ML20138F866

Application for Amend to License DPR-22,providing Suppl to 961125 Amend Request Re Safety Limit Minimum Critical Power Ratio

ML20138F866
Person / Time
Site:	Monticello
Issue date:	04/29/1997
From:	Hill W NORTHERN STATES POWER CO.
To:
Shared Package
ML19355F130	List: ML20138F862 ML20138F866
References
NUDOCS 9705060075
Download: ML20138F866 (6)

Text

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UNITED STATES NUCLEAR REGULATORY COMMISSION NORTHERN STATES POWER COMPANY MONTICELLO NUCLEAR GENERATING PLANT DOCKET NO. 50-263 REQUEST FOR AMENDMENTTO OPERATING LICENSE DPR-22 SUPPLEMENT TO LICENSE AMENDMENT REQUEST DATED NOVEMBER 25,1996 Northern States Power Company, a Minnesota corporation, is submitting supplimental information to support License Amendment Request dated November 25,1996. This supplement responds to NRC Staff questions.

This letter contains restricted information as indicated by the attached General Electric (GE)

Proprietary Notice.

i NORTHERN STATES POWER COMPANY l By 5 William J Hill ' l Plant Manager Monticello Nuclear Generating Plant On thisd day of h ON k Wl7before me a notary public in and for said County, personally appeared William J H'ill, Plant Manager, Monticello Nuclear Generating Plant, and being first duly sworn acknowledged that he is authorized to execute this document on behalf of Northern States Power Company, that he knows the contents thereof, and that to the best of his knowledge, information, and belief the statements made in it are true and that it is not interposed for delay.

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' Samuel I. Shirey , nou m rueus asuuBI85 Notary Public - Minnesota geomm.EmJm M sees t

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My Commission Expires January 31,2000 9705060075 970423 I DR ADOCK 05000263 PDR

Exhibit A  !

n MONTICELLO NUCLEAR GENERATING PLANT l

Supplement to i License Amendment Request Dated November 25,1996 1 I

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Exhibit A

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• Supplement to License Amendment Request Dated November 25,1996

. Safety Limit Minimum Critical Power Ratio Question #1:

Discuss the conservative variations of projected control rod patterns that were used to determine the Monticello Cycle 18 SLCPR value.

He cycle specific SLCPR is not sensitive to the control rod depletion patterns. His is supported by the following

, information. Ec predicted target A2 sequence control rod patterns are used for the base 3D simulator (PANACEA) depletion through the cycle of interest. Restart PANACEA cases are performed at several cycle exposures fmm the base depletion to establish the initial condition for the SLCPR calculation. The initial condition is restricted a those conditions where the limiting bundles are close to MCPR limits while avoiding unreasonable power distributions and violation of LHGR limits. The objective in establishing the initial condition power distribution is to satisfy the total i power and local limits and to reasonably bound the total mds expected to experience boiling transition. These restart cases utilize non-typical control rod patterns to force the MCPR distribution to be conservatively flat and have the MCPR close to the OLCPR. Variations in the core depletion conditions do not have a significant impact on these forced distribution restart cases. He forced distribution restart cases are the initial starting conditions for the Monte Carlo SLCPR calculation. In fact, non-typical variations in control rod depletion such a stuck control blade would tend to make the initial CPR distribution for the SLCPR calculation more peaked (less flat). His would tend to non-conservatively reduce the calculated SLCPR. Since the calculation of the SLCPR is not sensitive to the base

! depletion, the calculated SLCPR is valid for typical variations in the actual operating control rod patterns.

Discuss the actual bundle parameters (e.g. local peaking) used to determine the Monticello Cycle 18 SLCPR value.

The initial condition for the SLCPR calculation is as mentioned above based on 3D Simulator (PANACEA) restart i cases. The PANACEA cases provide the initial condition for the nominal reactor state calculation. These cases 4

provide the flow , void fraction, and power distribution for each bundle in the core. The R-factors (E.G. bundle local peaking) for each bundle are a function of bundle exposure for each bundle and are accessed by the PANACEA ,

along with the appropriate GEXL correlation constants to calculate the critical power ratio for each fuel rmi in the  !

core, 4

%e R Factors for the Monticello cycle 18 specific SLCPR calculation are based on the fuel bundles consistent with I the actual core loading. His is consistent with the cycle specific SLCPR calculation methodology to ensure the applicability of the SLCPR to the particular plant / cycle ofinterest. Part of the problem with the old generic SLCPR 4

calculation was that the more recent fuel bundle designs evolved to have flatter bundle local peaking than the original fuel design utilized for the generic calculation. The flatter bundle local peaking results in more fuel rods participating in the boiling transition. The more fuel rods that participate in the boiling transition will yield a more restrictive (larger) SLCPR.

Question #2:

Discuss whether a Monticello cycle-specific Single Loop Operation adder calculation was performed and compare the result to generic results.

A cycle specific Single Loop Operation (SLO) penalty calculation for Monticello Cycle 18 was prepared by GE Nuclear Energy to provide additional support for the Technical Specification change. His analysis was prepared in accordance with GE Technical Design Procedures and Design Verification Guide corresponding to the Cycle Specific SLCPR calculation. Performing the SLO penalty was recently added to the Cycle Specific SLCPR Technical Design Procedure and is required for all current reload core applications.

The resulting SLO penalty calculated for Monticello Cycle 18 is 0.01. This is consistent with the previously reported SLO penalty from the original generic calculation. The original generic based SLO penalty (0.01) was transmitted to NSP along with the cycle specific SLCPR on May 8,1996.

Exhibit A

' Supplement to License Amendment Request Dated November 25,1996

, Safety Limit Minimum Critical Power Ratio

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l Question #3-

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Provide a table showing differences between generic calculations and Monticello Cycle 18 specific calculations in j the parameters that influence the SLCPR calculation to demonstrate that the 1.07 to 1.08 change in SLCPR calculated for Monticello Cycle 18 is reasonable.

See attached proprietary information letter by General Electric.

Question #4:

Discuss SLCPR determination for the Siemens fuel (8 bundles) currently resident in the Monticello core. j I I I

4 Exhibit B MONTICELLO NUCLEAR GENERATING PLANT Supplement to License Amendment Request Dated November 25,1996 l

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GE Nuclear Energy rodd R. Brohaugh  % tear fu~nAmvau; e,;er r&r Mrwie- Genew [Incmc Com;n PO % ?RG k.1 car A im.n , - 'E ;

• April 21,1997  :!NS S3 cc: C. A. Bonneau TRB:97-089

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C. L. Heck K. S. Schnoebelen T. Slayton C. W. Smith D. B. Waltermire D. G. Wegener Mr. H. H. Paustian Northern States Power Company Monticello Nuclear Generating Plant 2807 West Highway 75 Monticello, MN 55362

Subject:

Monticello Cycle 18 SLMCPR Calculation

Dear Harold:

Attached, please find information pertaining to the Safety Limit MCPR for Monticello Cycle 18.

The attached information is in the format with which the NRC is familiar and which has been used for recent submittals from other plants. This should minimize any questions.

The attachment contains GE Proprietag Information. A proprietay aflidavit will be provided for your use if you provide us a copy of your letter to the NRC transmitting this information.

Ifyou have any questions, please call me.

I Very truly yours, /

Ydi M T. R. Brohaugh

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