ML052350122

Additional Information Regarding Kinetic Expansion Inspection and Repair Criteria

ML052350122
Person / Time
Site:	Crane
Issue date:	08/11/2005
From:	Cowan P AmerGen Energy Co
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
5928-05-20207, TAC MB6475
Download: ML052350122 (19)

Text

AmerGen SM AmerGen Energy Company, LLC 200 Exelon Way Kennett Square, PA 19348 www.exeloncorp.com An Exelon Company 10 CFR 50.55a August 11, 2005 5928-05-20207 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555-0001 Three Mile Island, Unit I (TMI Unit 1)

Operating License No. DPR-50 NRC Docket No. 50-289

Subject:

Additional Information Regarding Kinetic Expansion Inspection and Repair Criteria (TAC No. MB6475)

Reference:

1) AmerGen Energy Company, LLC letter to NRC, dated May 3, 2005 (5928-05-20102), "Additional Information Regarding Kinetic Expansion Inspection and Repair Criteria."

This letter provides additional information in response to the NRC draft request for additional information received via NRC email, dated July 12, 2005, regarding TMI Unit 1 Once-Through Steam Generator Kinetic Expansion Inspection and Repair Criteria submitted in Reference 1. The additional information is provided in Attachment 1. Please note that the response to Question No. 10 is planned to be submitted separately by August 19, 2005.

If any additional information is needed, please contact David J. Distel at (610) 765-5517.

Respectfully, Pamela B. Cowan Director - Licensing & Regulatory Affairs AmerGen Energy Company, LLC Attachments: 1) NRC Questions and AmerGen Responses cc: S. J. Collins, USNRC, Administrator Region I, c)I D. M. Kern, USNRC, Senior Resident Inspector, TMI Unit 1 1

P. S. Tam, USNRC, Senior Project Manager, TMI Unit 1 File No. 02077

ATTACHMENT 1 NRC Questions and AmerGen Responses 5928-05-20207 Page 1 of 17 Request For Additional Information Related to TMI-1 Kinetic Expansion Inspection and Acceptance Repair Criteria May 3, 2005 Letter

1. NRC Question Page 20 of ECR #02-01121, Rev. 2, states that for sleeved tubes the parent tube is only inspected up to the kinetic expansion transition. Table 3-3 of the licensee's 15R OTSG Report dated 2/24/2004 states that all three roll expansions in the sleeve, including the transitions, are inspected with +Point. Please clarify whether the inspection of the upper-most roll expansion in the sleeve includes inspection of the parent tube at that location. If the parent tube at the upper sleeve joint is not inspected, how is the structural and accident leakage integrity of the upper sleeve joint ensured?

Response

The two documents are correct: all three of the sleeve roll expansions are inspected using Plus-Point probes, but the parent tubing, behind the sleeve, is not inspected above the kinetic expansion transition. Therefore, inspection of the uppermost sleeve roll expansion does not include the parent tube "behind" the sleeve roll.

(TMI-1 sleeves were installed to prevent fatigue cracking of unexpanded tubing at the upper tubesheet secondary faces. All OTSG plants installed sleeves in the lane-wedge region to arrest fatigue cracking.)

The integrity of the upper sleeve joints is ensured due to a number of factors: The TMII-i sleeves are Inconel 690 which has corrosion resistance better than that of the original parent tubing. The upper sleeve joints are protected, by the constraint of the tubesheet, from bending loads and secondary side loose parts. The upper sleeve joints are normally in compression since the sleeve joints were expanded into the tubesheets. The design of the sleeves and sleeve expansions incorporated design features to minimize their subsequent susceptibility to stress corrosion cracking.

Prior to their installation, qualification tests included leak testing to determine normal operating and accident condition leak rates from installed sleeves. The average accident condition leak rate was 0.078 gpm for 5,000 sleeves. An average leak rate was used since testing was performed on specimens of both high and low yield strengths. (TMI-1 has approximately 250 sleeved tubes in each steam generator)

The leak testing was performed on specimens, after they were fatigue tested, which included both the upper tubesheet roll joints and the lower sleeve-to-freespan-tube rolled joints. A complete freespan tube severance of the parent tube was present near the secondary faces of the specimens. The qualification work also included pull-out (i.e. tensile) testing of the sleeve joints. There was no significant movement of the sleeves even at the maximum accident loads, indicating a large margin of joint strength. Additional testing and analyses included flow-induced vibration analyses, thermal-hydraulic analyses, fatigue testing, corrosion testing, pressure cycling, axial 5928-05-20207 Page 2 of 17 load cycling, and thermal cycling. A more detailed description of the sleeve qualification work is available in a 1991 B&W Topical Report (BAW-2120P).

Prior to the installation of TMI-1 sleeves testing was performed on 3/4" sleeves rolled into parent tube samples with through-wall axial and circumferential cracks in the tubesheet roll area. After installation of the sleeves into the test joints all of the joints were leak and pull tested. Based on the testing it was concluded that axial and circumferential cracks within the parent tubing prior to sleeve installation would not adversely affect the integrity of the sleeves' tubesheet rolled joint. These 3/4" sleeves were similar to the TMI-1 sleeves except for the tubing and sleeve size.

The condition of the TMI-1 parent tubing installed behind roll-expanded Inconel 690 sleeves in the upper tubesheets is physically analogous to parent tubing behind thousands of 1-690 rolled tube plugs (i.e., rolled joints of 1-690 material over parent tubing). Rolled plug-to-tubesheet joints have successfully been utilized in these installations without subsequent inspection of the parent tubing behind the plugs.

2. NRC Question The staff acknowledges efforts underway by the BWOG to identify needed changes to the plant licensing bases for plants with OTSGs to address OTSG tube structural and leakage integrity under the most limiting LBLOCA. Pending completion of these efforts and consistent with commitments made by licensees at the time they submitted license applications for reroll repairs, the staff requests that the licensee for TMI-1 commit to the following:

Determine the best estimate total primary-to-secondary leakage that would result from the limiting LBLOCA based on as-found circumferential and volumetric indications along the entire length of tubing inspected with appropriate allowance for flaws that may be located outboard of regions inspected, and demonstrate that it is acceptable. For purpose of this evaluation, acceptable means a best estimate of the leakage expected in the event of a LBLOCA that would not result in a significant increase of radiological release (e.g., in excess of 10 CFR100 limits). A summary of this evaluation shall be included in the 90-day report as required by TS 4.1 9.5.b.

Response

TMI-1 will provide the results of the best estimate leakage assessment for the limiting LBLOCA in the 90-day report required by TS 4.19.5.b.

3. NRC Question Discuss the calculations performed to confirm that MSLB is the most limiting DBA (when compared to FLB, SBLOCA, Rod Ejection, etc) in terms of satisfying the accident leakage performance criterion in NEI 97-06 (also, TSTF-449, Rev. 4).

Figure 15 of ECR #02-01121, Rev 2 indicates that differential pressure for the assumed MSLB accident is at 1300 psi or less throughout the transient. Do these pressure loads bound those that are calculated to occur during FLB or, if not, why is 5928-05-20207 Page 3 of 17 MSLB the most limiting accident? Axial loads during a SBLOCA, 2097 lb maximum, are higher than those for the assumed MSLB transient, 1310 lb. Has SBLOCA been confirmed by analysis to be less limiting from a leakage and dose standpoint than MSLB?

Response

In 1983, as part of the original work to qualify and implement the TMI-1 steam generator kinetic expansion repairs, analyses were performed of the various transients that could impact the expansions' design. Among the various documents submitted to the staff was the "Three Mile Island Unit 1 Once-Through Steam Generator Repair: Kinetic Expansion Technical Report" (GPUN letter to the NRC dated April 20,1983, 5211-83-122, GPUN TDR-007, Rev. 1/BAW 1760, Rev.1). This proprietary document included the results of analyses of normal operation and transient tube loads. This document stated:

"...Three accident conditions cause significant loads on the steam generator tubes:

large break LOCA, main steam line break (MSLB), and feedwater line break (FWLB).

The axial loads on the tubes are as follows:

Event Load, lb LOCA 2641 Main steam line break 3140 Feedwater line break

-570 Based on these analyses the MSLB was selected as the worst-case condition based on tubing axial loads.

The large break LOCA is discussed in Question 2, above, and its response. Primary pressure is rapidly lost during a large break LOCA event.

Tube loads imparted by the Feedwater Line Break (FWLB) transient are compressive, vice tensile. Therefore the FWLB transient is not expected to impact kinetic expansion integrity or postulated leakage from the kinetic expansions. The axial tube load for the FWLB is compression over all tubesheet radial locations. The peak primary pressure reached during the FWLB will not overcome the compressive tube load regardless of the magnitude of the primary-to-secondary pressure difference. In addition, the contact pressure of the kinetically expanded tube-to-tubesheet joint will increase during a FWLB, due to the compressive tube load, resulting in added resistance to primary-to-secondary leakage. Tube compression during an FWLB will not result in buckling of the kinetic expansions because buckling loads are not exceeded and due to the presence of the tubesheet.

Primary-to-secondary pressure difference is quickly lost during hypothetical SBLOCAs. An analysis performed in 1999 of a SBLOCA event did result in peak axial tube loads of 2097 lbs. The peak tube load occurred at a time 0.20556 hours into the initiating transient. At this time in the analysis the calculated primary system pressure was 62 psia and the secondary pressure was 77 psia. The results of the 1999 analysis showed that there was essentially no primary-to-secondary pressure 5928-05-20207 Page 4 of 17 difference, or a negative primary-to-secondary pressure difference, for all times after 0.03 hours3.472222e-5 days <br />8.333333e-4 hours <br />4.960317e-6 weeks <br />1.1415e-6 months <br /> into the event. The 1999 analysis assumed a guillotine rupture of the pressurizer surge line so, while calculated axial tube loads were relatively high, the primary system was rapidly depressurized.

Transient analyses performed in 1990, including LOCA analyses, were also described in BAW-10146, "Determination of Minimum Required Tube Wall Thickness for 177-FA Once-Through Steam Generators". (These analyses were not performed specifically for TMI-1; rather they were performed for the BWOG and represent a conservative representation of the various BWOG plants.) A summary of tube loads contained in that document also illustrates the combination of primary-to-secondary pressure difference and tube load for the MSLB with respect to the other transients.

The MSLB results were 3140 Ibs. peak axial tensile tube load and the peak MSLB primary-to-secondary pressure was 2500 psid, while the FWLB resulted in compressive tube loads and the various analyzed LOCAs resulted in a loss of primary pressure.

In summary, transient analyses have demonstrated that the MSLB transient has a combination of tube tensile axial loading and positive primary-to-secondary pressure difference that are most challenging to structural and leakage integrity of the joint.

While SBLOCA and FWLB, respectively, may result in an instance where the postulated axial tensile tube load is greater than that calculated for an MSLB, or an instance where the primary-to-secondary pressure difference is greater than that calculated for an MSLB, these instances do not occur concurrently.

NEI 97-06's accident-induced leakage performance criterion requires that plants have less than 1 gpm leakage per steam generator (for accidents other than tube rupture).

Potential leakage in greater quantities may be acceptable if approved by NRC.

Based on analyses of hypothetical leakage from the kinetic expansions, which demonstrated that doses remain within the applicable dose acceptance criteria, TMI-1 Amendment No. 204, dated October 2,1997, approved leakages greater than 1 gpm (i.e., the leakage limits currently described in ECR 02-01121).

4. NRC Question Are the 300 KHz +Point coils and the 600 KHz 0.80-inch pancake coils, discussed in Section 4.1.3 of ECR #02-01121, Rev 2, qualified specifically in accordance with EPRI Appendix H guidelines for application to 0.625 diameter, 0.034 thick tubing for detection of PWSCC and ID IGA? For both freespan and Kinetic Expansion (KE) locations? If not Appendix H qualified, what plans does the licensee have to perform an Appendix H qualification of these coils applicable to TMI-1?

Response

The 300 KHz +Point coil examination technique is EPRI Appendix H qualified to detect axial and circumferential PWSCC at expansion transitions and axial PWSCC adjacent dents. These qualifications are based on pulled tube and laboratory induced PWSCC cracking in 0.043", 0.048", and 0.050" wall thickness Inconel 600 5928-05-20207 Page 5 of 17 tubing. These qualifications do not contain 0.034" wall OTSG tubing. There are no industry Appendix H qualifications directly applicable to expanded tubing. In order to confirm that these qualifications could be conservatively applied to OTSG kinetically expanded tubing the 1997, 1999, and 2001 analyses identified in sections 4.1.2 and 4.1.3 of ECR #02-01121 were performed to evaluate the expected performance for OTSG tubing with flaws similar to those previously identified at TMI-1. The 300 KHz

+Point coil is a surface riding probe so fill factor is not a concern for the examination technique provided the area being examined does not have different extraneous test variables (e.g., denting, deposits, tube geometry, noise). The tube noise studies and site validations performed for TMI-1 have confirmed that the TMI-1 kinetic expansion region eddy current data is similar to the Appendix H qualification data and TMI tubes with freespan ID IGA that were previously in situ pressure tested. The studies confirmed that similar performance was expected for OTSG kinetically expanded tubing and the 300 KHZ +Point coil examination technique is considered Appendix H qualified for TMI-1.

The 600 KHz high frequency shielded pancake coil examination technique is used for measuring the axial and circumferential extent of ID IGA indications only and has been qualified to the intent of EPRI Appendix H. Sections H2.2.2 and H2.2.3 of Supplement H2 to the EPRI Guidelines suggest that the majority of the flaws in a qualification data set include flaws that have axial lengths >0.7" or circumferential lengths >100 degrees (>0.55" for an OTSG tube). These lengths greatly exceed the measured lengths of the TMI-1 flaw population (Reference Section 4.1.4 of ECR #02-01121) and would not provide a good measure of the length sizing performance for flaws similar to those encountered at TMI-1. Length sizing performance was evaluated on 23 machined "ID IGA Like" flaws and 9 TMI pulled tube ID IGA indications. This TMI-1 qualification data set of 32 volumetric flaws included flaws that ranged from 0.02" to 0.16" in length. The TMI-1 kinetic expansion measured flaw population from Outage 1 R1 5 (Fall 2003) is very similar to the measured length of the flaw population in qualification data set. TMI-1 also performed site validation.and noise studies for the 600 KHz pancake coil similar to those that were performed for the 300 KHz +Point coil technique, as described above, and it was determined that the 600 KHz high frequency shielded pancake coil technique would perform similarly in the kinetically expanded region. The 600 KHz high frequency shielded pancake coil examination technique used for length sizing of volumetric ID IGA indications at TMI-1 is qualified in accordance with the intent of the EPRI Steam Generator Examination Guidelines by evaluating the performance of the length sizing capability for flaws similar to those encountered at TMI-1.

The studies performed to date have identified performance errors expected for these techniques and TMI-1 is conservatively applying these errors in its dispositioning criteria, therefore, TMI-1 does not plan to perform additional qualifications.

5. NRC Question On page 32 of ECR #02-01121, Rev 2, the licensee states that machined flaws were introduced into OTSG tubes to represent circumferential, axial, and volumetric damage. It is the staff's experience that machined flaws are not representative of real cracks in terms of the ability of eddy current to detect and size such flaws. This,

5928-05-20207 Page 6 of 17 in part, is because the machined flaws tend to have larger volumes than actual cracks, tending to produce larger amplitude responses for a given length and depth and, thus, making the machined flaws easier to detect and size. Please provide data demonstrating that the machined flaws used in the study produce similar signal characteristics, signal amplitude, and signal to noise ratio for a given flaw size as actual PWSCC and ID IGA flaws at TMI-1.

Response

TMI-1 agrees with the NRC staff that machined flaws will generally produce larger amplitude eddy current signals than those produced from similar depth/length IGA/SCC flaws. Machined flaws generally produce larger amplitude signals and correspondingly larger signal-to-noise ratios. Machined flaws may be used to validate eddy current examination technique performance if the performance from the machined flaws produce errors for measured values that are reasonably similar or conservative when compared to the errors produced from known IGA/SCC flaws.

Table 1 below provides the analyst measured depths from 1997-2001 testing for machined ID notches and OTSG tube laboratory grown axial PWSCC. A review of the data in this table reveals that the worst average eddy current underestimate of through wall depth involved flaw Mliii, which is a machined notch. (Each flaw was evaluated by five eddy current analysts, so the average of the five analysts' calls is reported herein) Table 2, below, provides analyst measured depths for machined ID pits and TMI-1 pulled tube ID IGA and, again, the worst average underestimate of through wall depth involved a machined flaw (M1294). Of the 36 flaws evaluated in Table 1, 23 were measured as having a through wall depth less than actual. Of the 32 flaws evaluated in Table 2, 13 were measured as having a through wall depth less than actual.

These results can be compared to the +Point depth measurement performance for the 300 KHz +Point probe phase angle depth measurement technique in EPRI Appendix H qualification for Examination Technique Specification Sheet (ETSS)

1. 20510.1. This ETSS is typically cited for industry qualification of +Point probe use in steam generator tubing. ETSS #20510.1, Revision 5, included 23 laboratory grown and 6 pulled tube PWSCC flaws. (One flaw was not detected.) Of the 28 detected flaws included in ETSS #20510.1, 6 were estimated with through wall extent less than the actual and there were underestimates similar to those in Table 1 and 2. This type of performance is not unexpected for "thumbnail" type flaws that are small in size because the eddy current response is based on the average of the depth over the eddy current field so an underestimate of maximum through wall extent is an expected result. This indicates that machined flaws can be used to provide a conservative error for estimate of depth using phase angle analysis. TMI-1 uses conservative results for calculating estimated leakage from kinetic expansion flaws by assuming that all flaws >67% through wall by eddy current be considered 100%

through wall for leakage calculation purposes.

Table 3, below, provides the analyst measured 300 KHz +Point length measurements for machined ID axial notches and OTSG tube laboratory grown axial PWSCC.

Tables 4 and 5, below, provide analyst measured axial length and circumferential 5928-05-20207 Page 7 of 17 length, respectively, for machined ID pits (i.e., ID IGA like indications) and TMI-1 pulled tube ID IGA. There are no OTSG circumferential PWSCC or additional ID IGA flaws available for inclusion in the TMI-1 sizing error study and, in fact, the industry has done little qualification work for small circumferential PWSCC flaws of the sizes typically detected in the TMI-1 required kinetic expansion region.

Review of the 6 laboratory grown flaws in Table 3 results indicates that the 300 KHz

+Point coil examination technique average axial length measurement ranged from approximately 1 to 4 times the actual flaw length. The average axial length measurement error for the 10 machined ID axial notches ranged from approximately 2 to 5 times the actual flaw length. The error indicates that there is reasonable correlation between the laboratory grown PWSCC flaws and the machined notches included in Table 3. It should also be noted that the 300 KHz +Point coil examination technique is used for depth sizing (all kinetic expansion flaws) and length sizing of circumferential indications only. TMI-1 has recently committed to plug all crack-like indications in the required kinetic expansion region (i.e., plug on detection regardless of length) so length sizing error for the 300 KHz +Point coil examination technique will no longer be applicable to repair decisions. Length sizing error for the 300 KHz

+Point coil examination technique will only be applicable for calculating as found leakage and growth evaluations.

Review of Tables 4 and 5 provides the eddy current measured axial and circumferential lengths for TMI-1 pulled tube ID IGA and machined simulated ID IGA using the 600 KHz shielded pancake coil examination technique. The estimated average axial length of the 9 pulled tube flaws ranged from -1.5 to -4 times the actual flaw length compared to -2 to 8 times the actual length for the machined flaws.

The estimated average circumferential length of the 9 pulled tube flaws ranged from

-4 to -8 times the actual length compared to -2 to -7 times for the machined flaws.

This demonstrates reasonable consistency between the machined and pulled tube flaws for this examination technique.

In summary TMI-1 has performed a comprehensive study of the expected eddy current performance for the TMI-1 kinetic expansion region and is applying the results of this study in a conservative manner that meets the intent of the EPRI Steam Generator Examination and Tube Integrity Guidelines.

5928-05-20207 Page 8 of 17 Table 1

+Point Probe Depth Sizing Performance for Machined Notches and Axial PwSCC Flaw Depth (% TW)

Analyst Flaw A

B C

D E

Averages Actual Milol 69 47 65 48 71 60.0 79 M1102 49 43 51 45 56 48.8 62 Ml103 26 37 38 28 39 33.6 36 M1104 19 17 22 21 23 20.4 20 Mlii 52 44 44 46 40 45.2 74 M1112 30 22 22 26 31 26.2 51 M1113 13 9

5 17 15 11.8 37 M1114 0

0 0

0 3

0.6 17 M1121 78 78 70 78 74 75.6 79 M1122 46 44 38 41 40 41.8 56 M1123 21 22 17 21 27 21.6 39 M1124 9

17 5

9 12 10.4 18 M1131 99 100 99 99 100 99.4 74 M1132 46 70 50 46 62 54.8 57 M1133 30 38 22 30 31 30.2 36 M1134 26 1

22 9

27 17.0 17 M1141 52 50 44 52 51 49.8 56 M1142 93 93 85 78 81 86.0 77 M1143 93 100 93 86 94 93.2 100 M1144 26 32 17 21 22 23.6 39 M1145 17 0

13 0

3 6.6 17 Ml151 65 85 70 65 68 70.6 63 M1152 100 99 99 71 100 93.8 74 M1153 100 100 100 93 100 98.6 100 M1531 56 65 58 55 59 58.6 66 M1532 41 40 44 42 46 42.6 42 M1533 19 21 24 33 26 24.6 23 M1541 69 69 69 86 75 73.6 67 M1542 38 43 47 45 42 43.0 41 M1543 26 23 24 26 26 25.0 21 Pi 91 91 82 85 78 85.4 91 P71 97 96 82 80 86 88.2 99 P72 92 91 89 93 87 90.4 96 P131 19 32 26 53 40 34.0 53 P132 45 29 48 35 26 36.6 35 P24 97 92 70 98 97 90.8 88 Note-H~awv identifications beginning with "M" are machined notches and flaw identifications beginning with "P" are laboratory grown axial PWSCC flaws.

5928-05-20207 Page 9 of 17 Table 2

+Point Probe Depth Sizing Performance for Machined ID Pits and TMI-1 Pulled Tubes With ID IGA Flaw Depth (% TW)

Analyst Flaw A

B C

D E

Averages Actual M1291 26 23 29 31 31 28.0 20 M1292 26 28 35 36 26 30.2 43 M1293 35 47 38 39 39 39.6 57 M1294 49 58 51 36 52 49.2 83 M1301 41 31 44 33 15 32.8 20 M1302 41 34 44 45 46 42.0 40 M1303 60 54 62 55 63 58.8 63 M1304 60 74 62 74 63 66.6 83 M1311 19 31 22 23 23 23.6 20 M1312 29 19 32 33 34 29.4 17 M1313 38 54 41 42 42 43.4 23 M1314 41 43 44 45 46 43.8 20 M1321 38 31 41 42 42 38.8 20 M1322 35 34 38 39 39 37.0 17 M1323 26 37 29 31 34 31.4 20 M1324 29 28 32 33 34 31.2 17 M1331 52 40 54 26 56 45.6 20 M1332 29 47 58 33 34 40.2 43 M1333 49 58 62 62 36 53.4 59 M1341 45 31 47 48 26 39.4 23 M1342 41 65 44 45 46 48.2 20 M1343 38 28 41 42 42 38.2 20 M1344 26 28 29 31 31 29.0 20 TM11 33 37 36 29 30 33.0 32 TMI2 21 21 25 33 25 25.0 30 TMI3 17 21 25 28 25 23.2 49 TMI4 39 33 22 26 42 32.4 38 TM15 39 36 39 52 39 41.0 32 TM16 19 17 20 33 20 21.8 32 TMI7 24 12 16 26 16 18.8 43 TM18 21 39 25 38 42 33.0 19 TMI9 1

1 0

28 3

6.6 38 Note-Flaw identifications beginning with "M" are machined ID pits similar to TMI-I ID IGA shapes and flaw identifications beginning with "TMI" are TMI-I pulled tube volumetric ID IGA flaws.

5928-05-20207 Page 10 of 17 Table 3

+Point Probe Axial Length Sizing Performance for Machined Axial Notches and Axial PwSCC Ax Length (Inches)

Analyst Flaw A

B C

D E

Average Actual M1101 0.33 0.33 0.37 0.33 0.3 0.332 0.063 M1102 0.3 0.33 0.34 0.3 0.34 0.322 0.063 M1103 0.27 0.33 0.4 0.33 0.3 0.326 0.063 M1104 0.2 0.36 0.17 0.2 0.34 0.254 0.063 M1531 0.47 0.47 0.47 0.5 0.54 0.490 0.247 M1532 0.47 0.47 0.5 0.46 0.5 0.480 0.247 M1533 0.5 0.5 0.5 0.53 0.5 0.506 0.248 M1541 0.43 0.43 0.43 0.43 0.53 0.450 0.188 M1542 0.43 0.43 0.43 0.43 0.43 0.430 0.188 M1543 0.33 0.43 0.43 0.46 0.47 0.424 0.187 P1 0.17 0.39 0.17 0.17 0.47 0.274 0.13 P71 0.39 0.39 0.26 0.43 0.26 0.346 0.21 P72 0.43 0.43 0.21 0.43 0.47 0.394 0.1 P131 0.12 0.42 0.25 0.21 0.21 0.242 0.16 P132 0.21 0.33 0.25 0.21 0.17 0.234 0.08 P24 0.37 0.37 0.29 0.37 0.29 0.338 0.32 Note-Flaw identifications beginning with "M" are machined ID notches similar to TMI-I flaw shapes and flaw identifications beginning with "P"' are laboratory grown axial PWSCC indications in OTSG tubing.

5928-05-20207 Page 11 of 17 Table 4 600 KHz Shielded Pancake Coil Axial Length Sizing Performance for Machined IGA Flaws and Pulled Tube ID IGA Axial Length (inches)

Analyst Flaw A

M1291 0.19 M1292 0.23 M1293 0.23 M1294 0.28 M1301 0.19 M1302 0.23 M1303 0.23 M1304 0.33 M1311 0.23 M1312 0.23 M1313 0.23 M1314 0.23 M1321 0.14 M1322 0.23 M1323 0.33 M1324 0.28 M1331 0.19 M1332 0.24 M1333 0.24 M1341 0.19 M1342 0.24 M1343 0.24 M1344 0.24 TMI1 0.16 TMI2 0.11 TMI3 0.11 TMI4 0.22 TMI5 0.11 TMI6 0.11 TMI7 0.17 TMI8 0.11 TMI9 0.11 B

0.23 0.23 0.23 0.23 0.19 0.19 0.19 0.28 0.18 0.18 0.23 0.18 0.19 0.19 0.28 0.24 0.23 0.23 0.23 0.19 0.19 0.23 0.23 0.05 0.11 0.11 0.11 0.06 0.06 0.11 0.06 0.06 C

0.23 0.23 0.23 0.23 0.14 0.19 0.23 0.23 0.23 0.23 0.23 0.19 0.14 0.19 0.28 0.28 0.19 0.19 0.19 0.19 0.19 0.19 0.24 0.09 0.06 0.06 0.11 0.06 0.11 0.06 0.06 0.11 D

0.19 0.23 0.23 0.28 0.19 0.23 0.23 0.33 0.18 0.23 0.23 0.23 0.19 0.19 0.33 0.28 0.19 0.28 0.28 0.19 0.23 0.23 0.23 0.11 0.11 0.11 0.17 0.11 0.11 0.11 0.11 0.11 E

0.19 0.23 0.23 0.23 0.14 0.23 0.28 0.33 0.23 0.23 0.23 0.23 0.19 0.23 0.33 0.28 0.24 0.24 0.24 0.19 0.28 0.24 0.24 0.13 0.11 0.11 0.17 0.11 0.11 0.17 0.11 0.06 FIELD Average Actual 0.206 0.079 0.230 0.078 0.230 0.078 0.250 0.0798 0.170 0.02 0.214 0.042 0.232 0.0615 0.300 0.111 0.210 0.079 0.220 0.078 0.230 0.079 0.212 0.079 0.170 0.0395 0.206 0.079 0.310 0.1602 0.272 0.119 0.208 0.079 0.236 0.0795 0.236 0.0785 0.190 0.079 0.226 0.0793 0.226 0.078 0.236 0.079 0.11 0.108 0.024 0.1 0.100 0.066 0.16 0.110 0.033 0.16 0.157 0.054 0.16 0.102 0.042 0.1 0.100 0.029 0.1 0.120 0.03 0.1 0.092 0.02 0.2 0.108 0.04 Note-Flaw identifications beginning with "M" are machined ID pits similar to TMI-I ID IGA shapes and flaw identifications beginning with "TMI" are TMI-I pulled tube volumetric ID IGA flaws.

5928-05-20207 Page 12 of 17 Table 5 600 KHz Shielded Pancake Coil Circumferential Length Sizing Performance for Machined IGA Flaws and Pulled Tube ID IGA Circ Length (inches)

Flaw M1291 M1292 M1293 M1294 M1301 M1302 M1303 M1304 M1311 M1312 M1313 M1314 M1321 M1322 M1323 M1324 M1331 M1332 M1333 M1341 M1342 M1343 M1344 TMI1 TMI2 TMi3 TMI4 TMI5 TMI6 TMI7 TMI8 TMI9 Analyst A

0.2 0.2 0.26 0.26 0.13 0.2 0.2 0.33 0.26 0.2 0.2 0.2 0.13 0.2 0.26 0.2 0.26 0.2 0.26 0.2 0.2 0.26 0.26 0.11 0.21 0.26 0.21 0.21 0.1 0.21 0.1 0.1 8

0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.16 0.16 0.16 0.16 0.2 0.2 0.26 0.26 0.2 0.2 0.2 0.2 0.2 0.2 0.2 0.06 0.1 0.16 0.16 0.1 0.05 0.1 0.05 0.05 C

0.26 0.2 0.26 0.26 0.13 0.2 0.2 0.27 0.21 0.16 0.16 0.16 0.13 0.27 0.27 0.27 0.2 0.2 0.2 0.26 0.26 0.26 0.26 0.11 0.1 0.1 0.1 0.1 0.05 0.1 0.05 0.1 D

0.13 0.2 0.2 0.26 0.13 0.2 0.26 0.39 0.16 0.16 0.16 0.16 0.13 0.2 0.26 0.33 0.27 0.27 0.27 0.2 0.2 0.2 0.27 0.17 0.1 0.16 0.1 0.1 0.1 0.1 0.1 0.1 E

0.2 0.2 0.27 0.27 0.13 0.2 0.27 0.33 0.27 0.2 0.2 0.27 0.2 0.27 0.27 0.27 0.26 0.26 0.26 0.2 0.26 0.26 0.26 0.17 0.1 0.21 0.16 0.1 0.1 0.16 0.1 0.1 FIELD Average 0.198 0.200 0.238 0.250 0.144 0.200 0.226 0.304 0.212 0.176 0.176 0.190 0.158 0.228 0.264 0.266 0.238 0.226 0.238 0.212 0.224 0.236 0.250 0.11 0.122 0.11 0.120 0.11 0.167 0.19 0.153 0.11 0.120 0.06 0.077 0.11 0.130 0.06 0.077 0.14 0.098 ID IGA shapes and laws.

Actual 0.079 0.078 0.078 0.0798 0.02 0.042 0.0615 0.111 0.079 0.078 0.079 0.079 0.0395 0.079 0.1602 0.119 0.079 0.0795 0.0785 0.079 0.0793 0.078 0.079 0.022 0.032 0.02 0.025 0.019 0.018 0.018 0.016 0.025 Note-Flaw identifications beginning with "M" are machined ID pits similar to TMI-I flaw identifications beginning with "TMI" are TMI-I pulled tube volumetric ID IGA f

6. NRC Question On page 33 of ECR #02-01121, Rev. 2, top paragraph, the licensee states that a comparison of the Appendix H qualification results (for 0.75 and 0.875 inch tubing) with the OTSG machined flaw results confirmed the validity of the defined examination performance in the study. Please provide that comparison. In addition, describe the number and type of specimens (e.g., pulled tube ID IGA, pulled tube ID IGA, laboratory ID cracks and IGA, machined flaws) represented in the Appendix H qualification data set.

5928-05-20207 Page 13 of 17

Response

See Tables 1 through 5 in the response to Question 5, above, for TMI-1 examination technique performance for flaw specimens and technique results for flaws included in the TMI-1 examination technique performance study. Table 6, below, provides length and depth-sizing performance results for three EPRI PWSCC +Point examination techniques that are available for industry use.

Sections 6.2.4 and 6.2.5 of the EPRI Steam Generator Examination Guidelines require that examination technique performance be adjusted as appropriate for the conditions being encountered. A review of the EPRI Appendix H PWSCC Qualification depth sizing performance provided in Table 6 reveals that the two worst underestimates of depth were -19% TW and -23% TW. In fact the depth sizing performance in Table 6 is dominated by overestimates of through wall extent. TMI-1 assumes that any flaws measured as >67% TW be considered 100% TW for leakage calculation purposes. Thus, in the kinetic expansions TMI-1 applies a depth sizing performance that is significantly more conservative than the performance supported by the EPRI Appendix H qualifications in Table 6.

As stated in the answer to Question 5, above, the industry has done little sizing qualification work with short circumferential PWSCC flaws so there is a limited database for comparison. TMI-1 has committed to plug all "crack-like" flaws in the required kinetic expansion length so length measurement error is only applicable for calculating as found accident induced leakage and assessing growth, and is no longer used for repair decisions.

There are no industry Appendix H qualifications for the 600 KHz high frequency shielded pancake coil examination technique for comparison. Tables 4 and 5, above, provided the examination performance for this technique. This performance included 9 TMI-1 pulled tube flaws and the machined flaws in the study provided verification of expected performance. See the response in Question 5 for further validation.

5928-05-20207 Page 14 of 17 Table 6 - EPRI ETSS Performance ETSS #20510.1 Circumferential PNVSCC at ETSS #20511.1 Atxial PVSCC at Expansion ETSS #96701.1 Circumferential PNVSCC at Expansion Expansion Transitions Transitions Tra nsitions ECT ECT ECT ECT Measured Actual Measured Measured Actual Measured ECT MNeasured Actual Depth %

Length Length ctual Depth %

Length Length ECT Measured Actual Length Length epth TV (Degrees) (Degrees)

I)epth TV (Inches)

(Inches)

Xctual Depth Depth % TWV (Degrees)

(Degrees) 70 66 186 140.3 39 NDD 0.187 NDD 42 30 360 360 100 98 178 110.8 47 77 0.203 0.26 38 38 360 360 96 HY0 148 127.5 60 61 0.156 0.19 57 42 360 360 79 90 360 360 47 50 0.163 0.15 84 96 209 222 89 100 77 79.5 66 87 0.547 0.19 79 82 360 360 66 83 331 336.6 35 57 0.125 0.15 22 NDD 177 NDD 77 98 46 54.7 64 73 0.295 0.38 100 99 240 204 67 99 153 183.3 84 100 0.504 0.67 49 48 222 158 89 99 123 55.4 41 57 0.224 0.27 67 44 205 176 100 100 240 223 40 82 0.245 0.19 100 98 256 241 49 99 222 185 37 NDD 0.205 NDD 53 56 115 139 67 100 205 195.1 38 NDD 0.152 NDD 100 99 236 185 100 100 256 232.3 47 50 0.268 0.34 75 76 182 185 53 56 115 111.5 63 73 0.738 0.49 49 56 170 167 100 99 192 184 44 73 0.116 0.15 31 48 162 130 100 99 170 127.6 89 100 0.909 0.67 53 56 177 167 100 100 193 147.7 64 86 0.176 0.27 90 100 88 71 100 100 236 185.8 68 82 0.196 0.19 75 56 182 185.8 57 77 0.198 0.19 49 61 170 157.9 75 86 0.808 0.45 31 86 162 148.6 62 69 0.171 0.15 53 52 177 148.6 100 98 0

0 22 NDD 177 NDD 90 99 88 69.2 42 100 360 229.3 38 100 360 307.3 57 97 360 187.2 44 52 22.68 30.9 84 100 209 216 Data set is comprised of 6 pulled tube specimens and 23 ata set is comprised of I pulled tube specimen and ata set is comprised of 5 pulled tube specimens and 12 laboratory grown laboratory grown circumferential PWSCC cracks.

2I laboratory grown axial PWSCC cracks.

itcumferential PWSCC cracks.

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7.

NRC Question Please provide a table or graph comparing the axial (and/or circumferential) and depth measurements by the mid-range +Point and HF pancake coils for all machined flaws, laboratory grown PWSCC, and pulled tube IGA flaws considered in the "1999 Analyses" discussed beginning on page 33 of ECR #02-01121, Rev. 2. If this information has been previously provided to the staff, please cite the reference.

Response

See Tables 1 through 5 in the response to Question 5, above. Note that the 600 KHz shielded pancake coil technique is not used for depth sizing so there is no depth sizing data available for this technique.

8.

NRC Question Please provide a table or graph comparing the axial (or circumferential) and depth measurements by the mid-range +Point and HF pancake coils to the destructive examination measurements for the six laboratory grown PWSCC flaws described on page 35 of ECR #02-01121, Rev. 2. If this information has been previously provided to the staff, please cite the reference.

Response

See Tables 1 and 3 in the response to Question 5, above. Note that the 600 KHz high frequency shielded pancake coil technique is not used for length sizing PWSCC (crack like) flaws so no data is available for length sizing of PWSCC with this technique.

9.

NRC Question Please provide a table or graph comparing the depth measurements by the mid-range

+Point and HF pancake coils to the destructive examination measurements for the nine TMI-1 pulled tube ID IGA flaws described on page 35 of ECR #02-01121, Rev. 2. If this information has been previously provided to the staff, please cite the reference. Please comment on the staff's observation that the range of flaw depths in the pulled tube specimen (which range to 49% maximum depth) does not address the range of flaw depth of interest which are depths higher than 49% and ranging to 100%. In particular, comment on what the pulled tube data contributes to the licensee's conclusion that depth measurement error is 95% bounded by -28.1%.

Response

Table 2 in the response to Question 5, above, provides the ID IGA depth sizing performance for the 300 KHz +Point coil examination technique. Note that TMI-1 does not use the 600 KHz high frequency shielded pancake coil examination technique for depth measurements so there are no depth sizing results to present.

Five of the machined flaws in Table 2 ranged from 57% TW to 83% TW in actual depth.

The measurement errors for these five flaws were similar to the errors observed for the 5928-05-20207 Page 16 of 17 pulled tube specimens of Table 2, as was discussed in the response to Question 5. As discussed above, the similarity of nine pulled tube flaws in terms of depth sizing errors provides validation that the machined flaws can be used in a full spectrum of depth samples supports the -28.1% TW error. This approach meets the intent of the EPRI Steam Generator Examination Guidelines by evaluating the sizing error for flaws ranging from 17% TW to 83% TW. TMI-1's evaluation was similar to some industry Appendix H qualifications (ETSSs), shown in Table 6, where pulled tube flaws are supplemented by lab-grown flaws in order to obtain a broader spectrum of sizes and depths in the flaw datasets.

10. NRC Question Provide leak rate estimates (in terms of gallons per minute), based on the licensee's PICEP leakage model, for circumferential cracks with lengths of 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, and 0.7 inches for 0.625 inch diameter, 0.034 inch thick tubes. Utilize assumptions on pressure and temperature consistent with those used to generate PICEP leak rates for axial cracks shown on Table 6 of the licensee's report ECR No. TM 01-00328, which was enclosed with the licensee's letter, dated July 13, 2001. Describe values of all other input parameters used to generate these estimates (e.g., material properties, crack tortuosity, surface roughness, etc.).

Response

A response to this question is planned for submittal by August 19, 2005.

11. NRC Question In its letters dated August 16, 2004, and May 3, 2005, the licensee provided its updated inspection acceptance criteria and leakage assessment methodology for the TMI-1 OTSG Kinetic Expansion examinations. This information was submitted for the NRC's review and acceptance in accordance with Section IWB-3630 of ASME Code Section Xl. However, Attachment 3 of the May 3, 2005 submittal purports to identify commitments made in the document (presumably the May 3, 2005 letter and the attached ECR #02-01121, Rev. 2) by the licensee. Attachment 3 states that any other actions discussed in the submittal representing intended or planned actions by the licensee are described to the NRC for the NRC's information and are not regulatory commitments. The staff does not understand what the licensee is trying to accomplish here. The list of "commitments" in Attachment 3 are but a small subset of the inspections, inspection acceptance criteria, and leakage assessment methodology discussed in ECR #02-01121, Rev. 2 which the staff is currently reviewing. Upon the staff's review and acceptance of the report, the report becomes part of the TMI-1 licensing basis. Any changes to the methods and criteria contained the report would be subject to prior NRC review and approval. Therefore, we recommend that the list of regulatory commitments in Attachment 3 be deleted.

5928-05-20207 Page 17of 17 Response of the May 3, 2005 AmerGen submittal will be deleted upon submittal of the final ECR #02-01121, Revision 2. These commitments are being incorporated into the final ECR #02-01121, Rev. 2, which will become part of the TMI-1 licensing basis.