ML20133F963
| ML20133F963 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 01/08/1997 |
| From: | Roche M GENERAL PUBLIC UTILITIES CORP. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 6730-96-2377, TAC-M96405, NUDOCS 9701150077 | |
| Download: ML20133F963 (10) | |
Text
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GPU Nuclear, Inc.
U.S. Route #9 South NUCLEAR Poi, ofric, sox 383 Forked River, NJ 08731-0388 -
Tel 609-971-4000 January 8, 1997 6730-96-2377 U. S. Nuclear Regulatory Commission Att: Document Control Desk
, Washington, DC 20555 Gentlemen:
Subject:
Oyster Creek Nuclear Generating Station Operating License No. DPR-16/ Docket No. 50-219 Response To Request For Additional Information (RAI) to TSCR 245 Regarding The Pressure-Temperature (P-T) Limit Curves For Oyster Creek Nuclear Generating Station
- (TAC No. M96405)
By letter dated August 23,1996, GPU Nuclear submitted a request to amend the technical specifications by incorporation of t.pdated P-T limit curves for 22,27, and 32 effective full power years.
Your letter dated November 27,1996 which we received on December 9,1996 requested additional information within 30 days of our receipt of the letter. The information is needed to clarify issues raised by the NRC staff based upon the review of our submittal.
Attached herewith is our response to the RAI. If you have any questions regarding our response, please contact Yosh Nagai of our stafTen (201) 316-7974.
Sincerely,
)
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Michael B. Roche Vice President and Director Oyster Creek Attachments c:
Administrator, Region I NRC Resident Inspector Oyster Creek NRC Project Manager
-)i 9701150077 970108 l
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i GPU NUCLEAR RESPONSE 10 the
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NRC REQUEST FOR ADDITIONAL INFORMATION
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regarding OYSTER CREEK NUCLEAR GENERATING STATION LICENSE AMENDMENT REQUEST (TSCR 245)
TO UPDATE REACTOR VESSEL PRESSURE-TEMPERATURE LIMITS FOR 22,27, AND 32 EFFECTIVE FULL POWER YEARS (EFPY)
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Question 1 1
i Section 4.2 of attachment GENE B13-01769 to your August 23,1996 submittal provides l
a very general discussion of the methodology used to assess non beltline vessel components. It is stated that this methodology is based upon detailed stress analyses of a 1
l BWR/6 design: It is stated on page 4-2:
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i
' Detailed stress analyses, specifically for the purpose of fracture toughness' analysis, of i
non-beltline components were performed for the BWR/6.... stresses due.to the most 4
severe of these transients were used according to [7] to develop plots of allowable pressure (P) versus temperature relative to the reference temperature (T-RTm)."
i The BWR/6 non-beltline region results were applied to Oyster Creek by adding the highest Oyster Creek RTm values for the non-beltline discontinuities to the appropriate P versus I
(T-RTmyr) curves for the BWR/6 CRD penetration or feedwater noule."
i-Provide the results of the stress analysis for the feedwater nonle region of the BWR/6 model.
Provide in tabular form the generic pressure versus'(T-RTmyr) relationship developed for 1
the BWR/6 feedwater nonle region and explain how this curve was developed.
Response
i When GE developed non-beltline P-T curves, the approach was to develop curves 'for a i
conservatively large BWR/6 (nominal 251-inch inside diameter) and then apply the curves
{
generically to other vessels by using the appropriate RTmyr values.for those vessels. The j
one characteristic of the upper vessel and bottom head, that made the analysis different j
from a shell analysis like that for the beltline, was the presence of nonles and control rod drive (CRD) penetration holes, with their associated stress concentrations and higher i
thermal stresses for certain transient conditions.
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Since the non-beltline curves fo'r Oyster Creek are based on the bottom head curve (CRD-j curve), the methodology for the bottom head curve will be provided first. Since the NRC j
specifically requested information regarding the feedwater nonle curve, the methodology j
for the upper vessel (feedwater nonle) curve will be provided also. As will be seen in the j
following discussion, the bottom head curve was used for Oyster Creek, because that j
curve was more limiting than the upper vessel curve.
4 BOTTOM HEAD CURVE METHODOLOGY i
j CBI Nuclear (CBIN) modeled the BWR/6,251-inch CRD penetration region to compute local stresses for determination of the stress intensity factor, Kr. The results of that computation were K = 154.3 ksifm for an applied pressure of 1593 psig (1563 psig t
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preservice hydrotest pressure plus 30 psig hydrostatic pressure at the bottom of the vessel). The comput:d value of(T-RTwor) was 161*F.
To evaluate the CBIN result, Ki is calculated for the bottom head nominal stress, PR/2t, according to the methods in ASME Code Appendix G (Section III or XI). The result is compared to that determined by CBIN in order to quantify the K magnification associated with the stress concentration created by the multiple bottom head penetrations.
A calculation of Kiis shown below using the BWR/6,251-inch dimensions:
Bottom Head Radius, R.
138.2 inches Bottom Head Thickness, t -
8.0 inches Bottom Head Material Sy 70 ksi Bottom Head Pressure 1593 psig j
i Pressure stress:
4 i
o
=
PR/2t =
1593 osia
- 138.2 inches = 13800 psi (2
- 8.0 inches)
The factor M. from Figure G-2214-1 of ASME Appendix G depends on (o/S,) and Vt :
13800/70000 =
0.2 (use e/Sy = 0.5) o/S,
=
l 4t (8.0)"=
2.83 Vin
=
M.
2.7 Including the safety' factor of 1.5, the stress intensity factor, Kr, is 1.5M.o :
55.9 ksiVin No'minal Ki 1.5
- 2.7
- 13800
=
=
The CBIN result of 154.3 ksifm is a factor of 2.76 times the nominal result. This is somewhat conservative compared to the stress computed by CBIN at the penetration, which was 2.6 times the PR/2t stress.
The method to solve for (T-RTwor) for a specific Ki is based on the curve in Figure G-2210-1 in ASME Appendix G:
1n [(K - 26.78) /1.223) / 0.0145 - 160 (T-RTwor)
=
i 1n ((154.3 - 26.78) /1.223] / 0.0145 - 160 (T-RTwor)
=
(T-RTwur) 161*F
=
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The generic curve was generated by scaling 154.3 ksiVin by the nominal pressures and i
calculating the associated (T RTm):
4 Nominal Pressure K
(T-RTm)
(Psig)
(ksifm)
('F) 1 1563 154.3 161 i
1400 138.2 151 l
1200 118.5 138
)
1000 98.7 121 l
800 79.0 99 I
600 59.2 66 400 39.5 1
I l
Applicability to Oyster Creek j
i The P-T curve is dependent on the Ki value calculated, which is proportional to the stress and the crack depth according to the relationship:
Kics o 4xa The stress is proportional to R/t and, for the P-T curves, crack depth, a, is t/4. Thus, Ki is i
proportional to R/Vt. The generic curve value of R/Vt, based on the BWR/6, 251-inch bottom head dimensions,is i
l Generic R/Vt 138.2 / 48 48.9
=
=
l The Oyster Creek specific bottom head dimensions are R = 106.5 inches and t = 8.5 l
mehes.
166.5 / 48.5 dyster Creek specific R/Vt 37
=
=
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j Since the generic value of R/Vt is greater than that for Oyster Creek, the generic P-T l
curve is conservative when applied to the Oyster Creek bottom head.
d l
As discussed below, the highest RTm for the bottom head materials is 66'F. The generic curve is applied to the Oyster Creek bottom head by shifting the P vs. (T-RTm) val 0es i
above to reflect the RTm alue of 66'F.
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l The resulting P-T values are below:
f Nominal Pressure Bottom Head Temperature (psig)
(*F) 1400 217 1200 204 1000 187 800 165 600 132 400 67 Fracture Toughness (RTm) l The highest RTm for the bottom head plates and welds is 66'F, based on fracture toughness data for the plates, shown in Table 1 (below). The bottom head welds have RTm values less than 66*F, based on the vessel purchase specification requirements and QA documentation confirming that there were no bottom head plate or weld RTm alues v
greater than 66*F.
Table 1. Fracture Toughness of Bottom Head Plates (Transverse Orientation)
Plate Heat No.
Charpy Test Impact RTm Comments Location Temperature Energy
('F)
(ft-lb)
('F) _
Bottom A7153-2
-40 11,4.5,9.5 66 Initial RTm taken Head 10 19,13.5,28 from plot of data Torus 60 -
46.5,44,49 with 2 ei ncluded i
110 60,65,63 160 87,78.5,82 UPPER VESSEL CURVE METHODOLOGY CBI Nuclear (CBIN) modeled the BWR/6,251-inch feedwster nozzles to compute local stresses for determination of the stress intensity factor, Kr.
The results of that computation were Ki = 143.1 ksifm for an applied pressure of 1563 psig preservice hydrotest pressure. The computed value of(T-RTm) was 154'F.
To evaluate the CBIN result, Ki s calculated for the upper vessel nominal stress, PR/t, i
according to the methods in ASME Code Appendix G (Section III or XI). The result is compared to that determined by CBIN in order to quantify the K magnification associated with the stress concentration created by the feedwater nozzles.
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t 1
i A calculation of K is shown below using the BWR/6,251-inch dimensions:
Vessel Radius, R.
126.7 inches Vessel Thickness, t 6.5 inches Vessel Pressure.
1563 psig Pressure stress:
PR/t 1563 psig
- 126.7 inches o
=
=
(6.5 inches) 30466 psi o
=
The factor F (a/rw) from Figure A5-1 of WRC-175 is 1.6 where :
lesser of 1/4 Tu or 1/4 Tv a
=
Tu = 71/8 inch T. = 61/2 inch Ri + 0.29 R.
rw
=
R; = apparent radius of nozzle = 6 inches R. = actual inner radius of the nozzle = 3.25 inches 1.63/6.94 = 0.23
~
a/rw
=
Including the safety factor of 1.3, the stress intensity factor, Kr, ist.3 o Vna
- F(a/r ):
s a
1.3 *.30.466* 4x*l.63
- l.6 =
143 kri. Vin Nominal Ki
=
The method to solve for (T-RTm) for a specific Ki is based on the curve in Figure G-2210-1 in ASME Appendix G:
(T-RTm) 1n ((K - 26.78) /1.223) / 0.0145 - 160
=
i (T-RTm) 1n [(143 - 26.78) /1.223) / 0.0145 - 160
=
(T-RTm) 154*F
=
l 4
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The generic curve was generated by scaling 143 ksiVin by the nominal pressures and calculating the associated (T-RTmt):
Nominal Pressure Ki (T-RTwr)
(psig)
(ksiVin)
(*F) 1563 143 154 1400 128 145 1200 110 131 1000 92 114 800 73 91 600 55 56 400 37
-16 Applicability to Oyster Creek The P-T curve is dependent on the K value calculated, which is proportional to the stress and the crack depth according to the relationship:
KiaeVxa The stress is proportional to R/t and, for the P-T curves, crack depth, a, is t/4. Thus, Ki is proportional to R/Vt. The generic curve value of R/Vt, based on the BWR/6, 251-inch feedwater nozzle dimensions, is 4
Generic R/Vt 127 / V6.5 50
=
=
The Oyster Creek specific feedwater nozzle dimensions are R = 106.5 inches and t = 7.125 inches.
106.5 / V7.125 =
40 Oyster Creek specific R Vt
=
Since the generic value of RNt is greater than that for Oyster Creek, the generic P-T curve is conservative when applied to the Oyster Creek feedwater nozzle.
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i As discussed below, the highest RTm for the nozzle materials is 60*F. The generic curve is applied to the Oyster Creek feedwater nozzle curve by shiRing the P vs. (T-RTm) values above to reflect the RTm alue of 60'F The resulting P-T values are below:
v Nominal Pressure Upper Vessel Temperature (Psig)
(*F) 1400 205 1200 191 1000 174 800 151 4
600 I16 400 44 Fracture Toughness (RTm)
The highest RTm for the upper vessel nozzles, plates and welds is 60*F, based on fracture toughness data for the plates, shown in Table 2 (below). The upper vessel welds.
have RTwr alues less than 60*F, based on the vessel purchase specification requirements v
and QA documentation confirming that there were no upper vessel plate or weld.RTm values greater than 60*F.
i Table 2. Fracture Toughness of Upper Vessel Plate (Transverse Orientation) l Plate Heat No.
Charpy Test Impact RTer Comments Location Temperature Energy
(*F)
(ft-lb)
(*F)
Upper Vessel BT-1676 40 25,34,38 60 2'F/A Ib correlation CRD Return applied.
Node l
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o Question 2 Identify the location and instruments used for pressure and temperature measurements during vessel hydrostatic and leak rate testing. Identify instrument error and explain how instrument uncertainties are accounted for in verifying compliance with the proposed leak rate testing pressure-temperature limit curve (Curve A).
Response
INSTRUMENTS USED FOR llYDROTEST AND LEAK TEST AT OYSTER CREEK INS I RtiMEN I -
I AG NO.
IAKAlloN RANGE ERROR / -:
i PRO ( LDtlRL.
ACCIRACY l' SED '
PRESSURii PI-M 163 REACTOR 0-1800 or 10.5% OF Tile 602.4.001 VESSEL 0-3000 PSIG FULL SCALE Note i STEAM SPACE
TEMPERATURE TEK-210-0031 R ECIRC. PUMP 0-600 *F il % O F Tile 602.4.001 A/K SUCTION FULL SCALE Note 1 (16 F)
Note 1:
A calculation was performed by GPU Nuclear, as described below, to incorporate instrument accuracy to determine the required test pressure and temperature for vessel hydrostatic and leak rate testing.
Pressure:
After determining the test pressure, a correction is made for the head between the gauge location and the highest point in the test boundary. Then, the gauge inaccuracy is added to account for the instrument uncertainties.
The resultant pressure is used for the leak rate testing.
Temperature: Using the resultant pressure described above, a minimum temperature is determined by the pressure-temperaturc limit curve. Then, the gauge inacurracy is added to account for the instrument uncertainties, thereby
+
determining the test temperature.
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