ML20148P991

Submits Written Response to NRC Questions Concerning Amend to P/T Limit Curves

ML20148P991
Person / Time
Site:	Grand Gulf
Issue date:	06/26/1997
From:	Hughey W ENTERGY OPERATIONS, INC.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
GNRO-97-00058, GNRO-97-58, TAC-M97520, NUDOCS 9707030188
Download: ML20148P991 (16)

Text

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e Entergy Operation 0, Inc.

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. gh RO. Box 756 Port Gbson, MS 39150 l Tel 601437-6470 W.K.Hughey Duector Nuclear Safety & Regulatory Anan June 26, 1997 l

l U.S. Nuclear Regulatory Commission Mail Station P1-37 Washington, D.C. 20555 Attention: Document Control Desk

Subject:

Grand Gulf Nuclear Station Docket No. 50-416 License No. NPF-29 Responses to NRC Questions Requested in a NRC letter dated April 10, 1997, related to Pressure-Temperature Limit Curves

Reference:

NRC Letter to Grand Gulf Nuclear Station, Request for Additional Information Related to Pressure-Temperature Limits in the Technical Specifications, Grand Gulf l Nuclear Station, Unit 1 (TAC NO. M97520) dated April 10, 1997 (GNRI-97/00067) i GNRO-97/00058 Gentlemen:

As requested in the NRC referenced letter, we are providing a written response to NRC questions concerning an amendment to the pressure-temperature curves.

Yours truly, 5'WKH/MJL [#d' attachment: Attachment 1 - Responses to NRC Questions Requested in NRC letter dated April 10, /k' b{} j 1997 Attachment 2 - General Electric Response to NRC Question 1.

j cc: (See Next Page) 9707030188 970626 PDR ADOCK 05000416 p PM l llll.llll={lll*h}l

'l June 26, 1997 GNRO-97/00058 Page 2 of 2 cc: Ms. J. L. Heredity-Dixon, GGNS Senior Resident' (w/a)

Mr. L. J. ' Smith (Wise Carter) (w/a)

Mr. N. S. Reynolds (w/a)

Mr. H. L. Thomas (w/o)

.Mr. J. W. .Yelverton (w/o) J Mr. E. W. Merschoff (w/a) l Regional Administrator ]

U.S. Nuclear Regulatory Commission 1 Region IV j 611 Ryan Plaza Drive, Suite 400 Arlington, TX 76011 l l

Mr. J. N. Donohew, Project Manager (w/2) l Office of Nuclear. Reactor Regulation I U.S. Nuclear Regulatory Commission Mail-Stop 13H3  ;

Washington, D.C. 20555 l l

Dr. E. F. Thompson (w/a) ,

State Health Officer State Board of Health P. O. Box 1700 )

Jackson, Mississippi 39205 1

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4 Attachment 1 page 1 l

Attachment 1 to GNRO-97/00058 Responses to NRC Questions Requested in NRC letter dated April 10,1997 l

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4 Attachment 1 page 2 RESPONSE TO REQUEST FOR ADDITIONAL INFORMATION RELATED TO PFESSURE-TEMPERATURE LIMITS IN TECHNICAL SPECIFICATION _S ENTERGY OPERATIONS INC.

' GRAND GULF NUCLEAR STATION ,

DOCKET NO. 50-416 The following information are the answers to NRC questions in an NRC RAI issued on April -

l 10,1997:

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1. General question: Provide the methodology used to generate l pressure-temperature (P-T) limits for the bottom head and the feedwater nozzle.

ANSWER:

l Attachment 2 provides the response.

! 2. Page 2 of 8 :

l The detailed information needed to calculate the reported l adjusted reference temperature (ART) of 57.57 DEG F can be found in your letter of May 2, 1996, from which the internal-diameter (ID) fluence of 2.5E18 n/cm' at 32 EFPY was reported. l The May 2, 1996, letter indicated that this fluence value was I from General Electric (GE) Report EAS-35-0387 (April 1987).

The ID fluence value at 32 EFPY in the 2NRC reactor vessel '

integrity database (RVID), is 3.11 n/cm , which was reported to be the latest data in your letter dated May 5, 1994, in response to the NRC close-out letter regarding GL 92-01. The latter value is in line with all your recent submittals.

Resolve this discrepancy.

ANSWER The Fluence value in the letter dated May 5, 1994 (GL 92-01 l close-out) was based on the upper bound fluence calculated for the GGNS vessel. The Margin Term in Reg. Guide 1.99 Rev. 2 includes the cor.servatism for fluence uncertainty in the form of ca (Standard. Deviation for ARTm) . Therefore it was not necessary to v.s e the upper bound fluence value for the determination of ART. The value of fluence at the vessel ID, as provided to you in the May 2, 1996 letter, at 32 EFPY is 2.5E18 n/cm'.

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. l Attachment 1 page 3

< 3. Page 3.4-31 to 3.4-35 of the Technical Specifications:

Change of fluence should not affect the P-T limit curves which are controlled by the feedwater nozzle, as evidenced in the five figures of Figures 3.4.11-1. Explain the discrepancy ,

between the current curves that are controlled by the feedwater I nozzle for 10 EFPYs and the proposed curves that are controlled by the feedwater nozzle for various EFPY intervals.

ANSWER:

The P-T curves for the Feedwater Nozzle controlled portion has not been affected by the change in fluence levels. Table I shows the temperatures at various pressures which l encompass the portion of the P-T curve governed by the j Feedwater Nozzles for Curve "B of the P-T curves. The l numbers in Boldface in Column 2 were used to generate Curve

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'B for the 10 EFPY curve in the current TS. In the succeeding columns, (Values for 16 - 32 EFPY) , the domain of control by the feedwater nozzle is shown to diminish. This is because as the accumulated fluence in the Beltline increases with increasing EFPY of operation, making the ART of the Beltline dictate the behavior of this curve. Table I shows that the values for the curves submitted in GNRO-96/00120 remain unchanged. In order to use a computer generated curve intermediate values were interpolated and fractions rounded to the next higher temperature. This process may have given the appearance that the Feedwater Nozzle controlled portion of the curve shows a small shift.

l Attachment 1 page 4 I Table I for RAI Question 3  ;

Pressure Temperature { Degrees Fahrenheit} at Pressure: Curve"B"

{psig} 10 EFPY 16 EFPY 20 EFPY 24 EFPY 28EFPY 32 EFPY

{ Current TS) 525 130 130 130 130 130 550 130' 130 130 130 130 RV Beltline 575 130 130 130 RV Beltline 600 133 133 133 133 625 135 135 RV Beltline 650 137 137 675 139 139 700 142 142 142 725 143" 143 RV Beltline 750 145 775 146 800 147 147 825 RV Beltline 850 875 900 925 RV Beltline Numbers in boldface are the numbersfor Feedwater No::le Controlfrom the current TS Curves.

Notes:

a) Pressure of 560 psig in the current TS curve b) Pressure of 740 psig in the current TS curve l

l Attachment 1 page 5 1

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4. Page 3.4-31 to 3.4-32 of the Technical Specifications

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, Change of fluence should not affect the P-T limit curves which are controlled by the bottom j head. However, the curves controlled by the bottom head vary among the current Figure 4

3.4.11-1 and the first two figures of the proposed Figure 3.4.11-1. Provide an explanation for this variation.

i ANSWER:

l l The P-T curves for the Bottom Head controlled portion has.

not been affected by the change in fluence levels. Table II  ;

shows the temperatures at various pressures which encompass the portion of the P-T curve governed by the Bottom Head for Curve "A of the P-T curves. The numbers in Boldface in Column 2 were used to generate Curve "A for the 10 EFPY curve in the current TS. In the succeeding columns, (Values

for 16 -

32 EFPY) , the domain of control by the Bottom Head is shown to diminish. This is because ar the accumulated i fluence in the Beltline increases with increasing EFPY of operation, making the ART of the Beltline dictate the behavior of this curve. Table II shows that the values for the curves submitted in GNRO-96/00120 remain unchanged. In order to use a computer generated curve intermediate values were interpolated and fractions rounded to the next higher temperature. This process may have given the appearance that the Bottom Head controlled portion of the curve shows a small shift.

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Table II for RAI Question 4 I 'ressure Temperature { Degrees Fahrenheit) at Pressure: Curve "A" (psig} 10 EFPY 16 EFPY 20 EFPY 24 EFPY 28 EFPY 32 EFPY

{ Current TS}

725 100' 100 RV b c Beltline 750 100* 102 102 775 105 RV Beltline 800 109 109 825 112 850 114 875 117 900 120 925 123 123 950 126 975 128 1000 131 131 ,

1025 133 1050 135 1075 137 1100 140 140

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1125 142 1150 144 )

1175 146 I 1200 148 148 1225 150 1250 '

152 1275 153 1300 155 1325 157 1350 159 1375 161 161 Numbers in boldface are the numbersfor Bottom Head Controlfrom the current TS Curves.

NOTES:

a) Flange Limits b) RV Beltline Control begins at RV pressure of 700 psig.

c) RV Beltline Control begins at RV pressure of 675 psig.

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Attachment 2 to GNRO-97/00058 General Electric Response to NRC Question 1 in NRC letter dated April 10,1997 i

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l h GE Nuclear Energy Technical Services Business 175 Curtner Avenue, M/C 785 San Jose, California 95125 (408) 925-5714 BDF9718 June 24,1997 cc: B.J. Brantund L. Patterson W. Grimme DRF B13-01869-077

Mr. W. K. Hughey Director Nuclear Safety and Regulatory Affairs Entergy Operations, Inc.

Grand Gulf Nuclear Station P.O. Box 756 Port Gibson, MS 39150

SUBJECT:

Request for AdditionalInformation .

Regarding Entergy Operations,Inc. License Amendment Request to Amend P-T Curves Response to EOl/NRC Questions

REFERENCE:

1) Letter from E.C. Rucker to W.E. Grimme, " Contract Number NGC00186", dated June 18,1997.

2) Middle South Energy Inc. Grand Gulf Nuclear Station, FSAR and TECH SPEC PRESSURE TEMPERATURE CURVES, MPGE-86/161.

Dear Mr. Hughey:

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The purpose of this letter is to transmit GE's responses to the question presented in the Reference 1 communication. I have repeated the question in the attached response, if you have any questions, please call me at (408) 925-5714 or Betty Branlund at (408)925 1472.

My FAX number is (408) 925-4175.

Sincerely,

, Brian Frew, Senior Engineer RPV Surveillance Services

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l .. GE Nucle:rEn:rgy BDF9718 l

4 June 24,1997 l

l Question l

Confirm that the methodology used to generate pressure-temperature (P-T) limits for the  !

bottom head and feedwater nozzle is the same as that provided by Georgia Power l Company in support of the recent P-T limits for the Hatch Unite. Otherwise, submit this methodology for Grand Gulf.

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Response

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When GE developed non beltline P-T curves, the approach was to develop curves for a conservatively large BWR/6 (nominal 251-inch inside diameter) and then apply the I curves generically to other vessels by using the appropriate RTsor values for those vessels. The one characteristic of the upper vessel and bottom head, that made the '

i analysis different from a shell analysis like that for the beltline, was the presence of nozzles and control rod drive (CRD) penetration holes, with their associated stress concentrations and higher thermal stresses for certain transient conditions.

Only the methodology for the limiting curves is presented below. For the pressure test, the bottom head is the more limiting cv ve. For non-nuclear heatup and cooldown 1 operating conditions, the upper vessel is the limiting curve in the pressure range of 560 to l

925 psig (at higher pressures, the beltline curve is limiting).

Bottom Head Curve Methodology (Pressure Test)

The generic pressure test P-T curves for the bottom head are the same as those provided to Georgia Power in support of its recent P-T limits revision. The bottom head region was modeled using a finite element analyr,is of a BWR/6,251" vessel to determine the K i for an applied pressure of 1593 psig (1563 psig preservice hydrotest pressure plus 30 psig hydrostatic pressure at the bottom of the vessel). For 1593 psig, the Ki is 154.3 ksiVin.

The generi<, pressure test P-T curve was generated by scaling the K i of 154.3 ksiVin by the nomiral pressures and calculating the associated (T-RTsm):

Nominal Pressure Ki (T-RT3nr)

(psig) (ksiVin) (*F) 1563 154.3 161 1400 138.2 151 1200 118.5 138 1000 98.7 121 800 79.0 99 600 59.2 66 400 39.5 1 2

l GE Nucle:rEnergy BDF9718 i June 24,1997 Applicability to Grand Gulf l The P-T curve is dependent on the Ki value calculated. The generic P-T curve values l were based upon a BWR/6,251 inch vessel. Since Grand Gulf is a BWR/6,251 inch

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vessel, the generic P-T curve values are directly applicable to Grand Gulf.  !

As discussed below, the highest RTuor for the bottom head mat: ' ils is 10*F. The generic pressure test P-T curve is applied to the Grand Gulf bottom 1. Ad by shifting the  ;

- P vs. (T-RTuor) values above to reflect the RTuor value of10 F. 1 l

The resulting P-T values are below: l Nominal Pressure Bottom Head Temperature (psig) (F) ,

1400 161 l 1200 148 1000 131 800 109 600 76 l

400 11 j Fracture Toughness (RTuor)

The highest RTuo7 for the bottom head plates is 10*F, based on fracture toughness purchase requirements and QA documentation confirming that there were no bottom head plate values greater than 10 F. The bottom head welds have RTuor values less than

-20 F, based on the vessel purchase specification requirements and QA documentation confirming that there were no bottom head weld RTuor values greater than -20 F.

Upper Vessel Curve Methodology (Non-Nuclear Heatup/Cooldown)

The methodology for the non-nuclear heatup/cooldown curves was not provided in the Hatch submittal. Therefore, as requested, the methodology is described below.

The feedwater nozzle was selected to represent non-beltline components for fracture toughness analysis because the thermal conditions are the most severe experienced in the vessel. In addition to the more severe pressure and piping load stresses resulting from the nozzle discontinuity, the feedwater nozzle region experiences relatively cold feedwater flow in hotter vessel coolant.

Stresses are taken from finite element analysis done specifically for fracture toughness analysis purposes. Analyses were performed for all feedwater nozzle transients that involve rapid temperature changes. The most severe of these was normal operation with cold 40 F feedwater injection.

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GE NucI::rEn:tyy BDF9718 June 24,1997

The non-beltline curves based on feedwater nozzle limits were calculated according to the j methods' for nozzles in Appendix 5 of the . Welding Research Council (WRC)

Bulletin 175.

The stress intensity factor for a nozzle flaw under primary stress conditions is given in WRC Bulletin 175 Appendix 5 by the expression for a flaw at a hole in a flat plate:

l Kr, = SF e o e (na) v2

• F(a/rJ (1) where: SF is the_ safety factor applied per WRC Bulletin 175 recommended ranges, and' F(a/r n) is the shape correction factor.

L Finite element analysis of a nozzle corner flaw was performed to determine appropriate 1 values 'of F(a/rn ) for Equation 1. These va'ues are shown in Figure A5-1 of WRC l Bulletin 175. l i

t The stresses used in Equation I were taken from BWR/6 design stress reports for the l feedwater nozzle. Since Grand Gulf is a BWR/6, the use of the methodology is l appropriate. The stresses considered are primary membrane, op , and primary bending, i o3p Secondary membrane, o,, and secondary bending, o,3 stresses are included in the l total K iby using ASME Appendix G [2] methods for secondary portion, K i,:  !

l Kr, = M e (o,m + 2/3 e o,3) (2) l In the case where the total stress exceeded yield stress, a plasticity correction factor was applied based on the recommendations of WRC Bulletin 175 Section 5.C.3. However, the correction was not applied to primary membrane stresses. Kip and Kr, are added to obtain the total value of stress intensity factor, Ki .

l The safety factors applied to primary stresses were 1.3 for pressure test conditions and 1.6 for core not critical heatup/cooldown conditions.

Once Ki was calculated, the following relationship was used to determine (T - RTuor).

The highest RTwor for the appropriate non-beltline components was then used to establish the P-T curves.

(T - RTuor) = In [(K i- 26.78) /1.233] / 0.0145 - 160 (3) l Note that the above equation contains an error which was present in the ASME j~ Code at the time the curves were generated. Changing the coefficient 1.233 to the j correct value of1.223 results in a increase of 0.56*F in (T - RTwof which is not

? consideredsigmficant. The correct value was used to generate the Hatch Curves.

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. GENucle

rEn:my BDF9718

{- June 24,1997 l

The non-beltline core not critical heatup/cooldown curve was based on the feedwater l nozzle generic analysis, where feedwater injection of 40 F into the vessel while at operating conditions (551.4 F and 1050 psig) was the limiting normal or upset condition ,

from a brittle fracture perspective. The feedwater nozzle comer stresses were obtained  ;

from finite element analysis. These stresses, and other inputs used ia the generic calculations, are shown below:

! o p, = 20.49 ksi - o,, = 16.19 ksi c y, = 45.0 ksi t = 7.5 inch ops = 0.22 ksi o,3 = 19.04 ksi a = 1.88 inch r, = 6.94 inch l In this case, the total stress, 55.94 ksi, exceeds the yield stress oy ,, so the correction i factor, R, is calculated according to the following equation: I R = [o y, - o ,p + ((acow - o ,)y / 30)] / (ciow - opm) (4)

For the stresses given, the Ratio, R = 0.70. Therefore, all the stresses are adjusted by the factor 0.70, except for op . The resulting stresses are:

I o p, = 20.49 ksi o,, = 11.33 ksi '

ops = 0.15 ksi o,3 = 13.33 ksi The value of M from Figure G-2214-1, was based on a thickness of 7.5 inches, hence, t = 2.74. The stress to yield ratio, c/o ,yswas conservatively assumed to be 1.0.

The resulting value obtained was:

Mm = 2.84 The value F(a / ro) is taken from Figure A5-1 of WRC Bulletin 175 for an a/r, of 0.27.

F(a / ro ) = 1.6 K ipis calculated from Equation 1:

K ip= 1.6 e (20.49 + 0.15) * (x e 1.88) e 1.6 Kip= 128.4 ksi-in'8 K i,is calculated from Equation 2:

K i, = 2.84 * (11.33 + 2/3 e 13.33)

K i, = 57.4 ksi-in' 5

GE Nucle:rEn:rgy BDF9718 June 24,1997 The total Ki is therefore 186 ksi-in'# ,

l The total K iis substituted into Equation 3 to solve for (T - RTuor):

l (T - RTsor) = In[(186 - 26.78) / 1.233] / 0.0145 - 160 (T - RTuo7) = 175 F (Ifthe correct coeficient 1.223 was used. (T- RTxm) is 176*F)

The generic curve was generated by calculating the Ki at multiple pressures and using the K i value at each pressure to calculate the (T- RTuor) for each pressure. These values were then plotted and a curve drawn through the points. From the curve, the (T - RTsor) can be determined for each pressure. The following table is a listing of the values used to generate the curve:

Feedwater Nozzle K, and (T - RTuor) as a Function of Pressure Nominal Pressure Ki (T - RTuor)

(psig) (ksi-in'#) (*F) 1400 213 186 1050 186 175 700 159 162 350 103 125 150 66 79 The highest non beltline RTNor for a discontinuity in the upper vessel region is -20*F, the purchase specification limiting value for nozzles. The generic curve is applied to the Grand Gulf upper vessel by shifting P vs. (T-RTuor) values from the generic curve to reflect the nozzle RTuor value of-20*F.

Nominal Pressure (psig) Vessel MetalTemperature

~ ( F) 1400 166 1050 155 700 142 350 105 150 59 The values in the above table are plotted in Figure 1 (' generic values') along with the limiting values for curve BB' (' Grand Gulf values') identified as 'FW nozzle limits' in Table 1 of Reference 2.

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GE Nucle:rEn:rgy BDF9718

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1400 -

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I 800

-e -Generic Values e Grand GutValues 600 '

S 400 i /

j ,,, / ,

e l 0 0 50 100 150 200 250 Mininwne Reactor Veonel Metal Temperstwo (T)

Figure 1: Upper Vessel Pressure-Temperature Limits t

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