ML051940017
| ML051940017 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 07/12/2005 |
| From: | Tam P NRC/NRR/DLPM/LPD1 |
| To: | Distel D, David Helker Exelon Corp |
| Tam P NRR/415-1451 | |
| References | |
| TAC MC7001 | |
| Download: ML051940017 (4) | |
Text
From:
Peter Tam To:
David Distel; David Helker Date:
7/12/05 8:35AM
Subject:
Draft RAI - SG Tube Kinetic Expansion Inspection and Repair (TAC MC7001)
Dave:
Our reviewer, Emmett Murphy, has completed his initial review of your 5/3/05 submittal and found that he needs answers/clarification to a number of questions (below). Emmett will not be back in the office until after July. Please work with me to set up a conference call to discuss this draft RAI.
This e-mail aims solely to prepare you and others for the requested conference call. It does not convey a formal NRC staff position, nor does it formally ask for additional information.
Peter S. Tam Senior Project Manager Project Directorate I Division of Licensing Project Management Office of Nuclear Reactor Regulation
Reference:
AmerGen letter dated May 3, 2005, "Additional Information Regarding Kinetic Expansion Inspection and Repair Criteria"
- 1. 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 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?
- 2. 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 4.19.5.b.
- 3. 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 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?
- 4. 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?
- 5. 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, 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.
- 6. 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.
- 7. 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.
- 8. 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.
- 9. 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%.
- 10. Provide leak rate estimates (in terms of gallons per minute), based on the license'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.).
- 11. 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 XI. However, 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 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.
CC:
David Kern; Emmett Murphy Mail Envelope Properties (42D3B906.F4C : 10 : 20510)
Subject:
Draft RAI - SG Tube Kinetic Expansion Inspection and Repair (TAC MC7001)
Creation Date:
7/12/05 8:35AM From:
Peter Tam Created By:
PST@nrc.gov Recipients Action Date & Time David Transferred 07/12/05 08:36AM distel (David Distel) kp1_po.KP_DO Delivered 07/12/05 08:35AM DMK CC (David Kern) owf2_po.OWFN_DO Delivered 07/12/05 08:35AM ELM CC (Emmett Murphy) exeloncorp.com Transferred 07/12/05 08:36AM david.helker (David Helker)
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