ML20245L046

Proposed Tech Specs for Proposed Suppl 1 to Amend 134 Re Application for Amend to License DPR-54,clarifying Unacceptability of Analysis Allowing Imperfections Greater than 40% of Nominal Tube or Sleeve Wall Thickness

ML20245L046
Person / Time
Site:	Rancho Seco
Issue date:	04/27/1989
From:	SACRAMENTO MUNICIPAL UTILITY DISTRICT
To:
Shared Package
ML20245L043	List: ML20245L039 ML20245L046
References
NUDOCS 8905050251
Download: ML20245L046 (7)

Text

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RANCHO SECO UN!T 1 F . .

TECHNZCAL SPECIFICATIONS Surveillance Standards 4.17 STEAM GENERATORS Aeolicability

' Applies to inservice inspection of the steam generator tubes.

Obiective To verify the operability and structural integrity of the tubing as part of the reactor coolant boundary.

Specification Each steam generator shall be demonstrated OPERABLE by performance of the following augmented inservice inspection program and the requirements of Specification 1.3.

4.17.1 Steam Generator Samole Selection and Insoection Steam generator tubing shall be demonstrated OPERABLE by selecting and inspecting steam generators as specified in Table 4.17-1.

4.17.2 Steam Generator Tube Samole Selection and Insoection The steam. generator tube minimum sample size, inspection result classification, and the corresponding action required shall be as specified in Table 4.17-2A. The inspection result classification and the corresponding action required for inspection of " specific limited areas" (see paragraph 4.17.2e) shall be as specified in Table 4.17-28. The inservice inspection of steam generator tubes shall be performed at the frequencies specified in Specification 4.17-3 and the inspected tubes shall be verified acceptable per the acceptance criteria of Specification 4.17.4. The tubes selected for these inspections shall include at least 3% of the total number of tubes in both steam generators and be selected on a random basis except:

a. If experience in similar plants with similar water chemistry indicates critical areas to be inspected, then at least 50% of the tubes-inspected shall be from these critical areas,

b. The first sample inspection during inservice inspection (subsequent to the first inservice inspection) of each steam generator shall include:

1. All tubes that previously had detectable wall penetrations

(>20%), that have not been plugged or sleeve repaired in the affected area,

2. All sleeves that previously had detectable wall penetrations (>20%) that have not been plugged, and Proposed Amendment No. 76, 134, Supplement 1 4-51 8905050251 890427 PDR ADOCK 05000312 P PDC

4- -

RANCHO SECO UNIT 1 TECHNICAL S W IFICATIONS Surveillance Standards 4.17.2 (continued)

3. Tubes in those areas where experience has indicated I potential problems,

c. The second and third sample inspections during each inservice inspection may be less than a full tube inspection by concentrating (selecting at least 50% of the tubes to be inspected) the inspection c.n those areas of the tube sheet array and on those portions of the' tubes where tubes with imperfections were previously found.

d. A tube inspection (pursuant to Specification 4.17.4.5) shall be performed on each selected tube. If any selected tube does not permit the passage of the eddy current probe for a tube inspection, this shall be recorded and an adjacent tube shall be selected and subjected to a tube inspection. (" Adjacent" is interpreted to mean the nearest tube capable of being inspected.) Tubes which do not permit passage of the eddy current probe will be considered as degraded tubes when classifying inspection results.

e. Tubes in specific limited areas which are distinguished by unique operating conditions and/or physical construction (for example, tubes adjacent to t'e open inspection lane or tubes whose 15th tube support plate hole is not broached but drilled) may be excluded from random samples if all such tubes in the specific area of a steam generator are inspected. No credit will be taken for these tubes in meeting minimum sample size requirements.

The results of each ample inspection shall be classified into one of the following three categories:

Cateaory Iningction Results C-1 Less than 5% of the total tubes inspected are degraded tubes and none of the inspected tubes are defective.

C-2 One or more tubes, but not more than 1% of the total tubes inspected are defective, or between 5% and 10% of the total tubes inspected are degraded tubes.

C-3 More than 10% of the total tubes inspected are degraded tubes or more than 1% of the inspected tubes are defective.

Note: In all inspections, previously degraded tubes must exhibit significant (>10%) further wall penetrations to be included in the above percentage calculations.

Proposed Amendment No. 76, 134, Supplement 1 4-52

ie RANCHO SECO UNIT 1

, . TECHNICAL SPECZF! CATIONS F

4.17.4 Acceotance Criteria Surveillance Standards

3. Egaraded Tube means a tube in the pressure boundary l

containing imperfections 120% of the nominal wall thickness caused by degradation.

4. Defect means an imperfection 140% of the nominal tube or sleeve wall-thickness. A tube or sleeve containing a defect in its pressure boundary is defective and shall either be plugged or repaired by sleeving.

5. Tube Insoection means an inspection of the steam generator tube from the point of entry completely to the point of exit (except as noted in 4.17.2c).

b. The steam generator shall be determined OPERABLE after completing the corresponding actions required by Table _4.17-2A (and Table 4.17-28 if provisions of paragraph 4.17.2e are utilized).

c. Each steam generator shall not have more than 5,000 tubes repaired by sleeving.

4.17.5 Reoorts

a. Following each inservice inspection of steam generator tubes, the number of tubes plugged or repaired in each steam generator l shall be reported to the Commission within 15 days.

b. The results of the steam generator tube inservice inspection shall be included in a Monthly Operating Report for the period in which this inspection was completed. This report shall include:

1. Number and extent of tubes inspected.

2. Location and percent of wall-thickness penetration for each indication of an imperfection.

3. Identification of tubes plugged.

c. Results if steam generator tube inspections which fall into Category C-3 and require notification of the Commission shall be reported pursuant to Specification 6.9.5P prior to resumption of plant operation. The written followup of this report shall provide a description of investigations conducted to determine cause of the tube de prevent recurrence. gradation and corrective measures taken to-4.!7.6 OTSG Auxiliary Feedwater Header Surveillance On the first refueling outage following the 1983 refueling outage,  !

and at the 10-year ISI, the following inspections will take place:

{

Proposed Amendment No. 76, 134, Supplement 1 4-54

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o RANCHO SECO UNIT 1 TECHNICAL SPECIFICATIONS Surveillance Standards 4.17.6 OTSG Auxiliary Feedwater Header Surveillance I

a. Visual inspections of the secured Internal Header, attachment welds and external headers thermal sleeves will be made through selected openings, and will be performed in such a manner that the known cracks in the Internal Header will be inspected.

b. Selected special interest peripheral tubes, designated in Table 4.17-3, will be Eddy Current inspected but shall not be considered a part of the Eddy Current inspection that is conducted pursuant to Technical Specification 4.17.1 through 4.17.5.

4.17.7 Insoection Acceotance Criteria and Corrective Actions a.

Video taped insprotions of the known cracks performed during the initial discovery will be compared with the crack configuration found during this surveillance. This comparison will crackall1w a determination to be made as to whether or not the hat, propagated,

b. If any inspected special interest peripheral tube indicates clearance (less than 1/4") or greater than 40% through wall indications, it will be plugged.  ;

4.17.8 Reoorts A report of these inspections will be prepared and incorporated in the subsequent Monthly Report to the NRC.

Bases The Surveillance Requirements for inspection of the steam generator tubes ensure that the structural integrity of this portion of the RCS will be maintained. The surveillance requirements of steam generator tubes are based on a modification of B&W - Standard Technical Specifications dated June 1, 1976. Inservice inspection of steam generator tubing is essential in order to maintain surveillance of the conditions of the tubes in the event that there is evidence of mechanical damage or progressive degradation due to design, manufacturing errors, or inservice conditions that lead to corrosion. Inservice inspection of steam generator tubing also provides a means of characterizing the nature and cause of any tube degradation so that corrective measures can be taken. The surveillance requirements for inspection of the steam generator tubes are applicable to all tubes, including those previously repaired by sleeving.

Proposed Amendment No. 76, 134, Supplement 1 i

4-55

3 RANCHO SECO UNIT 1 TECHNICAL SPECIFICATIONS Surveillance Standards Bases (Continued) i 1

Operational experience has shown that tube defects can be the result of unique operating conditions or physical arrangements in certain areas of the l steam generators. A full inspection of all of the tubes in such limited areas will provide complete assurance that degraded or defective tubes in f these areas are detected. {

Because no credit is taken for these distinctive tubes in the constitution of the first sample or its results, the requirements for the first sample are unchanged. This requirement is es'sentially equivalent to and meets the intent of the requirements set forth in NRC Regulatory Guide 1.83, Supplement 1 and doos not reduce the margin of )

safety provided by those requirements. )

Hastage-type defects are unlikely with AVT chemistry treatment of the secondary coolant.

However, even if a defect should develop in service, it will be found during scheduled inservice steam generator tube examinations.

Repair or plugging will be required for defective tubes. Steam generator tube inspections of operating plants have demonstrated the capability to l reliably thickness.

detect degradation that has penetrated 20% of the original tube wall Degraded steam generator tubes can be repaired by the installation of sleeves which span the area of degradation and serve as a replacement pressure boundary for the degraded portion of the tube, thus permitting the tube to remain in service. Total tube sleeving is limited to 5,000 tubes in each steam generator due to cumulative increased pressure drop through the steam generator tubes as more and more are sleeved. The methodology for sleeving is detailed in Babcock & Hilcox report BAH-1823P, Revision 1, "Once-Through Steam Generator Mechanical Sleeve Qualification."

Whenever the results of any steam generator tubing inservice inspection fall into Category C-3, these results will be reported to the Commission pursuant to Specification 6.9 prior to resumption of plant operation. Such cases will be considered by the Commission on a case-by-case basis and may result in a requirement for analysis, laboratory examinations, tests, additional eddy-current necessary.

inspection and revision of the Technical Specifications, if The visual and eddy current inspections provide the capability of determining the success of the internal aux feedwater header stabilization by monitoring the long term effects to tube integrity and crack propagation. The inspections will focus on known crack growth, new crack identification (if any), and tube effects in localized areas near the internal header brackets.

Additionally, visual inspection of the external header thermal sleeves will provide assurance th;t the new design header will not introduce additional problems by demonstrating sleeve integrity.

i Proposed Amendment No. 76, 134, Supplement 1 4-55a

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