaluate the irreversible form loss of a thin-plate orifice and the bending loss at a TEE component L
Internal side-leg junction. A almilar capability is provided for the 3-D VESSEL component by input apacifying CFZL * (for *=R,T,Z) with a nogstive value.
I.
- 18. Wall-Drag Model Modified to Couple to Both Phases and to include the Affect of Surface n
Roughness Vold-fraction weighting is used to partition the wall area between the fluid phases and the affect of sur-face roughness on the friction factor is provided.
/N&
.. f..
TRAC-PF1/ MOD 2
'J
MODEL AND FEATURE IMPROVEMENTS u..
Development of an improved Reflood Heat L
Transfer Model Was Completed in July; the Model is Currently Being implemented e
With Full Generality in the VESSEL and Heat Structure Data Bases The TRAC reflood heat-transfer model has been rewritten removing Forslund-Rohsenow and non-physical models and fits and replacing them with defensible correlations for inverted-annular film bolling. These correlations depend upon distance L
from the quench front. In addition, improvements to the dispersed-droplet film-boiling heat-transfer i
i regime have been implemented including a cold-surface model. This modelis currently being L
extended to its full generality with multiple heat structures within the dimensionality of the VESSEL component.
Improvements in Time Step Size Control The MOD 2 time-step size control has been enhanced L
to meet the calculational stability requirement when computing with a much larger time step because of 2-step numerics in the VESSEL component. As developmental assessment proceeds, additional improvements are anticipated in this area.
Break Flow Time-Step Size Sensitivity Interfacial shear time-constant averaging has been implemented to reduce time-step size dependence
(
upon MOD 2 results. A UPTF sensitivity test is in
)
the process of being rerun to determine whether time-step size sensitivity still affects the solution.
L 7FN 13)
)
1 TRAC-PF1/ MOD 2 MODEL AND FEATUREIMPROVEMENTS
. Flexible VESSEL Component Noding The capability to finely node the downcomer and coarsely node the core region (developed during the CSAU method application to TRAC) is provided by MOD 2. PIPE components are required to connect VESSEL components to VESSEL or PLENUM com-ponents in order to provide such a model. Addi-1 tional programming is required to implement the capability to couple heat structures to a PLENUM component and to connect VESSEL or PLENUM components directly.
Developmental Assessment of MOD 2 Using UPTF, CCTF, SCTF, LOFT Large and Small Break L
Tests, and Separate-Effects Tests (Akimoto, Bankoff, INEL, Lehigh, Marviken, Thetis, and L
Winfrith) t Draft Documentation for TRAC PF1/ MOD 2 Documentation will be provided in four volumes
. Correlations and Models Manual
. User's Guide and input Description
. Programmer's Guide and Code implementation l
. Developmental Assessment
l
.m
,=
I Safety issue Accident Specification and Phenomena Evaluation
, r 1 r IV Code til issue Resolution 11 SASM e
and Development with Experimental Data Experimentation and Special Models
, r V
issue Resolution with Frozen Code p
and Uncertainty Quantification (cSAU)
Figure 1: Integrated Structures for Severe Accident issue Reso!ution l
s cf it.,
- = -
i
-i CODE QUALIFICATION 1
ASSESS CODE CAPABILITY AND ACCURACY i
USE FROZEN CODE VERSION (WC/T C15 M6) l PERFORM LINE-BY-LINE REVIEW OF CODING f
EXAMINE MODEL/ CORRELATION DATA
- BASE, i
- ACCURACY, SCALING A. APPLICABILITY FOCUS ON KEY PARAMETERS PHENOMENA TO IDENTIFY COMPENSATING ERRORS j
~k
~
- .1.
l UNCERTAINTY OUANTIFICATION
- QUANTIFY CODE UNCERTAINTY
- SEPARATE PLANT PARAMETERS FROM MODELS IN RESPONSE SUitFACE
- USE BOUNDING VALUES FOR SOME PLANT PARAMETERS WHICH ARE DIFFICULT TO SPECIFY STATISTICALLY j
1
- ASSESS CODE SCALING UNCERTAINTY BY CODE COMPARISONS TO COUNTERPART EXPERIMENTS i
- UNCERTAINTY PROPAGATION ACCOUNTED FOR AS A SEPARATE UNCERTAINTY ' COMPONENT i
- 3.,
p-D.2:
Response to Commission Staff f
Requirements Memorandum u
1.
Cooperative programs should have clear L
benefit to regulation.
L Response: Already done.
2.
Codes should be capable of systems interaction studies, and appropriate studies should be planned.
o I
Response: Codes are already capable.
L Many transinents already L
analyzed..
I Accident management strategy 1
[
studies planned.
l Other studies conducted under " Application Research."
k L
3 L
IMdM
___--7_-_.-
D.2: (continued) i l
3.
How can expertise from discontinued experimental program be maintained.
Response: Institutional expertise is lost when staffis dispersed upon y
end of program.
4.
RES should promote interaction between INEL and Universities.
Response: Work at INEIC to be 4
coordinated / integrated with universities.
5.
RES should help sustain the nation's academic nuclear engineering programs.
Response: Planned university experimental program account for about 1/4 of total planned funding, supporting about 20-25 graduate students.
4 pa.nl
,,2-E.1: MIST Status (continued)
Phase-III tests:
F Mapping - 9 Boundary system - 11 Leak-HPI configuration - 6 Feed and bleed - 4 Steam generator tube rupture - 6 Non condensible and venting - 6 Reactor cooling pump operation - 6 Other - 1 l
L Phase IV tests:
SBLOCA w/o HPI - 2 MIST scaling - 3 Station blackout - 1 Intermediate size break - 1
- Steam generator steady state - 1 Natural circulation - 4 l
1 l
+
1 f
a.'
s
((d >q
.__---_-__ v ---
FINFt_ ' DRTR o
o Phcse 4 Test.410BD1 Vs. Test 4 IORT3. Vs. Test 4NOK_3
,.d e
24m g..~
Test 4901, Pr emery
~
Test 4AT3. Primary Test 4 NOM. Pr s e sey 2000
~
2 U
-32 Ism 1
I (-
l 3
5 f
\\ l g,
e x
8 12m -
g a
i ce 1
s_
-s 3,
e
.m G-4 z
v-M \\.
f^'
r e
i a
50 1m 15e 2m 250 30s 35e de e
]N MIST T:me, min h
Figure 6.11 Primary System Pressures (RVGP01)
(
w oet o n -ss ss ases y,
abrPSGPi
,i e
e e
e e
=
t.
o' O s
B&WOG IST Benchmark Analyses i
RELAP5/ MOD 002 benchmarks performed on eleven OTIS, hilST, and hDST o
J Phase IV tests Test Number Test Descrintion OTIS 2202AA 15 cm' SBLOCA OTIS 220899 HPI cooling (feed and bleed) l hilST 3105AA 10 cm' SBLOCA with asymmetric cooldown hDST 320201 50 cm' SBLOCA MIST 320604 10 cm' SBLOCA with reduced capacity HPI hilST 330499
- HPI cooling with surgeline uncovery MIST 8404AA 10 tube SGTR with SG isolation MIST 350101 10 cm' SBLOCA with loop venting hDST 3601AA 10 cm' SBLOCA with reactor coolant pumps available and ATOG operator actions MIST 370199
- Cooldown with continuous vent line MIST 4SB011d "
Station blackout Spont.ored by Toledo Edison MIST Phase IV test r
o
[ wag -
l l
l THI-1 NATURAL CIRCULATION October 7, 1985
~~
.540 i
4 N
u J
[
)
a u
% \\
=
530 -
v u
i
,f l
TcoLo 520 I I i liiiijiie j
l iirj i i
r i i r 0
5 10 15 20 25 Time, Minutes a
b
.