ML20138R900

Topical Rept Evaluation of Amend 11 to Rev 6 to NEDE-24011-P-A, GE Std Application for Reactor Fuel (Gestar Ii).Rept Acceptable for Referencing in Licensing Applications

ML20138R900
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Issue date:	11/05/1985
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Enclosure Evaluation of Amendment 11 to NEDE-24011-P-A By letter dated February 28,1985 (Reference 1) General Electrih Company (GE) submitted Amendment 11 to the GE Licensing Topical Report NEDE;24

" General Electric Standard Application for Reactor Fuel" (GESTAR II).

Additional infonnation was submitted in a meeting on June 21, 1985 and subsequently in Reference 2 in response to a request from the staff (Reference 3). The Core Performance Branch and the Reactor Systems Branch have reviewed the information submitted and prepared the following evaluation.

Amendment 11 to GESTAR II alters the document to include an updated version f,

of the ODYN code among the calculational techniques used for plant transient

. analyses and alters the manner in which calculational uncertainties are treated in obtaining core operating limits. A description and justification *

- of the code revisions were included in References 1 andThe 2. changes to the ODYN calculational model include:

1. Improved Neutronics Methods

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These methods are described in Reference 4, which has been reviewed and

• p_ approved by the staff (Reference 5).

2.

Inclusion of GESTR-M Fuel Performance Model This model has been approved by the staff as part of the approval of

_ Amendment 7 to GESTAR-II (Reference 6).

3. Improved Bulkwater Model Improvements include more detailed nodalization, use of a drift flux rather than a homogeneous formulation in the void correlation and use of a void profile and feedwater quenching. Reference 2 presents comparisons of both the new and current void correlations with experiments and demonstrates the superiority of the new co'rre7ation.

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4. Improved Upper Plenum Model Theimprovedmodelusesadriftfluxratherthanahomogeneohsmodel and an improved calculation of the mass holdup. ' '

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5. Improved Separator Mass Storage Model P The improved model uses a transient, homogeneous mass balance rather that a quasi-steady-state mass balance.

Data were provided in Reference 2 on the results of comparisons of the old and new ODYN calculations to the Peach Bottom turbire trip tests. These data showed that the new ODYN results provided generally better agreement with the

' . test data than did the old ODYN calculations. Breakdown of the calculations L

to separate out the effects of the varicus improvements showed that most of the improvement occurred from the inclusion of the previously approved methods in the calculations. Based on improved agreement with experiments -

and the refinement of the calculational models as described above that the improvement to the ODYN code are acceptable.

- In addition to implementing the new model, GE intends to continue use of the current model for appropriate non-limiting calculations. We find this -

acceptable.

Ame'ndment 11 also revised the manner in which code u in obtaining the Option A and Option 8 MCPR operating limits.

However insufficient justification has been provided for this change and we conclude that the currently used treatment of uncertainties must continue to be used .

This has been discussed with GE and they concur in this condition to the staff approval of this amendment.

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References:

i 1)

Letter,J.S. Charnley (GE) toc.O. Thomas (NRC)," Amendment [1toGE LTR NEDE-24011-P-A", February 27,19a3.

2) i Letter, J. S. Charnley (GE) to C. O. Thomas, (NRC), " Response to R No. I for Additional Information on NEDE-24011 Rev. 6, Amendment 1 July 18, 1985.

3) . Letter, C. O. Thomas, (NRC) to J. S. Charnley (GE), " Request Numb w_ for Additional Information on NEDE-24011 Rev. 6, Amendment 11. May 1985. ,

4)

NEDE-30130-A, " Steady State Nuclear Methods" May,1985.

5)

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Letter, C. O. Thomas (NRC) to J. S. Charnley (GE), " Acceptance for Referencing of Licensing Topical Report NEDE-30130, ' Steady-State Nuclear Methods' December 22, 1983".

(See also page following the title page of the approved report). .

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Approval letter, C. O. Thomas (NRC) to J. S. Charnley (GE), dated March 1, 1985.

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