ML13322B180
| ML13322B180 | |
| Person / Time | |
|---|---|
| Site: | San Onofre  |
| Issue date: | 07/12/1990 |
| From: | Rosenblum R SOUTHERN CALIFORNIA EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9007160360 | |
| Download: ML13322B180 (7) | |
Text
Southern California Edison Company 23 PARKER STREET IRVINE. CALIFORNIA 92718 R.M.ROSENBLUM TELEPHONE MANAGER OF July 12, 1990 (714) 587 20 NUCLEAR REGULATORY AFFAIRS U. S. Nuclear Regulatory Commission Attention:
Document Control Desk Washington, D. C. 20555 Gentlemen:
Subject:
Docket No. 50-206 Flexure Fatigue Analysis Thermal Shield Support System Replacement San Onofre Nuclear Generating Station Unit 1 The enclosure to this letter provides the preliminary results of the new flexure fatigue analysis requested by the NRC in our meetings of June 25 to 27, 1990. The results of the analysis give the factor that would have to be applied to the flow induced vibrational (FIV) loads to obtain a usage factor of approximately 0.99 after 50 months of operation using a failure fatigue curve rather than the design fatigue curve. This analysis enables a one to one comparison of the original flexure to the new flexure using the same criteria.
The results presented in the enclosure are preliminary, since they need to be documented and verified. Westinghouse expects to complete the verification and documentation by July 20, 1990. If the verification results in any changes, you will be promptly notified.
If you have any questions or desire further information, please let me know.
Very truly yours,
Enclosure:
cc:
J. B. Martin, Regional Administrator, NRC Region V C. Caldwell, NRC Senior Resident Inspector, San Onofre Units 1, 2 and 3 90071603-60 900712 PDR ADOCK 05000206 61 P
Enclosure Westinghouse Proprietary Class 2 (Preliminary results)
Flexure Fatigue Analysis This evaluation was performed in response to the NRC request for a one to one comparison of the original flexure to the new flexure using the same criteria. The results of the evaluation give the factor that would have to be applied to the FIV loads to obtain a usage factor of approximately 0.99 after 50 months of operation using a failure fatigue curve rather than the design fatigue curve.
During the verification of the finite element model for the original flexure, the FIV adjustment factor was recalculated to reflect more accurate boundary conditions. This resulted in an increase in the adjustment factor used in the evaluation of the new flexure. The factor was 0.615, it is now 0.685.
The maximum alternating stress intensity, based on 4.45 Sigma FIV loads, for the flexure assuming the limiter keys are intact is 25.5 Ksi.
The fatigue evaluations presented to the NRC were based on an alternating stress intensity (Sa) value of 25.5 Ksi, which results in a usage factor of 0.3 for FIV loads for 15 years of operation at 10 Hz.
1
'Westinghouse Proprietary Class 2 (preliminary results)
F. I. V. FLEXURE Sa VALUES NODE 112 W/ KEYS W/O KEYS
( 646 )
( 606 )
LOCATION Sa (ksi)
I LOCATION Sa (ksi)
I 325 18.61 l
325 29.85 244 25.52 I
244 28.88 204 25.23 I
204 29.41 124 19.01 124 30.67 85 19.21 I
85 25.65 0
19.08 l
0 24.74 BASED ON 4.45 SIGMA AND A.685 FACTOR*
- Factor by which model-generated FIV loads would have to be multiplied to produce a usage factor approaching 1.00.
2
Westinghouse Proprietary Class 2 (preliminary results)
COMPARISON OF ORIGINAL TO NEW FLEXURE FIV LOADS WITH LIMITER KEYS (646)
ORIGINAL FLEXURE NEW FLEXURE LOCATION FACTOR*
USAGE l
LOCATION FACTOR*
USAGE 325 0.857 0.99 l
325 1.495 0.99 244 0.685 0.98 244 1.090 1.00 204 0.702 0.98 l
204 1.100 0.99 124 0.913 0.99 l
124 1.465 0.99 85 0.772 1.00 l
85 1.450 1.00 21 0.798 0.99 0
1.460 1.00
mmammmamam===mammama-ammmammamam-mmammmammema-ammam-mem-mmamm
==a BASED ON 50 MONTHS OF OPERATION AT 10 HZ, APPROX. 1.3E9 CYCLES
- Factor by which model-generated FIV loads would have to be multiplied to produce a usage factor approaching 1.00.
Westinghouse Proprietary Class 2 (preliminary results)
COMPARISON OF ORIGINAL TO NEW FLEXURE FIV LOADS NO LIMITER KEYS (606)
ORIGINAL FLEXURE NEW FLEXURE LOCATION FACTOR
- USAGE I
LOCATION FACTOR
- USAGE 325 0.438 0.99 I
325 0.930 0.99 244 0.610 0.99 I
244 0.960 0.98 204 0.608 0.98 I
204 0.945 1.00 124 0.496 0.98 l
124 0.905 0.99 85 0.667 1.00 l
85 1.084.
1.00 21 0.508 0.98 I
0 1.124 1.00 BASED ON 50 MONTHS OF OPERATION AT 10 HZ, APPROX. 1.3E9 CYCLES II Factor by which model-generated FIV loads would have to be multiplied to produce a usage factor approaching 1.00.
Westinghouse Proprietary Class 2 (preliminary results)
ORIGINAL FLEXURE ASSUMPTIONS
- 1. EVALUATION ASSUMES FLEXURES FAILED AFTER 50 MONTHS OF OPERATION (USAGE FACTOR OF APPROXIMATELY.99)
- 2. THE EVALUATION IS BASED STRICTLY ON F.I.V. LOADINGS ASSUMING A RAYLEIGH DISTRIBUTION OF LOADS
- 3. THE MEAN ASME FATIGUE (FAILURE) CURVE WAS USED FOR THE EVALUATION UP TO 1E+6 CYCLES, AT 70 DEG F Sa(l) =
(9159*NA-.5 + 47.35) KSI FROM 1E+6 TO 1E+11 CYCLES, AT 70 DEG F THE Sa VALUES OF CURVE "B" OF THE ASME CODE ARE INCREASED BY A FACTOR OF 2
- 4. A SIMIPLIED ELASTIC PLASTIC EVALUATION IS PERFORMED PER THE ASME CODE (Ke FACTOR) TO ADJUST THE ALTERNATING STRESS WHEN 3Sm (49.2 KSI AT 600 DEG F) IS EXCEEDED
- 5. THE Sa STRESS IS MODIFIED FOR THE EFFECTS OF MEAN STRESS WHENITHE (P + Q)
STRESS INTENSITY RANGE OF 44 KSI IS EXCEEDED.
THIS IS ONLY DONE FOR Sa VALUES UP TO THE 3Sm LIMIT.
ONCE A Ke FACTOR IS APPLIED THE SA VALUES ARE NO LONGER ADJUSTED FOR THE EFFECTS OF MEAN STRESS.
THE FOLLOWING EQUATION IS USED TO ACCOUNT FOR THE EFFECTS OF MEAN STRESS Sa'(l) -
Sa/(1-(Sy-Sa)/Su)
WHERE: SY -
44 KSI (1)
Su -
94 KSI (1)
(1)
REFERENCE, "FATIGUE DESIGN CRITERIA FOR PRESSURE VESSEL ALLOYS", C E JASKE AND W J O'DONNELL, JOURNAL OF PRESSURE VESSEL TECHNOLOGY, NOV 1977 5
Westinghouse Proprietary Class 2 (preliminary results)
NEW -FLEXURE ASSUMPTIONS
- 1. EVALUATION ASSUMES FLEXURES FAILED AFTER 50 MONTHS OF OPERATION (USAGE FACTOR OF APPROXIMATELY.99)
- 2. THE EVALUATION IS BASED STRICTLY ON F.I.V. LOADINGS ASSUMING A RAYLEIGH DISTRIBUTION OF LOADS
- 3. THE MEAN ASME FATIGUE (FAILURE) CURVE WAS USED FOR THE EVALUATION UP TO 1E+6 CYCLES, AT 70 DEG F Sa(1) -
(9159*NA-.5 + 47.35) KSI FROM 1E+6 TO 1E+11 CYCLES, AT 70 DEG F THE Sa VALUES OF CURVE "B" OF THE ASME CODE ARE INCREASED BY A FACTOR OF 2
- 4. A SIMIPLIED ELASTIC PLASTIC EVALUATION IS PERFORMED PER THE ASME CODE (Ke FACTOR) TO ADJUST THE ALTERNATING STRESS WHEN 3Sm (87.6 KSI AT 600 DEG F) IS EXCEEDED
- 5. THE Sa STRESS ISMODIFIED FOR THE EFFECTS OF MEAN STRESS WHEN THE (P + Q) STRESS INTENSITY RANGE OF 44 KSI IS EXCEEDED.
THIS IS ONLY DONE FOR Sa VALUES UP TO THE CYCLIC YIELD VALUE OF 44 KSI THE FOLLOWING EQUATION IS USED TO ACCOUNT FOR THE EFFECTS OF MEAN STRESS Sa'(l) -
Sa/(1-(Sy-Sa)/Su)
WHERE: SY -
44 KSI (1)
Su -
94 KSI (1)
FOR Sa > 44 KSI NO ADJUSTMENT IS MADE (1)
REFERENCE, "FATIGUE DESIGN CRITERIA FOR PRESSURE VESSEL ALLOYS", C E JASKE AND W J O'DONNELL, JOURNAL OF PRESSURE VESSEL TECHNOLOGY, NOV 1977 6