ML20082M828

Proposed Tech Specs,Eliminating L* SG Tube Repair Criteria

ML20082M828
Person / Time
Site:	Prairie Island
Issue date:	04/20/1995
From:	NORTHERN STATES POWER CO.
To:
Shared Package
ML20082M815	List: ML20082M809 ML20082M818 ML20082M828
References
NUDOCS 9504240387
Download: ML20082M828 (6)

Text

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.. l Attachment  !

April 20, 1995 Revision to License Amendment Request Dated January 9,1995 j Revised Technical Specification Pages i

Attachment contains revised Prairie Island Nuclear Generating Plant Technical i Specification pages with the original proposed changes and all revisions incorporated. The revised pages are listed below: ,

TS.4.12-2 f TS.4.12-4 TS.4.12-5 B.4.12-2 B.4.12-3 i

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9504240387 950420 PDR P

ADOCK 05000282 ,

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• • TS.4.12-2  !

REV I

2. The first sample of tubes selected for each in-service inspec-tion (subsequent to the preservice inspection) of each steam generator shall include-(a) All tubes that previously had detectable wall penetrations

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

affected area.  !

(b) Tubes in those areas where experience has indicated  !

potential problems.

(c) A tube inspection (pursuant to Specification 4.12.D.1.(h)) i i

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 l inspection.

3. In addition to the sample required in Specification 4.12.B.2.a  ;

through c, all tubes which have had the F* criteria applied will be inspected in the F* regions of the roll expanded region. The ;

roll expanded region of these tubes may be excluded from the-requirements of 4.12.B.2.a. ,

4. The tubes selected as the second and third samples (if required i by Table TS.4.12-1) during each inservice inspection may be j subjected to a partial tube inspection provided:

i (a) The tubes selected for these samples include - the tubes .

from those areas of the tube sheet array where tubes with l imperfections were previously found.  :

I (b) The inspections include those portions of the tubes where l imperfections were previously found, j The results of each sample inspection shall be classified into one  !

of the following three categories:  !

Category Inspection Results {

C-1 Less than 5% of the total tubes inspected are degraded j tubes and none of the inspected tubes are defective. j i

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. l t

C-3 More than 10% of the total tubes inspected are degraded tubes or more that 1% of the inspected tubes f are defective. l Note: In all inspections, previously degraded tubes must [

exhibit significant (>10%) further wall penetrations to i be included in the above percentage calculations, i 5

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.. TS.4.12-4 l REV j

~l D. Acceptance Criteria j

1. As used in this Specification:

J (a) Imperfection means an exception to the dimensions, finish or contour of a tube from that required by fabrication '

drawings or specifications. Eddy-current testing indica-tions below 20% of tbo nominal tube wall thickness, if detectable, may be considered as imperfections. '

(b) Derradation means a service-induced cracking, wastage, wear or general corrosion occurring on either inside or outside of a tube.

(c) Derraded Tube means a tube containing imperfections 220%

of the nominal wall thickness caused by degradation. ,

(d)  % Derradation means the percentage of the tube wall thickness affected or removed by degradation.

(e) Defect means an imperfection of such severity that it exceeds  !

the repair limit. A tube containing a defect is defective.  !

(f) Repair Limit means the imperfection depth at or beyond  !

which the tube shall be removed from service by plugging or repaired by sleeving because it may become unserviceable prior to the next inspection and is equal to 50% of the nominal tube wall thickness. If significant general tube thinning occurs, this criteria will be reduced to 40% wall penetration. This definition does not apply to the portion of ,

the tube in the tubesheet below the F* distance provided the tube is not degraded (i.e., no indications of cracks) within the .

F* distance for F* tubes. 1 i

(g) Unserviceable describes the condition of a tube if it leaks or contains a defect large enough to affect its structural integrity in the event of an Operating Basis Earthquake, a '

loss-of-coolant accident, or a steam line or feedwater line break. -

(h) Tube Inspection means an inspection of the steam generator tube from the point of entry (hot leg side) completely around the U-bend to the top support of the cold leg.

i (i) Sleeving means that tube sleeving is permitted only in areas l where the sleeve cpans the tubesheet area and whose lower joint  ;

is at the primary fluid tubesheet face.

(j) F* Distance is the distance from the bottom of the hardroll transition toward the bottom of the tubesheet that has been  !

conservatively determined to be 1.07 inches (not including eddy ,

current uncertainty).

(k) F* Tube is a tube with degradation, below the F* distance, equal to or greater than 40%, and not degraded (i.e., no indications of cracking) within the F* distance.

.- TS.4.12-5  ;

' REV ,

2. The steam generator shall be determined OPERABLE after completing the corresponding actions (plug or repair by sleeving all tubes }

exceeding the repair limit and all tubes containing through-wall cracks or classify as F* tubes) required by Table TS.4.12-1. l E. Reports

1. Following each in-service inspection of steam generator tubes, l if there are any tubes requirin6 plugging or sleeving, the number of tubes plugged or sleeved in each steam generator  !

shall be reported to the Commission within 15' days. [

2. The results of steam generator tube inservice inspections shall be included with the summary reports of ASME Code Section XI inspections submitted within 90 days of the end of each refueling outage. Results of steam generator tube ,

inservice inspections not associated with a refueling outage shall be submitted within 90 days of the completion of the ,

inspection. These reports shall include: (1) number and extent of tubes inspected, (2) location and percent of wall-I thickness penetration for each indication of an imperfection and (3) identification of tubes plugged or sleeved. t

3. Results of steam generator tube inspections which fall into l Category C-3 require notification to the Commission prior to  ;

resumption of plant operation, and reporting as a special  ;

report to the Commission within 30 days. This special report j shall provide a description of investigations conducted to <

determine cause of the tube degradation and corrective measures 1 taken to prevent recurrence.

4 The results of inspections performed under Specification 4.12.B for all tubes that have defects below the F* distance, and were not-plugged, shall be reported to the Commission within 15 days following the inspection. The report shall include:

1. Identification of F* tubes, and u

2. Location and extent of degradation.

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B.4.12-2 REV 4.12 STEAM GENERATOR TUBE SURVEILLANCE Bases continued plants have demonstrated the capability to reliably detect wastage type defects that have penetrated 20% of the original 0.050-inch wall thickness (Reference 2).

Plugging or sleeving is not required for tubes meeting the F* criteria.

The F* distance will be controlled by a combination of eddy current inspection and/or process control. For a new additional roll expansion, the requirement will be at least 1.2 inches of new hard roll. This is controlled by the length of the rollers (1.25 inch effective length).

The distance from the original roll transition zone is also controlled by the process in that the lower end of the new roll expansion is located one inch above the original roll expansion. In the case of the new roll, eddy current examination will confirm there are no indications in the new roll region and that there is a new roll region with well defined upper and lower expansion transitions.

When eddy current examination, alone, must determine the F* distance, such as in the existing hard roll region, or when multiple lengths of additional hard rolls have been added, the eddy current uncertainty is qualified by testing against known standards. That value is expected to be 0.18 inches. Therefore, the F* distance measured by eddy current (sum of 1.07 and 0.18) will be conservatively set at 1.3 inches.

When more than one Alternate Repair Criteria are used, the summation of leakage from all tubes left in service by all repair criteria must be less than the allowable leakage for the most limiting of those Alternate ,

Repair Criteria.

Whenever the results of any steam generator tubing in-service inspection fall into Category C-3, these results will be promptly reported to the Commission 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 inspection, and revision of the Technical Specifications, if necessary.

Degraded steam generator tubes may be repaired by the installation of sleeves which span the section of degraded steam generator tubing. A steam generator tube with a sleeve installed meets the structural requirements of tubes which are not degraded.

The following sleeve designs have been found acceptable by the NRC Staff;

a. Westinghouse Mechanical Sleeves (WCAP 10757)

b. Westinghouse Brazed Sleeves (WCAP-10820) j l

c. Combustion Engineering Leak Tight Sleeves (CEN-294-P) I I

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,. e . B.4.12-3 .

REV.

4.12 STEAM CENERATOR TUBE SURVEILIANCJ - l Bases ~ continued I i

t Descriptions of other future sleeve designs shall be submitted to the l NRC for review and approval prior to their use.in the repair of degraded steam generator tubes. The submittals related to other sleeve designs  !

shall be made at least 90 days prior to use. l p

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i References  !

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1. Testimony of J Knight in the Prairie Island Public Hearing on ,

1/28/75 }

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2. Testimony of L Frank in the Prairie Island Public Hearing on [

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