ML20134B055

Demonstration of Conformance of Exxon Nuclear Co Fuel to Westinghouse K(Z) Operating Envelope for Prairie Island Nuclear Power Plant

ML20134B055
Person / Time
Site:	Prairie Island
Issue date:	10/31/1985
From:	WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:
Shared Package
ML20134B053	List: ML20134B051 ML20134B055
References
NUDOCS 8511110207
Download: ML20134B055 (11)

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ATTACHMENT A u

DEMONSTRATION OF THE CONFORMANCE OF EXXON NUCLEAR COMPANY FUEL TO THE

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WESTINGHOUSE K(2) OPERATING ENVEIDPE FOR THE PRAIRIE ISIAND NUCLEAR POWER PIANT Westinghouse Electric Corporation Nuclear Technology Division Nuclear Safety Department i

Safeguards Engineering and Development i October 1985 8511110207 B51104 l PDR ADOCK 0%2 2 i

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l I. Introduction .

This document reports the results of an analysis that was rformed in crder to demonstrate conformance of Exxon Nuclear Company n'uclear fuel in the Prairie Island nuclear power plant to the Westinghouse K(s) operating cnvelope. The results of this analysis of top-skewed (8 ft. and 10.5 ft.)

cnd chopped cosine (6 ft. peak) power shapes seat the requirements of Appendix K and 10CFR50.46 acceptance criteria. l II. Method of Analysis i

Th3 analysis was performed using the SATAN, WRIFIDOD, COCO and IOCTA computer codes of the Westinghouse 1981 Large Break IOCA Evaluation Model (WEM) to calculate the PCT for Exxon fuel for three power shapes. The power shapes investigated were peaked at 6.0 ft., 8.0 ft., and at 10.5 t

ft. The power shapes used in the 14CA analyses are shown in Figures 1-3.

Tho peak power of each power shape is limited by the Westinghouse K(z)

( cnvelope for the Prairie Island (NSP/NRP) power plant. This analysis is l b3ced on a full core of Exxon 14X14 "TOPROD" fuel with a maximum total peaking factor of 2.32 and a hot channel enthalpy rise factor (F-delta-h) l l cf 1.60. i l

Tho study incorporates the new upper internals design package scheduled  !

fcr installation in the first quarter of 1986. The new upper internals c:nfiguration contains an inverted top hat upper support plate. The i

inverted top hat upper support plate displaces upper plenum free water

volume end icOv03 1003 watcr volum3 tvailtblo fer caro ficoding during

. blowdown. This factor establishes the new upper internal ' configuration as o bounding case for either upper internals package. Thus the results of l

thisanalysisareapplicabletoboththenewandoldupper[ internals d signs. '

The fuel design parameters for these LOCA analyses were prepared by the W stinghouse Nuclear Fuel Division using NRC approved Westinghouse methodology and fuel performance models, modified to accurately describe C0asured Exxon fuel operating performance data with detailed operating fuel rod power histories. The similarity of Exxon and Westinghouse fuel cledding as-built and irradiated mechanical properties further supports.

tho validity of the model development. The LOCA fuel design parameters calculated by Westinghouse with these modified and verified fuel i

parformance models were then compared with LOCA fuel parameters used by i

l Exxon in the previous cycle LOCA evaluations. This comparison showed good cgreement on the fuel temperatures and stored energy and, as expected, cenewhat lower fuel rod internal pressures as a function of fuel rod linear power. To assure that the new LOCA fuel performance parameters c:nservatively bound the values used by Exxon in the prior cycle analysis, tho fuel temperature and rod internal pressure results calculated with the t

W:ctinghouse models were adjusted upward to match the prior cycle limiting values. The fuel parameters, calculated with those finalized ociculational models, which included fuel pellet temperatures and fuel rod l internal pressures were then used as input in each of the SATAN, WRITLOOD Cnd IDCTA calculations. The results of the 1981 Evaluation Model calculation are summarized in the following table

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Connarison of Erron Fuel Peak Claddina Temneratures Power Shape Peak PCT PCT Elevation PCT Time a

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. 6.0 2034 F 7.5 ft 207.0 s 8.0 1688 F 8.0 ft 5.3 a 10.5 1679 F 10.5 ft 180.8 s i

j The'se results demonstrate that for Prairie Island, the chopped cosine power shape (i.e. 6.0 ft. peaked shape) generates the most limiting peak clad temperature.

Figures 4-6 show the clad temperature response for the j

peak node for the 6.0, 8.0, and 10.5 ft. power shapes respectively. A I

comparison of the peak clad temperatures during the blowdown and reflood

phases for each of these power shapes provides a conclusive demonstration that the chopped cosine power shape produces the most limiting IDCA rcsults with a wide margin between the chopped cosine shape and the

{ tcp-skewed power shapes. In addition to showing that the chopped cosine i

power shape is the " worst" power shape for a I4CA analysis of Prairie i

Icland with Exxon fuel, it also demonstrates a large margin to the 2200

) dCg-F limit for the top-skewed shapes for this plant.

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III. conclusions The Westinghouse Large Break LOCA 1981 Evaluation Model was used to Cnalyse Exxon fuel for three power shapes.

The results confirmed that the power shape peaked at the center of the core produces the highest peak cladding temperature. i This result for the Exxon fuel is consistent with  :

power shape studies performed by Westinghouse with the same computer codes fer Westinghouse fuel. The results of this study demonstrate that the Exxon fuel in the Prairie Island nuclear power plant conforms to the current operating K(z) envelope for top-skewed power shapes.

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NSP ilEW UI 5% TUBE PLUGGING CD=0.4 DECLG FD=2.02

' CLAD AVG. TEMP. HOT ROD BURST. 6.25 Fil ) PEAK. 7.50 FT(*)

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for the 6.0 ft. Power Shape.

i NOTE: Asterisks (*) do ngt represent a separate curve, L:tt, provide a tracer at to identify the peak the curve temperature node. representing clad avg. temperature Where the peak and burst nodo coincide, only one curve (with asterisk tracer) will be seen.

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• NSP NEW UI 5% TUBE PLUGGING CD=0.4 DECLG FQ:2.32 14X14 ENC TOPROD CLAD AVG. TEMP. HOT ROD . BURST. 7.25 FT( ) PEAK. 7.25 FT(*)

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,s 10/t1/85 Figure 5. Clad Temperature Response for PCT Location for 8.0 ft. Power Shape NOTE Asterisks (*) do not represent a separate curve, but provide a tracer to identify the curve representing clad avg. temperature at the peak temperature node. Where the peak and burst nodes coincide, only one curve (with asterisk tracer) will be seen.

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• e Figure 6. Clad Temperature Response for PCT Location for the 10.5 ft. Power shape NOTE: Asterisks (*) do not represent a separate curve, but provide a tracer to identify the curve representing clad avg. temperature at the peak temperature node. Where the peak and burst nodes coincide, only one curve (with asterisk tracer) will be seen.

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