1CAN049803, Application for Amend to License DPR-51,allowing Upper Tubesheet Volumetric Indications to Remain in Svc for Cycle 15,as Discussed W/Nrc on 980318 & 26
| ML20217P788 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 04/01/1998 |
| From: | Hutchinson C ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20217P792 | List: |
| References | |
| 1CAN049803, 1CAN49803, NUDOCS 9804100194 | |
| Download: ML20217P788 (32) | |
Text
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l- En y opettions, inc.
RusseMa AR 72801
,. .- vc wsaa cn sotchin.on awm ue April 1,1998 1CAN049803 U. S. Nuclear Regulatory Commission Do- Control Desk Mail Station OPI-17 Washington, DC 20555 l
Subject:
Arkansas Nuclear One - Unit 1 Dccket No. 50-313 License No. DPR-51 Emergency Technical Specification Change Allowing Upper Tubesheet Volumetric Indications to Remain in Service for Cycle 15 Gentlemen-As discussed with the NRC staff on March 18 and March 26,1998, attached for your review and approval is a proposed amendment to the Arkansas Nuclear One Unit 1 (ANO-1)-
Technical Specifications. This amendment will allow approximately 440 steam generator tubes with confirmed volumetric indications within the upper tubesheet to remain in service during Cycle 15. ANO-1 began its fourteenth refueling outage (IR14) on March 28,1998.
Steam generator inservice inspections and testing will be completed on or about April 9,1998.
At this time, the proper disposition of the upper tubesheet outer diameter intergranular attack indications will be required. The current ANO-1 technical specifications require plugging or sleeving of the tubes containing these indications. Bued upon studies conducted to date and additional in-situ pressure / load testing planned for tlw 1R14 outage, Entergy Operations will demonstrate that the upper tubesheet volumetric indications do not represent an =m>ptable risk to public health and safety and therefore, may remain in service during Cycle 15. Due to the immediate need for this amendment, it is requested that this amendment request be processed under the emergency provision described in 10CFR50.91(a)(5). The justification for processing this change as an emergency request is provided in the attachment The proposed change has been evaluated in accordance with 10CFR50.91(a)(1) using criteria in 10CFR50.92(c) and it has been determined that this chage involves no significant hazards considerations. The bases for these determinations are included in the attached submittal.
Entergy Operations requests that the effective date for this change be upon issuance
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, U. S. NRC l April 1,1998 1CAN049803 Page 2 l
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CRH/jjd attachment To the best of my knowledge and belief, the statements contained in this submittal are true.
SUBSCRIBED AND SWORN TO before me, a Nota Publicin and for M/
County and the State of MS , this / day of (M__,1998.
0 0JLL /Y }
Notary Public 88amyPekauhdthduggiAstage l My Commission Expkas "n e Yew *a.m.n 6 Y Z l cc: Mr. Ellis W. Merschoff Regional Administrator U. S. Nuclear Regulatory Commission Region IV 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011-8064 NRC Senior Resident Inspector Arkansas Nuclear One P.O. Box 310 London, AR 72847 Mr. William D. Reckley NRR Project Manager Region IV/ANO-1 & 2 U. S. Nuclear Regulatory Commission NRR Mail Stop 13-H-3 One White Flint North 11555 Rockville Pike Rockville, MD 20852 l Mr. David D. Snellings !
Director, Division of Radiation i Control and Emergency Management Arkansas Department of Health 4815 West Markham Street Little Rock, AR 72205 i l
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ATTACHMENT TR ICAN049803 PROPOSED TECHNICAL SPECIFICATION AND RESPECTIVE SAFETY ANALYSES IN TIE MATTER OF AMENDING LICENSE NO. DPR-51 ENTERGY OPERATIONS. INC.
ARKANSAS NUCLEAR ONE. UNIT ONE DOCKET NO. 50-313 l
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[. . . _ __
r Attachment to ICAN049803 Page1of28 DESCRIPTION OF PROPOSED CHANQES E Arkansas Nuclear One, Unit 1 (ANO-1), Technical Specification (TS) 3.1.6.3.b is revised to lower the leakage limit through any one steam generator to less than 150 gallons per day (0.104 gpm) from the current limit of 500 gallons per day (0.347 gpm). The 500 gallons per day limit was reduced in the current technical specification to 144 gallons per day (0.1 gpm) for the remainder of Cycle 14. This temporary reduction was associated with Amendment 189 to the ANO-1 TSs.
ANO-1 TS 4.18.5.b is revised to allow outer diameter intergranular attack (ODIGA) between the roll transition and 2.75 inches above the upper tubesheet (UTS) secondary face to remain in service for Cycle 15. Four criteria for leav?ng ODIGA in service are added:
1 1) 100% of the unsleeved tubes are examined by bobbin coil eddy current in the UTS region l during the fourteenth refteling outage (IR14),
l L 2) Bobbin coil indications are examined by rotating pancake coil (RPC) eddy current and confirmed to be volumetric,
- 3) A comparison shall be made between the bobbin coil voltage measured during IR13 for the confirmed indications and the bobbin coil voltage for the same indications measured during IR14. The comparison shall confirm essentially no ine: case in voltage on average, and l
l 4) In-situ pressure / load testing in the "A" steam generator (SG) during IR14 confirms, at a 95% confidence level, that the bounding accident leakage due to volumetric ODIGA flaws within the UTS will be less than 0.5 gallon per minute due to a main steam line break (MSLB).
BACKGROUND The inservice inspection of the ANO-1 SGs is conducted in accordance with ANO-1 TS 4.18.
Specification 4.18.2 states: " Inservice inspection of steam generator tubing shall include non-destructive examination by eddy-current testing or other equivalent techniques." Specification l
4.18.3 requires that a minimum sample size be examined in accordance with specification 4.18.5. Specification 4.18.5.b. notes: "The steam generator shall be determined operable after completing the corresponding actions (plug or sleeve all tubes exceeding the plugging limit and all tubes containing through-wall cracks) required by Table 4.18-2." Table 4.18-2 specifies the expansion criteria for sampling of the steam generator tubes and requires
" defective" tubes to be plugged or sleeved. Specification 4.18.5 defines Defect as: "an imperfection of such severity that it exceeds the plugging limit except where the imperfection has been spanned by the installation of a sleeve. A tube containing a defect in its pressure boundary is defective." Plungina Limit is defined in the same specification as: "the imperfection depth at or beyond which the tube shall be restored to serviceability by the 1
.. AtMehment to ICAN049803 Page 2 0f 28 installation of a sleeve or removed from service because it may become unserviceable prior to 4 the next inspection; it is equal to 40% of the nortdfW1 tube wall thickness "
The bases for specification 4.18 states: "The surveillance requirements for inspection of the steam generator tubes ensure that the structural integrity of this portion of the RCS will be l maintained."
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! ODIGA is known to be present above the 15th tube support plate (TSP) within the ANO-1 once through steam generators (OTSGs), as verified by destructive examination from previous tube pulls. ODIGA is a damage mechanism caused by corrosion of the material grain l boundaries. The corrosion resulted from contaminants introduced on the tubing during the early years of plant operation. The contaminant causing ODIGA of the ANO-1 tubing is
- sulfur as a result of thermal decomposition ofion exchange resins. The ANO-1 ODIGA can i be categorized as volumetric or " patch-like," with no specific orientation. Since discovery, there has been no evidence ofleakage from ODIGA flaws at ANO-1.
During the IR13 refueling outage, an eddy current technique was employed to deptn-size the ODIGA. This technique was qualified per revision 4 to Appendix H of the Electric Power Research Institute (EPRI) "PWR Steam Generator Tube Examination Guidelines."
l Compliance with the EPRI guideline was considered an acceptable method to qualify non-l destructive examination (NDE) techniques for the detection and sizing of damage mechanisms. This technique was used to depth-size ODIGA flaws within the UTS. During this inspection, greater than 25% of the indications detected within the UTS region by the bobbin coil examination technique were exar6ed using the RPC technique to characterize these flaws. UTS ODIGA indications with a depth size of >40% through-wall (TW), as determined by the qualified sizing technique, were removed from service by plugging during this inspection.
- During IR13, three tubes with ODIGA bobbin indications within the UTS (and subsequent RPC confirmation) were removed from the "B" steam generator. Two of the three tubes contained flaws that would have required repair. The third tube was near the repair limit and may have been preventively repaired. The tubes were selected because they contained multiple indications with depths representative of the average indication depths as sized by eddy current. The tubes were burst in the laboratory without the presence of a tubesheet. All three tubes burst at approximately 10,000 psi, only slightly below virgin tt.be burst pressure.
'- After bursting the tubes, the flaws were examined and sized. If a flaw was not opened by the
. burst of the tube, it was bent open for destructive examination (DE). The DE results were not consistent with the corresponding eddy current (EC) depth measurements. The reason for the inconsistency in sizing ODIGA in the UTS is indeterminate. As a result of this condition, it is possible that tubes were left in service with through-wall defects greater than the technical l specification plugging limit.
When non-compliance was determined at 2012 CDT on April 8,1997, the time clock for TS 4.0.3 was entered allowing 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to seek regulatory relief. Entergy Operations verbally requested notification of enforcement discretion at 1400 CDT on April 9,1997. Verbal l
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- Attyh' - *to 1CAN049803 Page 3 of 28 l
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. . approval of this enforcement discretion request was received at 1535 CDT on April 9,1997.
. This discretion was in effect until May 7,1997, or until the NRC staff acted on a proposed technical speci5 cation change request to be submitted by Entergy Operations, whichever occurred Srst.
j Entergy Operations submitted an exigent TS change on April 11,1997 (ICAN049703), to l allow a one time exception to the surveillance requirements of Section 4.18.5.b. This :
l exception allowed tubes with ODIGA indications within the upper tube sheet with potential through-wall depths greater than '.he plugging limit to remain in service for the remainder of l Cycle 14. The April 11, 1997, submittal was supplemented on May 2,1997, by letter l ICAN059702 which reduced the leakage limit through the steam generator tubes from 500 l gallons per day (gpd) to 144 gpd for the remainder of Cycle 14. In response to this request, the NRC issued Amendment No.189 to the ANO-1 license dated May 7,1997. This amendment allowed the unit to continue operation through the remainder of Cycle 14 with i
tubes that had potential through-wall defects in excess of the 40% plugging limit. l
! Prior to IR13, the Babcock and Wilcox Owners Group (B&WOG) was working on the
! development of an alternate repair criteria (ARC) for volumetric ODIGA flaws anywhere in
- the OTSG. In response to the events at ANO-1, the B&WOG expedited its schedule and l focused its initial work on volumetric ODIGA indications within the tubesheet. The B&WOG l plans were discussed with the NRC in a meeting at the NRC offices in Rockville, Maryland on June 16,1997. During this meeting, it was noted that ANO-1 would serve as the lead plant for NRC review of proposed technical specification changes associated with the implementation of the ARC. It was agreed that submittal of the ARC m ' formation as it was developed would facilitate a more timely NRC staff review. A series of three submittals were i proposed, with the last submittal containing the final topical repon and the application for a !
technical specification change including the no significance hazards consideration. The first !
submittal was transmitted on August 13,1997, via letter ICAN089702. This initial version of the repon ir.cluded a general OTSG description and discussion of plant chemistry, flaw morphology of pulled tubes, NDE of pulled tubes and a demonstration that laboratory developed ODIGA is fully representative of field ODIGA. This initial information was critical to the final document in that the leakage testing would be performed primarily on laboratory samples since the field data was limited and none of the volumetric ODIGA flaws removed to !
date from OTSGs have leaked under acciden'. loads.
Since the final repon (BAW-10226P, " Alternate Repcir Criteria For Volumetric Outer Diameter Intergranular Attack In The Tubesheet Of once Through Steam Generators") was l completed within weeks of the material that was planned for the second submittal, it was .
determined to be more efficient to only make one additional submittal transmitting the final topical repon and the proposed technical specification change request with its associated no significance hazards consideration. - This submittal was made on December- 12, 1997 (ICAN129702), with a request for approval for use during IR14, which was scheduled to begin on March 28,1998.
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Attachment ts 1CAN049803 Page 4 of 28
. .Through discussions with the NRC staff during March 1998, it was determined that
. insufficient time was available to resolve outstanding issues related to the ARC prior to IR14.
Since ODIGA flaws within the tubesheet cannot burst and are not anticipated to leak under accident conditions, a one-cycle technical specification change has been developed and is discussed below. This change will allow ODIGA flaws in the upper tubesheet to remain in service during Cycle 15 while resolution of the outstanding issues related to the previously submitted ARC proposal are pursued.
DISCUSSION OF CHANGE Burst Evaluation Three UTS ODIGA tube samples were removed during IR13 and subjected to room temperature burst testing. Burst testing was performed separately within the flawed and unflawed regions of the tube samples. No simulated tubesheet was e:nployed during the tests.
The tests were performed using bladders in the flawed region. No foils or lateral restraint systems were used. The burst pressures for the flawed regions were between 10,000 and 11,000 psig. The unflawed regions burst at pressures between 10,700 and 11,200 psig. For ANO-1 OTSGs, structural integrity is conservatively demonstrated by pressurizing the steam generator tubing to three times normal operating differential pressure. This pressure for ANO-1 is 3765 prig. The burst testing results indicate that substantial stmetural margin exists.
The tube samples removed from ANO-1 in 1996 included eleven ODIGA indications in the UTS. Since it was confirmed that the inservice ODIGA indications are volumetric, bobbin amplitude (voltage) was used as a bounding parameter. The eddy current responses from these flaws were compared with the population of inservice ODIGA indications observed during the IR13 inspection to determine how representative the flaws were of those remaining in service. The 600 KHz bobbin coil signal amplitude of flaws in tubes that were pulled during 1996 ranged from 0.46 to 2.69 volts. Of the 470 inservice ODIGA indications, all were bounded by the 2.69 volt value.
Experiments have been performed to determine the burst pressures for tubes having outer diameter initiated axial cracks that are contained within a support with relatively small annular distances. The results from these experiments show that flawed tube burst below th burst pressure for an unflawed tube is precluded by the constraint of the tube radial displacement when the cracked section of the tube remains within the tubesheet and the diametral gap is less than approximately 0.030".
The bounding tube-to-tubesheet dian ral difference for all OTSGs is computed by assuming the minimum tube OD (0.625") and the maximum tubesheet bore ID (0.646"), resulting in a diametral gap of 0.021". Based upon the results of the EPRI testing discussed above, this gap is not sufficient to burst an axially cracked tube within the tubesheet.
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- Attachment ',o l ICAN049803 Page 5 of 28
..Framatome Technologies, Inc. performed burst testing of machined 100% TW defects
. confined within a tubesheet to determine if this assumption is also applicable to volumetric defects. Ten tube specimens of OTSG size (0.625" x 0.037" wall, nominal) alloy 600 tubing were burst tested. Each specimen had a transverse through-wall hole machined through one wall at the approximate midspan to conservatively simulate volumetric ODIGA. The removed material was placed back in the hole to represent tube material which has suffered from intergranular attack and has r.o tensile strength but fdis the cavity and provides only bearing strength. A split steel block with a bore ID of 0.646" surrounded the simulated ODIGA to j represent the tubesheet. No lateral restraint was applied to the freespan end of the tube. A !
summary of the test results follows. J Burst Testing of Volumetric Defects in a Tubesheet Test Top of Defect Nominal Hole Burst Pressure, Sequence Location below Diameter, inches psi Tubesheet Face 1 N/A None 10,941 2 0.5" 0.27 10,973 11,010 I 3 0.5" 0.39 4 0.5" 0.52 10, % 7 5 0.25" 0.27 11,000 6 0.25" 0.39 11,003 7 0.25" 0.52 10,973 8 0" 0.27 10,978 9 0" 0.39 10,990 4 10 0" 0.52 No burst *
- - tube bent due to lack oflateral restraint, causing a hole in the shim at 9,577 psi.
Burst testing of the 10 samples was performed in accordance with current EPRI guidelines (with the exception of shim sizes due to the large size of the defects). N'me of the samples burst at approximately 11,000 psi in the freespan, typically 1.5" to 2.0" away from the tubesheet. The tenth sample (top of defect located st the secondary face of the tubesheet, nominal hole diameter 0.52") did not burst. Instead, the absence of a simulated tube support plate ariowed the tube to bend above the simulated tubesheet as the pressure hereased At a pressure of 9,577 psi, the tube had bent to the extent that the 0.52" diameter hole was no longer completely restrained by the tubesheet, and consequently a hole in the shim developed.
Examination of the defect region revealed that it had not opened up. These test results demonstrate that volumetric ODIGA which is located within the tubesheet is precluded fram burst.
- Attachment to 1CAN049803 Page 6 of 28 I~
.. Structural integrity of the tubing within the tubesheet is assured for Cycle 15 based upon
. demonstration of the following:
- 1) The actual tube samples removed from ANO-1 during 1R13 exhibited burst pressures that substantially exceeded the required structural limit.
- 2) The structural support provided by the tubesheet precludes tube rupture.
j 3) The inservice ODIGA bobbir, voltage indications are bounded by those flaws contained in the tube samples that were pulled.
Potential Leakage Evaluation 1 Destructive examination of the ODIGA patches removed in IR13 showed none of the flaws to be through-wall. These ODIGA indications ranged from 0.46 volts to 2.69 volts (600 kHz).
Since none of the flaws were through-wall, no leakage would have been expected from them.
Bounding leak testing was performed on similar tubing with electrodischarge machining l (EDM) holes. The EDM patches were machined to depths ranging from approximately 84%
to 95% through-wall, with patch diameters of 0.30 and 0.50 inches. The severity of the EDM patches bound the potential effects of having an ODIGA patch in a tube that is of similar depth and diameter. These EDM patches bound the extents (length, width and depth) of the IR13 pulled tube volumetric ODIGA flaws. None of the EDM patches showed signs of leakage when suojected to accident loads and thus provide a basis for concluding the flaws removed from the steam generators during IR14 would not leak under accident conditions.
As discussed in Appendix C of BAW-10226P, Rev.1, the OTSG tubes are subjected to tensile loads during a MSLB due mainly to tube-to-shell temperature differentials. Twenty-nine (29) ODIGA samples representative of the flaws contained within the ANO-1 upper tubesheet with a maximum voltage of 1.62 were tested at MSLB temperature and pressure.
While the MSLB load is 1402 lbs., the testing resulted in no leakage or tensile rupture at the maximum tested load of 2376 lbs., which is 1.7 times the MSLB load. It is therefore expected that ODIGA indications in the ANO-1 upper tubesheet region will not leak or have a tensile I
rupture concern when subjected to accident conditions.
Historical ANO-1 plant data also shows the ODIGA flaws to be resistant to leakage. There have been no known primary-to-secondary leaks in the history of ANO-1 attributed to an volumetric ODIGA indication despite the fact that many of these indications have remained in service for years.
During May 1996, the "B" OTSG tubing was subjected to a differential pressure of approximately 2100 psid for several hours as a result of a feedwater transient. No immediate l
increase in primary-to-secondary leak rate was noted during the event or following startup.
The primary-to-secondary leak rate did increase by approximately 18 gpd three days following startup; however, none of the leakage detected during the IR13 refueling outage was from ODIGA flaws.
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, . - Am,.u to 1 1CAN049803 Page 7 of 28 l l
. It is concluded that leakage through patch ODIGA flaws in the UTS is highly unlikely at i MSLB pressures due to the historic evidence and testing documented in BAW-10226P, Rev.1.
Evaluation of Growth l An extensive growth rate study was performed on ANO-1 previous eddy current bobbin data. !
l The change in bobbin voltage from 1993-1996 was determined for 129 UTS indications. The I results show that the average voltage change per effective full power year is "zero" and the ,
variability about this average is attributed to eddy current uncertainty. This study indicates I
l that the volumetric ODIGA'in the ANO-1 UTS is not growing. Details of this study are presented in BAW-10226P, Rev.1.
l l Of the 129 indications that were studied,25 were removed from service during IR13. Per the l proposed TS change, a growth rate study will be conducted during IR14 utilizing the )
remaining 104 indications. This study will con 6rm there has been no growth in the confumed !
indications since the IR13 outage. A comparison will be made of the bobbin voltages from l
. the two outages. The average growth rate will be calculated from this data. As was the case in the last growth rate study, which showed a negative growth of 0.04 volt on average, some ,
fluctuation about zero is expected due to variability in equipment setup and analyst
- interpretation of data. A maximum variability of 0.1 volt is considered reasonable and is based upon a 95% upper tolerance limit for the data from the growth rate study for a full cycle. ,
Therefore, an average growth rate of 0.1 volt would be considered essentially zero growth. l Fatigue Evaluation i
Fatigue loading on OTSG tubes can be classified as either high cycle or low cycle. Tube degradation due to high cycle fatigue has been observed in OTSGs at the 15th (uppermost)
TSP and at the secondary face of the upper tubesheet. The resulting flaw morphology is a circumferential fatigue crack which propagates rapidly around the tube onc: initiated. The .
tubes affected are located adjacent to the open tube lane, where secondary side cross flow is high. This damage mechanism was first identified in the late 1970s, and confirmed through examinations of tube pull samples from the Oconee plants. It was concluded that the flaws were initiated at sites oflocalized corrosion or wear, and then were propagated into a fatigue :
l crack by flow induced vibration associated with the high cross flow.
High cycle fatigue has been addressed in OTSGs by preventively sleeving the susceptible tubes. The lack of tube leaks attributed to fatigue in recent years supports the adequacy of the ;
defred sleeving zone in bounding the susceptible area.
Fatigue due to low cycle loading resuhs primarily from mechanical, thermal, and pressure cycling during normal plant operation. If flaws were to propagate due to low cycle fatigue, this'would be evident as a change in the EC response of the flaw from one cycle to the next.
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I Attachment to ICAN049803 Page 8 of 28 l .Therefore, any historical effects oflow cycle fatigue on tubesheet ODIGA would be detected
. in the growth rate analysis.
l Tubesheet Interface Exclusion Zone l
Bending moments exist at both tubesheet faces due to cross-flow loads during normal and ,
faulted conditions. The limiting bending moment exists at the UTS secondary face during a i MSLB event, when the secondary side steam rapidly accelerates up through the tube bundle l and then radially out of the SG through the steam outlet nozzles due to the pressure differential caused by the downstream break. While these lateral loads exist for only the first few seconds of the MSLB transient, they could potentially change the condition of the volumetric ODIGA defect that is exposed to the high primary-to-secondary pressure l differential and axial load later in the transient. A program was therefore undertaken to define the relationship between the lateral load, the bending moment, and the position of the defect within the tubesheet, for the purpose of defming an exclusion zone outside of which the cross-flow loads are determined to have a negligible effect on the condition of the volumetric ODIGA defect.
Based upon the analyses presented in Appendix C of BAW-10226P, Rev.1, the exclusion zone was determined to be the first 2.50 inches from the secondary face of the tubesheet. ;
This ODIGA exclusion zone length has been expanded to encompass the first 2.75m' ches of ;
both tubesheet interfaces to account for eddy current uncertainty. ]
Leakage Probabuity Based Upoa IR14 In-Situ Pressure / Load Tests Prior to leaving any ODIGA indications in the UTS in service after the IR14 inspection, in-situ pressure / load tests will be conducted on a sample of the ODIGA indications to provide a 95% confidence that the volumetric ODIGA in the upper tubesheets of the ANO-1 OTSGs l will not result in exceeding 1/2 the primany-to-secondary leak rate limit assumed in the MSLB accident analysis (1/2 of 1.0 gpm). The process for determining the number of flaws to be tested is described below.
As stated previously, leak testing oflaboratory volumetric ODIGA samples r.nd bounding EDM holes resulted in no leakage under MSLB conditions. As a result, a probability of
, leakage as a function of voltage response could not be developed. The purpose of the IR14 in-situ testing is, therefore, to provide a 95% confidence that the volumetric ODIGA in the upper tubesheets of the ANO-1 OTSGs will not result in exceeding the MSLB primary-to-secondary leak rate limit of 1.0 gallon per minute (gpm). If bobbin voltage or phase angle is not considered to be related to the probability of an ODIGA patch leaking, a sample size can be determined which provides a degree of confidence that no more than a certain percentage l of the ODIGA population will leak under MSLB conditions. The appropriate mathematical model to utilize when determining a sampling program with a finite population without replacement is the hypergeometric distribution. This approach is similar to the bases for recommended steam generator EC initial inspection scopes (the probability of a tube being degraded is not known).
AM=ch=~* to 1CAN049803 Page 9 of 28 Based on the 1996 inspection, there are 285 bobbin indications in SG "A" and 185 in SG "B".
Assuming that an approximately equal percentage of these indications will be confirmed volumetnc by RPC examination and therefore classified as volumetric ODIGA, SG "A" is limiting in terms of potentially leaking ODIGA patcham This is because the larger the population, the greater the assumed number of leaking ODIGA patches. The in-situ pressure / load testing should therefore be performed on a selection of volumetric ODIGA in SG "A".
The next step in the process of determinq how many ODIGA flaws to in-situ test is to determine a bounding leak rate to apply to an ODIGA patch, should it leak. This approach is as follows.
- 1) Representative leakage values for axial crack lengths were utilized to bound the leakage expected from ODIGA patches. A crack was chosen because experience with ODIGA both in the field and in the laboratory is ODIGA will develop a crack before it will leak.
An axial crack will leak more under MSLB conditions than a circumferential crack based on a given crack size.
- 2) To bound the results of the destructive examination of tubes removed during the 1996 refueling outage at ANO-1, an axial crack with a length of 0.30 inch was assumed for all leaking ODIGA patches. From the pulled tube examination the largest indication had a measured axial extent of 0.23 inch. The 6 eld bobbin voltage measurement for this indication was 2.69 volts. The field RPC measured axial length for this indication was 0.22 inches. During the IR13 autage approximately 25% of the bobbin indications within the upper tubh~+ were avamined with RPC. Appendix A provides the analysis of this data. A review of this data shows the esenmad 0.30 inch axial length to be conservative considering the tendency of RPC to over size the flaws length due to probe look ahead and fall behind. This premise is demonstrated in Appendix A by examination of the RPC data for the 10 pulled tube indications that did not contain adjacent flaws in the same plane and thus, are unaffected by other signals. One of the 11 indications contained multiple flaws. During the study,9 of the 10 flaw lengths were sized greater than the destructive examination lengths when the 0.115" coil was used. The average oversizing was 65%.
During IR14 all bobbin indications will be examined with RPC. Any crack like indications will be removed from service or repaired. Entergy Operations will also evaluate the RPC data and measure the flaws maximum length and width. The results of the RPC examination will be submitted to the NRC.
- 3) The volumetric ODIGA is elEp.,idal in shape, with the surface length and width being greater than the length rA wUth at the point of maximum depth. It is assumed that 50%
of the flaw axial length will be 100% TW (see Appendix B).
The leak rate was calculated at standard pressure and temperature consistent with the ANO-1 safety analysis for a main steam line break accident. Assuming 50% of the length of a 0.3 inch axial flaw will be 100% TW, the leak rate will be 0.0126 gpm for MSLB conditions.
Attachment to 1CAN049803 Page 10 of 28 Actual 100% TW L,eak Rate @ Leak Rate @ Number of Axial Axial Crack MSLB Normal MSLB Crack Length Pressure, Operating Leakers Length Assumed 50% Room Pressure and for 0.5 Flaw 100% TW Temperature Temperature GPM (Inches) (Inches) (GPM) (GPM) (Patches) 0.3 0.15 0.01260 0.003941 39 Assuming that the ODIGA patches can contribute approximately 0.5 gpm of the licensing basis leak rate (1.0 gpm),39 ODIGA patches can be assumed to leak and still maintain the current licensing basis leak rate. Based on previous testing detailed in BAW-10226P, EDM holes up to 0.5" in diameter and up to 95% TW did not leak. Because these dimensions bound those of ODIGA patches found in the field, patches that are not leaking at normal operating conditions are not likely to leak under MSLB conditior.s. This means that most or all of the patches assumed to leak at MSLB conditions would also be leaking at normal operating conditions. The current primary-to-secondary leak rate at ANO-1 is approximately 25 gpd, or 0.017 gpm. This total leak rate would only support a small number of ODIGA patches leaking if 100% of this leakage is due to ODIGA. This fact highlights the conservatism in the leak rate and/or number of allowable leaking ODIGA patches utilized in determining the in-situ sample size.
After the allowable number ofleaking ODIGA patches has been determined (39), the required sample size for a given population can be calculated. The appropriate mathematical model to j utilize when determining a sampling program with a finite population without sample replacement is the hypergeometric distribution. The following equation was solved for the required number of ODIGA patches to be in-situ pressure / load tested:
- -' l P(d 21) = ' d *'
.+ > C, where:
a = assumed number ofleaking patches in SG,39 b = number of non-leakmg patches in SG, total population - a d = number ofleaking patches found in sample (zero in this approach) e = sample size, variable to be solved for based on population size C = binomial coefficient P(d>1) = probability that 1 or more leaking patches will be found in a sample size e, if there are a leaking patches in the SG, 0.95 Because the in-situ pressure / load testing will be performed in SG "A", no credit will be taken for the 11 ODIGA patches from SG "B" that were considered not to leak due to the high burst pressures obtained and the fact that they had no areas of 100 % TW extent. Using the above equation, the following correlation between the population of ODIGA patches and the ,
required sample size is determined. A few sample results are also shown.
1 Attachment to ICAN049803 ;
Page 11 of 28 '
Population Minimum Sample Size 50 2 100 6 150 10 200 14 250 18 300 21 i l
350 25
{
400 29 l 450 32 l 500 36 l
l Population Versus Sample Size ]
J l Assuming 39 lenkers in population and 95% confidence 3$ = i l
30 .= '
h' i
2
=
y 20 *
.=
jis -
. .,=
10
.= j
. l
$ ,,.=
0 l 0 100 200 300 400 500 600 Pepelades ofIGA Patches I n-=ie ra l The relationship in the chart can be approximated by the following equation:
1 i l
Sample Size = Roundup (0.0742
- Population - 1.512)
For any population size from 50 to 500 ODIGA patches, this equation will result in the same (or greater) sample size as the hypergeometric equation. All that must be done is to enter the population size and then round the answer up to the nearest whole number. This regression 1
i
r At*=hmaat to 1 1CAN049803 l Page 12 of 28
.will be used to determine the number of samples that will need to be in-situ pressure / load tested based on the population ofvolumetric ODIGA in SG "A". If a leaking ODIGA patch is found within the sample, then additional ODIGA patches will be tested to ensure, with a 95%
confidence, that there are not more than 39 ODIGA leaking patches in the population. These additional samples would be determined in accordance with the hypergeometric distribution techniques.
The following figure illustrates the in-situ pressure / load test configuration. The axial pull probe is inserted through the lower head and positioned vertically between the 14th and 15th support plates where it is hydraulically locked in place. A toothead is then inserted in the upper head and water is added until the test chamber has been filled. The full length toolhead is then locked in place, sealing off the tube area of interest within the water-filled test chamber. The pressure testing process is then initiated and proceeds up to the target MSLB differential pressure. Once the MSLB differential pressure has been achieved, the pull cable is tensioned through a reaction sleeve and a hydraulic jack cylinder to achieve the postulated I thermally induced MSLB axial load. Since the test chamber MSLB pressure creates an axial I load, the additional load provided by the cable is that load necessary to create a total axial l' load of 1402 lbs. (the postulated thermal load for MSLB at ANO-1). The results of this testing has been verified through qualification and analysis.
Severe Accident Considerations The proposed TS change will be applied only to flaws within the upper tubesheet region at ANO-1. Based on structural testing described above, it was concluded that burst within the tubesheet is not possible due to the tight clearance between the tube OD and tubesheet ID.
Conditions associated with a postulated severe accident do not affect this conclusion, therefore the probability of tube rupture does not increase.
Although the probability of tube rupture within the tubesheet region does not increase with postulated severe accidents, the B&WOG and EPRI are currently evaluating the SG tube ,
thermal challenge frequency of severe accidents in B&W plants. ANO-1 is participating in the '{
EPRI program as a pilot plant. Preliminary results from these evaluations indicate that B&W j plants are not susceptible to the hot leg counter-current natural circulation phenomenon that presents a challenge to the steam generator tubes in other pressurized water reactor designs.
The B&W OTSG design is inherently protected against this natural circulation procen because of the vertical orientation of the hot legs. This is in general agreement with the conclusions made by the NRC in NUREG-1570, " Risk Assessment of Severe Accident-Induced Steam Generator Tube Rupture," that " severe accident thermal challenges to steam ,
generator tubes are not a concern for the B&W design." l l
1
l
- Attachment to i l ICA?'049803 l, Page 13 of 28 l
In-Situ Pressure / Load Test Tooling i (P
0 m l
_w_ l 1
[
C- A N FULL LENGTH PROBE l UPPER ;;;;
TUBESHEET =
ISTH SUPPORT PLATE l L<:I i m N
A
- N CHAMBER E
- a AXIAL PULL PROBE LOWER -
TUBESHEET ,
1
~i NJACK PULL ___
~ REACTION SLEEVE CABLE O I-
(
Atteh=at to i
!CAN049803 j Page 14 of 28
. DETERMINATION OF NO SIGNIFICANT HAZARDS CONSIDERATION An evaluation of the proposed change has been performed in accordance with 10CFR50.91(a)(1) regarding no significant hazards considerations using the standards in 10CFR50.92(c). A discussion of these standards as they relate to this amendment request follows.
Criterion 1 - Does Not Involve a Significant Increase in the Probability or i Consequences of an Accident Previously Evaluated. l The steam generators are used to remove heat from the reactor coolant system during normal !
operation and during accident conditions. The steam generator tubing forms a substantial i portion of the reactor coolant pressure boundary. A steam generator tube failure is a breach !
of the reactor coolant pressure boundary and is a specific accident analyzed in the Arkansas ,
Nuclear One, Unit 1 (ANO-1), Safety Analysis Report. )
The purpose of the periodic surveillance performed on the steam generators in accordance with ANO-1 Technical Specification (TS) 4.18 is to ensure that the structural integrity of this portion of the reactor coolant system will be maintained. The technical specification plugging limit of 40% of the nominal tube wall thickness requires tubes to be repaired or removed from ,
service because the tube may become merviceable prior to the next inspection.
Unserviceable is defined in the TS as the coz tion of a tube ifit leaks or contains a defect large enough to affect its structural integrity in the event of an operating basis earthquake, a i loss-of-coolant accident, or a steam line break. The dose consequences of a main steam line i break %fSLB) accident are analyzed in the ANO-1 accident analysis. This analysis assumes the oa is operating with a 1 gpm steam generator tube leak and that the unit has been operating with 1% defective fuel.
The proposed technical specification allows upper tubesheet volumetric outer diameter intergranular attack (ODIGA) indications within the upper tubesheet to remain in service for Cycle 15. Based upon extensive testing and plant experience, it has been determined that upper tubesheet volumetric ODIGA flaws can remain in service while maintaining the serviceability of the tube for Cycle 15 operation.
From testing performed on simulated flaws within the tubesheet, it has been shown that the patch ODIGA indications within the upper tubesheet, with depths up to 100% through-wall, do not represent structurally significant flaws which would increase the probability of a tube failure beyond that currently assumed in the ANO-1 Safety Analysis Report.
Increased leakage during a nostulated MSLB accident due to leaving upper tubesheet volumetric ODIGA in service is not expected. ODIGA has been present in the ANO-1 steam generators for many years with no known leakage attributed to this damage mechanism.
Because of its localized nature and morphology, the flaw does not open under accident conditions. To further support this conclusion, hot leak testing at the bounding MSLB temperature, pressure, and load was performed on tubing with representative laboratory
R At**h'=d to 1CAN049803 Page 15 of 28
. generated flaws. The leak testing was performed on 29 samples with volumetric ODIGA.
None of these flaws showed signs ofleakage as a result of these loads. Additionally, four specimens created by electrodischarge machining with depths up to approximately 95%
through-wall were tested with no leakage detected.
Additionally, prior to leaving any ODIGA indications in the upper tubesheet in service after the IR14 inspection, in-situ pressure / load tests will be conducted on a sample of the ODIGA indications to provide a 95% confidence that the volumetric ODIGA in the upper tubesheets of the ANO-1 once through steam generators (OTSGs) will not result in exceeding a primary-to-secondary leak rate of 0.5 gpm, which is half of the MSLB 1.0 gpm limit. This testing will provide added confidence that the dose consequences associated with a MSLB will not be increased by application of this technical specification change.
This change allows volumetric ODIGA flaws within the tubesheet to remain in service for Cycle 15. Continued operation with these flaws present does not result in a significant increase in the probability or consequences of an accident previously evaluated for ANO-1.
Therefore, this change does g involve a significant increase in the probability or consequences of any accident previously evaluated.
Criterion 2 - Does Not Create the Possibility of a New or Different Kind of Accident from any Previously Evaluated.
The steam generators are passive components. The intent of the technical specification surveillance requirements are being met by this change in that adequate structural and leakage integrity will be maintained. Additionally, the proposed change does not introduce any new modes ofplant operation.
Therefore, this change does g create the possibility of a new or different kind of accident from any previously evaluated.
Criterion 3 - Does Not Involve a Significant Reduction in the Margin of Safety.
Testing of tubes removed from the ANO-1 OTSGs during IR13 showed the flawed tubes to be capable of withstanding differential pressures in excess of 10,000 psid without the presence of the tubesheet. Testing of simulated through-wall flaws of up to 0.5 inch in diameter within a tubesheet showed that the tubes always failed outside of the tubesheet. Thus the structural requirements listed in the bases of the technical specification is satisfied considering this change.
Tubes with volumetric ODIGA indications within the upper tubesheet are not anticipated to leak under accident conditions. This is due to the small size of the flaws and their morphology. This premise has been demonstrated through years of actual plant operation i
L . . _
Attachment to ICAN049803 Page 16 of 28
. with no known leakage attributable to these flaws, even considering a plant transient in 1996 which exposed the "B" steam generator to a primary-to-secondary pressure differential of 2100 psid. The potential for leakage under accident conditions was the focus of testing I performed on representative samples of flawed OTSG tubing. These tests confirmed for tubesheet flaws of similar size to those present in the ANO-1 upper tubesheet, that leakage is not expected under accident conditions. Additional in-situ testing will be performed during l
the fourteenth refueling outage to provide a 95 percent confidence level that the flaws in the limiting steam generator will not leak in excess of that assumed in the ANO-1 accident analysis. With little to no increased accident leakage anticipated as a result of the proposed technical specification change, the offsite dose consequences from a MSLB accident remain unchanged from that currently analyzed in the ANO-1 Safety Analysis Report.
l Therefore, this change does nglinvolve a significant reduction in the margin of safety.
Therefore, based upon the reasoning presented above and the previous discussion of the I amendment request, Entergy Operations has determined that the requested change does D91 involve a significant hazards consideration.
I STATEMENT OF EMERGENCY CIRCUMSTANCES i
10CFR50.91(a)(5) states that whenever an emergency situation exists, a licensee requesting an amendment must explain why this emergency situation occurred and why it could not avoid this situation.
During the IR13 refueling outage, an eddy current technique was used for the satisfactory 1 completion of the ANO-1 steam generator inspection surycillance. The technique used had been qualified per revision 4 to Appendix H of the EPRI "PWR Steam Generator Tube ,
Examination Guidelines." This technique was used to depth size all intergranular attack flaws
, within the upper tubesheet. As required by the technical specifications, all upper tube sheet l ODIGA indications with a depth size of greater than the plugging limit as determined by the qualified sizing technique, were removed from service by plugging.
During the steam generator inspections, three tubes containing eleven upper tubesheet l ODIGA flaws were removed from the "B" OTSG and sent offsite to be analyzed. The i destructive examination results indicated that the flaw depths did not correlate well with the depths sized using the qualified eddy current technique. Based upon this information, Entergy Operations determined that the application of the sizing criterion was not valid. With the qualified sizing technique invalidated, there was a potential that tubes could have been left in service with indications that have through-wall depths greater than the plugging limit specified in the technical specifications.
As discussed in the background secticn of this attachment, Entergy Operations pursued and received enforcement discretion and an exigent TS change (Amendment No.189) allowing
Attachment ts ICAN049803 Page 17 of 28 i
. ANO-1 to continue operation through the remainder of Cycle 14 with these known flaws potentially exceeding the TS plugging limit.
Immediately following receipt of Amendment 189, Entergy Operations through the B&WOG began the development of an ARC that would allow leaving inservice upper tubesheet patch ODIGA indications below a specified voltage threshold. These plans were shared with the NRC in a meeting at the NRC's offices in Rockville, Maryland on June 16,1997. At that meeting it was agreed that the submittal of the ARC information as it was developed would facilitate a more timely NRC staff review. The first submittal was provided on August 13, 1997 (ICAN089702). The second and final submittal, with the complete technical justification (BAW-10226P) and the proposed TS changes, was transmitted on December 12, 1997 (1CAN129702).
Since the transmittal of the ARC TS change request, Entergy Operations has interacted with the NRC staff on several occasions providing requested clarification. Based upon the most recent communications with the NRC in late March 1998, it is Entergy Operations' understanding the NRC staff will be unable to grant a permanent ARC TS change prior to completion of the IR14 refueling outage.
Without the availability of the ARC, the current ANO-1 TS requires the affected tubes to be plugged or repaired. Plugging the tubes will remove from service a substantial portion of the heat transfer area between the reactor coolant system and the secondary steam plant. This reduction in heat transfer area will reduce the efficiency of the unit and potentially cause a reduction in power output from the station. Additionally, the reduction in heat transfer area reduces the amount of heat the secondary system can remove during transient and accident conditions. While adequate heat transfer area remains to meet safety analysis assumptions, margins are unnecessarily reduced.
No plans were made to perform sleeving during the current outage. To mobilize the necessary equipment and personnel, procure the required materials and perform the sleeving operation in the steam generators would delay the unit's restart for several weeks. The added personnel dose associated with the sleeving of 440 tubes is estimated at 13.6 rem. The cost to sleeve 440 tubes is estimated at $2,400,000.
Entergy Operations expects to receive in the near future an amendment to the technical specifications that will allow upper tubesheet repair by rerolling the tube below the flaw. The reroll repair technique requires less resources, time, and dose to implement than the sleeving option. However, it is less desirable than this proposed change because of the residual stresses left in the tube as a result of the reroll process. The residual stresses left in the tube make it more susceptible to primary water stress corrosion cracking. While this damage '
mechanism would not be anticipated to occur for many years, ifit does occur in the future the tube will require subsequent repair or plugging.
As discussed above, Entergy Operations had taken the necessary steps to obtain a TS change which would have allowed a majority of tubes with patch ODIGA indicatbns within the upper 1
x Attachment to 1CAN049803
, Page 18 of28
.tubesheet to remain in service following the IR14 outage. Only recently have we been
. notified that the proposed ARC TS change submitted last December would not be granted before the end of the IR14 refueling outage. Once notified of this fact we inurMiately pursued alternate plans. Entergy Operations considers the approach outlined in this proposed change to be the preferred option to address the upper tubesheet patch ODIGA indications this outage. As discussed above, the decision on how Entergy will disposition these flaws during 1R14 will have to be made on or about April 9,1998.
Therefore, Entergy Operations requests that this proposed technical speci6 cation change be considered under emergency circumstances as described in 10 CFR 50.91(a)(5).
I
Attachment to ICAN049803 Page 19 of 28 Appendix A 1R13 Upper Tubesheet Volumetric IGA l S/G A l 8 l 39 l 0.21 l 0.22 l 0.85 l UTS +7.52 l l S/G A l 8 l 39 l 0.2 l 0.24 l 0.85 l UTS +7.52 l l S/G A l 8 l 39 l 0.21 1 0.22 l 1.06 l UTS +7.52 l l S/G A l 8 l 39 l- 0.2 l 0.24 l 1.06 l UTS +7.52 l
- l S/G A l 9 l 32 l 0.21 l 0.2 l 0.76 l UTS +6.99 l l S/G A l 10 l 35 l 0.21 l 0.2 l 0.26 l UTS +6.63 l l S/G A l 11 l 30 l 0.22 l 0.2 l 1.07 l UTS +8.47 l l S/G A l 13 l 25 l 0.22 l 0.2 l 1.53 l UTS +8.73 l l S/G A l 14 l 26 l 0.22 l 0.26 l 0.50 l UTS +9.45 l l S/G A l 15 l 37 l 0.16 l 0.2 l 0.64 l UTS +8.34 l l S/G A l 17 l 44 l- 0.21 l 0.2 l 1.02 l UTE -3.61 l 1 S/G A l 21 l 49 l 0.16 l 0.2 l 0.79 l UTS +5.60 l 1-S/GAl 24 l 16 l 0.21 l 0.2 l 0.61 l UTS +9.79 l l S/G A l 25 l 85 l 0.22 l 0.2 l 0.49 l UTS +5.58 l 1 S/G A l 26 1 55 l 0.21 l 0.2 l 0.40 l UTS +8.18 l l S/G A l 27 l 31 1 0.22 l 0.2 l 1.17 l UTS +6.08 l l S/G A l 27 l 31 l 0.16 l 0.2 l 0.45 l UTS +5.71 l l S/G A l 28 l 8 l 0.22 l 0.2 l 1.09 l UTS +18.97 l I S/G A l 33 l 101 l 0.21 l 0.13 l 0.41 l UTS +14.03 l I S/G A l 37 l 12 l 0.22 l 0.2 1 0.62 l UTS +5.83 l l S/G A l 44 l 108 l 0.21 l 0.22 1 0.64 l UTS +9.81 l l S/G A l 44 l 108 l 0.16 l 0.15 l 0.23 l UTS +8.95 l IS/GAl 45 l3 l 0.22 l 0.19 l 0.59 l UTS 49.18 l 1 S/G A l 49 l 2 l 0.22 l 0.19 l 0.42 l UTS +8.11 l l S/G A l 51 l 116 l 0.21 l 0.2 l 0.32 l UTS +4.77 l FjG A l 51 l 116 l 0.16 l 0.2 l 0.74 l UTS +8.44 l S/G A l 55 l 123 l 0.21 l 0.2 l 0.92 l UTS +11.53 l S/G A l 56 l 124 l 0.16 l 0.13 l 0.25 l UTS +8.35 l
. l S/G A l 56 l 124 l 0.16 l 0.13 l 0.33 l UTS +10.80 l
-l S/G A l 56 l 124 l 0.16 l 0.13 l 0.26 l UTS +13.29 l l S/G A ' 58 l 26 l 0.16 l 0.07 l 0.28 l UTS +8.21 l lS/GA 58 l 26 l 0.16 l 0.07 l 0.93 l UTS +11.89 l l S/G A 59 l 8 l 0.22 l 0.2 l 0.91 l UTS +12.08 l l S/G A 60 l 124 l 0.21 l 0.2 l 0.97 l UTS - +10.84 l l S/G A 61 l 40 l 0.21 1 0.22 l 1.09 l UTS +7 42 l l S/G A 65 l 56 l 0.15 1 0.16 -l 0.27 l UTS +14.28 l l S/G A 65 l 56 l 0.2 l 0.16 l 0.34 l UTS +12.89 l
Attachment to ICAN049803
. Page 20 of 28 S/G A Q 65 u 63 ll 0.15 Q 0.16 L 0.82 k UTS +17.31 S/G A l 67 l 120 l 0.26 l 0.15 l 0.31 l UTS +4.98 l S/G A l 68 l 16 l 0.21 l 0.15 l 0.70 l UTS +12.23 l S/G A l 68 l 59 l 0.2 l 0.16 l 1.09 l UTS +6.21 l S/G A l 69 l 16 l 0.22 l 0.26 l 0.95 l UTS +3.12 l S/G A l 69 l 30 l 0.21 l 0.15 l 0.86 l UTS +12.03 l S/G A l 69 l 40 l 0.22 l 0.2 l 1.13 l UTS +10.00 l S/G A l 69 l 40 l 0.21 l 0.22 l 1.54 l UTS +9.76 l S/G A l 69 l 54 l 0.21 l 0.22 l 1.68 l UTS +13.56 l S/G A l 69 l 54 l 0.21 l 0.29 l 1.25 l UTS +13.94 l S/G A l 69 l 54 l 0.27 l 0.26 l 1.03 l UTS +13.80 l S/G A l 69 l 54 l 0.05 l 0.07 l 0.38 l UTS +18.71 l S/G A l 69 l 74 l 0.26 l 0.2 l 0.38 l UTE -5.20 l S/G A l 69 l 117 l 0.16 l 0.13 l 0.66 l UTS +6.31 l S/G A l 70 l 21 l 0.22 l 0.2 l 2.53 l UTS +20.88 l S/G A l 70 l 21 l 0.16 l 0.2 l 1.79 l UTS +8.77 l S/G A l 71 l 19 l 0.21 l 0.22 l 0.84 l UTS +7.11 l S/G A l 71 l 19 l 0.27 l 0.2 l 1.64 l UTS +6.97 l S/G A l 72 l 106 l 0.21 l 0.2 l 0.84 l UTS +12.05 l S/G A l 76 86 l 0.18 l 0.15 l 0.48 l UTE -2.64 l S/G A l 80 29 l 0.22 l 0.26 l 1.54 l UTS 40.62 l S/G A l 80 67 l 0.2 l 0.21 l 1.43 l UTS +1.09 l S/G A l 81 56 l 0.21 l 0.2 l 0.86 l UTS +15.33 l S/GAl 81 56 l 0.21 l 0.2 l 0.90 l UTS +10.58 l S/G A l 85 43 l 0.16 l 0.13 l 0.54 l UTS +21.50 l S/G A l 85 53 l 0.21 l 0.2 l 1.08 l UTS +17.30 l S/G A l 85 53 l 0.21 l 0.2 l 1.77 l UTS +16.72 l S/G A l 86 10 l 0.22 l 0.2 l 1.19 l UTS +9.18 l S/G A l 86 16 l 0.21 l 0.2 l 0.73 l UTS +5.32 l S/G A l 86 34 l 0.26 l 0.2 l 1.20 l UTS +8.53 l S/G A l 88 55 l 0.16 l 0.13 l 0.69 l UTS +17.40 l S/G A l 89 52 l 0.27 l 0.27 l 2.06 l UTS +17.90 l S/G A l 91 56 l 0.16 l 0.14 l 0.82 l UTS +15.15 l S/G A l 91 56 l 0.16 l 0.14 l 0.% l UTS +16.60 l S/G A l 94 2 l 0.22 l 0.2 l 1.32 l UTS +1.03 l S/G A l 94 2 l 0.22 l 0.2 l 1.60 l UTS +6.16 l S/G A l 98 6 l 0.22 l 0.2 l 2.24 l UTS +6.21 l S/G A l 98 122 l 0.22 l 0.21 l 0.80 l UTS +12.11 l S/GAl 99 14 l 0.22 l 0.19 l 1.81 l UTS +9.58 l S/G A l 99 17 l 0.22 l 0.2 l 1.26 l UTS +8.27 l S/G A l 99 123 l 0.22 l 0.14 l 1.14 l UTS +9.75 l S/G A l 102 2 l 0.21 l 0.2 l 1.03 l UTS +12.63 l
1 Attachment to ICAN049803
. - Page 21 of 28
- l S/G A l 102 l 2 l 0.21 l 0.2 l 1.07 l UTS +11.39 l l S/G A l 102 l 14 l 0.22 l 0.2 l 0.54 l UTS +9.86 l l S/G A l 103 l 8 l 0.21 l 0.13 l 1.09 l UTS +10.67 l ,
l S/G A l 104 l 15 l 0.27 l 0.27 l 2.41 l UTS +12.17 l l l S/G A l 104 l 15 l 0.27 l 0.27 l 2.% l UTS +8.81 l l S/G A l 116 l 107 l 0.15 l 0.15 l 0.92 l UTS +14.81 l l S/G A l 117 l 99 l 0.27 l 0.29 l 1.23 l UTS +3.88 l l S/G A l 122 j 101 l 0.16 l 0.15 l 0.77 l UTS +9.48 l l S/G A l 123 l 9 l 0.26 l 0.2 l 1.37 l UTS +8.56 l l S/G A l 126 l % l 0.16 l 0.15 l 0.61 l UTS +8.55 l l S/G A l 142 l 49 l 0.26 l 0.15 l 0.47 l UTS +6.52 l l S/G A l 142 l 49 l 0.21 l 0.15 l 0.52 l UTS +7.28 l l S/G A l 146 l 42 l 0.16 l 0.15 l 1.36 l UTS +4.23 l l
l
1 Attachment to ICAN04980.1
. Page 22 of 28 e
S/G B J 106 Q 74 ll 0.21 j 0.21 ll 0.88 ll UTE -3.56 S/GBl 73 l 93 l 0.22 l 0.21 l 1.00 l UTE -3.67 l S/GBl % l 22 l 0.1 l 0.13 l 0.27 l UTS +0.39 l S/GBl 83 l 17 l 0.21 l 0.21 l 0.69 l UTS +2.44 l S/GBl 72 l 29 l 0.2 l 0.22 l 1.03 l UTS +2.95 l )
S/GBl 72 l 14 l 0.25 l 0.22 l 2.20 l UTS +3.15 l S/GBl 74 l 58 l 0.15 l 0.15 l 0.35 l UTS +3.39 l S/GBl 39 l 14 l 0.14 l 0.16 l 0.42 l UTS +4.02 l S/G B l 128 l 2 l 0.16 l 0.15 l 0.86 l UTS +4.11 l S/GBl 54 l 2 l 0.2 l 0.16 l 1.76 l UTS +4.20 l S/GBl 78 l 44 l 0.21 l 0.14 l 0.52 l UTS +4.22 l S/GBl 80 l 28 l 0.14 l 0.1 l 0.13 l UTS +4.23 l S/GBl 48 l 7 l 0.2 l 0.16 l 1.22 l UTS +4.2j 5
S/GBj 50 l 2 l 0.15 l 0.16 l 2.01 l UTS +4.33 l S/GBl 86 l 25 l 0.16 l 0.14 l 0.38 l UTS +4.33 l S/GBl 96 l 22 l 0.1 l 0.13 l 0.78 l UTS +4.46 l S/GBl 87 l 14 l 0.15 l 0.15 l 0.68 l UTS +4.48 l S/GBl 74 l 58 l 0.15 l 0.15 l 0.44 l UTS +4.52 l S/GBl 83 l 48 l 0.28 l 0.16 l 1.38 l UTS +4.58 l S/GBl % l 1 l 0.25 l 0.15 l 2.15 l UTS +4.58 l S/G B l 128 l 2 l 0.26 l 0.15 l 0.48 l UTS +4.59 l l S/G B l 118 l 3 l 0.16 l 0.22 l 0.55 l UTS +4.60 l l S/GBl 84 l 30 l 0.21 l 0.16 l 0.51 l UTS +4.77 l S/GBl 69 l 41 l 0.2 l 0.22 l 1.23 l UTS +4.87 l S/GBl 60 l 96 l 0.26 l 0.15 l 0.19 l UTS +5.03 l S/GBl % l 22 l 0.21 l 0.2 l 0.68 l UTS +5.05 l S/GBl 50 l 2 l 0.24 l 0.16 l 3.11 l UTS +5.22 l S/GBl 53 l 5 l 0.15 l 0.08 l 0.60 l UTS +5.32 l S/G B l 118 l 3 l 0.16 l 0.15 l 0.73 l UTS +5.33 l S/GBl 72 l 57 l 0.15 l 0.15 l 0.55 l UTS +5.35 l S/GBl 72 l 56 l 0.15 l 0.15 l 0.86 l UTS +5.37 l S/G B l 102 l 9 l 0.21 l 0.13 l 1.62 l UTS +5.40 l S/GBl 64 l 51 l 0.2 l 0.15 l 1.16 l UTS +5.51 l S/GBl 98 l 9 l 0.21 l 0.22 l 0.33 l UTS +5.60 l S/G B l 117 l 4 l 0.16 l 0.15 l 0.59 l UTS +5.69 l S/G B l 128 l 2 l 0.21 l 0.22 l 0.89 l UTS +5.69 l S/G B l 84 l 30 l 0.14 l 0.1 l 0.44 l UTS +5.84 l S/G B l 118 l 3 l 0.21 l 0.15 l 0.40 l UTS +5.95 l S/GBl 98 l 9 l 0.16 l 0.13 l 0.44 l UTS +6.13 l S/G B l 79 l 57 l 0.22 l 0.15 l 0.93 l UTS +6.26 l S/G B l 117 l 4 l 0.21 l 0.15 l 0.58 l UTS +6.27 l
a Attachment to 1CAN049803
, Page 23 of 28
- li S/G B .I 53 ;I
. 3 ll 0.17 L 0.2 ll 2.48 l UTS +6.28 ,
lS/GBl 53 l 4 l 0.2 l 0.16 l 0.83 l UTS +6.28 l l S/G B l 86 l 25 l 0.16 l 0.21 l 0.54 l UTS +6.29 l l S/G B l 120 l 5 l 0.2 l 0.15 l 0.52 l UTS +6.36 l l S/G B l 85 l 45 l 0.16 l 0.14 l 0.42 l UTS +6.37 l l S/G B l 78 l 63 l 0.22 l 0.27 l 1.29 l UTS +6.40 l l S/G B l 79 l 53 l 0.15 l 0.22 l 0.78 l UTS +6.40 l l S/G B l 101 l 10 l 0.2 l 0.2 l 0.53 l UTS +6.47 l l S/G B l 65 l 7 l 0.2 l 0.22 l 0.% l UTS +6.48 l l S/G B l 101 l 10 l 0.15 l 0.2 l 0.87 l UTS +6.50 l l S/G B l 29 l 102 l 0.21 l 0.22 l 1.00 l UTS +6.61 l l S/G B l 83 l 52 l 0.21 l 0.21 l 0.67 l UTS +6.66 l
[ S/G B l 77 l 57 l 0.21 l 0.21 l 0.70 l UTS +6.71 l l S/G B l 100 l 5 l 0.2 l 0.15 l 0.76 l UTS +6.73 l l S/G B l 58 l 87 l 0.21 l 0.22 l 1.10 l UTS +7.31 l l S/G B l 53 l 3 l 0.17 l 0.13 l 2.77 l UTS +7.45 l :
l S/G B l 70 l 37 l 0.25 l 0.22 l 1.90 l UTS +7.61 l l l S/G B l 80 l 28 l 0.21 l 0.16 l 0.42 l UTS +8.02 l !
l S/G B l 85 l 45 l 0.22 l 0.21 l 0.65 l UTS +8.13 l l S/G B l 78 l 37 l 0.21 l 0.22 8 1.53 l UTS +9.47 l l S/G B l 82 l 56 l 0.22 l 0.15 0.50 l UTS +9.65 l l S/G B l 50 l 2 l 0.15 l 0.16 2.03 l UTS +9.93 l l S/G B l 83 l 14 l 0.14 l 0.16 0.28 l UTS +11.53 l l S/G B l 79 l 24 l 0.21 l 0.14 0.92 l UTS +18.22 l l S/G B l 79 l 2.! l 0.16 l 0.14 0.42 l UTS +19.03 l l S/G B l 84 l 20 l 0.21 l 0.21 0.75 l UTS +19.34 l l S/G B l 89 l 110 l 0.2 l 0.23 0.56 l UTS +20.51 l l S/G B l 89 l 110 l 0.2 l 0.14 0.61 l UTS +21.56 l l S/G B l 89 l 110 l 0.2 l 0.14 0.46 l UTS +22.07 l 4
Attachment ts 1CAN049803
, Page 24 of 28 1R13 Pulled Tube Volumetric IGA l S/G B l 79 l 63 l 0.16 l 0.27 l 0.22 l UTS +3.70 l l S/G B l 79 l 63 l 0.071 l 0.16 l 0.15 l UTS +4.00 l l S/G B l 79 l 63 l 0.23 l 0.27 l 0.22 l UTS +4.30 l l S/G B l 79 l 63 l 0.135 l 0.16 l 0.15 l UTS +6.00 l l S/G B l 80 l 18 l 0.142 l 0.24 l 0.19 l UTS +7.30 l l S/G B l 80 l 18 l 0.09 l 0.24 l 0.13 l UTS +8.80 l l S/G B l 80 l 18 l 0.057 l 0.27 l 0.19 l UTS +11.50l l S/G B l 83 l 47 l 0.161 l 0.26 l 0.18 l UTS +6.75 l l S/G B l 83 l 47 l 0.072 l 0.26 l 0.18 l UTS +9.10 l l
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1 AM-* to ICAN049803
, Page 25 of 28 Appendix B This WN presents data supporting the conservative assumption that 50% of the overall extent of the ODIGA patch will develop into a through-wall crack. This assumption becomes necessary because only volumetric ODIGA patches that develop cracks have been found to ,
leak. This appears to happen because as an ODIGA patch gets larger and deeper, if a load or I stress is not present to drive the ODIGA deeper, it stops growing. If a suf5cient load or stress is present to drive the ODIGA deeper, when suf5cient wall degradation has occurred (less than 100% TW), a crack develops. It is this crack which may propagate through-wall and cause primary-to-secondary leakage.
As rtated in BAW-10226P, the volumetric ODIGA is generally ellipsoidal in shape Based on the fractography data from destructive examination of the tubes removed from ANO-1 in 1996 (Westinghouse report 97-8TC5-ANOTE-RI), the percentage of the maximum depth as a function of the percentage of the axial extent of those patches with maximum depths greater than 60% TW were plotted. These plots show that ifit is assumed that the extent of the ODIGA that is within 10% of the maximum depth of penetration is assumed to crack 100%
TW, less than 50% of overall extent of the ODIGA will crack.
IGA Profiles Max Depth = 77*/., Estest=4.12"
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l Attachment to !
ICAN049803 l t .- Page 26 of 28 j
- IGA Profiles Max Depth =88%, Extent =0.17"
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IGA Profiles Max Depth = 76%, Extent = 0.135"
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Attachment to ICAN049803
. Page 27 of 28 l
- IGA Profiles Max Depth = 65%, Extent = 0.057" 100 %
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i IGA Profiles l Max Depth = 61%, Extent = 0.23" ;
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Attachment to 1CAN049803
. Page 28 of 28 IGA Profiles Max Depth = 83%, Extent = 0.161" 100 %
90 %
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i PROPOSED TECHNICAL SPECIFICATION CHANGES (Amming Prior Approval of Repair Roll Change) i l --
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