ML20057F146

Forwards Response to RAI 900.1 Transmitted by NRC 930901 Re Sbwr Design

ML20057F146
Person / Time
Site:	05200004
Issue date:	10/08/1993
From:	Marriott P GENERAL ELECTRIC CO.
To:	Joshua Wilson NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM), Office of Nuclear Reactor Regulation
References
MFN-164-93, NUDOCS 9310140193
Download: ML20057F146 (6)

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h) GENuclear Energy l Genera!De:tnc Compan 175 Curtner Aanue. San Jase. CA 95125 October 8,1993 MFN No.164-93 Docket No. STN 52-004 Document Control Desk U.S. Nuclear Regulatory Cominission Washington, D.C. 20555 Attention: Jerry N. Wilson, Acting Director Standardization Project Directorate

Subject:

NRC Requests for Additional Information (RAls) on the Simplilled Boiling Water Reactor (SBWR) Design

Reference:

Transmittal of Requests for Additional Information (RAls) for the SBWR Design, Letter from M. Malloy to P. W. Marriott dated September 1.1993 The reference requested additionalinformation on the SBWR Design. In fulfillment of this ,

request, GE is submitting this response to RAI 900.1. >

Sincerely,

'b P. W. i arriott SBWR Project Manager MC-781, (408)925-6948

Enclosure:

RAI Response 1300:;3 1 0

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RAI Number: 900.1 Question:

The staff has learned that GE Nuclear Energy (GE) is planning to perfonn tests in the

" ATLAS" flicility on the SBWR fuel design. There is no specific mention of this testing in any documentation on the SBWR design certification testing program, although a view graph from aJuly.1991 meeting between the staff and GE refers to a

" confirmatory test schedule established at time of plant order." We infer that the tests would be for the purpose of verifying the applicability of thermal-hydraulic correlations, e.g., critical power, form loss coefficients, etc., in analysis codes to the-SBWR fuel design, and for providing the data for extending or modifying such correlations, if necessary.

Despite GE's assertion that this test program is "confinnatory," the staff views the testing as a part of the required design certification test program for the SBWR, due to the differences between the SBWR fuel design and that used in current-generation BWRs. The staff also views the testing as a safety-related activity under GE's LBWR QA requirements. The validity of relevant thermal-hydraulic correlations for SBWR fuel must be demonstrated, since these correlations play a direct role in safety evaluations of the SilWR, such as in Chapters 4,6, and 15 transient and accident analyses appearing in the SSAR. A reference fuel design was employed in the SSAR analyses as submitted to the NRC, without specific documentation demonstrating that the correlations used for the analyses were appropriate for that fuel design.

The staff is aware that a natural circulation BWR (Dodewaard) is currenth operating.

Ilowever, the fuel design of the Dodewaard plant differs in a number ofingw rtant aspects (length, diameter, pitch, average power, and power shape) from the reference SBWR design. The staff therefore requests that the following information regarding planned SBWR fuel performance testing:

1. Details of the planned testing, including test specification, test matrix, and test schedule.

2. Details of the analyses planned in conjunction with the fuel performance test program, including documentation for the thermal-hydraulic correlations to be '

validated for use in SBWR safety analyses. l

3. Verification that the ATLAS facility is able to match approximately the appropriate thermal-hydraulic conditions for SBWR fuel. In particular, how I will ATLAS simulate the natural circulation flow behavior that will exist in the  !

SBWR?

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GE Response: .

RAI ON SBWR DESIGN i

900.1 Fuel Performance Testine ,

GE Nuclear Energy is planning to perform tests in the ATLAS facility of the SBWR fuel design prior to use but not as part of the certification program. This is the reason why there is no specific mention of this testing in any documentation on the-  !

SBWR design certification testing progmm. The GE's plan is to establish the schedule for testing of the specific fuel bundle design to be loaded in the SBWR core (this may or not be the 9ft GE8 fuel) at the time of plant order.

The SBWR fuel bundle design is the same as the GE8 fuel bundle design used in current-generation BWRs except shorter fuel length (9 feet long). The SBWR .

SSAR analysis was performed using the GEXL correlation (GEXLO2) derived from the  !

12 ft fuel bundle test data in the ATLAS test facility. Applicability of GEXLO2 for ,

SBWR was established by comparing analytically generated SBWR fuel bundle }

critical powers with those calculated by GEXLO2. l The analytical data was generated using the COBRA-G analysis code. COBRA- l G is a steady state subchannel analysis code for performing analyses of critical power, ,

liquid film dryout location, pressure drop, and void fraction distribution of BWR-type fuel bundles. Currently, the code is used in support of development of new BWR fuel bundle designs. Two-fluid / multi-field two-phase flow model, mechanistic film  ;

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dryout model, and semi-mechanistic spacer model are some of analytical models inchided in the code. The code has been qualified extensively against ATLAS test data for different designs of fuel bundle, spacer, and axial power shape. The .,

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<fualincation results show that the absolute relative error for COBRA-G critical power piediction is less than 5%. For example, comparison between COBRA-G and ATLAS l critical power test data for the GE8 with 12 ft fuel length is shown in Figure 1. In  ;

order to check the capability of predicting the effect of fuellength on critical power i performance, the Columbia University critical power test data for the 4x4 lattice bundle  ;

with 6 ft long fuel was analyzed using COBRA-G. Figure 2 shows comparison between COBRA G and the test data, showing the COBRA-G's capability of predicing [

the effect of fuel length.

Cui A-G was used to calculate the critical power performance of the SBWR l' 4 fuel bundle. The results show an average reduction of 10.5% in critical power compared to that of the standard GE812'ft fuel bundle. Figure 3 shows comparison between the critical powers calculated by GEXLO2 and COBRA-G for the SBWR fuel j bundle. As noted from the figure, the difference is within the accuracy of the ATLAS 1 measurements. This verifies the applicability of GEXLO2 for the SBWR fuel bundle. l l

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