ML073170370
| ML073170370 | |
| Person / Time | |
|---|---|
| Site: | Limerick  |
| Issue date: | 11/08/2007 |
| From: | Cowan P Exelon Generation Co, Exelon Nuclear |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| Download: ML073170370 (44) | |
Text
200 Exelon Way Kennett Square, PA 19348 10 CFR 50.55a November 8,2007 U. S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 Limerick Generating Station, Units 1 and 2 Facility Operating License Nos. NPF-39 and NPF-85 NRC Docket Nos. 50-352 and 50-353
Subject:
Response to Request for Additional Information - Submittal of Relief Requests Associated with the Third lnservice Inspection (ISI) Interval
References:
- 1) Letter from P. B. Cowan (Exelon Generation Company, LLC) to U. S.
Nuclear Regulatory Commission, dated March 6, 2007
- 2) Letter from P. J. Bamford (U. S. Nuclear Regulatory Commission) to C. M.
Crane (Exelon Generation Company, LLC), dated October 26, 2007 In the Reference 1 letter, Exelon Generation Company, LLC requested your review of relied requests associated with the third lnservice Inspection (ISI) Interval for Limerick Generating Station (LGS), Units 1 and 2. The third interval of the LGS, Units 1 and 2 IS1 program complies with the 2001 Edition through 2003 Addenda of the American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel (B&PV) Code. The third IS1 interval began on February 1, 2007, and is scheduled to conclude on January 31,201 7, for LGS, Units 1 and 2.
In the Reference 2 letter, the U. S. Nuclear Regulatory Commission requested additional information. Attached is our response.
No commitments are contained in this letter.
Should you have any questions concerning this letter, please contact Tom Loomis at (610) 765-5510.
Pamela B. Cowan Director - Licensing & Regulatory Affairs Exelon Generation Company, LLC Attachments: 1) Response to Request for Additional Information - Relief Requests Associated with the Third Ten-Year Interval for Limerick Generating Station, Units 1 and 2
- 2) Tables 2 and 3 - Response to Request for Additional Information 13R-02 Question 6
- 3) Drawings cc: S. J. Collins, Regional Administrator, Region I, USNRC S. Hansell, USNRC Senior Resident Inspector, LGS P. Bamford. Proiect Manaaer [LGSl USNRC
ATTACHMENT 1 Response to Request for Additional Information Relief Requests Associated with the Third Ten-Year Interval for Limerick Generating Station, Units 1 and 2
Response to Request for Additional Information Attachment 1 Third Interval IS1 Relief Requests Page 1 Relief Request 13R-02:
Background:
Relief Request 13R-02, dated March 6, 2007, states that in lieu of the evaluation and sample expansion requirements in Electric Power Research Institute (EPRI) TR-112657, Section 3.6.6.2, RISI Selected Evaluations, LGS will utilize the requirements of Subarticle - 2430, Additional Examinations contained in Code Case N-578-1. The alternative criteria for additional examinations contained in Code Case N-578-1 provide a more refined methodology for implementing necessary additional examinations. Relief Request 13R-02 also states that to supplement the requirements of EPRI TR-112657, Table 4-1, Summary of Degradation-Specific Inspection Requirements and Examination Methods, LGS will utilize the provisions listed in Table 1, Examination Category R-A, Risk-Informed Piping Examinations contained in Code Case N-578-1.
The NRC staff notes that Regulatory Guide (RG) 1.I 93 ASME Code Cases Not Approved for Use, dated August 2005, lists the code cases that the NRC has determined not acceptable for use on a generic basis. Code Case N-578-1 is listed in Table 2, Unacceptable Section XI Code Cases, of RG 1.I 93. The summary given in Table 2 of RG 1.I93 states in regards to Code Case N-578-1 that:
(1) The Code Case does not address inspection strategy for existing augmented and other inspection programs such as intergranular stress corrosion cracking, flow-assisted corrosion, microbiological corrosion, and pitting.
(2) The Code Case does not provide system-level guidelines for change in risk evaluation to ensure that the risk from individual system failures will be kept small and dominant risk contributors will not be created.
Based on this background discussion the NRC staff has the following questions:
NRC Request 1:
- 1. It is not clear what is meant by a more refined methodology for implementing additional examinations. How do the alternative criteria for additional examinations contained in Code Case N-578-1 provide a more refined methodology?
ResDonse 1:
Additional examinations are discussed in Section 3.6.6.2 of Electric Power Research Institute (EPRI) TR-112657, Revised Risk-Informed Inservice Inspection Evaluation Procedure, Revision B-A. This section discusses requirements for additional examinations at a high level, based on service conditions, degradation mechanisms, and the performance of evaluations to determine the scope of additional examinations.
A more specific discussion regarding the requirements for additional examinations is contained within paragraph -2430 of American Society of Mechanical Engineers (ASME) Code Case N-578-1, Risk-Informed Requirements for Class 1, 2, or 3 Piping, Method B,Section XI, Division
- 1. The Limerick Generating Station (LGS), Units 1 and 2 statement that the alternative criteria for additional examinations contained in Code Case N-578-1 provides a more refined methodology for implementing necessary additional examinations refers to the additional
Response to Request for Additional Information Attachment 1 Third Interval IS1 Relief Requests Page 2 specificity and clarity discussed within paragraph -2430 of ASME Code Case N-578-1, when compared to the high level discussion in EPRl TR-112657.
NRC Request 2:
- 2. Please verify that any additional examinations required due to the identification of flaws or relevant conditions will be conducted during the current outage.
Response 2:
While not explicitly specified in paragraph -2430 of Code Case N-578-1, LGS intends to perform additional examinations required due to the identification of flaws or relevant conditions, which exceeds the acceptance standards, during the current outage in which the flaws are identified.
NRC Request 3:
- 3. Discuss what examination methods will be performed for each degradation mechanism.
What volumes will be examined and what techniques will be used?
Response 3:
Section 4 of EPRl TR-112657 states "Application of RI-IS1 uses NDE techniques that are designed to be effective for specific degradation mechanisms and examination locations".
Section 4 also identifies methods of examination for each degradation mechanism with the primary method being ultrasonic testing (UT) techniques. However, EPRI TR-112657 does not identify the examination volumes for components without a degradation mechanism. In addition, EPRI TR-112657 does not specify examination volumes and methods for socket welds.
LGS has requested to use the examination methods from Code Case N-578-1 instead of the methods from EPRl TR-112657, except that the volumetric method will be used to examine intergranular stress corrosion cracking (IGSCC), as discussed in response to NRC question 5 below. In addition, the VT-2 examination method will be used to examine socket welds in accordance with the provisions of Code Case N-578-1 Table 1.
The examination figures specified in Section 4 of EPRl TR-112657 will be used to determine the examination volume based on the degradation mechanism and component configuration. Table 1 below provides a comparison of degradation mechanisms, examination volumes, and examination methods.
Response to Request for Additional Information Attachment 1 Third Interval ISI Relief Requests Page 3 Table 1: Application Degradation Mechanisms, Examination Volumes, and Examination Methods Degradation Mechanism (Initials) N-578-1 Item Number TR-112657 Section XI TR-112657 N-578-1 Examination Examination Volume Configuration Exam Exam Exam Exam Method Comments Figure Figure Method Method Comments Thermal Fatigue (TF) R1.11 Butt-welds 4-1 IWB-2500- RI-ISI volume increased Volumetric Volumetric No difference 4-2 8(c) beyond counter bore, in method IWC-2500- and is applied to smaller 7(a) piping diameters and thicknesses.
Sweep-o-lets 4-3 IWB-2500-9 RI-ISI volume shifted to blend area of branch connection fitting.
IWC-2500-11 UT not required for Class 2 Weld-o-lets 4-4 IWC-2500-10 RI-ISI volume increased for thicker material IWC-2500-10 UT not required for Class 2 Intergranular Stress Corrosion Cracking (IGSCC) R1.16 Butt-welds 4-10 IWB-2500- RI-ISI volume increased Volumetric Volumetric No difference 4-11 8(c) beyond counter bore, in method IWC-2500- and is applied to smaller 7(a) piping diameters and thicknesses.
Sweep-o-lets 4-12 IWB-2500-9 RI-ISI volume shifted to blend area of branch connection fitting.
IWC-2500-11 UT not required for Class 2 Weld-o-lets 4-13 IWC-2500-10 RI-ISI volume increased for thicker material IWC-2500-10 UT not required for Class 2 Flow Accelerated Corrosion (FAC) R1.18 Piping 4-16 thru N/A Section XI does not Volumetric Volumetric No difference Components 4-22 address this per FAC in method examination type. Program Currently, all FAC susceptible components are within the station FAC Program.
No Damage Mechanism R1.20 Butt-welds N/A IWB-2500- Examination N/A Volumetric Examination 8(c) requirements are not requirements IWC-2500- identified in TR-112657. are not 7(a) Examination figures are identified in taken from N-578-1 and TR-112657.
Sweep-o-lets IWB-2500-9 include the expanded exam volume specified Weld-o-lets IWB-2500-10 in Table 1 Note (1).
All Damage Mechanisms Socket welds N/A N/A No volumetric N/A VT-2 Examination examination figure requirements specified are taken from N-578-1 Table 1 Note (2).
Response to Request for Additional Information Attachment 1 Third Interval IS1 Relief Requests Page 4 NRC Request 4:
- 4. Please describe how volumetric examinations will be performed. Will volumetric examinations include the volume required for American Society of Mechanical Engineers (ASME)Section XI examinations? Will ASME Section XI, Appendix Vlll qualified examiners and procedures be used for all volumetric exams? Will the examination volume be scanned for both axial and transverse indications for all exams?
Response 4:
In general, LGS plans to use UT techniques for volumetric examinations.
For the components addressed by the Risk Informed lnservice Inspection (RI-ISI) program, ASME Section XI focuses primarily on weld examinations. Risk Informed examination volumes also include portions of piping and fitting base materials that are susceptible to particular degradation mechanisms. The examination figures specified in Section 4 of EPRl TR-112657 differ from the examination figures in ASME Section XI for certain component configurations and evaluated degradations. The differences between the examination programs are summarized in Table 1 above. Table 1 is limited to the current degradation mechanisms and component configurations at LGS.
The ASME Section XI, Mandatory Appendix I, "Ultrasonic Examinations," specifies that UT examination procedures, equipment, and personnel used to detect and size flaws in piping welds shall be qualified by performance demonstration in accordance with ASME Section XI Appendix VI II, "Performance Demonstration for Ultrasonic Examination Systems." The RI-IS1 program complies with Appendix Vlll for weld examinations. In cases where the examination requirements cannot be met, LGS will submit a request for relief in accordance with 10CFR50.55a, "Codes and standards."
The examination methods are designed to be effective for specific degradation mechanisms and examination locations. The volumetric scanning will be in both axial and circumferential directions to detect the flaws in these orientations.
NRC Request 5:
- 5. How will dissimilar metal welds be addressed? Discuss in detail the technical basis for including alloy 600 pressure-retaining dissimilar metal welds in your risk-informed inservice inspection (Rl-El), rather than a separate augmented program to the RI-IS1 program.
Response 5:
All dissimilar metals (DM) welds, as characterized in ASME Section XI IWA-9000, have been evaluated for failure potential and consequence of failure along with the other non-exempt piping. The piping segments containing the DM welds were classified into the appropriate RI-IS1 categories, and appropriate elements were selected per the category requirements for examination during the third inspection interval.
DM welds that are susceptible to IGSCC (Le., lGSCC Categories B through G, as applicable) and not subject to other degradation mechanism(s) are removed from the RI-IS1 program population. They are contained in the Limerick IS1 Augmented Program 01, "USNRC Generic Letter 88-01, lntergranular Stress Corrosion Cracking" and are subject to the inspection
Response to Request for Additional Information Attachment 1 Third Interval IS1 Relief Requests Page 5 requirements of BWRVIP-75-A "BWR Vessel and lnternals Project Technical Basis for Revisions to Generic Letter 88-01 Inspection Schedules". Furthermore, all DM welds classified as Category A (resistant material) per BWRVIP-75-A are included in the RI-IS1 program.
NRC Request 6:
- 6. Is your proposed RI-IS1program the same program as the prior program authorized by the NRC via letter dated March 3, 2003 ADAMS Accession No. ML030620491, (Le., are the number and locations of the exams the same or have they changed)? Provide information regarding: examinations, system, components, degradation mechanisms, class, etc., similar to that provided in Attachment 1 of the Callaway submittal dated March 28, 2006 (ADAMS Accession No. ML061010704). The information should show a summary of the changes in inspections from the ASME Section XI program and changes from the previous RI-IS1 program to the proposed RI-IS1 program.
Resoonse 6:
The requested information regarding examinations, system, components, and degradation mechanisms for the pre-RI-ISI, the second interval RI-ISI, and the third interval RI-IS1 plans is provided in Tables 2 and 3, which is contained in Attachment 2. As a "living program," the RI-IS1 program methodology requires on-going revisions due to changes that occur after the original implementation. Component and configuration changes, major PRA model revisions, and weld coverage/accessibility, are maintained as part of the LGS RI-IS1program. The following tables provide a summary of the changes to the RI-IS1 inspection populations for LGS, Units 1 and 2 from the initial issuance of the program up to the latest revision currently being implemented:
RISK EXAMS EXAMS ITEMS AFFECTING CHANGES CATEGORY High (RISI REV. 0) 41 (RISI REV. 3) 62 9
Limited Exam Coverage RI-IS1 Category Reclassifications due to updated PRA Model
.. PlanUComponent Modifications Limited Exam Coverage Medium Total I 55 96 II 79 141 I RI-IS1 Category Reclassifications due to updated PRA Model
= PlanUComoonent Modifications I
RISK EXAMS EXAMS ITEMS AFFECTING CHANGES CATEGORY (RISI REV. 0) (RISI REV. 3) 9 Limited Exam Coverage High 46 63 9 RI-IS1 Category Reclassifications due to updated PRA Model PlanffComponent Modifications Medium 51 82 . Limited Exam Coverage RI-IS1 Category Reclassificationsdue to updated PRA Model PlanUComoonent Modifications Total I 97 I 145 I I
Response to Request for Additional Information Attachment 1 Third Interval IS1 Relief Requests Page 6 Limited Exam Coveraqe- The location of several examinations changed to increase code coverage.
Plant Modifications- Several plant modifications were installed on both Limerick Unit 1 and Unit
- 2. Several of these modifications increased the number of welds (valve replacements) and other modifications affected plant risk (Le., ESW valve replacements, SRV accumulators, Digital Feedwater Control System, and APRM Modifications).
RI-IS1 Cateaorv Reclassifications due to an uodated PRA model- There were many changes to the PRA model that affected the number and locations of the required inspections. Some of these changes were:
Incorporated Interfacing Systems LOCA (ISLOCA) and Break Outside Containment (BOC)
. initiators Incorporated a few new Special Initiators (i.e., Loss of Instrument Air, Loss of TECW, and Loss of an AC Bus)
= Revised LOOP analysis for initiating event frequencies and non-recovery probabilities including the 2003 Northeast Blackout.
Incorporated loss of any of the four divisional AC and DC buses as initiating events (previously only loss of Division I was included).
NRC Request 7:
- 7. In section 4.0 of relief request 13R-02, you state that, the original risk impact assessment is not a necessary element of the implementing process and is not required to be continually updated
- The risk assessment need not be continually updated. LGS is, however, requesting to use a risk-informed alternative in accordance with Title 10 of the Code of Federal Regulations 50.55a(a)(3)(i) for the third IS1 interval that began on February 1, 2007, and that is based on Electric Power Research Institute (EPRI) TR-112657. A vital element of the NRC staffs conclusion that your proposed alternative satisfies the EPRI guidelines and provides an acceptable level of quality and safety is the evaluation of the change in risk between the ASME inspection program and your proposed program. The staff requests an estimate of the change in risk between the ASME IS1 program in place at your facility prior to the implementation of the first RI-IS1 program, and the RI-IS1 program that you are proposing for the third IS1 interval. Please provide this information. The estimate should include all changes to the facility and to the Probabilistic Risk Assessment models that might affect the change in risk estimate.
Response 7:
As part of updating the RI-IS1analysis for the third 10-year interval, the original risk impact assessment was also updated to confirm the change in risk was maintained within the acceptance guidelines. The original methodology of the calculation was not changed, and the change in risk was simply re-assessed using the initial 1989 Section XI program prior to RI-IS1 and the new element selection for the third 10-year interval RI-IS1 program. This same process has been maintained in each revision to the Limerick RI-IS1 report that has been performed to date.
Response to Request for Additional Information Attachment 1 Third Interval IS1 Relief Requests Page 7 Using this process, the change in risk for Unit 1 was 2.21 E-08 for delta-core damage frequency (delta-CDF) and -1.25E-09 for delta-large early release frequency (delta-LERF). For Unit 2, the values were 2.68E-08 for delta-CDF and 1.02E-09 for delta-LERF. These values are all within the 1 .OOE-06 and 1.00E-07 acceptance criteria for delta-CDF and delta-LERF, respectively.
The change in risk analysis was likewise down at a system level, and no system acceptance criteria are exceeded in the current program using the latest RI-IS1 element elections.
Relief Request 13R-05:
NRC Request 1:
- 1. Page two of RR 13R-05, second paragraph, sixth line states that The Technical Specifications functional testing program is based on the ASME/ANSI OMc-1990 Addenda to the ASME/ANSI OM4987 Edition Part 4. The Relief Request states that LGS is using ASME Section XI, 2001 edition through the 2003 addenda. ASME Section XI, requires the use of ASMElANSl OM-1987 edition Part 4 with OMa 1988 Addenda (Ref. Table IWA-1600-1). Also, the NRC never endorsed OMc-1990 addenda to OM-4 for use. Therefore, please provide the basis for using the OMc-1990 addenda as the basis for the LGS Technical Specification (TS) Testing Program.
Response 1:
As discussed in the U. S. Nuclear Regulatory Commission letter to Philadelphia Electric Company, dated May 11, 1992, the Staff issued Amendment No. 54 to the Limerick Unit 1 Facility Operating License and Amendment No. 19 to the Limerick Unit 2 Facility Operating License. These amendments incorporated the use of the ASMEIANSI OM-1990 Addenda to ASME/ANSI OM-1987 Part 4 into the Limerick Technical Specifications as discussed in the amendments.
NRC Request 2:
- 2. Page two of RR 13R-05, fifth paragraph, states that The examinations are performed by qualified personnel and meet the intent of the inspections and tests of ASME Section XI.
Please provide justification for this statement and explain how the TS 3/4.7.4 visual examination method is equivalent to the VT-3 visual examination method described in IWA-2213.
Response 2:
The Limerick Technical Specifications do not describe the personnel qualification for performing the inspections. The Limerick Technical Specifications describe the acceptance criteria for the visual inspections. The personnel that perform the examinations are qualified to a limited VT-3 certification (IWA-2350). This limited certification meets the requirements of an ASME Section XI VT-3 certification (IWA-2213) for snubber examinations only. Exelon Procedure TQ-AA-122, Qualification and Certification of Nondestructive (NDE) Personnel, controls this certification.
NRC Request 3:
- 3. OM-4, Paragraph 3.2.1.1, Operability Test, states that snubber operational readiness shall be tested by either an in-place or bench test. Please verify that at LGS, snubbers are tested by an in-place or bench test, because TS 3/4.7.4 does not specify this.
Response to Request for Additional Information Attachment 1 Third Interval IS1 Relief Requests Page 8 Response 3:
The testing of LGS snubbers is controlled by procedure ST-4-103-301-1, "Snubber Functional Test", for Unit 1, and ST-4-103-301-2, "Snubber Functional Test", for Unit 2. These procedures control the testing of snubbers. General practice is to bench test snubbers for functionality.
NRC Request 4:
- 4. Snubbers are tested in defined test groups using either a 10 percent testing plan or the 37 Testing Sample Plan. The 37 Testing Sample Plan: OM-4, Paragraph 3.2.3.2(b) states that for any snubber(s) determined to be unacceptable as a result of testing, an additional random sample of at least one-half the size of the initial sample lot shall be tested. Explain how the requirements of Section 3.2.3.2(b) will be met, if the 37 testing sample plan is used.
Response 4:
Limerick Technical Specification 4.7.4.e.2 describes the 37 testing sample plan. The testing plan for a snubber failure is based on Technical Specification Figure 4.7.4-1 "Sample Plan 2)
For Snubber Functional Test". This figure uses the equation C=0.055n-2.007 where C is the total number of snubbers of that type not meeting the acceptance requirements and N is the cumulative number of snubbers of the type tested. If the point falls above the line then additional testing is required. Snubber testing is completed when the point falls in the "Accept" region or all the snubbers of that type have been tested.
If one (1) snubber fails to meet the acceptance criteria then an additional random sample of 19 snubbers of the failed type will be tested. If a second snubber fails to meet the acceptance criteria then an additional random sample of 18 snubbers of the failed type will be tested. This testing continues until the number of failed snubbers falls below the equation contained in Technical Specification Figure 4.7.4-1 or all the snubbers of that type have been tested.
Relief Request 13R-06:
- 1. For Relief Request 13R-06, Revision 0, relief is requested pursuant to 10 CFR 50.55a(g)(5)(iii), from the ASME Code required volumetric examination of essentially 100 percent of the weld length on the basis that conformance to the ASME Code is impractical.
NRC Request 1a:
- a. Provide the following residual heat removal (RHR) heat exchanger drawings as referenced in Relief Request 13R-06: XI-IE-205 (LGS, Unit 1) and XI-2E-205 (LGS, Unit 2);
Response la:
The requested drawings are included in Attachment 3.
NRC Request 1b:
- b. In the Applicable Code Requirement section of RR 13R-06, ASME Code Figure IWC-2500-1 for circumferential welds is referenced. Identify whether the applicable weld configuration is Figure IWC-2500-l(a) or (b) or (c);
Response to Request for Additional Information Attachment 1 Third Interval IS1 Relief Requests Page 9 Response 1 b:
Weld Name Figure IWC-2500-1 RHR-HXAR-4 Shell Ring 1 to Flange Weld (a)
RHR-HXBR-4 Shell Ring 1 to Flange Weld (a) 2AE-205 SG-1 Shell (Ring # I ) to Flange Weld (a) 2BE-205 SG-1 Shell (Ring # I ) to Flange Weld (a)
NRC Request Ic:
- c. ASME Code,Section XI, Table IWC-2500-1, Examination Category C-A, Item C1 .lo, Note 3 states that in the case of multiple vessels of similar design, size, and service (such as steam generators, heat exchangers), the required examinations may be limited to one vessel or distributed among the vessels. LGS, Units 1 and 2 each have two RHR heat exchangers.
Are exams of all four heat exchangers planned to distribute the examinations in order to meet the ASME Code required volumetric examination of essentially 100% of the weld length?
Response Ic:
Each RHR heat exchanger contains four (4) welds that require examination. Since the RHR heat exchangers are the same design for each Unit, only one heat exchanger is examined. The UT examinations on three (3) of the welds obtain the required coverage. Only one ( I ) weld (shell to flange) has limited coverage, and this limitation is due to the bolting of the heat exchangers bottom head to the heat exchanger. Since both heat exchangers are the same design, performing an examination of the shell to flange weld on both RHR heat exchangers will not increase the examination coverage.
Re1ief Request 13R-07:
NRC Request la:
- a. Provide the following pump drawings as referenced in Relief Request 13R-07:
XI-1 P-202 and XI-1P-206 (LGS, Unit I), XI-2P-202 and XI-2P-206 (LGS, Unit 2)
Response la:
The requested drawings are included in Attachment 3.
NRC Request 1 b:
- b. Clarify the pump designations regarding 1 (2) and what pumps are assigned to LGS, Units 1 and 2 and to what systems.
Response 1 b:
Limerick uses the following designation for pumps:
0 First number is the unit (example: l(2) - This number refers to Unit 1(Unit 2))
0 First letter is the loop that contains the pump (example: 1(2)A-P202) 0 Second letter is P for pumps (example: 1(2)A-P202)
Response to Request for Additional Information Attachment 1 Third Interval IS1 Relief Requests Page 10 The last three numbers are the pump designation (example: 1(2)A-P202).
The designation "l(2)" is used when a pump is on both units. This methodology is used so both pump component numbers need not be written. The following is a listing of the Limerick pumps affected by this relief request:
1(2)A-P202 is the Unit 1 and Unit 2 "A" Residual Heat Removal Pumps 1(2)B-P202 is the Unit 1 and Unit 2 "B" Residual Heat Removal Pumps 1(2)C-P202 is the Unit 1 and Unit 2 "C" Residual Heat Removal Pumps 1(2)D-P202 is the Unit 1 and Unit 2 'ID" Residual Heat Removal Pumps 1(2)A-P206 is the Unit 1 and Unit 2 "A" Core Spray Pumps 1(2)B-P206 is the Unit 1 and Unit 2 "B" Core Spray Pumps 1(2)C-P206 is the Unit 1 and Unit 2 "C" Core Spray Pumps 1(2)D-P206 is the Unit 1 and Unit 2 "D" Core Spray Pumps Relief Request 13R-09, l3R-10, 13R-11, and l3R-12:
NRC Request 1:
- 1. The NRC staff understands that LGS, Units 1 and 2 is proposing to extend its Integrated Leak Rate Test (ILRT) interval from 10 to 15 years in accordance with the submittal dated February 20,2007 (ADAMS Accession No. ML070530296). Based on the proposed new ILRT frequency, provide a detailed evaluation and justification of the effect of the proposed ILRT extension on the level of qualify and safety for relief requests 13R-09 and 13R-10.
Response 1:
As noted in 13R-09 and 13R-10, a VT-2 examination looking for a nitrogen gas leak with less than 1 psig driving pressure for the drywell pressure instrumentation (13R-09) and the suppression pool pressure and level instrumentation (l3R-10) would be inconclusive.
Additionally, significant tubing leaks would be identified in the control room as part of the Technical Specification required monitoring. As also discussed in our response to Question No.
4 concerning your request for additional information for the ILRT extension (P. B. Cowan (Exelon Generation Company, LLC) to U. S. Nuclear Regulatory Commission, "Response to Request for Additional Information Technical Specifications Change Request - Type A Test Extension", dated September 14, 2007), a history of combined Type B and Type C test leakage rate totals were provided to justify the ILRT extension. These totals do not identify adverse trends in overall leak tightness through measurement of the Type B and C leakages, which would include the drywell pressure instrumentation (13R-09) and the suppression pool pressure and level instrumentation (13R-10). Therefore, there is no issue / impact on the level of quality and safety with regards to these two relief requests. If the ILRT extension request is approved the current schedule for performing the ILRTs is 2012 (1R14) for Unit 1 and 201 1 (2R11) for Unit 2. The dates for the ILRTs are subject to change, but will be completed in the interval.
NRC Request 2:
- 2. For the components of relief requests 13R-09, l3R-10, 13R-11, and l3R-12, please identify any tests conducted, e.g. TS surveillance tests, which affect internal pressure other than the ILRT and local leak rate tests, the frequency conducted, the internal pressure achieved, and the feasibility of conducting a system leak test concurrent with the test.
Response to Request for Additional Information Attachment 1 Third Interval IS1 Relief Requests Page 11 Response 2:
A review of LGS test procedures was performed, which did not identify any tests other than the ILRT and local leak rate tests that affect the internal pressure of the piping identified in the relief requests.
NRC Request 3:
Response 3:
The requested drawings are included in Attachment 3.
ATTACHMENT 2 Table 2 Response to Request for Additional Information 13R-02 Question 6 Unit 1 Table 3 Response to Request for Additional Information 13R-02 Question 6 Unit 2
Submittal of Relief Requests Associated with Third ISI Attachment 2 Response to Request for Additional Information I3R-02 Question 6 Page 1 of 6 Table 2 Response to Request for Additional Information I3R-02 Question 6 Unit 1 Table 2: System/Selection Comparisons Between ASME Section XI and Risk Informed Programs for Unit 1 Unit 1 2nd Interval Unit 1: 2nd Interval RI-ISI (1989 Edition) Unit 1: 3rd Interval RI-ISI (2001Edition/ 2003 Addenda)
System ASME XI (1989 Edition)
Cat. Weld Weld Risk Conseq Failure Potential Weld RI-ISI Risk Conseq Failure Potential Weld RI-ISI Count Sel. Cat. Rank Rank DM(s) Rank Count Sel. Cat. Rank Rank DM(s) Rank Count Sel.
CRD C-F-2 53 4 6/7 L - - - 53 0 6/7 L - - - 53 0 B-F 9 9 4 M H None L 3 1 2 H H TASCS IGSCC M 14 4 FAC TASCS CS B-J 31 8 5 M L/M H/M 14 9 4 M H None L 20 2 IGSCC Note 1 C-F-1 1 1 6/7 L - - - 241 0 6/7 L - - - 224 0 C-F-2 243 19 1 H H TASCS FAC H 2 2 1 H H TASCS TT FAC H 72 18 FW B-J 90 23 3 H M TASCS FAC TT H 72 24 3 H H TASCS FAC M 17 5 Note 1
&2 5 L L TASCS FAC H 13 2 5 M M TASCS M 7 1 C-F-2 28 3 6/7 L - - - 12 0 6/7 L - - - 5 0 3 H M FAC TT H 27 7 3 H M TT FAC H 27 7 HPCI B-J 23 6 4 M H None L 30 7 4 M H None L 40 4 Note 1
&2 5 M M TT M 4 1 5 M M TT M 4 1 C-F-2 204 16 6/7 L - - - 155 0 6/7 L - - - 146 0 MS B-J 107 27 4 M H None L 138 16 4 M H None L 237 24 Note 1
&2 C-F-2 142 11 6/7 L - - - 103 0 6/7 L - - - 4 0 B-F 2 2 3 H M TT FAC H 28 7 3 H M TT FAC H 28 7 RCIC B-J 26 7 5 M M TASCS IGSCC TT M 7 1 4 M H None L 25 3 Note 1
&2 5 M M TASCS TT M 9 1 C-F-2 129 10 6/7 L - - - 120 0 6/7 L - - - 94 0 TASCS IGSCC B-F 20 20 2 H H E-C M 2 1 2 H H M 63 16 E-C RHR B-J 104 26 4 M H None L 5 1 4 M H None L 126 13 Note 1 TASCS IGSCC C-F-1 13 13 5 M M M 73 12 5 M M TASCS E-C M 44 5 E-C C-F-2 659 50 6/7 L - - - 517 0 6/7 L - - - 364 0 RPV- B-F 14 14 APP 6/7 L - - - 38 0 4 M H None L 38 4 Note 1 B-J 27 7 B-F 12 12 5 M M TASCS M 12 2 2 H H TASCS M 12 3 RR Note 1 4 M H None L 95 10 B-J 111 28 6/7 L 99 0 6/7 L - - - 4 0
Submittal of Relief Requests Associated with Third ISI Attachment 2 Response to Request for Additional Information I3R-02 Question 6 Page 2 of 6 Table 2: System/Selection Comparisons Between ASME Section XI and Risk Informed Programs for Unit 1 Unit 1 2nd Interval Unit 1: 2nd Interval RI-ISI (1989 Edition) Unit 1: 3rd Interval RI-ISI (2001Edition/ 2003 Addenda)
System ASME XI (1989 Edition)
Cat. Weld Weld Risk Conseq Failure Potential Weld RI-ISI Risk Conseq Failure Potential Weld RI-ISI Count Sel. Cat. Rank Rank DM(s) Rank Count Sel. Cat. Rank Rank DM(s) Rank Count Sel.
RWCU BJ 121 31 4 M H None L 3 1 2 H H TASCS M 2 1 Note 1 5 M M TASCS M 2 1 4 M H None L 96 10
&2 C-F--1 3 3 6/7 L - - - 113 0 6/7 L - - - 23 0 5 M M TASCS M 4 1 2 H H TASCS M 4 1 SLC B-J 64 16 4 M H None L 6 1 6/7 L - - - 60 0 6/7 L - - - 54 0 Systems:
CRD - Control Rod Drive CS - Core Spray FW - Feedwater HPCI - High Pressure Coolant Injection MS - Main Steam RCIC - Reactor Core Isolation Cooling RPV-APP - Reactor Pressure Vessel RR - Reactor Recirculation RWCU -Reactor Water Cleanup System SLC - Standby Liquid Control Abbreviations:
Cat. - Category Sel. - Selection Conseq. - Consequence DM - Degradation Mechanism Ranking:
L - Low M - Medium H - High Note: Low Risk Categories 6 and 7 do not require examinations. The tables do not show the six possible combinations of Failure Potential and Consequence rankings that result in a Low Risk ranking.
Degradation Mechanisms (Initials) (RI-ISI Item Number) (Name)
TASCS - R1.11 -Thermal Stratification, Cycling and Stripping TT - R1.11 - Thermal Transient IGSCC - R1.16 - Intergranular Stress Corrosion Cracking E-C - R1.18 - Erosion-Cavitations FAC - R1.18 - Flow Accelerated Corrosion Note 1: Systems or portion of system that have a degradation mechanism addressed by a separate augmented program are examined under the augmented program for that particular degradation mechanism. If no other degradation mechanism is identified, the element is removed from the RI-ISI element selection population and retained in the appropriate augmented inspection program. The augmented programs are the Flow Accelerated Corrosion for FAC and Intergaranular Stress Corrosion for IGSCC. If another degradation mechanism is present, which is not addressed by the augmented program, the remaining degradation mechanism is examined as part of the RI-ISI program.
Submittal of Relief Requests Associated with Third ISI Attachment 2 Response to Request for Additional Information I3R-02 Question 6 Page 3 of 6 Note 2: To assist in the comparison between programs, the inclusion of the High Energy Line Break (HELB) Augmented program is not shown.
The tables are limited to the non-exempt Class 1 and 2 elements subject to examination under the ASME Section XI program and subsequently incorporated into the RI-ISI program. The merger of the RI-ISI and HELB programs occurred in the third inspection interval using the methods specified in EPRI TR-1006937. This merger involved the addition of the welds beyond the Class 2 boundary within the break exclusion area.
Submittal of Relief Requests Associated with Third ISI Attachment 2 Response to Request for Additional Information I3R-02 Question 6 Page 4 of 6 Table 3 Response to Request for Additional Information I3R-02 Question 6 Unit 2 Table 3: System/Selection Comparisons Between ASME Section XI and Risk Informed Programs for Unit 2 Unit 2 2nd Interval Unit 2: 2nd Interval RI-ISI (1989 Edition) Unit 2: 3rd Interval RI-ISI (2001Edition/ 2003 Addenda)
System ASME XI (1989 Edition)
Cat. Weld Weld Risk Conseq Failure Potential Weld RI-ISI Risk Conseq Failure Potential Weld RI-ISI Count Sel. Cat. Rank Rank DM(s) Rank Count Sel. Cat. Rank Rank DM(s) Rank Count Sel.
CRD C-F-2 57 5 6/7 L - - - 57 0 6/7 L - - - 57 0 B-F 9 9 4 M H None L 3 1 2 H H TASCS IGSCC M 17 6 CS B-J 35 9 5 M M TASCS IGSCC M 17 6 4 M H None L 19 2 Note 1 C-F-1 2 2 6/7 L - - - 263 0 6/7 L - - - 247 0 C-F-2 265 20 1 H H TASCS FAC H 3 1 1 H H TASCS TT FAC H 67 18 FW B-J 92 23 3 H M TASCS TT FAC H 65 30 3 H H TASCS FAC M 19 5 Note 1
&2 5 M L TASCS FAC H 16 3 5 M M TASCS M 5 1 C-F-2 25 2 6/7 L - - - 9 0 6/7 L - - - 4 0 3 H M TT FAC H 28 7 3 H M TT FAC H 28 7 HPCI B-J 24 6 4 M H None L 30 7 4 M H None L 40 4 Note 1
&2 5 M M TT M 5 1 5 M M TT M 5 1 C-F-2 202 16 6/7 L - - - 153 0 6/7 L - - - 143 0 MS B-J 107 27 4 M H None L 136 14 4 M H None L 235 24 Note 1
&2 C-F-2 140 11 6/7 L - - L 103 0 6/7 L - - - 4 0 B-F 2 2 3 H M TT FAC H 26 7 RCIC 3 H M TT FAC H 26 7 B-J 31 8 4 M H None L 30 3 Note 1
&2 5 M M TASCS TT M 9 1 C-F-2 140 11 6/7 L - - - 114 0 6/7 L - - - 77 0 TASCS IGSCC B-F 20 20 2 H M E-C H 2 1 2 H H M 59 15 E-C RHR B-J 92 23 4 M H None L 5 1 4 M H None L 123 13 Note 1 E-C TASCS C-F-1 10 10 5 M M M 72 12 5 M M TASCS E-C M 49 5 IGSCC C-F-2 664 50 6/7 L - - - 508 0 6/7 L - - - 356 0 RPV- B-F 14 14 APP 6/7 L - - - 63 0 4 M H None L 41 5 Note 1 B-J 27 7 B-F 12 12 5 M M TASCS M 9 1 2 H H TASCS M 9 3 RR Note 1 4 M H None L 97 10 B-J 108 27 6/7 L M None L 101 0 6/7 L - - - 4 0
Submittal of Relief Requests Associated with Third ISI Attachment 2 Response to Request for Additional Information I3R-02 Question 6 Page 5 of 6 Table 3: System/Selection Comparisons Between ASME Section XI and Risk Informed Programs for Unit 2 Unit 2 2nd Interval Unit 2: 2nd Interval RI-ISI (1989 Edition) Unit 2: 3rd Interval RI-ISI (2001Edition/ 2003 Addenda)
System ASME XI (1989 Edition)
Cat. Weld Weld Risk Conseq Failure Potential Weld RI-ISI Risk Conseq Failure Potential Weld RI-ISI Count Sel. Cat. Rank Rank DM(s) Rank Count Sel. Cat. Rank Rank DM(s) Rank Count Sel.
B-F 2 2 4 M H None L 4 3 2 H H TASCS M 2 1 RWCU B-J 133 34 5 M M TASCS M 2 1 4 M H None L 119 12 Note 1
&2 C-F-1 1 1 6/7 L - - - 111 0 6/7 L - - - 22 0 C-F-2 3 1 5 M M None M 4 1 2 H H TASCS M 4 1 SLC B-J 68 17 4 M H None L 5 1 Note 1 6/7 L M None L 64 0 6/7 L M None L 59 0 Systems:
CRD - Control Rod Drive CS - Core Spray FW - Feedwater HPCI - High Pressure Coolant Injection MS - Main Steam RCIC - Reactor Core Isolation Cooling RPV-APP - Reactor Pressure Vessel RR - Reactor Recirculation RWCU -Reactor Water Cleanup System SLC - Standby Liquid Control Abbreviations:
Cat. - Category Sel. - Selection Conseq. - Consequence DM - Degradation Mechanism Ranking:
L - Low M - Medium H - High Note: Low Risk Categories 6 and 7 do not require examinations. The tables do not show the six possible combinations of Failure Potential and Consequence rankings that result in a Low Risk ranking.
Degradation Mechanisms (Initials) (RI-ISI Item Number) (Name)
TASCS - R1.11 -Thermal Stratification, Cycling and Stripping TT - R1.11 - Thermal Transient IGSCC - R1.16 - Intergranular Stress Corrosion Cracking E-C - R1.18 - Erosion-Cavitations FAC - R1.18 - Flow Accelerated Corrosion Note 1: Systems or portion of system that have a degradation mechanism addressed by a separate augmented program are examined under the augmented program for that particular degradation mechanism. If no other degradation mechanism is identified, the element is removed from the RI-ISI element selection population and retained in the appropriate augmented inspection program. The augmented programs are the Flow Accelerated Corrosion for FAC and Intergaranular Stress Corrosion for IGSCC. If another degradation mechanism is present, which is not addressed by the augmented program, the remaining degradation mechanism is examined as part of the RI-ISI program.
Submittal of Relief Requests Associated with Third ISI Attachment 2 Response to Request for Additional Information I3R-02 Question 6 Page 6 of 6 Note 2: To assist in the comparison between programs, the inclusion of the High Energy Line Break (HELB) Augmented program is not shown.
The tables are limited to the non-exempt Class 1 and 2 elements subject to examination under the ASME Section XI program and subsequently incorporated into the RI-ISI program. The merger of the RI-ISI and HELB programs occurred in the third inspection interval using the methods specified in EPRI TR-1006937. This merger involved the addition of the welds beyond the Class 2 boundary within the break exclusion area.
ATTACHMENT 3 Drawinas Relief Request 13R-06 XI-1 E-205 (Unit 1)
XI-2E-205 (Unit 2)
Relief Request 13R-07 XI-I P-202 (Unit 1)
XI-1P-206 (Unit 1)
XI-2P-202 (Unit 2)
XI-2P-206 (Unit 2)
Relief Request 13R-09 1st-M-42, Sht. 1 (Unit 1)
ISI-M-42, Sht. 3 (Unit 2)
ISI-M-57, Sht. 1 (Unit 1) 1st-M-57, Sht. 4 (Unit 2)
ISI-M-59, Sht. 1 (Unit 1)
ISI-M-59, Sht. 3 (Unit 2)
Relief Request 13R-10 ISI-M-52, Sht. 1 (Unit 1)
ISI-M-52, Sht. 3 (Unit 2)
Relief Request 13R-11 ISI-M-57, Sht. 2 (Unit 1) 1st-M-57, Sht. 3 (Unit 1)
ISI-M-57, Sht. 5 (Unit 2)
ISI-M-57, Sht. 6 (Unit 2)
ISI-M-58, Sht. 1 (Unit 1) 1st-M-58, Sht. 2 (Unit 1)
ISI-M-58, Sht. 3 (Unit 2)
ISI-M-58, Sht. 4 (Unit 2)
Relief Request l3R-12 ISI-M-55, Sht. 1 (Unit 1)
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