ML20127P713

Submits Addl Info Re Type of Hafnium Control Rod Blades to Be Installed During Jan 1986 Refueling Outage.Cycle 9 Will Be Operating Under Control Cell Core Loading Strategy w/29 Asea Atom,Inc Control Blades in Control Cells

ML20127P713
Person / Time
Site:	Quad Cities
Issue date:	06/26/1985
From:	Rybak B COMMONWEALTH EDISON CO.
To:	Harold Denton Office of Nuclear Reactor Regulation
References
0263K, 263K, NUDOCS 8507020493
Download: ML20127P713 (2)

Text

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i Commonwealth Edison one Fi.st Nanon:1 Plaz9, Chic'go. Illinois Address Reply to: Post Office Box 767 Chicago, Illinois 60690 June 26, 1985 Mr. Harold R. Denton, Director Office of Nuclear Reactor Regulation U.S. Nuclear Regulatory Commission Washington, DC 20555

Subject:

Quad Cities Station Unit 1 l Supplemental Information on Use of Hafnium Control Blades NRC Docket No. 50-254 l

References (a): B. Rybak letter to H. R. Denton dated October 2, 1984. <

l (b): GE NEDE 22290 - Safety Evaluation of '

the GE Hybrid I Control Rod Assembly.

(c): D. M. Crutchfield letter to D. L. Farrar dated March 9, 1984.

(d): R. B. Bevan letter to D. L. Farrar dated May 30, 1985.

Dear Mr. Denton:

l As noted in Reference (a), it is Commonwealth Edison's intent to install control rod blades using hafnium in upcoming outages for its Dresden and Quad Cities units. Approval has been obtained via a technical specification amendment for Dresden Units 2 and 3 and for Quad Cities Unit

2. Members of your staff require specific information as to the number and type of control rod blades to be installed at Quad Cities Unit 1 during its upcoming refueling outage in January, 1986. The purpose of this letter is to provide that information.

Commonwealth Edison has purchased 29 ASEA-ATDM control blades to be installed at Quad Cities Unit 1 for Cycle 9 operation. Q1C9 will be operating under the control cell core loading strategy and these blades will be placed in the control cell locations.

The Quad Cities control blades are very similar to the hafnium-bearing A-A/EPRI demonstration blades previously approved for use at Dresden. The differences with respect to the Dresden blades are as follows:

1. The demonstration blades at Dresden have a relative reactivity worth of 7-9% higher than a standard GE control blade whereas the worth of the control rods for QlC9 will more closely match the reactivity worth of a standard blade. The blades are designed 8507020493 DR 850626 '0 p ADOCK 05000254 d PDR

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1 H. R. Denton June 26, 1985 to be nominally 2.5% higher worth than the standard blade.

Considering the uncertainty in blade worth calculations (1.0-1.5%), this will then ensure the worth of the A-A blades is not less than the standard GE blades.

Due to the closely matched worth of the A-A and standard GE blades, there will be no significant effect on scram reactivity or the transient response for accidents. Thus, there will be no impact on reload licensing analyses such as Rod Drop Accident, Shutdown Margin and Rod Withdrawal Error.

2. To accomplish the matching of reactivity worth, the hole depth in the control blade for B C 4 filling has been reduced from 103 mm to 87 mm so that less4 8 C will be filled.

3. The above reduction in hole depth results in a slight increase in the weight of the control blade. To maintain the same overall weight, the length and width of the blade wing " cut-out" sections along the control rods centerline have been increased from 100 mm to 230 mm and 8 to 12 mm, respectively. This necessitates a decrease in the number of centerline welds from 30 per blade wing for the Dresden design to 16 per wing in the new control blades to be used for Q1C9. All control blades currently manufactured by A-A utilize the 16-weld (230 mm cut-out section length) design. ASEA has performed a supplemental stress evaluation addressing the weld reduction and increased cut out sections and confirmed that compliance with ASME strain criteria is maintained.

It is also our understanding that ASEA will be submitting a generic report on their current control blades design.

If you have any further questions regarding this matter, please contact this office.

One signed original and forty (40) copies of this letter is provided for your use.

Very truly yours, b Ef B. a Nuclear Licens Administrator 1m cc: Region III Inspector - Quad Cities R. Bevan - WR M. C. Parker - IL 0263K