ML20101G211

Forwards Summary Description of Computer Codes Used in Safety Analysis,Including Odyna/Redya Models for Advanced BWR Transient Analysis

ML20101G211
Person / Time
Site:	05200001
Issue date:	06/16/1992
From:	Fox J GENERAL ELECTRIC CO.
To:	Poslusny C, George Thomas NRC
References
NUDOCS 9206250342
Download: ML20101G211 (6)

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' ODYNA/REDYA Models for ABWR Transient Analvs_is For ABWR transient analysis, the ODYNA code is used to simulate pressurization events, and the REDYA code is used for other trant.ient I events. Both ODYNA and REDYA codes are similar to previous models, ODYN and REDY, which have been approved by the NRC for transient

analysis for operating BWR's, in all aspects except the recirculation

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model and ECC systerns unique for ABWR. The REDYA code also i 4 - ,

incorporated some model improvements already included in the ODYN l

, coca. (e.g.: safety / relief valve model, steam line model, etc.). 1 The major model modification in both ODYNA and REDYA codes I

is the recirculation model. This new recirculation model consists with three groups of reactor internal pumps, RIP, (no limit on number of RIP)

with separate speed controls. RIP characteristics, initial conditions, pump trip and runback functions are assumed to be identical for RIP in the same

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j group, and can different from other groups. A recirculation flow control

system as shown in Figure 1 is modeled for RIP and core flow control.

i The performance of this recirculation model has been qualified against plant startup data obtained frorn European plants with RIP. The events

simulated for qualification purpose included all pump trip (two plants),

\ one pump trip att momentary voltage drop event. The comparison between c ilculated results and plant data is generally favorable. (See

, Figure 2 as an example.) Therefore, it is concluded that ODYNA/REDYA j are acceptable for design analysis for plants with RIP, sur.h as ABWR, 6

i In addition, model - to model comparison and comparison with other test data (e.g., Peach Bottom turbine trip test) have also been t performed to assure that the models perform correctly in other areas, i aj Finally, a design review was initiated. The review concluded that the t

computer programs are acceptable for design analysis.

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Figure 1. Recircula*.lon Punp P*od e l for ODYNA/REDYA ,.

L' (Master Tliree Loop Recirculation System

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Controller sd - pump speed demand ..

v err - pump speed error Flux fd - frequency demand I.

Controller li sync - synchronous frequency t

- pump speed

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Speed fd Frequency sync Pump N*

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Controller ] Inverter Model

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Frequency l sync Inverter Pump Model N

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I nop 2; p err= Speed fd Frequency Isync= Pump  !

N 7 T I/ Controller inverter Model

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\ h De Use of thdAFER Model for ABWR LOCA Analyse _s 9

i, The same SAFER model documented in NEDE 30996P-A and

'appfoved by the NRC has been used to perform LOCA analyses

( presented in the ABWR SAR. NEDE 30990A P documents good b

' agreement between SAFER predictions and test results from the i ABWR FIST facility SAFER has the input flexibility to model ECC systems at any combination of injection pressure and injection location.

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i d p i SAFER also has a reactor internal recirculation pump input option for the ABWR. This modeling is similar to thejet-pump recirculation i

fmodel except the induced flow from the jet-pumps and the external j l loop volume Ipve been eliminated. ABWR specific data is input to

' describe the pump coastdown following a trip on loss of offsite S power, and flow area and losses through the pump.

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4 4 The Use of the G3'.5TR Compliter Model for ABWR LOCA Analyses

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The same GESTR computer model documented in NEDE L

h0996P A and approved by the NRC has been used to perform LOCA l pnalyses presented in the ABWR SSAR. The results from GESTR are t used to establish the initial conditions (i.e. stored energy and rod

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internal pressure) at the start of the LOCA within each fuel rod. The BWR core design is based on a GE standard fuel which is similar to BP8x8R with two water rods. This type of fuel has already been gnalyzed with GESTR for operating HWRs. The differences in ABWR

( from previous BWRs does not impact the fuel thermal-mechanical performance predicted by the CESTR modch Therefore the use of GESTR for ABWR does not represent _ any special application.of the GESTR model.

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[ The Use of the LAMR Computer Model for ABWR LOCA Anahses The same LAMR computer model documented in NEDE 20506P-

{ A and approved by the NRC has been used to perfor presented in the ABWR SSAR. The ABWR input to the LAMB i

computer model is the same as operating plants except for the recirculation system modeling. Since ABWR has reactor internal

' pumps (IUPs) instead ofjet-pumps. the recirculation system is modeled assuming no induced Dow from ajet pump. Thus the drive flow from i

the recirculation pumps is set equal to the total recirculation flow.

Five RIPS are modeled by each of the two recirculation pumps in 1.AMB. RIP performance input data was used to describe the

, performance of the recirculation pumps and the flow area and losses g

ithrough the recirculation system are based on those through the RIPS.

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i The Use of the SCAT Comonter Model for ABWR LOCA Analyses J

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The same SCAT computer model documented in NEDE 20566P-j A and approved by the NRC has been used to perform analyses

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L presented in the ABWR SSAR. SCAT is used to determine the

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tnmsient thermal hydraulic conditions within a bundle and predict the i

time when the loss of nucleate boiling occurs. It only models the hot j bundle and sets the boundary conditions based on I.AMB results. The ABWR core design is based on a GE standard fuel which is similar to BP8x8R with two water rods. This type of fuel has already been

analyzed with SCAT for operating BWRs. Therefore the differences in ABWR fromsprevious BWRs does not represent any special j application of the SCAT model.

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