ML072780532
| ML072780532 | |
| Person / Time | |
|---|---|
| Site: | Oyster Creek |
| Issue date: | 08/14/1997 |
| From: | AmerGen Energy Co |
| To: | NRC/SECY |
| SECY RAS | |
| References | |
| 50-219-LR, AmerGen-Applicant-45, RAS 14259 | |
| Download: ML072780532 (6) | |
Text
RA.S I4.?s'y U.S. NUCLEAR REGULATORY GONIMt'ION IntheMatterof kAFVA k\ iRAU. C0 U.
Docket No.J) C21,9-L., Official Exhibit No.
F E icensec i'tren~r PPLICANT'S EXHIBIT 45 NR St ff V CASE OENTIFIED on*1 " Witne.*s/saneli A- N-513 M~ona~w: ipi~iii J~E~ CTED BOILER AND PRESSU'RE VESSEL CODE DOCKETED USNRC Approval Date: Ai ugust 14, 1997 October 1, 2007 (10:45pm)
See Numeric Inde.x for expiration OFFICE-OF SECRETARY and any reaffirrnation dates. RULEMAKINGS AND ADJUDICATIONS STAFF Case N-513 (d) A flaw evaluation shall be performed to determine Evaluation Criteria for Temporary Acceptance of the conditions for flaw acceptance. Section 3.0 provides Flaws in Class 3 Piping accepted methods for conducting the required analysis.
Section XM,Division 1 (e) Frequent periodic inspections of no more than 30 day intervals shall be used to determine if flaws
- iquiry: What rules may be used for temporary ac- are growing and to establish the time at which the ceptance of flaws, including through-wall flaws, in detected flaw will reach the allowable size. Alterna-moderate energy Class 3 piping, without repair or tively, a flaw growth evaluation may be performed to replacement? predict the time at which the detected flaw will grow to the allowable size. When a flaw growth analysis is Reply: It is the opinion of the Committee that the used to establish the allowable time for temporary following rules may be used to accept flaws, including operation, periodic examinations of no more than 90 through-wall flaws, in moderate energy Class 3 piping, day intervals shall be conducted to verify the flaw without repair or replacement for a limited time, not growth analysis predictions.
exceeding the time to the next scheduled outage. ([) For through-wall leaking flaws, leakage shall be observed by daily walkdowns to confirm the analysis conditions used in the evaluation remain valid.
1.0 SCOPE (g) If examinations reveal flaw growth rate to be (a) These requirements apply to the ASME Section unacceptable, a repair or replacement shall be per-III, ANSI B31.1, and ANSI B31.7 piping, classified formed.
by the Owner as Class 3. (h) Repair or replacement shall be performed no (b) The provisions of the Case apply to Class 3 later than when the predicted flaw size from either piping whose maximum operating temperature does not periodic inspection or by flaw growth analysis exceeds exceed 200'F and whose maximum operating pressure the acceptance criteria of Section 4.0, or the next does not exceed 275 psig. scheduled outage, whichever occurs first. Repair or (c) The following flaw evaluation criteria are permit- replacement shall be in accordance with IWA-4000 or ted for pipe and tube. The flaw evaluation criteria are IWA-7000, respectively, in Editions and Addenda prior permitted for adjoining fittings and flanges to a distance to the 1991 Addenda; and, in the 1991 Addenda and of (Rot)" 2 from the weld centerline. later, in accordance with IWA-4000.
(d) The provisions of this Case demonstrate the (i) Evaluations and examination shall be documented integrity of the item and not the consequences of in accordance with 1WA-6300. The Owner shall docu-leakage. It is the responsibility of the Owner to demon- ment the use of this Case on the applicable data strate system operability considering effects of leakage. report form.
2.0 PROCEDURE 3.0 FLAW EVALUATION (a) The flaw geometry shall be characterized by (a) For planar flaws, the flaw shall be bounded by volumetric inspection methods or by physical measure- a rectangular or circumferenrual planar area in accord-ment. The full pipe circumference at the flaw location ance with the methods described in Appendix C or shall be inspected to characterize the length and depth Appendix H. IWA-3300 shall be used to determine of all flaws in the pipe section. when multiple proximate flaws are to be evaluated as (b) Flaw shall be classified as planar or nonplanar. a single flaw. The geometry of a through-wall planar (c) When multiple flaws, including irregular (com- flaw is shown in Fig. 1.
pound) shape flaws, are detected, the interaction-and (b) For planar-flaws in austenitic piping, the evalua-combined area loss of flaws in a given pipe section tion procedure in Appendix C of Section XI, Division shall be accounted for in the flaw evaluation. 1, shall be used. Flaw depths up to 100% of wall 765 rFelrAP (cfe=5 -C_ y'- 06 9
CASE (continued)
N-513 CASES OF ASME BOILER AND PRESSURE VESSEL CODE a,= (Sy + S&)12 (3) where p = is pressure for the loading condition D0 = is pipe outside diameter of= is the flow stress Sy= is the code yield strength S,= is the code tensile strength and SF= is the safety factor as specified in C-3420 of Appendix C Material properties at the temperature of interest shall be used.
(c) For planar flaws in ferritic piping, the evaluation procedure in Article H-7000 of Appendix H,Section XI, Division 1, shall be used. Flaw depths up to 100%
(a) Circumferential Flaw of wall thickness may be evaluated. When through-wall flaws are evaluated, the formulas for evaluation given in Articles H-7300 and H-7400 of Appendix H may be used, but with values for F0 ,, Fb, and F applicable to through-wall flaws. Relations for Fm, Fb, and F that take into account flaw shape and pipe geometry (R11 ratio) shall be used. The appendix to this Code Case provides equations for F, Fb, and F for a selected range of Rit. Geometry of a through-
-t wall crack is shown in Fig. 1.
(d) For nonplanar flaws, the pipe is acceptable when the remaining pipe thickness (tp) is greater than or equal to the minimum wall thickness trai):
pDo (4)
(b) Axial Flaw 2(S + 0.4p) where FIG. 1 THROUGH-WALL FLAW GEOMETRY p = is the maximum operating pressure at flaw lo-cation S = is the allowable stress at operating temperature Where appropriate, bending load at the flaw location (
thickness may be evaluated. When through-wall circum- shall be considered in the determination of t*,. When ferential flaws are evaluated, the formulas for evaluation t, is less than trai, an evaluation shall be performed given in Articles C-3320 of Appendix C may be used, as given below. The evaluation procedure is a function with the flaw penetration (alt) equal to unity. of the depth and the extent of the affected area as When through-wall axial flaws are evaluated, the allow- illustrated in Fig. 2.
able flaw length is: (1) When the width of wall thinning that exceeds t
mi,, Win, is less than or equal to 0.5 (Rotmi,,)2, where R,, is the outside radius and Wm is defined in Fig. 2,
-~t = l.58',- 1 (1) the flaw can be classified as a planar flaw and evaluated o F(SF)pOf/ (2) under para. 3(a) through pari. 3(c). When the above requirement is not satisfied, (2) shall be met.
(2) When the transverse extent of wall thinning
=- pD 0 I2t (2) that exceeds tmji, Lm(,), is not greater than (Rotmn, )t2, 766
CASE (continued)
N-513 CASES OF ASME BOILER AND PRESSURE VESSEL CODE
(.
(
FIG. 2 ILLUSTRATION OF NONPLANAR FLAW DUE TO WALL THINNING taroc is determined from Curve 1 of Fig. 3, where L,,qO When the above requirements are not satisfied, (4) is defined in Fig. 2. When the above requirement is shall be met.
not satisfied, (3) shall be met. (4) When the requirements of (1), (2) and (3)
(3) When the maximum extent of wall thinning above are not satisfied, ta* is determined from Curve that exceeds t j, L,,, is less than or equal to 2.65 2 of Fig. 3. In addition, ta shall satisfy the following (Rotmli)t2 and t,,,m is greater than 1.13t,,,aoc is equation:
determined by satisfying both of the following equa-tions:
to10C + m.5* (7)
> I1-- o +1.0 (5) tm.1 .8 where o-b is the nominal pipe longitudinal bending stress resulting from all primary pipe loadings.
t0 r,. 0.353L,.
(6) (e) For nonferrous materials, nonplanar and planar t-->j,, flaws may be evaluated following the general approach 767
CASE (continued)
N-513 CASES OF ASME BOILER AND PRESSURE VESSEL CODE 1.0 0.8 2
0.6 0.4 0.2 0
0 1 2 3 4 5 6 7 8 Lma)/I f n FIG. 3 ALLOWABLE WALL THICKNESS AND LENGTH OF LOCALLY THINNED AREA of (a) through (d) above. For ductile materials, the (a) From the engineering evaluation, the most suscep-approach given in (b) may be used; otherwise, the tible locations shall be identified. A sample size of at approach given in (c) and (d) should be applied. Safety least five of the most susceptible and accessible loca-factors provided in Section 4.0 shall be used. It is the tions, or, if fewer than five, all susceptible and accessible responsibility of the evaluator to establish conservative locations shall be examined within 30 days of detecting estimates of strength and fracture toughness for the the flaw.
piping material. (b) When a flaw is detected, an additional sample of the same size as defined in 5(a) shall be examined.
(c) This process shall be repeated within 15 days 4.0 ACCEPTANCE CRITERIA for each successive sample, until no significant flaw The piping containing a circumferential planar flaw is detected or until 100% of susceptible and accessible is acceptable for continued temporary service when locations have been examined.
flaw evaluation provides a safety margin, based on load, of a factor of 2.77 for Level A and B and 1.39 6.0 NOMENCLATURE for Level C and D service loading conditions. Piping containing a nonplanar flaw is acceptable for continued c = half crack length temporary service if tp, taloc, where td., is determined D, = outside pipe diameter from Section 3(d). F= nondimensional stress intensity factor for Lower safety factors may be used, provided that a through-wall axial flaw under hoop stress detailed engineering evaluation of continued operation Fb= nondimensional stress intensity factor for demonstrates that lower safety factors are justified. through-wall circumferential flaw under pipe bending stress Fro= nondimensional stress intensity factor for 5.0 AUGMENTED EXAMINATION through-wall circumferential flaw under mem-An augmented volumetric examination or physical brane stress measurement to assess degradation of the affected sys- = total crack length = 2c tem shall be performed as follows: eui = allowable axial through-wall length 768
CASE (continued)
N-513 CASES OF ASMFE BOILER AND PRESSURE VESSEL CODE L= maximum extent of a local thinned area with t
<tnom LL,= maximum extent of a local thinned area with t
< tmin L,,(a,)= axial extent of wall thinning below trmi L,(= circumferential extent of wall thinning below train p = maximum operating pressure at flaw location R = mean pipe radius R, = outside pipe radius S= .allowable stress at operating temperature S, = code specified ultimate tensile strength S, = code specified yield strength t= wall thickness tto,= allowable local thickness for a nonplanar flaw that exceeds t,,i, tmln = minimum wall thickness required for pressure loading t,,om = nominal wall thickness t,= minimum remaining wall thickness W,. = maximum extent of a local thinned area perpen-dicular to Lm with t < t m A= nondimensional half crack length for through-wall axial flaw of= material flow stress o'h = pipe hoop stress due to pressure o-b = nominal longitudinal bending stress for primary loading without stress intensification factor 0= half crack angle for through-wall circumferen-tial flaw 769
CASE (continued)
N-513 CASES OF ASME BOILER AND PRESSURE VESSEL CODE APPENDIX I RELATIONS FOR Fm, Fb, AND F FOR THROUGH-WALL FLAWS
(
2 B,,= 7.09987 - 4.42394 (RIt) + 0.21036 (R/t) 3
- 0.00463 (R/t) 2 1-1.0 DEFINITIONS Cm = 7.79661 + 5.16676 (RIt) - 0.24577 (R/t)
+ 0.00541 (R/t) 3 For through-wall flaws, the crack depth (a) will be 2 replaced with half crack length (c) in the stress intensity Ab= -3.26543 + 1.52784 (R =It) - 0.072698 (R/t) 3 factor equations in Articles H-7300 and H-7400 of + 0.0016011 (R/t) 2 Section XI, Appendix H. Also, Q will be set equal to Bb= 11.36322 - 3.91412 (RIt) +.0.18619 (R/t) 3
- 0.004099 (R/t) unity in Article H-7400. 2 Cb= -3.18609 + 3.84763 (RI) - 0.18304 (R/t)
+ 0.00403 (R/t)3 1-2.0 CIRCUMFERENTIAL FLAWS
( Equations for F,,, and Fb are accurate for Rlt between 5 and 20 and become increasingly conservative for RI For a range of Rit between 5 and 20, the following t greater than 20. Alternative solutions for Fm and Fb equations for Fm and Fb may be used:
may be used when Rit is greater than 20.
35 F. = 1 + Am (011f)'-" + m (e/"tr)2"5 + C. ((9") "
1-3.0 AXIAL FLAWS Fb = 1 + A, (l/.r)I"5 + B, (t/f7) 2 5 35
" + Cb (e/ir)" For internal pressure loading, the following equation for F may be used:
F= I + 0.072449A + 0.64856A2 m-0.2327A3 +
where 0.038154A 4 - 0.0023487A5 e= Half crack angle = c/R where R= Mean pipe radius A= c/(Rt)l 2
( and t= Pipe wall thickness c = half crack length The equation for F is accurate for A between 0 and 2
Am= -2.02917 + 1.67763 (RIt) - 0.07987 (R/t) 5. Alternative solutions for F may be used when A is
+ 0.00176 (R/t) 3 greater than 5.
(
771