ML20116L618

Forwards Startup Rept for Cycle 18.Submittal Contains No New Commitments Nor Modifies Any Existing Commitments

ML20116L618
Person / Time
Site:	Monticello
Issue date:	08/12/1996
From:	Hill W NORTHERN STATES POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9608190123
Download: ML20116L618 (3)

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Northem States Power Company Monticello Nuclear Generating Plant 2807 West Hwy 75 Monticello, Minnesota 55362-9637 August 12,1996 Technical Specifications Section 6.7.A.1 U S Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22 Startuo Report for Cycle 18 Section 6.7.A.1 of the Monticello Technical Specifications requires that a Startup Report be submitted within 90 days following resumption of commercial operation with a fuel installed that has a different design or has been manufactured by a different fuel supplier. Cycle 18 is the first cycle to utilize General Electric's GE11 and GE12 fuel designs. In compliance with i

Technical Specification Section 6.7.A.1, a Startup Report for Cycle 18 is provided as Attachment A.

This submittal contains no new NRC commitments nor does it modify any existing commitments.

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Please contact Mel Opstad (612-295-1653) if you require further information related to this submittal.

l h$dt l S4 William J Hill Plant Manager Monticello Nuclear Generating Plant c:

Regional Administrator-Ill, NRC NRR Project Manager, NRC Resident inspector, NRC State of Minnesota Attn: Kris Sanda Attachment A: Startup Report for Cycle 18 Fite; J:\\D04560'MoNTILMiiPERioDIC RPT\\SU_RPT18 Doc 9608190123 960912 ADOCK0500g3 DR 9

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ATTACHMENT A STARTUP REPORT FOR CYCLE 18 l

Monticello Cycle 18 started up with 2 new fuel designs in-core that have not previously l

operated in the Monticello core. These are the GE11 and the GE12 designs. The GE11 l

design was loaded in reload quantities (140 bundles for Cycle 18), while the GE12 design was loaded as part of a Lead Use Assembly (LUA) program (4 bundles for Cycle 18).

The features of the GE11 and GE12 bundle designs are described in references 1,2,3 and 4.

A summary of these features is as follows:.

Two different GE11 bundle nuclear designs were loaded for Cycle 18. These designs differ very slightly in bundle average enrichment and in axial gadolinia shaping. Both have a 9x9 array of fuel pins with two central water rods which occupy seven rod j

positions, six inches of natural uranium at the bottom of the fuel rods, eight inches of natural uranium at the top of the fuel rods (except in the part length rods), axially zoned gadolinia, and eight part length fuel rods which decrease the two phase pressure drop and improve stability characteristics. The GE11 fuel design has a higher exposure limit and core residence time limit than the GE10 design.

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1 The GE12 design has a 10x10 array of fuel pins with two central water rods which occupy eight rod positions, six inches of natural uranium at the bottom of the fuel rods, i

i twelve inches of natural uranium at the top of the fuel rods (except in part length rods),

l axially zoned gadolinia, and fourteen part length rods which decrease the two phase l

pressure drop and improve stability characteristics. The GE12 design has a slightly l

heavier bundle weight than GE11, due in part to a 145.24" active fuel length for GE12 i

vs. a 141.24" active fuel length for GE11.

During startup of Cycle 18, standard post-refueling outage startup physics testing was performed, as well as one additional reactor physics test directed toward the GE12 LUAs.

Standard physics testing included one "few-rod-critical" centered around withdrawal of the l

highest worth (cold) control rod and enough diagonally adjacent control rods to reach criticality and measure the resulting reactor period. Also included in the standard physics testing was a

" dispersed critical" or "in-sequence critical" where data was taken as criticality was achieved during pulling of control rods using the normal startup sequence loaded in the Rod Worth Minimizer computer. The additional reactor physics test included a "few-rod-critical" centered around the withdrawal of a control rod in a cell containing two GE12 bundles (and two other l

bundles), and withdrawal of enough other diagonally adjacent control rods to achieve criticality.

The intent of this additional few-rod-critical was to demonstrate that biases and uncertainties in j

cold shutdown margin calculations involving the GE12 fuel design were comparable to that for other fuel bundle designs. This was confirmed by the testing. All startup reactor physics test results agreed with calculated and/or predicted values within expected differences.

d The features of the new fuel designs were included in the analysis of the plant transients listed in the Monticello FSAR to evaluate their effect on the transients. This evaluation is 1

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Attachment A August 12,1996 Page 2 documented in Reference 3 and the effects of the new fuel types are included in the Core Operating Limits Report for Cycle 18.

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l Section D.5 of the Monticello USAR describes the startup program that was followed for initial startup of the plant. The following tests were essentially repeated for the Cycle 18 startup, with modifications as noted in the parentheses: Section D.5.3.b - Control Rod Drive System tests (without dummy fuel testing); Section D.5.3.e - Shutdown Margin (full core loading and GE12 cell loading); Section D.5.4.1 - Process Computer; Section D.5.4.o - LPRM Calibrations (at 50% and 100% of rated power); and Section D.5.4.q - Core Performance Evaluations (Minimum Critical Power Ratio has replaced Minimum Critical Heat Flux Ratio). Results from l

these tests were all acceptable.

References:

1. "GE11 Compliance With Amendment 22 of NEDE-24011-P-A (GESTAR 11)",

NEDE-31917P, April 1991.

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2. "GE12 Compliance With Amendment 22 of NEDE-20411-P-A (GESTAR 11)",

NEDE-32417P, December 1994.

3. "Monticello Cycle 18 Final Reload Design Report (Reload Sr.fety Evaluation)",

NSPNAD-96001, Rev.1, May 1996.

4. "GE12 LUA Fuel Bundle Description Report", Letter from C. J. Pappandrea to Kirk S.

Schnoebeten, CJP2:96-019, January 30,1996.

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