ML18153C543

Proposed Tech Spec Table 4.2-1 Re Insp Interval for Low Pressure Turbine Blade Insps

ML18153C543
Person / Time
Site:	Surry
Issue date:	02/15/1991
From:	VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.)
To:
Shared Package
ML18153C542	List: ML18153C541 ML18153C543
References
NUDOCS 9102200240
Download: ML18153C543 (5)

Text

r ATTACHMENT 1 SURRY POWER STATION*

PROPOSED TECHNICAL SPECIFICATION CHANGE ONE-TIME INSPECTION INTERVAL EXTENSION FOR LOW PRESSURE TURBINE BLADE INSPECTIONS

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TABLE 4.2-1 SECTION A. MISCELLANEOUS INSPECTIONS Required Required Examination Examination Tentative Inspection Item No. A re a Methods During 10-Year Interval Remarks

1. 3 1 .4 Primary Pump Flywheel Low Pressure See remarks Visual and See remarks 100% of blades every 5 Examination to be conducted in accordance with regulatory position C.4.b of regulatory guide 1.14 Rev. 1, August 1975 None Turbine Rotor Magnetic years*

Particle or Dye Penetrant SECTION B. SENSITIZED STAINLESS STEEL 2.1 .1 Circumferential Visual and By the end of the interval, A minimum of 5% of the welds and longitudinal Volumetric a cumulative 75% of the will be examined every 1-2/3 pipe welds and circumferential welds in the years (generally each normal branch pipe piping system would have refueling outage). See connections been examined, including Transcript of Hearing (pp.

larger than 4 one foot on any longitudinal 303-304) and Initial Decision inches in weld on either side of the (p.7,p.10) diameter butt welds 2.1.2 Circumferential Visual By the end of the interval, A minimum of 50% of the welds and longitudinal a cumulative 100% of the will be examined every 1-2/3 pipe welds and welds and pipe branch years (generally, each normal branch pipe connections would be refueling outage). See connections examined a minimum of Transcript of Hearing (pp.

three times 303-304) and Initial Decision (p.7, p.10)

I N

• For Unit 2, the 5 year inspection schedule can be extended until the Cycle 11 refueling outage. I u,

The 5 year inspection schedule for Unit 2 will be reinitiated following the Cycle 11 refueling outage.

ATTACHMENT 2 SURRY POWER STATION SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION PROPOSED TECHNICAL SPECIFICATION CHANGE ONE-TIME INSPECTION INTERVAL EXTENSION FOR LOW PRESSURE TURBINE BLADE INSPECTIONS

. DISCUSSION OF CHANGE The original Surry Technical Specifications included an augmented inservice inspection program to cover equipment and systems not included in the ASME Code at that time. Over the years, the Code has subsequently included several of these areas. Based on Code inclusion, they could then be removed from Technical Specifications. In this case the requirements for the turbine blade inspections have not been incorporated in the Code, but the industry has established a methodology that develops the necessary inspection frequency to ,ensure that the probability of a turbine missile remains acceptably low. This methodology is based on turbine operating time and several other key parameters. In discussions with the turbine manufacturer, it has been concluded that the blades can be inspected on the same frequency as other turbine components and not impact the safe operation of the turbine.

Because Surry experienced extended outages in 1987 and 1989, the total operating time on the turbine will only be 46 months at the planned April 1991 refueling outage.

In addition, the low pressure turbines were refurbished and placed in service during the 1985 Unit 2 refueling outage. Based on an evaluation of the critical parameters (e.g.,steam quality, crack size, etc) and discussions with the manufacturer, the inspection interval for the disks, hubs, and keyways, was reevaluated and reestablished for the February 1993 refueling outage. Performance of the blade inspections in conjunction with the other required turbine component inspections is consistent with the manufacturer's recommendations. The low pressure turbine blade inspections, along with the disks and hubs inspections will be performed during the 1993 refueling outage at approximately sixty-six months of turbine operating time.

Sixty-six months is well within the calculated inspection interval determined by the approved Westinghouse methodology, which calculated greater than 100 months for both low pressure turbines.

.. :. : r 10 CFR 50.92 SIGNIFICANT HAZARDS CONSIDERATION REVIEW Virginia Electric and Power Company has reviewed the proposed Technical Specification change against the criteria of 10 CFR 50.92 and has concluded that the Technical Specification change as proposed does not pose a significant hazards consideration. Specifically, operation of the Surry Power Station in accordance with the proposed change will not:

1. Involve a significant increase in the probability of occurrence or consequences of an accident previously evaluated. Because the low pressure turbine blade inspections will be performed well within the manufacturer's recommended inspection interval there is no significant increase in the probability of a blade failure occurring that could result in a plant transient. The proposed blade inspection interval is consistent with the operational time based inspection requirements for the turbine's disks, which are a critical component for turbine missile generation. In addition, since the low pressure turbine blades are not considered a contributor to turbine missiles that could affect safety-related equipment, the extended inspection interval does not impact the probability or consequences of any previously evaluated accident.

2. Create the possibility of a new or different kind of accident from any accident previously evaluated. Extending the inspection interval for the low pressure turbine blades does not significantly increase the probability of a turbine blade failure and, therefore does not generate any additional accident precursors.

Turbine missiles have been evaluated and the blade components are not considered of sufficient mass to penetrate the turbine casing and affect safety-related equipment. Therefore, a new or different accident from those previously evaluated has not been created.

3. Involve a significant reduction in a margin of safety. The low pressure turbine blades will be inspected well within the manufacturer's recommended inspection interval. Therefore, the possibility of turbine blade failure occurring that could result in a plant transient due to blade failure will not increase significantly. The low pressure turbine blades are not considered to be a source of a turbine missile that could affect safety-related equipment. Therefore, extending the inspection interval will not significantly reduce the margin of safety, (i.e., change the probability of a turbine missile damaging a safety-related piece of equipment).