ML18065B236

Rev 0 to CEOG-01Q-305, Relaxation of RCP Flywheel Insp Requirements.

ML18065B236
Person / Time
Site:	Palisades
Issue date:	04/21/1998
From:	STRUCTURAL INTEGRITY ASSOCIATES, INC.
To:
Shared Package
ML18065B235	List: ML18065B234 ML18065B236
References
CEOG-01Q-305, CEOG-01Q-305-R00, CEOG-1Q-305, CEOG-1Q-305-R, NUDOCS 9805050354
Download: ML18065B236 (8)

Text

• ATTACHMENT CONSUMERS ENERGY COMPANY PALISADES PLANT DOCKET 50-255 PRIMARY COOLANT PUMP FLYWHEEL INSPECTION TECHNICAL SPECIFICATIONS CHANGE SUPPLEMENTAL CALCULATION 7 Pages I - - .

9805050354 980427f PDR ADOCK 05000255

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• CALCULATION FILE No.: CEOG-OlQ-305 STRUCTURAL INTEGRITY PACKAGE PROJECT No.: CPC-07Q Associates, Inc.

PROJECT NAME: Relaxation of Reactor Coolant Pump Flywheel Inspection Requirements CLIENT: CE Owners Group I Consumers Energy CALCULATION TITLE: Fracture Mechanics Evaluation of Palisades RCP Flywheel PROBLEM STATEMENT OR OBJECTIVE OF THE CALCULATION:

• Determine the stress intensity factor for centrifugal and shrink fit stresses at normal operating speed.

• Determine lower fracture toughness of the flywheel material.

• Determine allowable flaw size.

Project Mgr. Preparer(s) &

Document Affected Approval. Checker(s)

Revision Description Signature & Signatures.&

Revision Pages Date Date 0 1-7 Original Issue SIC-98-033 Page l of 7

1. INTRODUCTION The objective of this calc~lation package is to perform fracture mechanics evaluations to determine the flaw tolerance of th.e reactor coolant pump flywheel at Palisades. These evaluations are performed with respect tQ requests for additional information (RAis) submitted by the NRC to Consumers Energy

[1] and a subsequent telephone conversation between the NRC, Consumers Energy and Structural Integrity Associates on March 12, 1998 [2]. Previous fracture mechanics evaluations have been performed for the Palisades flywheel and flywheels of other CE plants in References 3, 4 and 5. Some of the analysis results of these* previous evaluations are used to perform the evaluations to address the RAis ..Three issues are discussed in this calculation package to determine the flaw tolerance of the Palisades flywheel.

1. Applied stress intensity factor due to centrifugal and shrink-fit stresses.

2. Fracture toughness of the Palisades flywheel which is fabricated from SAE 1017, Type 1020 carbon steel.

3. Allowable flaw size.

2. APPLIED STRESS INTENSITY FACTOR The fracture mechanics stress intensity factor, K 1 , is determined for the centrifugal and the shrink-fit stresses as a function of flaw depth at normal operating speed since it has been determined in the previous evaluations [3,4,5] that this is controlling. This was also recognized by the NRC in a previous safety evaluation [8]. The stress intensity factor distribution for the centrifugal stresses has been determined previously in Reference 3 using the pc-CRACK computer software [6] with a model consisting of a longitudinal flaw with t/R = 1.2 (t =thickness and R = inside radius). The stress intensity factor distribution as a function of flaw depth for this case is shown in Table l and also in Figure l.

Revision 0 Preparer/Date *'I c. "'/z // 9 r Checker/Date f,Jsm ijll ft 8 File No. CEOG-OlQ-305 Page 2 of ;

The shrink-fit stresses _~e maximum at zero speed of the flywheel and they decrease as the speed increases. Analysis was done in Reference 5 to determine the residual shrink-fit and the associated stresses at no~Tiial operating speed of the flywheel. Using the same model as for the centrifugal stresses, the stress intensity factor distribution as a function of flaw size was determined for the residual shrink-fit stresses at normal speed. This is shown in Table 1 and also in Figure 1.

3. FRACTURE TOUGHNESS OF FLYWHEEL MATERIAL The material of the flywheel at Palisades is SAE 1017, Type 1020 carbon steel with NDT of+ 40°F.

A 1though the value of RT NOT is not available, it is believed that this value of NDT can be used in determining the fracture toughness of the flywheel based on the lower bound fracture toughness (K1c) curve in ASME Section XI Appendix A for Class 1, 2 and 3 vessels (Reference 7). Strictly speaking_,

this curve applies only to SA-533 Grade B Class 1, SA-508 Class 2 and SA-508 Class 3 steels.

Because of the uncertainty surrounding the RT NOT of the flywheel material and the fact that the fracture toughness curve in ASME Sec_tion XI is restricted to pressure vessel steels, an uncertainty factor of 0.75 is applied to thefracture toughness calculated from the ASME Section XI in application to this evaluation. The operating temperature (T) of the flywheel is no less than 100°F and therefore

. (T - RT NOT) is conservatively taken as 60°F. From the ASME Section XI curve, the value of K 1c is 114 ksi .Jinch . Using an uncertainty factor of 0.75 yields a fracture toughness value of 85.5 ksi .Jinch .

4. ALLOWABLE FLAW SIZE DETERMINATION A safety factor of 2.5, which was approved by the NRC in Reference 8 for use in this application, was applied to the combination of the centrifugal and the shrink-fit stresses at normal operating condition.

This is shown as the "Total" stress intensity factor in Figure 1. The fracture toughness value of 85.5 ksi .Jinch determined above is also plotted in Figure 1 and compared to the total applied stress Revision 0

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intensity factor with a safety factor of 2.5 as shown in Figure 1. The allowable flaw size which is the intersection of the two curves is 1.52 inches.

5. CONCLUSIONS In a previous safety evaluation [8], the NRC recommended a bounding initial flaw size of 0.33 inch and a conservative crack growth of 0.013 inch for a ten year period resulting in a postulated crack _size of 0.343 inch after 10 years of operation of the flywheel. The allowable flaw size.of 1.52 inches calculated in this evaluation far exceeds this postulated crack size demonstrating adequate flaw tolerance of the flywheel at Palisades.

• REFERENCES

1. Request for Additional Information by USNRC on December 5, 1997 Regarding Technical Specification Change Request (TSCR) Submitted by Consumers Energy on October 1,. 1997, SI File CEOG-lOQ-240-7.

2. Telecon between USNRC, Consumers Energy and Structural Integrity Associates on March 12, 1997, SI File CEOG-OlQ-103.

3. SI Calculation Package No. CEOG-OlQ-302, Rev. 0 "Fracture Mechanics Evaluation".

• 4. Structural Integrity Associates Report No. SIR-94-080, Rev. 1, "Relaxation of Reactor Coolant .

Flywheel Inspection Requirements," March 1995, SI File CEOG-OlQ-401.

5: SI Calculation Package No. CEOG-OlQ-304, Rev. 0, "Fracture Mechanics Evaluation".

6. Structural Integrity Associates, pc-CRACK Fracture Mechanics Software, Version 2.1, 1991.

7. ASME Boiler and Pressure Vessel Code,Section XI, Appendix A, Figure A-4200-1, 1989 Edition. ,

8. Letter from Brian W. Sheron (USNRC) to Dwight C. Mims (ANO-Entergy Operations),

"Acceptance for Referencing of Topical Report SIR-94-080 - Relaxation of Reactor Coolant Flywheel Inspection Requirement," dated May 21, 1997, SI File CEOG-OlQ-240-7.

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• File No. CEOG-OlQ-305

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• Table 1 Stress Intensity Factors Crack Stress Intensity Factors (psi ~ ) -

Depth Centrifugal Shrink Fit Sum Total a c s C+S 2.S*(C+S)

(in) 0.04 5480 7721 13201 33003 0.08 . 7520 10317 17837 44593 0.12 8930 11914 20844 52110 0.16 10000 13046 23046 57615 0.2 10900 13778 24678 61695 0.24 11600 14244 . 25844 64610 0.28 12200 14577 26777 66943 0.32 12600 14710 27310 68275 0.36 13100 14766 27866 69665 0.4 13400 14776 28176 70440 0.44 13800 14710 28510 71275 0.48 14000 14577 28577 . 71443 0.52 14300 14444 28744 71860 0.56 14500 14310 28810 72025 0:6 14800 14111 28911 72278 0.64 15000 13911 28911 72278 0.68 15100 13711 28811 72028 0.72 15300 13578 28878 72195 0.76 15500 13445 28945 72363 0.8 15700 13312 29012 72530 0.84 15900 13179 . 29079 72698 0.88 16000 13046 29046 72615 0.92 16200 12979 29179 72948 0.96 16400 12979 29379 73448 1 16600 12913 29513 73783 1.04 16800 12913 29713 74283 1.08 17000 12979 29979 74948 1.12 17200 13046 30246 75615 1.16 17400 13112 30512 76280 1.2 17600 -13245 30845 77113 1.24 17800 13379 31179 77948 1.28 18000 13512 31512 78780 1.32 18300 13645 31945 79863 1.36 18500 13844 32344 80860 1.4 18700 14044 32744 81860 1.44 18900 14244 33144 82860 1.48 19200 14510 33710 84275 Revision 0 u Preparer/Date Checker/Date File No.

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Table 1 Stress Intensity Factors (continued)

Crack Stress Intensity Factors (psi~)

Depth Centrifugal Shrink Fit Sum Total a c s* C+S 2.S*(C+S)

(in) 1.52 19400 14710 34110 . 85275 1.56 19700 14976 34676 86690 1.6 19900 15176 35076 87690 1.64 20100 15375 35475 88688 1.68 20300 15642 35942 89855 1.72 20600 15841 36441 91103 .

1.76 20800 15974 36774 91935 1.8 21000 16174 37174 92935 1.84 21200 16307 37507 93768 1.88 21300 16374 37674 94185 1.92 21500 16440 37940 94850 1.96 21700 16440 38140 95350 2 21800 16440 38240 95600 Revision 0 I

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.. _!,l Applied ?tress Intensity Factor, Fracture Toughness and Allowable Flaw Size (1 ): Total includes a safety factor of 2.5 90000

-l l) c:i 80000 70000 s::

i"

• u; a; Total r 1

-.... 60000 if 0

CJ 50000 Ill

.s

~

Ill Ill

_40000 30000 en

~

Shr~k.Fit .

• Centrifug~~

20000 10000* ~-

......................... l' .. ....... *

~ l. I.

Allowable flaw si e 0+-....__..___.__._-+__.__..__..__...._-+-_.__..___._..........-+....__.~..__...._~

0 0.5 1.5 2

• Flaw Depth (in.)

Figure 1. Applied Stress Intensity Factor, Fracture Toughness and Allowable Flaw Size Revision 0 Preparer/Date' v~ <::: 11/21 / 'l!

Checker/Date File. No. CEOG-OlQ-305 Page 7 of 7

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