ML20077M518

Fatigue Evaluation Power Uprate Operating Conditions, Rev 1

ML20077M518
Person / Time
Site:	Nine Mile Point
Issue date:	09/13/1994
From:	Dias K, Faynshtein K, Stevens G GENERAL ELECTRIC CO.
To:
Shared Package
ML20077M517	List: ML20077M515 ML20077M518
References
NEDC-32015, NEDC-32015-R01, NEDC-32015-R1, NUDOCS 9501130085
Download: ML20077M518 (15)

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9 GENuclear Energy Y. ?.YI!*:i NEDC-31015 GE-NE-523-59-0591 Class II September 1994 Revision 1 NINE MILE POINT 2 FATIGUE EVALUATION POWER UPRATE OPERATING CONDITIONS 9 ~ '3 -9f Prepared by:

K.P. Dias, Engineer Stmetural Mechanics Projects J./

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Verified by:

A MT K. Faynsh'tein, Engineer Stmetural Mechanics Projects N n d' blw %

G.L. devens, Senior Engineer Stmetural Mechanics Projects f

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Approved by:

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S.1:siiganath, Mmager' #

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Stmeturel Mechanics Projects GE Nuclear Energy San Jose, California 9501130005 950103 PDR ADOCK 05000410 P

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NEDC-32015 Revision 1 REPORT CERTIFICATION This design certiScation, with the documents listed below, constitutes the reconciliation to the Nine Mile Point 2 (NMP2) reactor pressure vessel Code Stress analysis for a power uprate program. I certify, to the best of my knowledge and belief, that the stress report, listed below is correct, complete, and complies with the ASME Boiler and Pressure Vessel Code,Section III, Division 1, Nuclear Power Plants Components, - 1971 Edition with Addenda to and including Winter 1972. I also hereby certify that I am a duly Registered Engineer under the laws of the State of California.

SUPPORTING DOCUMENTS Document Revision Type of Title 25A5000 0

Design Specificatic!.

Reactor Vessel-Power Uprate NEDC-32015 1

Stress Report Nine Mile Pobt 2 Fatigue Evaluation Power Uprate Operating Conditions

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Certified by:

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Date: 9fMlif Regisidred Professig/Iftihineer

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NT.DC 32015 Revision i IMPORTANT NOTICE REGARDING CONTENTS OF THIS REPORT

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l' Please Read Carefully The only undertakings of the General Electric Company (GE) respecting information in this document are contained in the contract between Niagara Mohawk Power Corporation (NMPC) and GE, as identined in Attachment 10 of the Settlement Agreement and nothing contained in this document shall be construed as changing the contract. The use of this information by anyone other than NMPC o. for any purpose other than that for which it is intended, is not authorized; and with respect to any unauthorized use, GE makes no representation or warranty, and assumes no liability as to the completeness, accuracy, or usefulness of the information contained in this document, or that its use may not infringe privately owned rights.

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NEDC42015 Revision 1 4

1 TABLE OF CONTENTS J

NOMENCLATURE

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1.0 INTRODUCTION

... 5 2.0 AN ALYSIS AND RES ULTS.....................................

..............6 1

2. I General Analysis and Procedure..................................................................... 6 2.2 Thermal Stress Calculation Methodology................

......6 2.3 Altemating Stress Calculation..............

..............8 2.4 Fatigue Usage Factor Calculation....................................................

.....9 2.5 Power Uprate Maximum P+Q Stress Intensity Range, Sn.................................. 9 2.6 Thermal Stress Ratchet Requirements............................................................... 9 2.7Results.........................................................................................................10 3.0 S UMMARY AND CONCLUSIONS......................................................... 13 4. 0 REFE RENC ES...................................................................... 14 I

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NEDC-32015 Rnision 1 NO %1ENCI.ATURE o

- Stress (psi or ksi)

- Influence Factor (psi /A*F) a i

F.

- Allowable Stress Intensity Sn

- Maximum Stress Intensity Range (P+Q stress)

S

- Peak Stress Intensity Range p

Salt-

- Alternating Stress Intensity 6

Ea

- Actual Elastic Modulus at 552"F (26 x 10 p,;)

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Ec

- Fatigue Curve Elastic Modulus Value (30 x 10 p,;)

Ke

- Strain Concentration Factor

.AU

- Incremental Fatigue Usage Factor I(AU)

- Sum of Differences between O'riginal and Power Uprate Incremental Usages UCUM

- Cumulative Fatigue Usage Factor 1

Nallow

- Number of Allowable Fatigue Cycles Nactual

- Number of Actual Fatigue Cycles M+B

- Membrane + Bending Stresses M+B+P

- Membrane + Bending + Peak Stresses P+Q

- Primary + Secondary Stresses i

O, PU

- Original" and " Power Uprate" Subscripts a

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I NEDC-32015 Revision I

1.0 INTRODUCTION

A fatigue evaluation of the Nine Mile Point 2 (NMP-2) Nuclear Pow:r Plant has been performed

. for the new power uprate operating conditions. The original analysis is still bounding with respect l

to the new maximum vessel temperature, pressure, flow, and feedwater (FW) pressure for

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NMP 2. Only FW temperature and steam outlet flow increased beyond the upper bounds of the original analyses.

E An increase of approximately 6% in steam outlet flow resulted in a 4.7% increase in heat transfer coefficients for the steam outlet nozzle. However, it was found that an increase of this order has -

t negligible effect on temperatures. Since no other operating parameters increased for the steam outlet nozzle, fatigue usage was not re-evaluated for this component.

The new operating parameters for FW temperature and flow are given in the Power Uprate Design Specification (Reference 1). The upper limit of the new operating pressure is 1055 psia (Reference 2) and is still within the operating conditions defined in the current thermal cycle

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diagram (Reference 3). The governing stress repon (Reference 4) includes a generic analysis _

which is bounding for all replaceable sparger type FW nozzles. The thermal cycle diagrams contained in the referenced report were the basis for the original analysis. Those cycle diagrams

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remain-applicable as the design basis and will be modified as necessary to recalculate thermal stresses.

'l Onginally, a stainless steel (SS) clad location (element #374) was reported to have the most severe fatigue usage of 0.9503 (Reference 4). However, per Appendix 10 of the Reactor Vessel Purchase Specification (Reference 6), an additional cavironmental fatigue analysis (Reference 5) resulted in an incremental usage factor of 0.157 to account for the effects of stress corrosion in l

carbon steels. As a result of this analysis, another critical location was identified in the carbon steel section of the nozzle (element #228). Following a subsequent new loads assessment to account for new pool hydrodynamic loads (Reference 7), a cumulative usage of 0.%8 was reported for the carbon steel location (element #228).

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NEDC-32015 Redsion 1 '

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The analysis presented in this report will address the effects of power uprate on the two most critical Iccations identified above (element #374 and element #22R).

2.0 ANALYSIS AND RESULTS i

The following analysis methods are consistent with ASME Code Section III methodology and requirements, 2.1 General Analysis and Procedure Only stress cycle combinations with incremental usage factors of U>0.01 were re-evaluated.

Combinations with U<0.01 were neglected. The remaining dynamic cycles are not influenced by power uprate, and rapid cycles actually decrease as a result of power uprate. Therefore, the usage for these cycles was not changed. Since only thermal stresses increase due to power -

uprate, mechanical and dynamic stresses need not be considered. As su:h, the overall stresses.

were increased by a " delta" change in thennal stress.

i The allowable stress intensity, Sm and actual clastic moduli, Ea, remain unchanged for power uprate conditions, since they were initially evaluated using a vessel temperature of 552*F which remains bounding.

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Note that according to the special stress rules for stress corrosion mitigation, environmental l

fatigue is considered for only carbon steel and not for SS clad.

2.2 Therma! Stress Calculation Methodology Each stress cycle combination generally includes a cool-down and warm-up transient. He resulting thermal stresses are due to both the initial temperature and temperature range of each transient. Transient thermal stresses have essentially two components:

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NEDC42015 Revmon 1 othermal = css + cshock(AT)

[1]

where.

ass = Initial steady state thermal stress (prior to a ramp in temperature) oshock(AT) = Incremental thermal shock stress (relative to ss stress)

The initial steady-state (ss) component is independent of the transient temperature change and, if not defined, can be easily calculated from any other specified steady-state condition. For NMP-2, i

the Zeroload condP. ion (i.e. zero thermal stress) has been specified relative to 70'F. Alternately, the increment thernci shock stress is a function of the transient temperature range, regardless of the initial condition.

Thus, since each stress component is proportional to a temperature difference, the stresses can be normalized by some characteristic influencefactor, a, as follows, oss = ass (ATss) = ass (Tss - 70)

[2]

cshock = ashock (ATramp) = ass (Tfinal - Tss)

[3]

where, Tss = initial ss temperature of transient Tfmat = final temperature of transient

Thus, ass = [ css / ATss] = constant ss influence factor

[4]

ashock = [oshock/ ATramp) = thermal shock influence factor

[5]

For any specific nozzle location and time, the steady state influence factor is constant regardless of nozzle temperature, whereas, the thermal shock influence factor is dependent on the transient temperature profile and transient time.

Separate influence factors shou'd be calculated for membrane and bending (M+B) stresses and membrane, bending and peak (M+B+P) stresses.

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l Rension 1 Influence factors' were calculated based on the original stress report (Reference 4) transient descriptions using equations (4) and [5]. Power uprate thermal stresses may then be easily calculated using the influence factors and revised power uprate ATSS and ATramp values using equations (2) and (3] above.

I 2.3 Alternating Stress Calculation Stress ranges were originally computed based upon the worst permutation or combinations of minimum and maximum mechanical and dynamic load types However, since mechanical and -

dynamic loads are not affected significantly by power uprate, a simplified approach will be used here to recalculate stress ranges, peak stress ranges, and alternating stress intensities. Only

ncremental increases in alternating stress intensities due to changes in thermal stress as a result of power uprate will be computed and added to the previous alternating stress intensity, Salt, as follows

1 Salt, PU " Salt,O + ASalt, PU

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For each transient, a " delta" thermal stress is computed between original and uprate conditions.

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" Delta" peak thermal stresses, ASP, and " delta" alternating stresses, ASalt, are then calculated:

ASalt = 1/2 (Ec / Ea) Ke ASP

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For the transient cases considered here, the strain concentration factors, Ke, were assumed to be equal to 1.0. This was a reasonable assumption since in most cases the Salt values were on the.

order of 3Sm or less; the Sn values were vM to be less than Salt. However, for larger Salt values (>3Sm). Sn values and Ke factors were recalculated per the elastic-plastic methods of NB-3228.3 of the AShE Code (Reference 7). Per NB 3228.3 of the AShE Code (Reference 7),

only if the P+Q stress range (i.e. Sn) minus thermal bending is <3Sm-Sn may exceed 3Sm A

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NEDC 32015 Revision 1 2.4 Fatigue Usage Factor Calculation The allowable number of cycles - Nallow, was computed per Section III of the' ASME Code

- (Reference 8) using the fatigue table values and interpolation formula provided. The incremental usage for each stress cycle combination was then computed, AUPU = Nactual / Nallow

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j The incremental usage for the selected combinations is summed for both UO and UPU. The net difference between the original and power uprate incremental usages considered in this analysis is represented as I(AU). This value was added to the previous (pre-uprate) reported usage to derive the new cumulative usage factor for power uprate conditions.

2.5 Power Uprate Maaimum P+Q Stress Intensity Range, Sn The maximum stress intensity range (with thermal bending removed) reported aAer new loads evaluations were considered was 53.1 ksi (corresponding to 50.0+Dyn/Zeroload cycle combination). Thermal membrane stresses were generally small and the increase in membrane stress due to power uprate only resulted in an increase of 0.067 ksi in the P+Q minus thermal bending stress range. Thus the new maximum P+Q minus thermal bending stress range is 53.2 ksi

< 3Sm= 54.3 ksi, and thus satisfies ASME Code criteria (Reference 8).

2.6 Thermal Stress Ratchet Requirements Additional requirements for thermal stress ratcheting (NB-3222.5, Reference 7) in the carbon steel base metal were also met since the peak pressure, yield strength, and maximum P+Q stress of the previous analysis (Reference 4) remain bounding. Per Reference 4, the allowable thermal stress range is 74.5 ksi (unaffected by power uprate), which is still well above the power uprate maximum Sn value of 60.8 ksi.

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NEDC 32015 Revision 1 2.7 Results For the critical SS clad location, the cumulative usage actually decreases from 0.9503 to 0.916 (Table 1). The usage decreases because there was some conservatism included in estimating Nallow in the original analysis. As a result of providing more accurate values for allowable stress cycles, the overall usage decreased from the original value which more than offsets the small increase in the alternating stresses.

The total fatigue usage for the can :' a steellocation also decreased from 0.958 to 0.965 (Table 2).

Once again, minor increases in alternating stresses are more than offset by using more accurate values for Nallow.

The P+Q (i.e. Sn) stresses with thermal bending removed were scaled in a similar manner based upon the information given for the Zeroload/S.0+Dyn transient. None of the P+Q stresses with thermal bending removed exceeded the 3Sm imit. Furthermore, all thermal stress ratcheting l

requirements for the base metal were satisfied.

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NEDC-32015 Rension 1 Table 1 FW Nozzle Safe End, Thermal Sleeve, Primary Seal, Element #374 (Reference 4)

Transient Salt,0 Salt,PU

Nallow, Nactual AUO AUPU PU HS 4.70 145.1 145.1 412 56 0.1490 0.1359 LOFP 2.02 FHB 33.0 71.5 72.4 6095 330-0.0750 0.0541 HS 0.45 0.224 0.190 E(AU) =

-0.034 UcuM,o =

0.9503 Ucux,pu =

0.916 11

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v, NEDC42015 Revision 1 Table 2 FW Nozzle, Downstream of Thermal Sleeve, Element #228 (Reference 4)

Transient Salt,0 Salt,PU

Nallow, Nactual AUO AUPU PU TR 0.275 59.73 60.23 2427 260 0.1028 0.1071 FHB 33.0 FHB 33.0 59.54 60.04 2451 56 0.0220 0.0229 LOFP 2.02 Zeroload 45.38 45.82 5695 497 0.0940 0.0873 WR 50.0 WR 50.0 40.51 40.95 7941 820 0.1055 0.1033 DESHYDRO FHB 13,8 40.46 41.00 7982 228 0.0292 0.0286 S 1.0 S 0.0+Dyn 73.5 73.85 1365 10 0.0072 0.0073 Zeroload i

S 0.25 +Dyn 48.54 48.83 4734 220 0.0456 0.0465 Zeroload S 0.0 - Dyn 34.98 35.26 12902 10 0.0008 0.0008 Zeroload i

0.4071 0.4038 E(6U) =

-0.0033

- Ucug,o -

0.gg UCUM,PU =

0.965 l

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s, NEDC 320t5 Revision 1 3.0

SUMMARY

AND CONCLUSIONS The limiting location for the FW nozzle is still the low carbon steel location (element #228).. The cumulative fatigue usage, including environmental fatigue damage and additional hydrodynamic pool loads is 0.965 and is below the allowable value of 1.0. The cumulative fatigue usage for the SS clad location is 0.916, which is also below the allowable limit of 1.0. Therefore, the FW nozzle satisfies fatigue design requirements for the new power uprate operating conditions.

Power uprate has no significant effect on fatigue usage of the steam outlet nozzle, and the original usage factor of 0.54 (. Reference 9) remains applicable.

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4.0 REFERENCES

1 GE Document #25 A5000, Revision 0, Reactor Vessel-Power Uprate, Cenified Design Specification, NMP-2, GE-NE, San Jose, Ca., June 1991.

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GE Document # 23 A6942, Revision 0, NMP-2 Heat Balances for Power Uprate-100%

Power, GE-NE, San Jose.

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GE Document #762E673, Revision 2, NMP-2 Reactor Vessel Thermal Cycles, GE-NE, l

4 San Jose Ca.

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VPF #6038-81-1, "Special Analysis for New Loads Replaceable Sparger Type Feedwater Nozzle", CBI Nuclear Co., February 1981.

5.

F.E. Cooke, " Evaluation of Carbon Steel Environmental Design Rules", GE-NE, San Jose,-

Ca., June 1981 (DRF B13-00985).

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GE Document #21 A477AZ, Revision 0, Purchase Specification Data Sheet, GE-NE, l

San Jose.

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7.

NEDC-31145, NMP-2 New Loads Assessment, Lattin & Patel, GE San Jose,1986.

8.

ASME Boiler and Pressure Vessel Code,Section III,1971 Edition, with Addenda to and including Winter 1972.

f 9.

VPF 3516-51-2, "251 BWGL Vessel Thermal Analysis, Steam Outlet Nozzle", CBI

,j Nuclear Co., May 5,1976.

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