ML030230468
| ML030230468 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 01/20/2003 |
| From: | Katz P Constellation Energy Group |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| PEK/GT/bjd | |
| Download: ML030230468 (5) | |
Text
Peter E. Katz Vice President Calvert Cliffs Nuclear Power Plant Constellation Generation Group, LLC 1650 Calvert Cliffs Parkway Lusby, Maryland 20657 410 495-4455 410 495-3500 Fax Constellation I
Energy Group January 20, 2003 U. S. Nuclear Regulatory Commission Washington, DC 20555 ATTENTION:
SUBJECT:
Document Control Desk Calvert Cliffs Nuclear Power Plant Unit Nos. 1 & 2; Docket Nos. 50-317 & 50-318 Response to NRC Request for Additional Information Regarding ASME Section XI Relief Request to Use Alternative Techniques for Reactor Vessel Head Repair
REFERENCE:
(a) Letter from Mr. C. H. Cruse (CCNPP) to Document Control Desk (NRC),
dated February 7, 2002, ASME Section XI Relief Request to Use Alternative Techniques for Reactor Vessel Head Repair By letter dated February 7, 2002 (Reference a), Calvert Cliffs Nuclear Power Plant, Inc. submitted an American Society of Mechanical Engineers (ASME) Boiler and Pressure Vessel Code (Code) relief request to be used in the event that flaws requiring repair in the reactor vessel closure head penetrations are discovered during inspections. This letter provides Calvert Cliffs Nuclear Power Plant's response to a January 6, 2003, verbal request from the Nuclear Regulatory Commission for additional information regarding that relief request.
The requested information and our responses are contained in Attachment (1) to this letter.
Should you have questions regarding this matter, we will be pleased to discuss them with you.
Very trul yours, PEK/GT/bjd
Attachment:
(I)
Response to NRC Request for Additional Information cc:
J. Petro, Esquire J. E. Silberg, Esquire Director, Project Directorate I-1, NRC D. M. Skay, NRC H. J. Miller, NRC Resident Inspector, NRC R. I. McLean, DNR
,6,C)4'7
ATTACHMENT (1)
RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION Calvert Cliffs Nuclear Power Plant, Inc.
January 20, 2003
ATTACHMENT (1)
RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION NRC Request 1:
In your December 18, 2002, response (Reference 1) to our November 6, 2002, request for additional information (Reference 2), you referred to an American Society of Mechanical Engineers (ASME)
Section III analysis performed to demonstrate the structural integrity of the weld repair.
Provide the results of that analysis and indicating the margin with respect to ASME Code allowables.
CCNPP Response:
As indicated in Reference (1), the Section III analysis demonstrated that the weld repair design meets the stress and fatigue requirements of the design code, ASME Code,Section III 1989 Edition, no Addenda.
The Section III analysis consisted of a 3-D ANSYS finite element model of a penetration with the largest hillside angle. Thermal stresses were determined for the appropriate design transients and a fatigue analysis was performed.
Design, emergency, faulted, and test conditions cases were evaluated and compared against the appropriate ASME Section III stress limits. The ASME Section III requirements were met as shown below:
Design Conditions American Society of Mechanical EngineersSection III criteria contained in NB 3221.1, NB 3221.2 and NB 3221.3 were checked and had significant margins to allowables. The reactor vessel head was the location that had stresses with the least margin to the allowable and are listed below.
General Primary Stress Intensity (NB-3221.1) = 14.8 ksi < 1.0 Sm = 26.7 ksi Local Membrane Stress Intensity (NB-3221.2) = 25.9 ksi < 1.5 Sm = 40.1 ksi Primary Membrane + Primary Bending Stress Intensity (NB-3221.3) 29.2 ksi < 1.5 Sm = 40.1 ksi Emergency (Level C) and Faulted (Level D) and Test Conditions Had larger margins of safety than Design Condition case.
Primary + Secondary Stress Intensity Primary + Secondary Stress Intensity (NB3222.4) = 54.0 ksi < 3 Sm = 80.0 ksi Fatigue Analysis Cumulative fatigue usage factor = 0.997 < 1.0 (ASME Criteria)
NOTE: This is for 40 years of design transient cycles NRC Request 2:
In your December 18, 2002, response (Reference 1) to our November 6, 2002, request for additional information (Reference 2), you referred to a fracture mechanics evaluation performed to demonstrate the acceptability of a triple point anomaly modeled as a 0.1-inch long indication. Provide the results of that analysis and indicating the margin with respect to ASME Code allowables.
CCNPP Response:
As indicated in Reference (1), a fracture mechanics analysis was performed to evaluate a 0.100" semi-circular flaw extending 360 degrees around the circumference at the "triple point" location where the Alloy 600 (original nozzle), the Alloy 52 weld and the low alloy steel head meet. The flaw is assumed to 1
ATTACHMENT (1)
RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION propagate in each of the two directions on the uphill and downhill sides of the nozzle. Flaw acceptance is based on the 1998 ASME Code Section XI criteria for applied stress intensity (IWB-3612) and limit load (IWB-3642).
The results are summarized below and the flaw propagation paths are shown on the attached Figure.
The flaw evaluation results for 25 years of fatigue crack growth (FCG) are as follows.
Flaw Propagation Paths 1, 2, 5, and 6
- a.
FCG analysis of a continuous external circumferential flaw in weld:
Initial flaw size, Maximum final flaw size, Maximum stress intensity factor, Fracture toughness, Fracture toughness margin, ai= 0.100 in.
af= 0.112 in.
KI =
KIa =
KIa / KI =
13.3 ksWin 200 ksilin 15.0> 10
- b. Limit load analysis for a continuous external circumferential flaw inweld:
Bounding axial tube load, P = 21,606 lbs Limit load, Po= 108,697 lbs Limit load margins, PO / P = 5.03 > 3.0
- c.
FCG analysis of a semi-circular external axial flaw in weld:
Initial flaw size, Maximum final flaw size, Maximum stress intensity factor, Fracture toughness, Fracture toughness margin, ai = 0.100 in.
af = 0.113 in.
KI =
KIa =
Kia / KI =
15.3 ksi4in 200 ksi4in 13.1 > 410 Flaw Propagation Paths 3 and 4 FCG analysis of a semi-circular surface flaw at weld/head interface:
Initial flaw size, Maximum final flaw size, Maximum stress intensity factor, Fracture toughness Fracture toughness margin, ai = 0.100 in.
af= 0.101 in.
KI = 6.12 ksiNin Kia = 200 ksWin Kia / KI = 32.7 > 410 Therefore, the ASME Section XI requirements were met.
2
ATTACHMENT (1)
RESPONSE TO NRC REQUEST FOR ADDITIONAL INFORMATION FIGURE 1 Crack Propagation Paths on the Finite Element Stress Model Note:
Paths 1, 3, and 5 are located on the downhill (00) side of the nozzle and Paths 2, 4, and 6 are on the uphill (1800) side.
>NkY 17 2002 15:32:6 I
i~~~~~~~
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~~~~~~~~~~~~
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_ p
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= 7739
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~~~~No
7200 I~~~~~~~~~~~~~~~~~~~~~~~~~~~~~N Path~~~~~~~~~~~~~~~~~~~~~~~~Pt 6 Ni Ni=6 No, 7200o
Caet Clis a 2CED Ni = 6589 o~~~~c 3