ULNRC-05918, Enclosure 1 to ULNRC-05918, Callaway, Unit 1, Request for Additional Information (RAI) Set 10 Responses
| ML12290A117 | |
| Person / Time | |
|---|---|
| Site: |  |
| Issue date: | 10/15/2012 |
| From: | Ameren Missouri, Union Electric Co |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML122900161 | List: |
| References | |
| ULNRC-05918 | |
| Download: ML12290A117 (10) | |
Text
ULNRC-05918 October 15, 2012 Enclosure 1 Page 1 of 10 CALLAWAY PLANT UNIT 1 LICENSE RENEWAL APPLICATION REQUEST FOR ADDITIONAL INFORMATION (RAI) Set #10 RESPONSES
ULNRC-05918 October 15, 2012 Enclosure 1 Page 2 of 10 RAI 4.2.2-1a
Background:
By letter dated June 22, 2012, the NRC staff issued request for additional information (RAI) 4.2.2-1 pertaining to the Callaway Plant, Unit 1 (Callaway) license renewal application (LRA), Section 4.2, time-limited aging analyses (TLAAs) of reactor pressure vessel (RPV) neutron embrittlement. In RAI 4.2.2-1, the staff requested that the applicant identify the source of the initial upper shelf energy (USE) and copper (Cu) content data for all extended beltline materials. The staff also requested that the applicant justify the use of these initial USE and Cu content values if they were not obtained from certified material test reports (CMTRs). In its July 20, 2012, response to RAI 4.2.2-1, the applicant stated that the CMTRs for the Callaway inlet and outlet nozzle forgings did not contain measurements of Cu content because Cu content measurements were not required at the time of nozzle fabrication. The applicant stated that the Cu content of 0.16 weight percent for the Callaway inlet and outlet nozzle forgings is taken 'from the chemistry measurements available for SA-508, Class 2 forgings from Oak Ridge National Laboratory Report (ORNL) ORNL/TM-2006/530, "A Physically Based Correlation of Irradiation-Induced Transition Temperature Shifts for RPV Steels," November 2007 (ADAMS Accession Number ML081000630).
Issue:
The staff notes that the above ORNL report has not been approved by the NRC as a basis for the selection of a generic (i.e., non-heat-specific) Cu content for SA-508, Class 2 forgings. For those cases where no measured heat-specific Cu content exists, Regulatory Guide (RG) 1.99, "Radiation Embrittlement of Reactor Vessel Materials," Revision 2 recommends that an upper bound Cu content of 0.35 percent be assumed for embrittlement calculations. As an alternative to this upper bound estimation approach of the RG, the staff has occasionally accepted generic material property values derived from the statistical analysis of an industry-wide database for the material spec, if the generic value is based on a statistically-conservative position, such as the a 97.8 percent confidence limit (equivalent to a mean +
2 upper bound to a normal distribution).
Request:
Considering the issue identified above, please provide additional justification for the selection of a 0.16 percent Cu content for the SA-508, Class 2 inlet and outlet nozzles at Callaway. Alternatively, please revise LRA Sections 4.2.2 and 4.2.3 to include a revised USE and pressurized thermal shock analysis of the inlet and outlet nozzles that is based on a more conservative Cu content, consistent with the values described above.
ULNRC-05918 October 15, 2012 Enclosure 1 Page 3 of 10 Callaway Response Regulatory Guide 1.99 states that "- conservative estimates (mean plus one standard deviation) based on generic data may be used if justification is provided." Oak Ridge National Laboratory Report (ORNL) ORNL/TM-2006/530 Appendix G provides such generic data, including the mean, standard deviation, and maximum Cu values for the various material specifications. The results for A508 Class 2 forgings with high copper content based on 9 heats are shown below.
Cu Minimum 0.0800 Mean 0.1220 STD deviation 0.0313 Maximum 0.1600 In order to be consistent with the 97.8 percent confidence limit stated above, the best estimate copper data was determined from the ORNL/TM-2006/530 mean plus 2. This results in a copper value of 0.1846 wt% (0.122 + 2
- 0.0313 = 0.1846). The data is within the copper content range of 0.01 to 0.19 weight percent identified in BWRVIP-173NP, "BWR Vessel and Internals Project Evaluation of Chemistry Data for BWR Vessel Nozzle Forging Materials," for A508 Class 2 forgings. BWRVIP-173NP is one example where the staff has accepted the use of generic material property values derived from the statistical analysis of an industry-wide database.
Amendment 12 in Enclosure 2 revises the USE and pressurized thermal shock analyses data of the inlet and outlet nozzles in LRA Table 4.2-3 and Table 4.2-4 to use a copper content of 0.1846 wt% that is consistent with this RAI response. Corresponding Amendment Changes Refer to the Enclosure 2 Summary Table "Amendment 12, LRA Changes from RAI Responses," for a description of LRA changes with this response.
ULNRC-05918 October 15, 2012 Enclosure 1 Page 4 of 10 RAI 3.1.2.1-1
Background:
License renewal application (LRA) Table 3.1.2-1 provides a list of the aging management review (AMR) items for aging management of the Callaway reactor pressure vessel (RPV) and reactor vessel internal (RVI) components. In the LRA, aging management programs (AMPs) for aging management of the Callaway RVI components include: (a) AMP B2.1.1, ASME Section XI, Inservice Inspection, Subsection IWB, IWC, and IWD Program (lSI Program); (b) AMP B2.1.2, Water Chemistry Program; (c) AMP B2.1.6, PWR Vessel Internals Program; and (d) AMP B2.1.22, Flux Thimble Tube Inspection Program. Issue: The AMR items in LRA Table 3.1.2-1 for Callaway RVI components do not always match up with terminology used for Westinghouse-design RVI components in Electric Power Research Institute (EPRI) Report No. 1022863, "Materials Reliability Program: Pressurized Water Reactor Internals Inspection and Evaluation Guidelines (MRP-227-A)." Therefore, the staff seeks the following clarifications on nomenclature used for RVI-based AMR items in LRA Table 3.1.2-1: a) the two AMR items for the RVI baffle-former assembly on LRA page 3.1-69 b) the four AMR items for RVI baffle-former assembly bolting at the bottom of LRA page 3.1-69 and top of LRA page 3.1-70 c) the four AMR items for the RVI control rod guide tube (CRGT) assembly on LRA page 3.1-71 d) the two AMR items for the RVI CRGT bolts listed on LRA page 3.1-72 e) the three AMR items for the RVI core barrel or core barrel assembly on LRA page 3.1-73 f) the three AMR items for the RVI core barrel assembly former bolting on pages 3.1-73 and 3.1-74 g) the two AMR items for RVI head/vessel alignment pins on page 3.1-75 h) the two AMR items for RVI incore instrumentation (ICI) core support structure bolting on LRA page 3.1-76 i) the three AMR items for RVI ICI support structure - Bottom Mounted Instrumentation (BMI) instrument columns on LRA pages 3.1-76 and 3.1-77 j) two AMR items for RVl lower core support - energy absorber assembly on LRA page 3.1-81 k) three AMR items for RVI upper core plate guide pins on LRA pages 3.1-82 and 3.1-83 Request: a) For the two AMR items for the RVI baffle-former assembly on LRA page 3.1-69, clarify which specific baffle-former assembly components are within the scope of the AMR items. b) For the four AMR items for the RVI baffle-former assembly bolting at the bottom of LRA page 3.1-69 and top of page 3.1-70, clarify whether the AMR items are referring to baffle-to-former bolts. Otherwise identify which specific bolts are within the scope of the AMR items.
ULNRC-05918 October 15, 2012 Enclosure 1 Page 5 of 10 c) For the four AMR items for the RVI CRGT assembly on LRA page 3.1-71, clarify which specific CRGT assembly components are within the scope of the AMR items. d) For the two AMR items for the RVI CRGT bolts listed on LRA page 3.1-72, identify which specific bolts are within the scope of the AMR items. e) For the three AMR items for the RVI core barrel or core barrel assembly on LRA page 3.1-73, identify which specific core barrel assembly components are within the scope of the AMR items. f) For the three AMR items for the RVI core barrel assembly former bolting on LRA pages 3.1-73 and 3.1-74, clarify whether the AMR items are referring to baffle-former assembly barrel-to-former bolts, as defined in MRP-227-A. Otherwise identify which specific bolts are within the scope of the AMR items. g) For the two AMR items for RVI head/vessel alignment pins on LRA page 3.1-75, clarify whether these components correspond to the upper core plate alignment pins in MRP-227-A (i.e., alignment and interfacing components in MRP-227-A Table 3-3). Otherwise, clarify where the pins are located and which MRP-227-A defined RVI assembly corresponds to the location of these pins. h) For the two AMR items for RVI ICI core support structure bolting on LRA page 3.1-76; clarify where the bolts are located and which MRP-227-A defined RVI assembly corresponds to the location of these bolts. (These pins appear to be outside the scope of the condition monitoring bases in MRP-227-A.) i) For the three AMR items for RVI ICI support structure - BMI instrument columns on LRA pages 3.1-76 and 3.1-77, clarify whether the AMR items are referring to BMI column bodies. Otherwise, identify which specific BMI column components are within the scope of the AMR items. j) For the two AMR items for RVI lower core support-energy absorber assembly on LRA page 3.1-81, identify which energy absorber assembly components the AMR items are referring to and clarify which MRP-227-A defined assembly corresponds to the location of the components. k) For the three AMRs for RVI upper core plate guide pins on LRA pages 3.1-82 and 3.1-83, clarify whether the AMR items correspond to the upper core plate alignment pins that are listed as Alignment and Interfacing "Existing Program" components in MRP-227-A Table 3-3. Otherwise, clarify where these pins are located and which MRP-227-A defined RVI assembly corresponds to the location of the pins. Callaway Response Terminology used for LRA Table 3.1.2-1 is based on Callaway FSAR or Callaway RVI component drawings. The AMR items in LRA Table 3.1.2-1 may not always match up with terminology used for Westinghouse-design RVI components in MRP-227-A.
(a) RVI baffle-former assembly
- RVI baffle-former assembly includes the baffle plates and the former plates. It is consistent with the description of GALL line IV.B2.RP-270 and MRP-227-A, Table 3-3.
ULNRC-05918 October 15, 2012 Enclosure 1 Page 6 of 10 (b) RVI baffle-former assembly bolting - The AMR items of RVI baffle-former assembly bolting are referring to baffle-to-former bolts described in GALL line IV.B2.RP-271. Note that baffle edge bolts are evaluated by separate AMR items using GALL line IV.B2.RP-275 and IV.B2.RP-354.
(c) RVI control rod guide tube (CRGT) assembly
- The AMR items are referring to the lower flanges welds and the adjacent base metal of the CRGT assemblies. The guide tube bolts, guide plates (cards) and support pins (split pins) are evaluated by separate AMR items.
(d) RVI control rod guide tube bolts
- As described in FSAR Section 3.9(N).5, the control rod guide tubes are fastened to the top support plate. These bolts are not included in the scope of MRP-227-A. Therefore, the aging evaluation is based on GALL lines IV.B2.RP-24 and IV.B2.RP-382.
(e) RVI core barrel
- The core barrel cylinder welds, flange and welds, outlet nozzle and welds are addressed in separate AMR items. The subject AMR lines of this RAI item are referring to the balance of the core barrel assembly not addressed in MRP-227-A. The aging evaluation is based on GALL lines IV.B2.RP-24 and IV.B2.RP-382. An AMR line of TLAA for the aging effect of Cumulative Fatigue Damage used "RVI core barrel assembly" to represent the whole core barrel assembly.
(f) RVI core barrel assembly-former bolting
- It is presented in the LRA as "RVI core barrel assembly-former bolting," consistent with MRP-227-A, Tables 3-3 and 4-5. The AMR items are referring to barrel-to-former bolts described in GALL lines IV.B2.RP-273 and IV.B2.RP-274. (g) RVI head/vessel alignment pins
- The RVI head/vessel alignment pins are shown in FSAR Figure 3.9(N)-3 as Item #31. The upper core plate alignment pins (listed in LRA Table 3.1.2-1 as "RVI upper core plate guide pins" to avoid confusion with fuel alignment pins attached to the bottom of the upper core plate) are shown in FSAR Figure 3.9(N)-3 as Item #19. The RVI head/vessel alignment pins are not included in the scope of MRP-227-A as it was screened as Category "A" in MRP-191, Table 7-2. Therefore, the aging evaluation is based on GALL lines IV.B2.RP-24 and IV.B2.RP-382.
(h) RVI ICI core support structure bolting
- This represents the lower core ICI support BMI column bolts. The lower core BMI column bolts are shown in FSAR Figure 3.9(N)-3 as Item #27. The BMI column bolts are not included in the scope of MRP-227-A as it was screened as Category "A" in MRP-191, Table 7-2. Therefore, the aging evaluation is based on GALL lines IV.B2.RP-24 and IV.B2.RP-382.
(i) RVI ICI support structure-BMI instrument columns
- The components are shown in FSAR Figure 3.9(N)-8. The AMR items are referring to BMI column bodies described in MRP-227-A, Table 4-6.
(j) RVI lower core support-energy absorber assembly
- The function of the energy absorber assembly is described in FSAR Section 3.9(N).5. Assuming a downward vertical displacement, the potential energy of the system is absorbed mostly by the strain energy of the energy absorbing devices. The details of the energy absorber assembly are shown in FSAR Figure 3.9(N)-8. The components of the energy absorber assembly are not included in the scope of MRP-227-A as they were screened as Category "A" in MRP-191, Table 7-2.
ULNRC-05918 October 15, 2012 Enclosure 1 Page 7 of 10 (k) RVI upper core plate guide pins
- As discussed in item (g) above, the AMR items correspond to the upper core plate alignment pins described in MRP-227-A, Table 3-3 and 4-9. They are listed in LRA Table 3.1.2-1 as RVI upper core plate guide pins, consistent with the description in FSAR Figure 3.9(N)-8, to avoid confusion with fuel alignment pins that are attached to the bottom of the upper core plate. The fuel alignment pins are evaluated as integral parts of the upper core plate.
Corresponding Amendment Changes No changes to the License Renewal Application (LRA) are needed as a result of this response.
ULNRC-05918 October 15, 2012 Enclosure 1 Page 8 of 10 RAI 3.1.2.1-2
Background:
LRA Table 3.1.2-1 provides a list of the AMR items for aging management of the Callaway RPV and RVI components. LRA pages 3.1-77 and 3.1-78 provide the applicant's AMR items for managing cracking, loss of fracture toughness, and loss of material in Callaway ICI support structure, upper and lower tie plates. In the AMR items, the applicant credits the Water Chemistry Program (AMP B2.1.2) to manage loss of material that may be induced in these components by pitting or crevice corrosion. The applicant credits a combination of the Water Chemistry Program and the PWR Vessel Internals Program (AMP B2.1.6) as the basis for managing cracking in these components. The applicant also credits the PWR Vessel Internals Program as the basis for managing loss of fracture toughness in the components. In the AMR items on cracking and fracture toughness, the applicant identifies that the upper and lower tie plate components are "Expansion Category" components for the applicant PWR Vessel Internals Program. Issue: The staff cannot correlate the ICI support structure upper and lower tie plates to any of the components that are listed for Westinghouse-designed RVI components in MRP-227-A Table 3-3 or in MRP-227-A Table 4-6, for Westinghouse "Expansion Category" components. Therefore, the staff cannot determine which MRP-227-A "Primary Category" components would potentially provide lead indications of aging for the ICI support structure upper and lower tie plates or the types of inspection bases (including method and frequency) that would be applied to the tie plates if expansion inspections were warranted. Request: a) Clarify whether the ICI support structure upper and lower tie plates are within scope of "Expansion Category" components in MRP-227-A. If MRP-227-A does cover the components, identify which "Expansion Category" components in Table 4-6 of MRP-227-A correlate to the ICI support structure upper and lower tie plates. b) If these tie plates are within the scope of the current set of "Expansion Category" components in Table 4-6 of the report, identify which "Primary Category" component or components in Table 4-3 of MRP-227-A will be linked to the ICI support structure upper and lower tie plates, as "Expansion Category" components. Clarify the "Primary Category" inspection acceptance criteria that would kick in expansion inspections of the tie plates. Identify the inspection method and inspection frequency that would be applied to the tie plates and clarify whether the tie plates would be subject to baseline inspections prior to the period of extended operation, as well as re-inspection basis during the period of extended operation, and define such bases as appropriate. Callaway Response The functions of the ICI support structure, including the Bottom Mounted Instrumentation (BMI) column bodies and the upper and lower tie plates, are to protect the flux thimble tubes and to provide a path for the flux thimble tubes into the core from the bottom of the reactor vessel. The flux thimble tubes are part of the reactor coolant pressure boundaries. The BMI column bodies are included in MRP-227-A Table 3-3 and MRP-227-A Table 4-6 as "Expansion Category" components.
ULNRC-05918 October 15, 2012 Enclosure 1 Page 9 of 10 (a) The upper and lower tie plates have the function of supporting the structural integrity of the BMI column bodies to maintain the functions of the BMI column bodies. Since the tie plates and the BMI column bodies are located in the same area of the reactor and have the same function of protecting the flux thimble tubes, the upper and lower tie plates are included in the same group as the BMI column bodies to be within the scope of "Expansion Category" components.
(b) The "Primary Category" component linked to the ICI support structure upper and lower tie plates is the same as the "Primary Category" component linked to the BMI column bodies. As shown in MRP-227-A Table 4-6, the Primary link is the control rod guide tube (CRGT) lower flanges. The "Primary Category" inspection acceptance criteria that would require expansion inspections of the tie plates are the same as those for the BMI column bodies described in MRP-227-A Table 5-3.
The inspection method and inspection frequency that would be applied to the tie plates are the same as those of the BMI column bodies. As described in MRP-227-A Table 5-3, a confirmation of surface breaking indications in two or more CRGT lower flange welds, combined with flux thimble insertion/withdrawal difficulty, shall require visual (VT-3) examination of tie plates by the completion of the next refueling outage. Re-inspection interval is every 10 years following the initial inspection. Corresponding Amendment Changes No changes to the License Renewal Application (LRA) are needed as a result of this response.
ULNRC-05918 October 15, 2012 Enclosure 1 Page 10 of 10 RAI 3.1.1.50-2
Background:
LRA Section B2, "Aging Management Programs," states that GALL AMP XI.M12, "Thermal Aging Embrittlement of Cast Austenitic Stainless Steel Program (CASS)," is not credited. LRA Table 3.1-1, item 3.1.1.050 states that since control rod drive (CRD) pressure housings are made of stainless steel, the applicable GALL Report AMR lines were not used. In comparison, Callaway FSAR, Table 5.2-2 indicates that the CRD latch housings are made of SA-182, Grade F304 (non-cast stainless steel) or SA-351, Grade CF8 (cast stainless steel). Issue: Given the information regarding the CRD latch housing materials in the FSAR, the staff needs to confirm whether SA-351, Grade CF8 (cast stainless steel) has been used for the CRD latch housings. If the CASS material has been used for the CRD latch housings, the staff needs additional information regarding the applicant's material screening method for thermal aging embrittlement of the CASS material. Request: a) Clarify whether SA-351, Grade CF8, or SA-182, Grade F304, has been used for the CRD latch housings. b) If the CASS material listed in FSAR, Table 5.2-2 has been used for the CRD latch housings, provide the following information to confirm that the applicant's material screening method is consistent with GALL Report AMP XI.M12. i. Clarify whether the CRD latch housing material is static-cast material or centrifugal-cast material. ii. If the CASS material was statically cast, provide the bounding-case chemical composition of the CASS material that estimates the highest ferrite content of the CRD latch housings. In addition, provide the calculated ferrite content in order to confirm that the bounding case analysis indicates no susceptibility of these CASS components to thermal aging embrittlement. As part of the response, clarify whether the applicant's screening method is consistent with the guidance of NUREG/CR-4513, Revision 1, for ferrite content calculations using the Hull's equivalent factor as referenced in the GALL Report. Callaway Response (a) The control rod drive (CRD) latch housings and travel housings are made of forged Type 304 stainless steel according to Callaway FSAR Section 4.5.1.1.d SP and FSAR Section 15.4.8.1.1.d SP.
This is consistent with LRA Table 3.1-1, item 3.1.1.050 which states the CRD pressure housings are made of stainless steel.
(b) N/A Corresponding Amendment Changes No changes to the License Renewal Application (LRA) are needed as a result of this response.