ML20147E651

Proposed Tech Specs Modifying Specification 3.4.5 to Allow SG Tube Sleeving Using Framatome Process

ML20147E651
Person / Time
Site:	Beaver Valley
Issue date:	03/10/1997
From:	DUQUESNE LIGHT CO.
To:
Shared Package
ML20147E643	List: ML20147E637 ML20147E651
References
NUDOCS 9703180067
Download: ML20147E651 (12)

Text

. _.. _ _ _ _ _ _ _. _ _ _ _.. _. _ _.. _ _.. _ _ _ _ _ _ _ _ _ _

~

1 ATTACHMENT A-1 3

Beaver Valley Power Station, Unit No. 1 Proposed Technical Specification Change No. 242 i

.I j

The following is a list of the affected pages:

l Affected Pages:

3/4 4-10b a

i i

)

l 1

ii l

i i

i i

i I

t i

t l

1 i

4 i

i i

I i

1 l

i j

i ij 1

2 a

i e

i 9703180067 970310 ADOCKOSOOOg4

}

PDR P

4

.l r

.DPR-66 l

REACTOR COOLANT SYSTEM i

l' j

SURVEILLANCE REQUIREMENTS (Continued) a i

6.

Pluaaina or Renair Limit means the imperfection depth at or beyond which the tube shall be removed from service by plugging or repaired by sleeving in j

the affected area because it may become unserviceable prior to the next inspection.

The 4.

plugging or repair limit imperfection depths are specified in percentage of nominal wall thickness as

{

follows:

l a.

Original tube wall 40%

j This definition does not apply to tube support plate intersections for which the voltage-based i

repair criteria are being applied.

Refer to j

4.4.5.4.a.10 for the repair limit applicable to these intersections.

W h h m9 N... _&*Bl$$_& t* N h t Y.....***.Rf..

_M>$$

b.

l c.

Westinghouse laser welded sleeve wall 25%

i

.7.

Unserviceable describes the condition of a tube if j

it leaks or contains a defect large enough to affect j

its structural-integrity in the event of an Operating Basis Earthquake,

'a loss-of-coolant j

accident, or a steamline or feedwater line break as l-specified in 4.4.5.3.c, above.

i l

8.

Tube Insnaction 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 to the cold-leg.

i-l 9.

Tube Renair refers to sleeving which is used to maintain a tube in-service or return a tube to service.

This includes the removal of plugs that were installed as a

corrective or preventive i

measure.

The following sleeve designs have been found acceptable:

l-b kend e

l-7eckm0[03s'ta Ene,

a.

L.L eck Wil;;.

kin;ti

-;1d:d cle:Y :,

1

- gle&g7,ggg,

, 0;.U I C 4 7, Revisien 1 incl; ding kineti; ci;; c; M-hPAIN, tvfilm F"'*""

F"'"'"*""'

j' b.

Westinghouse laser welded sleeves, WCAP-13483, Revision 1.

j i

l-j j

I BEAVER VALLEY - UNIT 1 3/4 4-10b Amendment No.

Yfb)00CY &cYa r

a

,.-a a-

+

-,w--.,.

w

1 ATTACHMENT A-2 1

I Beaver Valley Power Station, Unit No. 2 i

Proposed Technical Specification Change No. 113 i

~

4 The following is a list of the affected pages:

Affected Pages:

3/4 4-14 3/4 4-14a 1

4 i

i i

b l

t i

i i

i I

i t

i i

1 l

l t

l 1

1 i

i I

i i

e i

1 1

i

.i l

I

NPF-73 REACTOR COOLANT SYSTEM

'URVEILLANCE REQUIREMENTS (Continued)

S 3.

A loss-of-coolant accident requiring actuation of the engineered safeguards, or 4.

A main steam line or feedwater line break.

4.4.5.4 Acceptance Criteria a.

As used in this Specification:

1.

Imoerfection means an exception to the dimensions, finish or contour of a tube or sleeve from that i

required by fabrication drawings or specifications.

Eddy-current testing indications below 20 percent of the nominal tube wall thickness, if detectable, may be considered as imperfections.

2.

Decradation means a service-induced cracking, wastage, wear or general corrosion occurring on either inside or outside of a tube or sleeve.

3.

Decraded Tube means a

tube or sleeve containing imperfections greater than or equal to 20 percent of the nominal wall thickness caused by degradation.

4.

Percent Dearadation means the percentage of the tube or sleeve wall thickness affected or removed by degradation.

5.

Defect means an imperfection of such severity that it exceeds the plugging or repair limit.

A tube containing a defect is defective.

Any tube which does not permit the passage of the eddy-current inspection probe shall be deemed a defective tube.

6.

Pluccina or ReDair Limit means the imperfection depth at or beyond which the tube shall be removed from service by plugging or repaired by sleeving in the af fected area because it may become unserviceable prior to the next inspection.

The plugging or repair limit imperfection depths are specified in percentage of nominal wall thickness as follows:

a.

Original tube wall 40%

Fu.efn Teobolusthfn,Ryta..g!qhg_9..// A6 b.

c.

Westinghouse laser welded sleeve wall 25%

14 Amendment No.

BEAVER VALLEY - UNIT 2 3/4 YM$0C00tj 00Yih

MPF-73 REACTOR COOLANT SYSTEM i

SURVEILLANCE REQUIREMENTS (Continued) 7.

Unserviceable describes the condition of a tube if it leaks or contains a defect large enough to affect its i

structural integrity in the event of an Operating Basis Earthquake, a loss-of-coolant accident, or a steam line t

or feedwater line break as specified in 4.4.5.3.c, above.

8.

Tube Insoection means an inspection of the steam generator tube from the point of e'ntry (hot leg side) completely around the U-bend to the top support to the cold leg.

9.

Tube Reoair refers to sleeving which is used to maintain a tube in-service or return a tube to service.

This includes the removal of plugs that were installed as a corrective or preventive measure.

The following i

sleeve designs have been found acceptable:

f/s.ul2hd.

Tkck ne 51 h c..

E 05

??.$b

> ? ?

5 ? ??'

E/eefnelesut r " M 7 ',Z :. '

._"_'.~l' ".2 _'.~..". A, ^ " T '_-' ' "' _'l- ".' "_1 - : : :

---

.~

c------

c-84ki-ML/4P,$0n S /

l b)

Westinghouse laser welded sleeves, WCAP-13483, Revision 1.

l b.

The steam generator shall be determined OPERABLE after completing the corresponding actions (plug or repair all tubes exceeding the plugging c'1 repair limit) required by Table 4.4-2.

4.4.5.5 Recorts a.

Within 15 days following the completion of each inservice inspection of steam generator tubes, the number of tubes plugged or repaired in each steam generator shall be reported to the Commission in a Special Report pursuant to Specification 6.9.2.

The complete results of the steam generator tube and sleeve b.

inservice inspection shall be submitted to the commission in a Special Report pursuant to Specification 6.9.2 within 12 months following the completion of the inspection.

This Special Report shall include:

1.

Number and extent of tubes and sleeves inspected.

2.

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

3.

Identification of tubes plugged or repaired.

BEAVER VALLEY - UNIT 2 3/4 4-14a Amendment No.

lWlek kl0tkI

4 ATTACHMENT B Beaver Valley Power Station, Unit Nos. 1 and 2 Proposed Technical Specification Change Nos. 242 and 113 FRAMATOME ELECTROSLEEVES P

A.

DESCRIPTION OF AMENDMENT REQUEST The proposed amendment would revise Technical Specification 3.4.5,

" Steam Generators," and associated Bases to allow repair of steam generator tubes by installation of sleeves with the Electrosleeving process developed by Framatome Technologies Inc.

j (FTI).

The option to use the B&W kinetic welded sleeves is being deleted in proposed Technical Specification Change 237 and 111.

B.

BACKGROUND Pressurized water reactor steam generators have experienced tube degradation related to corrosion phenomena such as

wastage, pitting, intergranular attack, stress corrosion cracking and crevice corrosion along with other phenomena such as denting and vibration wear.

Tubes that experience excessive degradation reduce the integrity of the primary-to-secondary pressure boundary.

These tubes are considered defective and must be repaired or plugged and removed from service.

The installation of steam generator tube plugs removes the heat transfer surface of the plugged tube from service and leads to a reduction in the primary coolant flow available for core cooling.

Sleeving is a steam generator tube repair method which was incorporated into the technical specifications by Amendments 173 and 176 for Unit 1 and 52 and 56 for Unit 2.

These amendments allowed the use of the B&W kinetic welded sleeves along with the Westinghouse laser welded sleeves.

Sleeving technology has been enhanced with the introduction of the FTI Electrosleeving process.

The option to use this sleeving method is requested to provide an additional option for use in maintaining the operability of the steam generators.

C.

JUSTIFICATION The sleeves will be installed in accordance with the process provided by the vendor and described in the associated reports which address sleeve design, qualification, installation methods, non-destructive examination and ALARA considerations.

The FTI sleeving process is described in a letter (Topical Report BAW-

10219P, Rev.

1, "Electrosleeving Qualification for PWR Recirculating Steam Generator Tube Repair," March 1996) from J.

H.

Taylor, Framatome Technologies, Inc. to K.

R.

Wichman, NRC 4

dated March 26, 1996.

e D.

SAFETY ANALYSIS Electrosleeves have been designed and qualified to Section III, Subsection NB-3300 of the 1989 Edition of the ASME Code and applicable code cases.

Fatigue and stress analyses of the

ATTACHMENT B, continusd Proposed Technical Specification Change Nos. 242 and 113 j

Page 2 4

i Electrosleeved tube assemblies have been completed in accordance with the requirements of Section III, subsection NB-3200 of the 1989 Edition of the ASME Code.

The results of the primary stress intensity range evaluation, primary plus secondary stress intensity range evaluation and fatigue evaluation indicate that the ASME Code allowable limits are not exceeded.

That is, stress intensities are bounded by the minimum limits for the Electrosleeve material and cumulative fatigue usage is less than 1.0.

Therefore, the design of the Electrosleeve pressure j

boundary meets the design objectives of the original tubing.

1 Regulatory Guide 1.121,

" Bases for Plugging Degraded PWR Steam Generator Tubes" and the ASME Code are used to develop the

~

plugging limit of the Electrosleeve should Electrosleeve end-of-cycle wall degradation occur.

Potentially degraded i

Electrosleeves are shown (by test and analysis) to retain burst strength in excess of three times the normal operating pressure differential at end-of-cycle conditions.

No credit for the presence of the parent tube behind the Electrosleeve is conservatively assumed when performing the minimum wall / burst s

i evaluation.

j The Electrosleeve structural analysis utilizes a generic set of design and transient loading inputs that bound Westinghouse steam

]

generator operating conditions.

An ultrasonic inspection of the Electrosleeve is performed prior j

to placing the Electrosleeve in service to verify correct Electrosleeve position, proper Electrosleeve to tube bonding, i

minimum acceptable Electrosleeve thickness is achieved and to provide a baseline inspection of the pressure boundary.

The i

loading cycles that are applied to the Electrosleeve analysis and testing are those for a 40 year plant life cycle.

The results of i

the fatigue analysis indicate acceptable usage factors for the entire range of permitted Electrosleeve thickness.

i Any combination of Electrosleeving and plugging is acceptable up to a level such that the effect will not reduce the minimum i

reactor coolant flow rate below the current technical specification limit or below the plugging limits analyzed in the Updated Final Safety Analysis Report.

The Electrosleeve/ plug equivalency results are contained in FTI Topical Report BAW-10219P, Revision 1.

J Leakage testing of 3/4" Electrosleeve assemblies under conditions j

considered to be more severe than expected during all operating i

plant conditions has shown that Electrosleeving does not l

introduce additional primary-to-secondary leakage during a

postulated steamline break event.

Electrosleeves, with 30%

through-wall axial Electrode Discharge Machining (EDM) notches 1" i

long, were subjected to internal pressure cycles at differentialc up to 3,429 psi which far exceeds the expected maximum feed line break or steamline break pressure differential.

Burst testing 3

i B-2 I

_ _._ 7.. _ _. _ ~ _

j

j. -

ATTACHMENT B, continutd Proposed Technical Specification Change Nos. 242 and 113 r

j Page 3 I,

3 7/8" Electrosleeve assemblies with 50% through-wall axial EDM notches 3/4" long resulted in burst pressures of 6600 psi.

1 Leakage testing has also shown that the Electrosleeve is leaktight during all plant conditions.

1 Electric Power Research Institute (EPRI) Report TR-105960 "PWR i

Steam Generator Sleeving Assessment Document" identifles the following degraded sleeving experiences due to corrosion:

Stress Corrosion Cracking in the parent tube material due to j

high residual stress attributed to the sleeving installation

process, i

The above mentioned EPRI report states that tensile residual stresses above 40 kai may cause Alloy 600 tubing to be j

susceptible to Pressurized Water Stress Corrosion Cracking.

For the secondary side in which a crevice or sludge pile exists, the t

i threshold for Stress corrosion Cracking may only be 25 ksi.

The

}

Electrosleeving installation process has the following beneficial advantages-concerning residual stress:

I Residual stresses.in the parent Alloy 600 material are mostly.

compressive in nature.

With a locked support plate, the field

{

stresses are approximately 3.2 ksi.

)

i e A thin Nickel Layer extends approximately 1/2" beyond the 1

deposited Electrosleeve which helps to protect the parent j

material from stress corrosion cracking at the Electrosleeve-

~

to-base-metal transition.

The Electrosleeving process effectively eliminates crevices associated with. conventional sleeving processes, with the exception of a through wall defect in the parent tubing material.

l When the tubing material is properly cleaned to remove oxides, i

the nickel strike layer and Electrosleeve deposition form a metallurgical bond with the tube material.

This metallurgical bond eliminates the crevices between the Electrosleeve and tube

}

material.

In the Electrosleeve Qualification Program, corrosion tests in both primary and secondary environment indicated that general -

corrosion, crevice corrosion, pitting, Stress Corrosion Cracking or Intergranular Attack (IGA) of the Electrosleeve material is l

not a concern in PWR environments.

Electrosleeve degradation can be detected by nondestructive examination (NDE).

Mechanical testing of 3/4" Electrosleeves indicates that the axial load bearing capability exceeds the most limiting pressure end cap loading established by Regulatory Guide 1.121.

The Electrosleeve structural integrity requirements include safety factors inherent to the requirements of the ASME Code.

L i

B-3

.- -~

1 e

ATTACHMENT B, continusd Proposed Technical Specification Change Nos. 242 and 113 Page 4 Installation of Electrosleeves restores the integrity of the primary pressure boundary and the tube is leaktight.

The Electrosleeve installation requirements applicable to active

tubes, which have been identifled as containing degradation L

indications exceeding the repair limit are no different for the Electrosleeving of previously plugged tubes.

A new " baseline" inspection of the entire tube length must be performed prior to Electrosleeve installation in a previously plugged tube.

Conclusion Based on the Regulatory Guide 1.121 guidelines for tube L

deoradation

limits, appropriate plugging limits -have been established.

Ultrasonic techniques are available to perforr necessary sleeve and tubc inspections for defect detection and to verify proper installation of the sleeve.

Available techniques are capable of providing adequate defect sensitivity in the required areas of the tube and sleeve pressure boundary.

Proprietary methods described in the vendor reports-with supporting qualification data demonstrate the inspectability of the sleeve and underlying tube.

In addition, we are committire to qualify the adequacy of any system that is used for periodis inservice inspection and to evaluate and, if practical, implement better testing methods as they are developed and qualified for use.

E.

NO SIGNIFICANT HAZARDS EVALUATION l

The no significant hazard considerations involved with the proposed amendment have been evaluated, focusing on the three standards.tet forth in 10 CFR 50.92(c) as quoted below:

The Commission. may make a final determination, pursuant to the procedures in paragraph 50.91, that a proposed amendment to an operating license for a

facility licensed under paragraph 50.21(b) or paragraph 50.22 or for a

testing facility involves no significant hazards consideration, if operation of the facility in accordance with the. proposed amendment would not:

(1)

Involve a significant increase in the probability or consequences of an accident previously evaluated; or (2)

Create the possibility of a new or different kind of l

accident from any accident previously evaluated; or (3)

Involve a significant reduction in a margin of safety.

o l.

The following evaluation is provided for the no significant

'ha Trds consideration standards.

-B-4 l

.-(.

_ - --~

ATTACHMENT B, continusd Proposed Technical Specification Change Nos. 242 and 113 Page 5 e

{

1.

Does the change involve a

significant increase in the l

probability or consequences of an accident previously evaluated?

The Electrosleeve configuration has been designed and analyzed in accordance with the requirements of the ASME i

Code.

The applied stresses and fatigue usage for the j

Electrosleeve are bounded by the limits established in the t.

ASME Code.

Minimum material property values are used for the structural. and plugging limit analysis.

Mechanical testing i

has shown that the structural strength of nickel j

Electrosleeves under normal, upset, and faulted conditions provides margin to the acceptance limits.

These acceptance i

lim ns bound the most limiting (3 times normal operating pressure differenticl) burst margin recommended by Regulatory Guide 1.121.

Leakage testing has shown that the Electrosleeve is essentially leaktight during all plant j

conditions.

~

The Electrosleeve nominal wall thickness depth-based plugging limit is determined using the guidance of Regulatory Guide i

1.121 and the pressure stress equation of Section III of the j

ASME - Code.

The limiting requirement of Regulatory Guide i

1.121 for the Electrosleeve, which applies to part through I

wall degradation, is the minimum acceptable wall thickness to j

maintain a nafety factor of three against tube failure under normal operating conditions.

A bounding set of design and j

transient' loading input conditions was used for the minimum j

wall thickness evaluation in the generic evaluation.

Evaluation of the minimum acceptable wall thickness for normal, upset and postulated accident condition loading per the ASME Code indicates these conditions are bounded by the design minimum wall thickness.

Bounding tube wall degradation growth rate per cycle and nondestructive examination uncertainty has been assumd for determining the Electrosleeve technical specification plugging limit.

Electrosleeve wall degradation extent determined by nonoastructive examination, which would require plugging Electrosleeved

tubes, is developed using the guidance of Regulatory Guide 1.121 and is defined in FTI Topical Report BAW-10219P, Revision 1, to be 20% throughwall of the nominal sleeve wall thickness.

The effect of Electrosleeving and plugging will remain below the plugging limit assumed in the UFSAR.

The proposed change will not increase the consequences of these accidents.

The results of the analyses and testing demonstrate that the Electroslerve is an acceptable means of maintaining tube integrity.

Further, per Regulatory Guide 1.83 recommendations, the Electrosleeved tube can be monitored B-5

ATTACHMENT B, continusd Proposed Technical Specification Change Nos. 242 and 113 Page 6.

through periodic inspections with present 3DE techniques.

These measures demonstrate that installation of Electrosleeves spanning degraded areas of the tube will restore the tube to a condition consistent with its original design basis.

Since the main steamline break post-accident primary-to-secondary leakage is not increased by the presence of Electrosleeves, the consequences of an accident previously evaluated in the UFSAR are not increased.

Conformance of the Electrosleeve design with the applicable sections of the ASME Code and results of the leakage and mechanical tests support the conclusion that installation of Electrosleeves does not increase the probability or consequences of an accident previously evaluated.

2.

Does the change create the possibility of a new or different kind of accident from any accident previously evaluated?

Electrosleeving will not adversely affect any plant component.

Stress and. f atigue analysis of the repair has shown that the ASME Code and Regulatory Guide 1.121 criteria are not exceeded.

Implementation of Electrosleeving maintains overall tube bundle structural and leakage integrity at a level consistent with that of the original tubing during all plant conditions.

Leak and mechanical testing of Electrosleeves support the conclusions of the calculations that each Electrosleeve retains both structural and leakage integrity during all conditions.

Electrosleeving of tubes does not provide a mechanism resulting in an accident outside of the area affected by the Electrosleeves.

Any accident resulting from potential tube or Electrosleeve degradation in the repaired portion of the tube is bounded by the existing tube rupture accident analysis.

Implementation of Electrosleeving will reduce the potential for primary-to-secondary leakage while not significantly impacting available primary coolant flow area in the event of i

a LOCA.

By effectively isolating degraded areas of the tube through repair, the potential for steamline break leakage is reduced.

These degraded intersections now are returned to a condition consistent with the Design Basis.

While the I

installation of an Electrosleeve reduces primary coolant flow, the reduction is far below that caused by plugging.

Greater primary coolant flow area is maintained through Electrosleeving versus plugging.

Therefore, the possibility of a new or diflTrent kind of accident from any accident previously evaluatad is not created, i

i B-6 i

)

A j

. ATTACHMENT B, continusd Proposed Technical Specification Change Nos. 242 and 113 Fage 7.

i 3.

Does the change involve a significant reduction in a margin of safety?

The Electrosleeve repair of degraded steam generator tubes has been shown by analysis to restore the integrity of the tube bundle consistent with its original design basis condition.

The tube /Electrosleeve operational and faulted condition stresses are bounded by the ASME Code requirements and the Electrosleeved tubes are leaktight.

The safety factors used in the design of Electrosleeves for the repair of degraded tubes are consistent with the safety factors in the ASME Code used in steam generator design.

The portions of the installed Electrosleeve assembly which represent the reactor coolant pressure boundary can be monitored for the initiation and progression of Electrosleeve/ tube wall degradation, thus satisfying the requirements of Regulatory Guide 1.83.

The portion of the tube bridged by the Electrosleeve is effectively removed from the pressure boundary, and the Electrosleeve then forms the new pressure boundary.

The areas of the Electrosleeved tube assembly which require inspection are defined in Framatome Technologies Inc. Topical Report BAW-10219P, Revisica 1.

j In addition, since the in~talled Electrosleeve represents a s

portion of the pressure boundary,. a baseline inspection of these areas is required prior to-operation with Electrosleeves installed.

The effect of sleeving on the design transients and accident analyses has been reviewed based on the installation of Electrosleeves up to the level of-steam generator tube plugging coincident with the minimum reactor coolant flow rate and UFSAR and has been found acceptable.

It is concluded that the proposed license amendment request does not result in a significant reduction in the margin of safety as defined in the UFSAR or technical specifications.

F.

NO SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION Based on the considerations expressed above, it is cc7cluded that the activities associated with this license amendment request satisfy the no significant hazards consideration standards of 10 CFR 50.92(c)

and, accordingly, a

no significant. hazards considerstion finding is justified.

I B-7 J