ML20072B291

SSC Development,Validation & Application & Crbr Balance of Plant Modeling, Monthly Highlights for Jan 1983

ML20072B291
Person / Time
Site:	Clinch River
Issue date:	01/11/1983
From:	Guppy J BROOKHAVEN NATIONAL LABORATORY
To:	Curtis R NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES)
References
CON-FIN-A-3015, CON-FIN-A-3041 NUDOCS 8303040155
Download: ML20072B291 (8)

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l Project Highlights  !

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[ January 1983 l l

i PROGRAM: A. SSC Development, Validation and Application (FIN No. A-3015) ~!

( B. CRBR Balance of Plant Modeling (FIN No. A-3041) l l:

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J. G. Guppy, Group Leader f i

Code Devele;pment, Validation and Application Group ,

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l Department of Nuclear Energy l

BROOKHAVEN NATIONAL LABORATORY  !

Upton, New York 11973  !

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I B303040155 830131 PDR RES PDR

This is the monthly highlights letter for (A), the Super System Code (SSC) Development, Validation and Application Program and (B) the CRBR Balance of Plant (BOP) Modeling Program f or the month of January 1983. These programs are covered under the budget activity number 60-19-01-40.

A. SSC DEVELOPMENT, VALIDATION AND APPLICATION (J.G. Guppy)

The prime activity of this program is to provide independent licens-ing tools to simulate plant-wide transients in liquid metal fast breeder re-actors (LMFBRs). A series of computer codes, denoted by the prefix SSC (Super System Code), is being developed. Versions of SSC presently under development include.1) SSC-L for the simulation of transients in loop-type LMFBRs, 2)

SSC-P for pool-type LMFBRs and 3) SSC-S for the simulation of long-term shut-down transients. The SSC Development, Validation and Application Program is currently focused to provide direct support to the on-going CRBRP licensing activities within NRC. f I. SSC-L Cod _e_ (M . Khat i b-Ra hba r )

1. CRBRP Accident Analyses Loss-of-Heat-Sink Stu_dy (M. Khatib-Rahba r , E .G. Cazzol i )

SSC was used to simulate loss-of-heat-sink events in CRBRP. The first series of transients analyzed included the impact of Direct Heat

, Removal Service (DHRS) on the sodium mixing inside the upper plenum.

Comparison of the simulated results, with the Project's base case F-2 event , showed excellent agreenent in the peak tenperature achieved.

Additional calculations were made to determine the consequences of f ailure to activate the DHRS, leading to a complete loss-of-heat-sink (LOHS) accident. Calculated results show that, due to the signifi-cantly lower pressure in the reactor upper plenum, the sodium satura-tion temperature is about 50 degrees lower than in the reactor core assemolies. Therefore, sodium flashing inside the upper plenum began m at about 11.5 hours5.787037e-5 days <br />0.00139 hours <br />8.267196e-6 weeks <br />1.9025e-6 months <br /> following LOHS, nearly two hours prior to boiling in the core regions. Furthermore, due to stable low quality sodium boiling inside the subassemblies, fuel pin dryout can be precluded until the entire inventory of sodium inside the upper plenum is boiled-off, leading to fuel pin uncovery at about 18 hours2.083333e-4 days <br />0.005 hours <br />2.97619e-5 weeks <br />6.849e-6 months <br /> af ter LOHS.

These results indicate that the timing of events following LOHS is significantly prolonged as a result of stable low quality sodium boil-ing in the reactor. Therefore, coolable geometry can be maintained f or several hours as compared to previously estimated time scales in the order of minutes.

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CRBR Natural Circulation Transient (W.C. Horak, J.G. Guppy, R.J.

hnnett, G.J. Van Tuyie)

Upon initial comparison with the Project's results reported in WARD-D-0308, two additional changes were made in the SSC input data for the natural circulation transient:

1) The intermediate piping lengths and elevations were selected to match those of the DEM0 code. Information on the inter-mediate piping was incomplete in the PSAR and isometrics had not yet been obtained from the Project.

2) The gap conductances were those used by the Project (obtain-ed using the LIFE code) and were held constant throughout the transient.

The transient was simulated for a total of 600(s) with and without interassembly flow redistribution. In general, the hot channels without flow redistribution were in good agreement with the Project's results, although the radial blanket temperature was slightly higher using SSC due to a higher power level being used in SSC. The results with flow redistribution were all lower than the Project's predic-ti ons . Some discrepancy still exists between the SSC results for the average radial blanket channel and those obtained by the Project using the DEMO code. Efforts are underway to resolve these differ-ences.

2. Intra-Assembly Flow Redistribution (M. Khatib-Rahbar, E.G.

Cazzoli)

The simple porous-body model was used to study the temperature flattening effect due to flow redistribution in the Westinghouse 61 pin blanket assembly experiments. Calculated results are in excel-lent agreement with the experimental measurements in the conservative direction. Furthermore, the calculated results were compared to the existing calculations using the COTEC, ENERGY 11 and COBRA IV com-puter codes. It was seen that, in general, most of the calculations (with the exception of COBRA IV), over-predict the data in the high Reynold's number flow regime. However, as the flow rate is reduced to natural convection level, the comparisons improve and all of the codes are in excellent agreement.

The impact of flow regime change on flow redistribution was also studied and found to be quite significant.

A draft report describing the model and its applications is in preparation.

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3. User Support (W.C. Horak, R.J. Kennett, J.G. Guppy, G.J. Van Tuyle)

CY-41, along with appropriate documentation, has been sent to the Argonne National Laboratory for use by the EBR-II Project.

Several plots were made of the SSC results for the CRBR natural circulation and DHRS events to assist the NRC in an upcoming ACRS presentation.

4. Color Graphics (R.J. Kennett)

Several test programs have now been made operational on the VAX computer system, which support the higher level DISSPLA 9.0 system.

II. SSC-P Code (E.G. Cazzoli)

1. Coae Maintenance (E.G. Cazzoli)

Due to the continued focus of this program to provide direct support for the CRBRP licensing activities, work on the pool version of SSC (SSC-P) has been slowed. However, modification of SSC-P to inaintain its compatibility with the latest cycle of the SSC program library is continuing, but on a reduced level.

III. SSC-S Code (B. C. Chan)

1. Improved Upper Plenum Modeling (B. C. Chan) l A buoyancy dominated flow model has been tested using the upper plenum 8 x 10 mesh 60 degree sector representation. The initial tem-l perature of the sodium is 950 0K. The sodium temperature from the

core is assumed to instantaneously decrease to 9000K. During steady-state testing with different inlet velocities, the results show that when inlet velocity is high, the flow in the upper plenum is separated into two regions

an upflow in the center and a downflow in the outer annular region. The temperature results show that the sodium in the plenum mixes very well. When inlet velocity decreases, the flow divides into two zones. The flow velocity becomes nearly zero in the upper zone, and the downflow in the outer annular region, generated by the outward radial flow at the location of the inlet flow, has a maximum penetration. The temperature remains high in the I upper zone and low in the lower zone, which shows that mixing is very poor. These results agree with the J.S. Turner experiment, which used heavy salt injected into a tank with fresh water.

IV. SSC Validation (W.C. Horak)

1. Release of New Cycle (W.C. Horak, R.J. Kennett)

CY-41 of SSC/MINET is now operational. The cycle was validated on four separate test problems and performed well on all of them.

Listings of CY-41, along with results of the four sample problems, have been made available to SSC group members.

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B. CRBR BALANCE OF PLANT MODELING (J.G. Guppy)

The CRBR Balance of Plant (80P) Modeling Program deals with the de-velopment of safety analysis tools for system simulation of nuclear power plants. It provides for the development and validation of models to represent and link together B0P components (e.g., steam generator components, feedwater heaters, turbine / generator, condensers) that are of direct application for the CRBRP, but at the same time are also generic to all types of nuclear power plants. This system transient analysis package is designated MINET to reflect the generality of the models and methods, which are based on a momentum inte-gral network method.

1. Balance of Plant Models (G.J. Van Tuyle)

The large set of MINET code modifications, needed to represent balance of plant components and configurations, is now undergoing testing. Heat transfer correlations for condensing steam and air will be added shortly.

2. MINET Code Improvements (G.J. Van Tuyle, T.C. Nepsee)

Updates that were used to create CY-41 of SSC were factored into the stand-alone version of MINET. Several sections of SSC, providing some minor functions to MINET, previously included in the MINET library have been eliminated in favor of data statements or smaller functions or sub-routines.

The large set of revisions to the steady-state and transient calcula-tions has been undergoing testing. The scope of these tests has been limited thus far by the lack of a compatible input processor, which is still under development. Even so, the tests completed to date have been very encouraging, particularly with regard to the heat exchanger model.

Revi sions to the data handling input processor functions are nearly complete, and will be tested shortly. The principal input processor routines will be written next, which will use the revised data handling functions to process the new input data.

A new utility package, GCM (Global Container Manager) has been intro-duced. Its purpose is to assign and manage variably-dimensioned global container storage. Several enhancements are provided over a similar method used in SSC:

o Full recovery is provided for assignment parameter errors. This allows completion of the allocation process before executing an error abort, thereby flagging the maximum number of errors pos-sible.

e Container overflow recovery is provided to allow completion of the allocation process. A full container map, including error messages, is printed before executing the overflow error abort.

This is useful in cases where the container size must be in-creased to accommodate large input data sets.

l e Provision is made for container segmentation. This allows shar-ing of storage by mutually-exclusive segments which reside in secondary storage when they are not being accessed.

3. MINET Standard Decks (G.J. Van Tuyle)

MINET decks C4 and C5 are currently the standard input decks for one-and two-loop analysis of CR8RP, using CY-41 of SSC/MINET. As the stand-alone version of MINET is undergoing extensive revisions, we do not plan to standardize any of the new test input decks -for some time.

4. MINET Applications (G.J. Van Tuyle)

The version of MINET in CY-41 of SSC is being used extensively in li-censing applications for CRBRP. This practice is expected to continue while the stand-alone version of MINET is extended.

The CY-41 version of MINET is also planned for use in our analysis of the EBR-II facility. Our current objective is to test our EBR-II repre-sentation using a previous test transient, and then to make pre-test pre-dictions for an upcoming ndtural circulation test series. We have re-quested additional information on the EBR-II reactor and data from prev-ious test transients. EBR-II support staff at ANL has sent us data from test series 8A, and are currently preparing the reactor data we request-ed.

The stand-alone version of MINET is being tested on several simple problems while necessary modifications to the input processor are being made. Several of the new capabilities have been tried, and all functions tested thus far are working correctly.

5. User Support (G.J. Van Tuyle, R.J. Kennett)

The EBR-II staff at Idaho and at ANL are interested in SSC and MINET, particularly the helical coil heat exchanger model in MINET. A CDC com-patible program library of CY-41 of SSC/MINET, along with supporting docu-mentation and test problems, have been sent to them for use on their CDC system in Idaho. They have also requested an IBM compatible library for their system at ANL, and we are preparing to provide such a version.

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DISTRIBUTION R. F. Audette, NRC R. A. Decker, NRC R. T. Curtis, NRC J. N. Grace, NRC A. Ignatonis, NRC C. N. Kelber, NRC T. L. King, NRC R. B. Minogue. NRC W. M. Morris, NRC F. Odar, NRC S. P. Sands, NRC P. M. Wood, NRC N. Zuber, NRC W. Y. Kato, BNL H. J. C. Kouts, BNL K. R. Perkins, BNL Associate Chairman /

Division Heads Division of Technical Information and Document Control

• P. J. McDaniel, Sandia J. E. Meyer, MIT N. Trikouros, GPU

• via W. Y. Kato's Office

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INTERIM REPORT

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M " l N k knted l f SS/SAccession h o** No. L k Contract Program or Project

Title:

A. SSC Development, Validation and Application B. CRBR Balance of Plant Modeling t  !

Subject of this Document: Monthly Highlights for January , 1983

. Type of Document: Monthly Highlights

! l Author (s): James G. Guppy, Group Leader i Date of Docur.ent: January 11, 1983 l Responsible NRC Individual I

and NRC Office or Division: Dr. Robert T. Curtis, Chief Severe Accident Assessment Branch Division of Accident Evaluation Office of Nuclear Regulatory Research U.S. Nuclear Regulatory Commission Washington , D.C. 20555 This document was prepared primarily for preliminary or internal

, use. It has not received full review and approval. Since there may be substantive changes, this document should not be considered final.

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Brookhaven National Laboratory Upton, NY 11973

' Associated Universities, Inc.

U.S. Department of Energy 4

Prepared for U.S. Nuclear Regulatory Commission Washington, D.C. 20555 Under Interagency Agreement DE-AC02-76CH00016 NRC FIN A-3015 INTERIM REPORT t

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