ML083020406
| ML083020406 | |
| Person / Time | |
|---|---|
| Site: | Three Mile Island  |
| Issue date: | 10/23/2008 |
| From: | Gallagher M AmerGen Energy Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 5928-08-20207, TAC MD7701 | |
| Download: ML083020406 (13) | |
Text
Michael P. Gallagher, PE Telephone 610.765.5958 AmerGen5 .
An Exelon Company Vice President www.exeloncorp.com License Renewal Projects michaelp:gallagher@exeloncorp.com 10 CFR 50 AmerGen 10 CFR 51 200 Exelon Way 10 CFR 54 KSA/2-E Kennett Square, PA 19348 5928-08-20207 October 23, 2008 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555 Three Mile Island Nuclear Station, Unit 1.
Facility Operating License No. DPR-50 NRC Docket No.50-289
Subject:
Response to NRC Request for Additional Information related to Three Mile Island Nuclear Station, Unit 1, License Renewal Application
Reference:
Letter from Mr. Jay Robinson (USNRC), to Mr. Michael P. Gallagher (AmerGen)
"Request for additional information for Time Limited Aging Analysis, Three Mile Island Nuclear Station, Unit 1, License Renewal Application (TAC NO. MD7701)",
dated September 3 0 th, 2008. (TAC No. MD7701)
In the referenced letter, the NRC requested additional information related to Time Limited Aging Analysis of the Three Mile Island Nuclear Station, Unit 1, License Renewal Application (LRA).
Enclosed are the responses to this request for additional information.
This letter and its enclosure contain no commitments.
If you have any questions, please contact Fred Polaski, Manager License Renewal, at 610-765-5935.
1 declare under penalty of perjury that the foregoing is true and correct.
Respectfully, Executed on /10 - 02 3- d465)
Michael P. Gallagher Vice President, License Renewal AmerGen Energy Company, LLC
October 23, 2008 Page 2 of 2 5928-08-20207 Enclosure A: Response to Request for Additional Information for Time Limited Aging Analysis, Three Mile Island Nuclear Station, Unit 1, License Renewal Application.
cc: Regional Administrator, USNRC Region I, w/Enclosure USNRC Project Manager, NRR - License Renewal, Safety, w/ Enclosure USNRC Project Manager, NRR - License Renewal, Environmental, w/o Enclosure USNRC Project Manager, NRR - TMIGS, w/o Enclosure USNRC Senior Resident Inspector, TMIGS, w/o Enclosure File No. 08001
Enclosure - A October 23, 2008 Page 1 of 11 5928-08-20207 Enclosure - A Response to Request for Additional Information for Time Limited Aging Analysis, Three Mile Island Nuclear Station, Unit 1, License Renewal Application.
Note: As a standard convention for AmerGen RAI responses, added text will be shown as bolded italicswhereas deleted text will be shown as stikethfouh.
Enclosure - A October 23, 2008 Page 2 of 11 5928-08-20207 RAI # 4.3.2-1 LRA Section: 4.3.2, Evaluation of Reactor Water Environmental Effects on Fatigue Life of Piping and Components (Generic Safety Issue 190)
Background:
Under the sub-section titled "Reduced Transient Cycle Administrative Limits - Pressurizer Surge Line," on page 4-31 of the License Renewal Application (LRA), the last sentence in the third paragraph states that "The Fen environmental correction factors shown are the overall average for each analysis."
Issue:
It is unclear what is meant by "overall average for each analysis", for example, since it could mean the average of all transients together for a single location or the average of all transients together for all locations having the same material. Justification is necessary if the average involves data from multiple locations. Since fatigue is localized damage, cross location averaging of Fen is not conservative.
Request:
Provide additional information regarding the Fen environmental correction factors and explain how the correction factors shown are the overall average for each analysis.
AmerGen Response The phrase "overall average for each analysis" means the average Fen multiplier for all of the transients together for a single location.
The referenced sentence on LRA page 4-31 only applies to the results from the refined fatigue analyses for Locations 3a and 3b in Table 4.3.2-2. The reported Cumulative Usage Factor (CUF) values were adjusted for the effects of Environmentally Assisted Fatigue (EAF). Each of these reported EAF-adjusted CUF values are associated with a single component location. The 0.951 CUF value identified as Location 3a is for the bounding elbow in the pressurizer surge line, which is the second elbow from the Reactor Coolant System hot leg piping. The 0.847 CUF value identified as Location 3b is for the bounding butt weld, located between the second elbow and the adjacent straight pipe section.
In these refined analyses for Locations 3a and 3b, an individual Fen correction factor was computed for selected load set ranges (transient pairings) based upon the equations provided in Section 4.1 of EPRI MRP-47, Revision 1. Each individual Fen correction factor was computed using only data appropriate for the location and for the transient pairing. There was no averaging of data from multiple locations in determining these individual Fen correction factors for Locations 3a and 3b.
As described in Note 2 of Table 4.3.2-2, the value reported as Fen Correction Factor is a composite of the overall average Fen correction factor for the fatigue analysis and the cycle reduction factor. It is computed by dividing the overall EAF-adjusted CUF value for the component by the current design CUF value for the component. It represents the combined effects of CUF increase due to reactor water environmental effects and CUF decrease due to the reduced numbers of cycles shown in Table 4.3.2-3.
Enclosure - A October 23, 2008 Page 3 of 11 5928-08-20207 RAI # 4.3.2-2 LRA Section: 4.3.2, Evaluation of Reactor Water Environmental Effects on Fatigue Life of Piping and Components (Generic Safety Issue 190)
Background:
In Tables 4.3.2-1 and 4.3.2-5, (and some other intermediate tables) in the LRA, a single value of Fen is used for low alloy/carbon steel and another single value of Fen is used for Alloy 600 material, disregarding the locations/components that they are associated with.
Issue:
Fen is a function of strain rate, dissolved oxygen concentration, and temperature. Therefore, Fen is expected to be different for each location because the strain rates are most likely different for each component and location.
Request:
Clarify how Fen is used for the various locations/components and materials.
AmerGen Response Maximum Fen values were computed for each material type by using bounding assumptions for each input variable in the applicable Fen equations. These maximum Fen values were used as a first attempt to qualify each of the NUREG/CR-6260 locations for environmental fatigue effects.
The maximum Fen value determined for Carbon Steel-is 1.74; for Low Alloy Steel is 2.455; for Austenitic Stainless Steel is 15.35; and for Nickel Alloy 600 is 1.49. This bounding approach results in conservative values for Fen and is acceptable as long as the environmentally adjusted Cumulative Usage Factor (CUF) value for each component remains below the acceptance limit of 1.0.
This maximum Fen approach, in combination with reduced numbers of transient cycles, was successful for qualifying each location except Locations 3a and 3b, as shown in Table 4.3.2-5.
Location 3a represents the stainless steel surge line elbows and Location 3b represents the stainless steel surge line piping (including welds). The initial results for these components exceeded 1.0, making a more refined Fen approach necessary. This refined approach is further described in AmerGens response to RAI 4.3.2-1, where an individual Fen multiplier was computed for selected load sets within the fatigue analysis rather than using the maximum Fen multiplier.
Enclosure - A October 23, 2008 Page 4 of 11 5928-08-20207 RAI #: 4.7-1 LRA Section: 4.7, Loss of Prestress in Concrete Containment Tendons
Background:
For the GALL Report AMP X.S1 "Concrete Containment Tendon Prestress," the "Monitoring and Trending" program element states that estimated and measured prestressing forces are plotted against time and the predicted lower limit (PLL), MRV, and trending lines developed for the period of extended operation.
Issue:
The plots or data for the historically inspected tendon forces, predicted forces, trend lines, and minimum required values (MRV) were not included in Section 4.7 of the LRA.
Request:
Provide log-year graphs of individual tendon forces versus 95% of the predicted force, and trend lines against MRV to confirm adequacy of the prestressing forces.
AmerGen Response The log-year graphs reviewed and discussed with the reviewer during the AMP audit are shown as follows:
The first three graphs illustrate the individual measured tendon forces and MRV for each tendon group for vertical, hoop and dome. These graphs also indicate the measured tendon force trend lines and 95% lower confidence limit (LCL) projected through the period of extended operation.
The last three graphs illustrate the measured control tendon forces and MRV for each control tendon. Also indicated are the measured control tendon force trend lines and predicted force trend lines for each control tendon projected through the period of extended operation.
Also, the third paragraph in the analysis portion of Section 4.7 should have included the acceptance criteria per ASME Section Xl, Subsection IWL, paragraphs IWL-3221.1(b)(1), (2) and (3). These criteria were used for one tendon in the year 10. All other measured tendon forces for years 10 through the last surveillance performed for year 35 have been greater than 95% of the predicted values. Prior to year 10 the acceptance criteria of ASME Section Xl, Subsection IWL, paragraphs IWL-3221.1 did not apply.
LRA Section 4.7 should have read:
4.7 LOSS OF PRESTRESS IN CONCRETE CONTAINMENT TENDONS Analysis The measured forces meet acceptance criteria specified ASME Section Xl, Sub-Section IWL, paragraphsIWL-3221. 1(a) and (b), as follows:
Enclosure - A October 23, 2008 Page 5 of 11 5928-08-20207 The force in each sample tendon is at least 95% of the force predicted for that tendon at the time of the measurement or the force is at least 90% of the predictedforce and (1) the force in the 2 adjacent tendons is at least 95% of the force predictedfor that tendon at the time of measurement and (2) the measured forces in all of the remaining tendons are not less than 95% of the predictedforce. Vertical, hoop and dome sample mean forces are above the minimum required value (MRV) specified in UFSAR Section 5.7.5.2.3.
Enclosure - A October 23, 2008 Page 6 of 11 5928-08-20207 Vertical Tendon Measured Forces, Trend and 95% LCL - 10 to 30 Years 1350 Trend Line [Equation: F=1214.7 - 5.1 Ln (T)]
Standard Error of Estimate, Se = 30.7 kip 1300 Extended License 4- Expires April 2034 (T = 60.1) 1250 1200 a -~
- 4. I ___________
- 1150-1/
95% LCL 1100 35 Year Surveillance Deadline, March 2010 MRV = 1033 kip- (T = 36.0) 1050 i i 1000 10 20 30 50 100 Years, T, Since SIT
Enclosure - A October 23, 2008 Page 7 of 11 5928-08-20207 Hoop Tendon Measured Forces, Trend and 95% LCL - 10 to 30 Years 1350 Trend Line [Equation: 1112.3 + 12.4 Ln (T)]
Standard Error of Estimate, Se = 38.3 kip 1300 Extended License Expires April 2034-0 (T = 60.1) 1250
.2. 1200 A :1 4
0 LL 1150 -V-A. K i 95% LCL V,
4 1100 vI MRV = 1108 kip 1050 35 Year Surveillance Deadline March 2010 (T = 36.0) 1000 10 20 30 50 100 Years, T, Since SIT
Enclosure - A October 23, 2008 Page 8 of 11 5928-08-20207 Dome Tendon Measured Forces, Trend and 95% LCL - 10 to 30 Years 1350 1300
- Trend Line [Equation: F = 1305.1 -47.7 Ln (T)]
Standard Error of Estimate, Se = 64.1 kip 1250 Extended License Expires
- April 2034 (T = 60.1)
.2-1200 __*
U-1100 ___
1050 ______________
MRV = 1064 kip 35 Year Surveillance Deadline March 2010 (T = 36.0) 1000 10 20 30 40 50 60 70 80 90 100 Years, T, Since SIT
Enclosure - A October 23, 2008 Page 9 of 11 5928-08-20207 Vertical Control Tendon V32 Measured Forces, Trend and Predicted Force 1350 1300 Extended License Expires April 2034 (T = 60.1)
Predicted Force, Fp = 1291.3 - 30.9 Ln (T) 1250
.- 1200 U
o 1150 Measured Force, Fro, Trend Line Equation: Fm = 1213.2 - 5.3 Ln (T) 1100 35 Year Surveillance Deadline March 2010 (T = 36.0) 1050 MRV = 1033 kip 1000 10 20 36 50 100 Years, T, Since SIT
Enclosure - A October 23, 2008 Page 10 of 11 5928-08-20207 Hoop Control Tendon H62-26 Measured Forces, Trend and Predicted Force 1350 1300 1250
.L 1200 0
-. 1150 1100 1050 1000 10 20 30 50 100 Years, T, Since SIT
Enclosure - A October 23, 2008 Page 11 of 11 5928-08-20207 Dome Control Tendon D225 Measured Forces, Trend and Predicted Force 1350 1300 Extended License Expires April 2034 (T = 60.1) 1250 Measured Force, Fm, Trend Line Equation: Fm = 1151.3 - 11.3 Ln (T)
.E 1200 U-0 11150 1100 I________ I_____
ZPredicted force, Fp = 1210.2 -40.1 Ln (T) 1050 MRV = 1064 kip 35 Year Surveillance Deadline March 2010 (T = 36.0) 1000 10 20 30 50 100 Years, T, Since SIT