ML13346A629
| ML13346A629 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 12/06/2013 |
| From: | Dellario D Calvert Cliffs, Constellation Energy Nuclear Group, EDF Group |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| RR-ISI-04-09 | |
| Download: ML13346A629 (31) | |
Text
Calvert Cliffs Nuclear Power Plant 1650 Calvert Cliffs Parkway Lusby, Maryland 20657 CENG.
a joint venture of 0Conlstellation ~~D Energy-0 D
CALVERT CLIFFS NUCLEAR POWER PLANT December 6, 2013 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
SUBJECT:
REFERENCES:
Document Control Desk Calvert Cliffs Nuclear Power Plant Unit No. 2; Docket No. 50-318 Response to Request for Additional Information Re: Proposed 10 CFR 50.55a Request for Unit 2 Repair of Saltwater Piping Leak (RR-ISI-04-09)
(a)
Letter from D. J. Dellario (CCNPP) to Document Control Desk (NRC),
dated November 14, 2013, Proposed 10 CFR 50.55a Request for Unit 2 Repair of Saltwater Piping Leak (RR-ISI-04-09)
(b)
Letter from N. S. Morgan (NRC) to G. H. Gellrich (CCNPP), dated December 4, 2013, Calvert Cliffs Nuclear Power Plant, Unit No. 2 -
Request for Additional Information Regarding Relief Request RR-ISI-04-09, Saltwater System Piping Repair (TAC No. MF3074)
In Reference (a), Calvert Cliffs Nuclear Power Plant, LLC, (Calvert Cliffs) requested Nuclear Regulatory Commission approval of 10 CFR 50.55a request for installing a mechanical clamping device on a leak discovered on a 12 inch, Code Class 3, Saltwater System pipe. In Reference (b), the Nuclear Regulatory Commission requested additional information in order to conduct their review. Calvert Cliffs' responses to the Nuclear Regulatory Commission request for additional information are contained in Attachment (1) and the accompanying enclosures. Also included in Attachment (1) is a minor correction to a table in Reference (a) that was identified during the preparation of these responses.
the regulatory commitment listed in Attachment (2) is a revised version of the regulatory commitment listed in Reference (a).
Acb7-
Document Control Desk December 6, 2013 Page 2 Should you have questions regarding this matter please contact Mr. Douglas E. Lauver at (410) 495-5219.
Very truly yours, David J. Dellario Manager - Engineering Services DJD/KLG/bjd
Attachment:
(1) Responses to Request for Additional Information - Relief Request RR-ISI-04-09, Alternative Repair for Saltwater System Piping
Enclosures:
1 Saltwater System Piping Photograph (I page) 2 Saltwater System Piping Drawings (2 pages) 3 Mechanical Clamping Device Sketches (3 pages) 4 Mechanical Clamping Device Photographs (6 pages) 5 UT Examination Report Photographs (2 pages) 6 Calculation M-93-038 (25 pages) 7 Calvert Cliffs Procedure LR-0 1 (69 pages)
(2)
N. S. Morgan W. M. Dean, NRC Resident Inspector, NRC S. Gray, DNR
ATTACHMENT (1)
RESPONSES TO REQUEST FOR ADDITIONAL INFORMATION -
RELIEF REQUEST RR-ISI-04-09, ALTERNATIVE REPAIR FOR SALTWATER SYSTEM PIPING Calvert Cliffs Nuclear Power Plant, LLC December 6, 2013
ATTACHMENT (1)
RESPONSES TO REQUEST FOR ADDITIONAL INFORMATION - RELIEF REQUEST RR-ISI-04-09, ALTERNATIVE REPAIR FOR SALTWATER SYSTEM PIPING By letter dated November 14, 2013, (Agencywide Documents and Access Management System (ADAMS) Accession No. ML13319B080), Calvert Cliffs, Nuclear Power Plant, LLC, the licensee, submitted a request for authorization of a proposed alternative to the requirements of the American Society of Mechanical Engineer Boiler and Pressure Vessel Code (ASME Code),Section XI, Sub paragraph IX-1000(c)(4) for Calvert Cliffs Nuclear Power Plant, Unit No. 2 (Calvert Cliffs). Specifically, the licensee proposed the installation of a mechanical clamping device on a leak discovered on a 12-inch, Code Class 3, saltwater [SW] system pipe. In order to complete its review, the Nuclear Regulatory Commission (NRC) staff requests the following additional information.
Relief Request NRC RAI 1:
(a) Confirm that the defect area of the subject pipe is located in the discharge section of the saltwater system piping that provides no safety function, that the piping is above ground where it can be readily inspected, and that the pipe is not insulated or otherwise obstructed so as to increase the difficulty of inspections.
(b) It appears that the degraded area of the pipe may be located within a building in which flooding limits exist. What is the current leak rate from the pipe? What is the flooding limit, if any? Please describe the trend in the leak rate. Provide aflooding analysis demonstrating that in case the clamp fails, the leakage from the subject pipe will not exceed the flooding limits.
(c) Provide a piping and instrumentation diagram [P&ID] showing the subject pipe with respect to the saltwater system. Provide a piping isometric diagram showing the locations of pipe supports that are nearby the defect area. Identify the defect area on these diagrams.
(d) Provide additional drawings and photos of the mechanical clamp showing the assembly and design of the clamp, including the tubing, tubing grooves, sidebar, and sealant grooves on the inside surface of the clamp.
(e) The licensee submitted the relief request pursuant to Title 10 of the Code of Federal Regulations 50.55a(a)(3)(ii).
Provide more information to justify the hardship of performing the repair/replacement in accordance with the ASME Code.
(a)
The piping at the location of the leak is accessible (see picture in Enclosure 1). It is located above ground, and is not insulated externally. It is safety-related piping, and is located on the discharge of the component cooling heat exchangers with no downstream components. Since it is located at the component cooling heat exchanger discharge, the leak has no adverse impact on the safety function, which is to remove heat from the system. The leak only has a potential impact on flooding.
(b)
Per Calvert Cliffs Engineering Standard ES-001 for flooding, the postulated leak for the Component Cooling Room is 2,852 gallons per minute, based on a crack in a 14 inch shutdown cooling line coupled with actuation of the fire protection sprinkler system. The mechanical clamp is designed to stop the leak and is credited to maintain system pressure boundary.
If there was a full circumferential break of the pipe, the pipe by design of the system supports upstream and downstream of the degraded area would exert minimal load on the mechanical clamp and the mechanical clamp would remain intact on the pipe. The piping supports would restrain the piping movement to a small value (displacement of 0.134 inches with no structural credit taken for the mechanical clamp) so the leakage would be contained inside the mechanical clamp.
1
ATTACHMENT (1)
RESPONSES TO REQUEST FOR ADDITIONAL INFORMATION - RELIEF REQUEST RR-ISI-04-09, ALTERNATIVE REPAIR FOR SALTWATER SYSTEM PIPING Because the system pressure and pipe loads are small, a rupture or catastrophic failure of the mechanical clamp resulting in significant discharge of SW is not considered a credible event. It is possible for the mechanical clamp to have some minor leakage into the room.
This leakage is expected to be low and much less than the previously analyzed 2,852 gallons per minute for flooding.
(c) Enclosure 2 contains Calvert Cliffs drawings 62708SH0002 (PI&D) and 91374SH0001 (Isometric).
The degraded piping and the associated supports are highlighted in the drawings.
(d) Drawings and pictures showing details of the mechanical clamp are provided in Enclosures 3 and 4.
(e) The SW piping has a rubber liner to protect it from SW corrosion. This prohibits welding which would damage the rubber liner. Any permanent repair cannot be done on-line, since it would require both trains to be secured. To perform a permanent repair, Unit 2 would need to be shutdown and cooled down to Mode 5. The 21 SW header would then be removed from service to accommodate the one remaining SW header (SW header 22) being placed in an emergency overboard configuration. This configuration limits the plant's heat removal capability to one SW header with its discharge routed to the bay via the 21 circulating water canal (normal intake canal) versus the discharge canal.
NRC RAI 2:
Page 3 of the relief request indicated 3 pin holes on the subject pipe. One pin hole is identified as having a diameter of 0. 06-inch. Provide the current size and trending information for each of the holes in the pipe.
Photos from the last two Ultrasonic Testing Examination Reports on 10/31/2013 and 11/14/2013 are provided in Enclosure 5 to show changes to the holes over this time period. As can be seen from the photos, Hole A has remained approximately constant at 1.10 inches in size. Hole B has increased in size from 0.06 inches to 0.09 inches. Hole C has increased in size from 0.38 inches to 0.75 inches.
NRC RAI 3:
Page 4 of the relief request states that the clamp design will encompass the projected growth of the flaw with additional margin. Discuss the additional margin and whether the margin is sufficient to provide reasonable assurance that the subject pipe will perform its intended function until the pipe will be repaired/replaced in accordance with the ASME Code during the 2015 refueling outage. Discuss how much rubber liner has been removedfrom the defect area ftom the inside surface of the pipe.
Based on the projected "High Growth Estimate" used in our original submittal, the total size of the defect region at the end of the cycle will be 10.3 inches axially and 11.0 inches circumferentially. Even at the "High Growth Estimate" rate, this estimated defect region will be totally enclosed by the 14 inch length of the mechanical clamp. Additionally, the analysis (ILD-CALC-0014, Revision 1) showed that there is sufficient remaining pipe wall for a postulated 11 inch diameter branch hole in the pipe without the addition of the mechanical clamp. Therefore, there is reasonable assurance that the defect area would be fully enclosed by the mechanical clamp and the remaining pipe material would be sufficient to support for the largest expected hole of 11 inches.
2
ATTACHMENT (1)
RESPONSES TO REQUEST FOR ADDITIONAL INFORMATION - RELIEF REQUEST RR-ISI-04-09, ALTERNATIVE REPAIR FOR SALTWATER SYSTEM PIPING We cannot confirm how much liner is missing from the defect area, however, based on the nondestructive examination results it appears that the missing or degradation of the liner is localized (possibly within an area of approximately 6.3 inches x 3.4 inches).
NRC RAI 4:
(a) The NRC staff understands that once the clamp is installed, it is impossible to determine the growth of the defect area and the hole size unless the defect area grows outside the length of the clamp.
Nevertheless, discuss any administrative leak rate and defect area in the axial, circumferential, or radial direction that will cause corrective actions to be initiated Also, discuss the corrective actions.
(b) Discuss the leak rate and/or defect area and the hole size that will require an immediate repair or replacement of the pipe in mid-cycle.
(c) Discuss the critical defect area or hole size that will cause the pipe to fail catastrophically.
(a) & (b) With the mechanical clamp in place, the exact hole size will not be known. Therefore, any identified leakage from the mechanical clamp will be addressed by the site's Corrective Action Program. Leakage will not be an indicator of flaw size but the tightness of the mechanical clamp to piping. Nondestructive examination in the adjacent area of the mechanical clamp will be performed per requirements of ASME Section XI, Appendix IX at a maximum interval of 90 days. If the nondestructive examination shows wall thinning starting along either edge of the mechanical clamp, the site's Corrective Action Program will be engaged and corrective actions will be initiated. If the wall thinning is determined to be due to bay water corrosion, it would indicate that the flaw has extended beyond the mechanical clamp and an early plant shutdown to repair/replace this pipe segment would be initiated.
(c) The mechanical clamp is designed to withstand a full guillotine break at the piping design pressure of 50 psig. The development of a critical crack inside the clamp is inconsequential to the design since the mechanical clamp has been shown via calculation to remain in place and contain any flow from a full guillotine pipe break. If the defect extends outside the perimeter of the mechanical clamp, it will be detected through ultrasonic testing of the area (wall thinning) and corrective action would be initiated.
NRC RAI 5:
(a) Discuss the potential for the galvanic corrosion, since the stainless steel clamp will be in contact with the carbon steel pipe.
(b) The austenitic stainless steel from which the clamp is made is subject to pitting from chloride containing waters, such as sea water. Describe why stainless steel is appropriate for this service and/or how pitting of the clamp will be avoided CCNPP Response RAI 5:
The mechanical clamp will be placed on coated carbon steel piping. The stainless area in contact with the carbon steel piping will be coated with paint sufficient to provide protection against galvanic corrosion.
In addition the perimeter seal annulus will be filled with a leak injection sealant that will provide 3
ATTACHMENT (1)
RESPONSES TO REQUEST FOR ADDITIONAL INFORMATION - RELIEF REQUEST RR-ISI-04-09, ALTERNATIVE REPAIR FOR SALTWATER SYSTEM PIPING additional protection in this area. The internal area of the mechanical clamp and the piping will also be coated to prevent galvanic corrosion.
The sequence of coating will go as follows:
The piping area that will be encased by the mechanical clamp will be coated with an epoxy material.
A rubber gasket material will be placed over the through wall holes and applied coatings. This will aid against future corrosion attack on the external portion of the piping if bay water should leak past the rubber gasket material into the mechanical clamp annulus area.
The internal surface of the clamp will also be coated with an epoxy material in addition to the piping.
This will protect against galvanic corrosion if bay water should leak into the sealing area between the piping and the mechanical clamp.
NRC RAI 6: to the November 14, 2013, letter specifies a regulatory commitment which states that "Verify that the installed mechanical clamping device is removed and replaced by a permanent code repair or component replacement [by] 04/01/2015." However, Section 6 of the relief request states that "The mechanical clamping device will remain in place until the next refueling outage scheduled for February 2015 or until Unit 2 enters a shutdown of sufficient duration prior to the refueling outage." The regulatory commitment is not consistent with the requirement in Section 6 of the relief request because it does not contain the following requirement "...or until Unit 2 enters a shutdown of sufficient duration prior to the refueling outage." Clarify the discrepancy.
The regulatory commitment listed in Attachment (2) has been revised to be consistent with the words contained in Section 6 of our original submittal. Calvert Cliffs will remove the mechanical clamp and replace it by a permanent code repair or component replacement should Unit 2 enter a shutdown of sufficient duration prior to its next refueling outage in 2015.
Design NRC RAI 7:
(a) Article IX-5000 of Appendix IX to the ASME Code,Section XI, requires that a pressure test be conducted as part of the mechanical clamp installation. Discuss whether a pressure test will be conducted as part of the proposed alternative. If not, provide justification.
(b) Discuss any other deviation from Appendix IX of the ASME Code, Section Xl, which will be taken besides the pipe size of 12 inches.
(a)
A Section XI VT-2 examination at normal operating pressure and temperature will be performed upon installation of the Mechanical Clamping Device as required by Section XI, Appendix IX, Article IX-5000.
(b)
We are requesting no deviations from ASME Section XI requirements other than the limitation on pipe size given in Section XI, Appendix IX, Article IX-1000, paragraph (c)(4).
4
ATTACHMENT (1)
RESPONSES TO REQUEST FOR ADDITIONAL INFORMATION - RELIEF REQUEST RR-ISI-04-09, ALTERNATIVE REPAIR FOR SALTWATER SYSTEM PIPING NRC RAI 8:
Page 4 of the relief request states that in an unlikely event, if the defect area would grow through wall around the circumference, the pipe would still be encapsulated inside the clamp.
The licensee's calculation, ILD-CALC-0014, Revision 1, does not appear to analyze the double-ended guillotine pipe break event inside the clamp. Please clarify.
The existing Calvert Cliffs pipe stress calculation (M-93-038) for the system was revised to include the impact of the mechanical clamp. Additionally, the calculation revision included an analysis to determine the extent of pipe separation in the event of a circumferential break. The analysis utilized the same ME-101 pipe stress model as the piping calculation of record. The pipe stress model determined that the axial separation of each end of the break is 0.02 inches with a resultant displacement of 0.134 inches.
Since the clamp is not designed to carry, by friction, the loads normally transmitted by the piping, the piping would move 0.02 inches out of the mechanical clamp in the axial direction, well within the total mechanical clamp length of 14 inches between the pipe seals. The displacement in the other directions would be resisted by the mechanical clamp.
A portion of the revised calculation (M-93-038) is attached (Enclosure 6). The loads and stresses imposed on the mechanical clamp are evaluated in ILD-CALC-0014, Revision 1 which was previously provided as part of our original submittal.
Installation NRC RAI 9:
Describe the step-by-step installation procedure in detail, including the pre-installation inspection, surface preparation, and acceptance examination.
The step by step installation of the mechanical clamp will be performed using Calvert Cliffs procedure LR-01, "On Line Leak Repairs to Various Pressure Retaining Components." This procedure is contained in Enclosure 8.
(a) Pre-installation inspections and checks are performed using the attachment 7, "Pre-Job Repair Data Sheet" of the LR-01 procedure.
(b) Surface preparation will include coating the pipe under the clamp and applying a two inch wide rubber gasket material over the flaw sites.
(c)
Acceptance examination is performed using the attachment 8, "Post -Job Repair Data Sheet" of the LR-0 1 procedure.
NRC RAI 10:
The relief request states that the defect area is located in an unisolable section of the pipe, meaning that coolant will be flowing inside the pipe while the clamp is being installed.
(a) Discuss whether the pin holes will be plugged before the clamp is installed.
5
ATTACHMENT (1)
RESPONSES TO REQUEST FOR ADDITIONAL INFORMATION - RELIEF REQUEST RR-ISI-04-09, ALTERNATIVE REPAIR FOR SALTWATER SYSTEM PIPING (b) Discuss the possibility of the plug falling into the pipe during the plant operation if the pin holes continuously expand due to corrosion, since the pin holes will still be in contact with corrosive saltwater.
(c) The relief request states that the outside diameter of the pipe will be coated under the clamp to prevent saltwater corrosion of the carbon steel pipe. Given the apparent size of the holes and the resulting large leak rate, discuss what coating will be used and how will it be applied given that it appears that the pipe will be wet at the time of application.
The following responses are provided for the denoted sections:
(a) The pin holes/holes will not be plugged but a rubber gasket material will be used to cover the leak area and wrap the pipe.
(b) The rubber gasket material will not have the possibility of falling in to the piping due to its attachment around the entire pipe.
(c)
Coal Tar will be used to coat the pipe in the area between the perimeter sealing areas. This will allow for protection of the piping from the SW System.
NRC RAI 11:
(a) The NRC staff notes that sealant will be injected into the annular space between the pipe and the clamp and that the holes in the pipe are of a significant size. Please describe the means by which it will be assured that the sealant completely fills the annulus.
(b) Provide information on the sealant such as, how the sealant is qualified, what industrial Code it satisfies, how many years is sealant qualified for, what is the sealant condition (solid or liquid) after it is injected into the clamp, and would the sealant composition be affected by the pipe or ambient temperature.
(c) Discuss the hole size that the sealant would not be able to stop the leakage.
(d) Given the potential for continued growth of the holes, please describe the potential that the sealant will be exposed to flow and/or flow instabilities and be removed from inside of the clamp.
(a) The sealant will be injected into the perimeter seal area during installation of the clamp. An amount of sealant required to fill the void is determined and that amount will be verified by technicians in the field. This amount is controlled using the attachment 7 from Calvert Cliffs procedure LR-01.
(b)
The sealant to be used for this encapsulation will be Team Inc. Sealant #6XR and G-Fiber. Sealant
- 6XR is an elastomeric type material to which G-Fiber is added to provide bridging. The service life of the sealant is two years if the sealant is used in a condition below 350'F. The condition in which this encapsulation and sealant will be used will allow for the approximate 14 months of service until removal during the February 2015 refueling outage.
(c) The perimeter seal is designed to seal leakage using the perimeter seals. The enclosure is designed to stop any leak present at the system design rated pressure.
6
ATTACHMENT (1)
RESPONSES TO REQUEST FOR ADDITIONAL INFORMATION - RELIEF REQUEST RR-ISI-04-09, ALTERNATIVE REPAIR FOR SALTWATER SYSTEM PIPING (d) The sealant will be contained within the perimeter seal and will not be exposed to the system fluid.
The sealant is only injected to the perimeter seals. The void area at the flaw will not be injected.
NRC RAI 12:
Is the clamp designed to prevent all leakage? Even if the clamp is designed to prevent leakage, is any leakage from the clamp permissible? If so, what is the allowable leak rate?
The mechanical clamp is designed to stop all leakage at the system rated design pressure. The acceptance criteria established is that no leakage is present after the installation is complete. Minor visual leakage is indication of the mechanical clamp seal surface not meeting with the pipe. More than minor leakage will be evaluated by the site and permanent repairs scheduled as appropriate.
Inspection NRC RAI 13:
Discuss the acceptance examination after the mechanical clamp is installed, as part of the installation procedure and the acceptance criteria (i.e., what clamp condition would be considered as unacceptable for service).
The acceptance of the clamp is performed using Calvert Cliffs procedure LR-01 to ensure no leakage exists as verified by visual inspection of the area around the mechanical clamp. Team Inc. technicians are involved in the installation of the mechanical clamp and ensure the OEM specifications for the mechanical clamp are met.
NRC RAI 14:
Page 5 of the relief request states that provisions have been made in the mechanical clamping device design and location to ensure that both edges of the mechanical clamping device are accessible for ultrasonic testing wall thickness measurement at least every ninety days. Provide the amount of the pipe area at both ends of the clamp that will be ultrasonically examined and discuss why this pipe area is sufficient for the ultrasonic examination.
The upstream inspection area is approximately 3/4 inches wide. This area will be inspected 360 degrees after the mechanical clamp installation at a frequency that does not exceed 90 days. This is in accordance with ASME Code Section XI, Appendix IX.
The inspection area downstream of the mechanical clamp is approximately 2.0 inches wide. This area will also be inspected at a frequency that does not exceed 90 days in accordance with the applicable code of reference.
The zero degree transducer used for the inspection is 1/4 inches in diameter which will ensure that adequate contact is maintained based on the inspection area dimensions described above.
7
ATTACHMENT (1)
RESPONSES TO REQUEST FOR ADDITIONAL INFORMATION - RELIEF REQUEST RR-ISI-04-09, ALTERNATIVE REPAIR FOR SALTWATER SYSTEM PIPING NRC RAI 15:
The relief request proposes to monitor leakage weekly. Discuss whether a continuous monitoring system will be implemented or other existing continuous monitoring system that is available at the clamp. If significant leakage occurs between the weekly monitoring, discuss the safety significance of such leakage for a maximum of 7 days without notification.
The leakage rate of the mechanical clamp will be visually inspected on a daily basis. Any leakage would be evaluated and the perimeter seal would be re-injected to stop any leakage. The maximum limit leakage amount would be the leakage amount that exceeds the flooding calculation for the room. Any leakage that is more than minimal will be entered into the corrective action process to determine if additional evaluation is required or if permanent repairs need to be made earlier than planned.
NRC RAI 16:
Describe the extent of condition examinations performed Has piping on this line, a few pipe diameters up and downstream of the defects, been examined? Have other similar valves and the areas immediately downstream been examined? Have other segments of the saltwater system piping been examined?
Extent of condition ultrasonic inspections were performed at identical locations on three different SW trains in Units 1 and 2. The examinations were performed on the upstream and downstream piping sections that are identical in layout and flow conditions as the subject for RR-ISI-04-09. The ultrasonic examination area was 2.0 inches wide and 360 degrees around the pipe; the area was scanned 100 percent for wall thinning with a zero degree transducer. All ultrasonic readings were consistent with nominal pipe thickness ranges of 0.38 - 0.40 inches at the four locations.
Analysis NRC RAI 17:
From the clamp design drawing, it appears that the tubing in the inside sumface of the clamp will touch the outside surface of the pipe. The metal-to-metal contact area affects how the clamp stresses, clamp imposed stresses on the pipe, and clamp fastener loading are calculated Equation Number 18 in the licensee's calculation, ILD-CALC-O014, Revision 1, alluded to this contact area. Provide a diagram showing the contact area.
CCNPP Response RAI 17: provides additional sketches of the sealing contact area. The contact area was developed based on the total width of contact between the two stainless steel tubes on each perimeter seal. This contact force results from the stud torque values, and is not dependent on any sealants, coatings or injections into the void area of the mechanical clamp.
NRC RAI 18:
Article IX-3300(c) of Appendix IX to the ASME Code,Section XI, requires that effects of the stiffness and weight of the clamp shall be considered in the evaluation of the piping system. It does not appear that the licensee's calculation, ILD-CALC-O014, Revision 1, considered the effects of clamp weight and stiffness on the pipe system. Clarify if the proposed alternative satisfies article IX-3300(c).
8
ATTACHMENT (1)
RESPONSES TO REQUEST FOR ADDITIONAL INFORMATION - RELIEF REQUEST RR-ISI-04-09, ALTERNATIVE REPAIR FOR SALTWATER SYSTEM PIPING CCNPP Response RAI 18:
The existing pipe stress calculation (M-93-038) for the system was revised to include the impact of the mechanical clamp. This revision includes the effect of the mechanical clamp weight on the piping. A portion of the revised calculation is attached (Enclosure 6). The analysis utilized the same ME-101 pipe stress model as the piping calculation of record to determine the effect of the clamp on the piping loads and stresses as well as the effect on pipe supports and equipment nozzles/anchors. The results show that there is little impact on the piping system loads and stresses and that significant system margin is maintained.
The proposed alternative satisfies article IX-3300(c). The length of the clamp is significantly longer than the projected growth of the defect. The pipe stresses were computed using the nominal thickness in the analysis using the ME-101 pipe stress model since the base material thickness at the load transfer area will be the nominal thickness. Since the clamp is not designed to carry, by friction, the loads normally transmitted by the piping, the stiffness of the clamp has no additional impact on the piping stiffness.
Correction to Original Relief Request Submitted 11/14/2013 During preparation of the responses to the request for additional information, an error was identified on the table located in Section 4, sub section Growth Rate Estimate of our original relief request submitted on 11/14/2013.
The table showed a comparison between the "High Growth Estimate" and the "Low Growth Estimate." The error was in the "Low Growth Estimate" calculated axial growth over 16 months which also impacted the "Low Growth Estimate" axial total final length value. The table with the revised values is included below:
Direction High Growth Estimate Low Growth Estimate Axial Circumferential Axial Circumferential Current Length 6.3 inches 3.0 inches 6.3 inches 3.0 inches Rate (in/month**)
0.25 inches 0.5 inches 0.15 inches 0.375 inches Growth Over 4.0 inches 8.0 inches 2.4 inches**
6.0 inches 16 Months IIII Total Final Length 10.3 inches 11.0 inches 8.7 inches**
9.0 inches
- - Revised values This error has no further impact as the "Low Growth Estimate" was not used in any other calculation.
9
ENCLOSURE (1)
SALTWATER SYSTEM PIPING PHOTOGRAPH (1 page)
Calvert Cliffs Nuclear Power Plant, LLC December 6, 2013
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ENCLOSURE (2)
SALTWATER SYSTEM PIPING DRAWINGS (2 pages)
Calvert Cliffs Nuclear Power Plant, LLC December 6, 2013
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ENCLOSURE (3)
MECHANICAL CLAMPING DEVICE SKETCHES (3 pages)
Calvert Cliffs Nuclear Power Plant, LLC December 6, 2013
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Attachment A to ILD-DLV-00214 Page A2 of A3 Top Section View Sealing Width
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SECTION A-A
ENCLOSURE (4)
MECHANICAL CLAMPING DEVICE PHOTOGRAPHS (6 pages)
Calvert Cliffs Nuclear Power Plant, LLC December 6, 2013
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ENCLOSURE (5)
UT EXAMINATION REPORT PHOTOGRAPHS (2 pages)
Calvert Cliffs Nuclear Power Plant, LLC December 6, 2013
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