ML20151Y705

Forwards post-Cycle 22 Operation Control Blades Insp Results & Continuing Surveillance Program for Approval,Prior to Continuing Operation W/Control Blades.Util to Implement Program at Next & All Subsequent Refueling Outages.Fee Paid

ML20151Y705
Person / Time
Site:	Big Rock Point File:Consumers Energy icon.png
Issue date:	04/28/1988
From:	Frisch R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.)
To:	NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM)
References
NUDOCS 8805050074
Download: ML20151Y705 (8)

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@powrams Power ANDWEAN'S MISEaE55 o tneral offices: 1945 West Pernali Road, Jackson MI 49201 e (517) 788 0650 April 28, 1988 Nuclear Regulatory Commission Document Control Desk Washington, DC 20555 DOCKET 50-155 - LICENSE DPR BIG ROCK POINT-PLANT -

REQUEST FOR APPROVAL FOR CONTINUED USE OF'NUCOM HAFNIUM HYBRID CONTROL BLADES By letter dated February 17, 1987, the Nuclear Regulatory Commission issued Amendment 88 to the Big Rock Point Operating License which approved use of hafnium hybrid control blade manufactured by NUCOM for cycle 22 operation.-

This approval; requires Consumers Power Company to submit the post cycle 22 operation control blades inspection results to the NRC and to submit a continu-ing surveillance program based on the results-of the post cycle 22 inspection results for NRC approval prior to continuing operation with these control blades. Attachment 1 provides the inspection results. Attachment 2 provides our proposed continuing surveillance program for the.NUCOM control' blades for NRC approval. Consumers Power Company will implement the described surveil-lance program at the next and all-subsequent refueling outages. . Future changes to the surveillance progras which may ba required will be discussed '!

with the NRC prior to implementation. Attachment 3 provides a_ reference list j of Consumers Power Company and NRC correspondence associated with this topic.

Big Rock Point is currently in a refueling outage and startup is. scheduled,for June 6, 1988. Since NRC approval of the surveillance program is required-prior to continuing operation with the hafnium hybrid control blades, a prompt evaluation would be appreciated.

Pursut.nt to the requirements of 10CFR170.12(c) a check in the amount of

$150.00 is remitted with this application for approval.

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Ralph R F sch Senior Li ensing Analyst b CC Administrator, Region III, NRC l' NRC Resident Inspector - Big Rock Point Plant -

Attachments j fI 8805050074 880428 M0488-0117-NLO4 050g

ATTACHMENT 1 Consumers Power Company Big Rock Point Plant Docket 50-155 I

i END OF CYCLE 22 VISUAL EXAMINATION RESULTS 0F NUCOM HAFNIUM / HYBRID CONTROL BLADES April 28, 1988 I

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I Background and Scope i Six NUCOM control blades were utilized in Big Rock Point's reactor core during cycle 22-operation (approximately 280 EFPD). At the end of the cycle, the j control blades were removed from the reactor to the spent fuel pool where a detailed visual examination was performed on each of the six control blades using an underwater self-lighted camera.

The visual examinations were conducted to determine the general structural condition of the control blade assemblies. Specifically, each wing of each control blade was inspected for the presence of wear / erosion patterns, cracks or the presence of debris, and loose or broken parts. Spot welds were inspected for any observacions of cracking or undercutting. Each upper handle and lower connector was visually inspected for structural condition and pin / roller integrity (upper handle) and latch mechanism integrity (lower connector).

Inspection Results No abnormalities were detected on any control blade handle, lower connector, or wing, No unusual wear patterns or signs of wing deformation were observed.

No cracking or undercutting of spot welds were detected. In general, each of the six control blades was visually inspected to be free from any physical defect.

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ATTACHMENT 2 Consumers Power Company l Big Rock Point Plant j Docket 50-155 l I

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CONTINUED SURVEILLANCE PROGRAM FOR NUCOM CONTROL BLADES AT BIG ROCK POINT April 28, 1988 i

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• Summary of Cycle 22 Surveillance Program The most important parameters applicable to the NUCOM control blade design are the : cram time and control blade worth. During cycle 22, the primary methods of verifying these parameters were through physics testing and core surveillance.

The cycle 22 physics testing program entailed verifying control blade scram time, performing shutdown margin verifications, and comparing expected critical control blade configurations to actual critical configurations. Scram times for the NUCOM control blades were verified to meet technical specifica tien requirements both at the beginning and end of cycle 22. The results indicated that the scrcm times for the NUCOM control blades compared well with the scram times for the GE Type IIA control blades, and all times fell within Technical Specification acceptance criteria. Shutdown margin verifications to Technical Specification requirements were performed at the beginning and during the middle of cycle 22. Also, several critical approaches occurred throughout cycle 22 and the reactivity differences between the expected and actual critical configurations were determined to be acceptable in meeting specific criteria.

The cycle 22 core surveillance program entailed comparing measured axial flux profiles to those predicted by the GROK computer code and also comparing calculated notch worths to actual notch worths. Thirteen flux profile compari-son runs were performed with no reactivity anomalies occurring between actual and predicted profiles. Also, actual notch worths when compared to calculated notch wcrths were found to be acceptable.

Continued Surveillance Program Consumers Power Company intends to continue its surveillance program of NUCOM control blades as specified below.

Visual Inspections:

At the end of each cycle a visual examination will be performed on each new control blade inserted at the start of that cycle and as a minimum on the control blade determined to have the greatest exposure from earlier cycles.

The visual examinations will be performed using an underwater camera to verify the overall integrity of each control blade inspected, as discussed earlier.

Physics Testing At the beginning of each new cycle, a) the scram time for each control blade I will be verified to meet Technical Specification acceptance criteria, b) I shutdown margin verification will be performed ensuring reactor suberiti cality, and c) a calculated cold critical approach will be performed and compared to the actual to verify that no reactivity anomaly exists. If shutdown margin verifications and critical approaches are performed subsequent to the start of a new cycle, each will be reviewed to verify that no reactivity anomaly exists.

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Core Surveillance:

Measured axial flux profiles will be compared to GROK predicted profiles for the presence of reactivity anomalies at the beginning of each cycle and then periodically thereafter.

Design Lifetime:

The present discharge program followed for the GE Type IIA control blade.s will also be followed for the NUCOM hafnium / hybrid control blades. Structural integrity and neutronic worth will be monitored throughout control blade design lifetime by use of the continued surveillance program. Upon successful comple-tion of a normal duty life cycle, Consumers Power Company will perform the necessary technical analyses, justifying a greater allowable exposure for NUCOM control blades, if deemed appropriate.

Cycle 23 Operation Two additional NUCOM control blades will be utilized during cycle 23 operation, bringing the total to eight NUCOM control blades in use in the interior of the core (remaining eight interior blades are GE Type IIA).

Control Blade Weight The cycle 22 scram times showed negligible differences between the GE and NUCCM control blades. Therefore, scram times were unaffected by small differences in i control blade weights which are within variations expected from dimensional i tolerances.

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a ATTACIOGNT 3 Consumers Power Company Big Rock Point Plant Docket 50-155 LIST OF REFERENCES April 28, 1988 1 Page OC0488-0117-NLO4

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l-Reference list of. Consumers Power Company and NRC correspondence associated with NUCOM hafnium hybrid control blade approval.

A. Technical Specification Change Request from CPCo to NRC dated 12/05/86, Hybrid Control Rods B. CPCo to NRC dated 01/20/87, Hybrid Control Rods - Supplemental Information-C. NRC to CPCo dated 01/30/87, Request for Additional Information D. CPCo to NRC dated 02/04/87, Response to Request for Additional Information E. NRC to CPCo dated 02/17/87, Approval of Hybrid Control Rod Technical Specification Change Request for Cycle 22 Operation 4

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