ML062090375
| ML062090375 | |
| Person / Time | |
|---|---|
| Site: | Surry  |
| Issue date: | 07/27/2006 |
| From: | Gerald Bichof Virginia Electric & Power Co (VEPCO) |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| 06-585 | |
| Download: ML062090375 (14) | |
Text
VIRGINIA ELECTRIC AND POWER COMPANY RICHMOND, VIRGINIA2326 1 July 27, 2006 United States Nuclear Regulatory Commission Serial No.06-585 Attention: Document Control Desk NLOSlGDM R1 Washington, D.C. 20555 Docket No. 50-281 License No. DPR-37 VIRGINIA ELECTRIC AND POWER COMPANY SURRY POWER STATION UNIT 2 ASME SECTION XI INSERVICE INSPECTION PROGRAM RELIEF REQUEST CMP-007 REGENERATIVE AND RESIDUAL HEAT EXCHANGERS In a letter dated February 9, 2006 (Serial No.06-057), Virginia Electric and Power Company (Dominion) submitted Relief Request CMP-006, Revision 1, for Surry Power Station Unit 2 pertaining to ASME Section XI Code required inspections on the Regenerative and Residual Heat Exchangers. NRC approval was requested to use Code Case N-706, Alternative Examination Requirements of Table IWB-2500-1 and Table IWC-2500- 1 for PWR Stainless Steel Residual and Regenerative Heat Exchanger Section XI, Division 1, as an alternative to the requirements in Table IWB 2500-1 for Categories B-B and B-D pertaining to the Regenerative Heat Exchanger and Table IWC 2500-1 for Categories C-A and C-B pertaining to the Residual and Regenerative Heat Exchangers. However, it was subsequently determined that the Code Case requirement "All welds shall have received at least one volumetric examination ..." could not be met for certain components on the Residual and Regenerative Heat Exchangers in that a volumetric examination was never a code requirement. Consequently, verbatim use of Code Case N-706 was not possible for all of the subject items included in the relief request. Discussions were held with the ASME Code Case writers and verification was made that the intent of the Code Case was to cover all of these heat exchanger components. A revision to the Code Case is now in the approval process, which will provide alternative examination requirements for all of the components included in this relief.
During a subsequent telephone conference call with the NRC, Dominion agreed to submit a separate relief request that did not rely upon Code Case N-706 rather than waiting on approval of the Code Case revision. Therefore, pursuant to 10CFR50.55a(a)(3)(ii), approval is requested to use an alternative to the requirements in Table IWB 2500-1 for Categories 6-6 and B-D associated with the Regenerative Heat Exchanger and Table IWC 2500-1 for Categories C-A and C-B associated with the Residual and Regenerative Heat Exchangers for complying with the code required examination. Compliance with the code requirements would result in a hardship
Serial No.06-585 Docket No. 50-281 Page 2 without a compensating increase in quality and safety due to the excessive personnel radiation exposure that would result from the performance of the examinations, as well as the geometric difficulties that would be encountered. The specified alternative and its supporting basis are provided in attached Relief Request CMP-007. Relief Request CMP-007 supercedes in its entirety the previously submitted Relief Request CMP-006, Revision 1.
If you have any questions or require additional information, please contact Mr. Gary D.
Miller at (804) 273-2771.
Very truly yours,
.G. T. Bischof u Vice President - Nuclear Engineering Attachment Commitments made in the letter: None cc: U. S. Nuclear Regulatory Commission Region II Sam Nunn Atlanta Federal Center 61 Forsyth St., SW, Suite 23T85 Atlanta, Georgia 30303 Mr. S. R. Monarque U. S. Nuclear Regulatory Commission One White Flint North 11!j55 Rockville Pike Mail Stop 8H12 Rolckville, Maryland 20852 Mr. N. P. Garrett NR:C Senior Resident Inspector Surry Power Station Mr. R. A. Smith Authorized Nuclear Inspector Surry Power Station
Serial No.06-585 Docket No. 50-281 Attachment Relief Request CMP-007 Virginia Electric and Power Company (Dominion)
Surry Power Station Unit 2
Serial No.06-585 Docket No. 50-281 Attachment RELIEF REQUEST CMP-007
- 1. IDENTIFICATION OF COMPONENTS Various welds on the Residual (2-RH-E-1A and 2-RH-E-1B) and Regenerative Heat Exchangers (2-CH-E-3). The welds are:
Welds Descri~tion Cateaorv/ltem Class 1-A0 1 Head Circumferential Weld C-NC1.20 2 1-A02 Shell Circumferential Weld C-NC1.10 2 1-A05, 1-A06, Reinforcing Plate Welds to C-BlC2.31 2 1-A07,1 -A08 Nozzle and Vessel Welds Descri~tion Cateaorvlltem Class 1-E)01 Head Circumferential Weld C-NC1.20 2 1-E102 Shell Circumferential Weld C-A/C1 .I0 2 1-El05, 1-B06, Reinforcing Plate Welds to C-BlC2.31 2 1-ElO7, 1-BO8 Nozzle and Vessel Page 1 of 11
Serial No.06-585 Docket No. 50-281 Attachment Welds Descri~tion Cateaorvlltem Class 1-04, 1-17, Circumferential Head Welds B-BlB2.51 1
&l-19 1-03, 1-18, Tubesheet-to-Shell Welds B-BlB2.80 1
& 1-22 1-06, 1-08, Nozzle-to-Vessel Welds B-DlB3.150 1 1-09, 1-11, 1-13, & 1-15 NIR-06, NIR-08, Nozzle Inside Radius Section B-DlB3.160 NIR-09, NIR-11, NIR-13, & NIR-15 1-01, 1-21, Head Circumferential Welds C-NC1.20
& 1-24 1-02, 1-20, Tubesheet-to-Shell Welds C-NC1.30
& 1-23 II. APPLICABLE CODE EDITION AND ADDENDA Su~rryUnit 2 is currently in the Fourth lnservice Inspection Interval under the 1998 Edition through the 2000 Addenda of the ASME Section XI Code.
111. CODE REQUIREMENTS Examination Categories B-B, B-Dl from Table IWB-2500-1 and C-A, C-B from Table IWC-2500-1 require that volumetric or surface examinations be performed on the welds and nozzle inside radius areas listed above.
IV. BA.SISFOR RELIEF The subject welds are shown in Figures 1, 2 and 3 for stainless steel cornponents 2-RH-E-1A, 2-RH-E-1B and 2-CH-E-3, respectively.
Page 2 of 11
Serial No.06-585 Docket No. 50-281 Attachment The Regenerative Heat Exchanger (2-CH-E-3) provides preheat for the normal charging water flowing into the Reactor Coolant System (RCS). The Residual Heat Exchangers are designed to cool the RCS during plant shut down operations.
A feasibility study has been performed within the ASME and prepared by Westinghouse Owner's Group (WOG) project MUHP 5093, Working Group lnservice lnspection Optimization Action 97-01, ISI-03-06, BC03-338, "Technical Basis for Revision of lnspection Requirements for Regenerative and Residual Heat Exchangers", August, 2004. Technical justification for eliminating the surface and volumetric inspections of the Residual and Regenerative Heat Exlchangers is supported in this report. The components at Surry Power Station (i.~?.,
2-RH-E-1A and 1B; 2-CH-E-3) are typical of the heat exchangers described by fabrication, geometric design, inspection requirements and geometric restrictions.
As stated in the Westinghouse report, these components were designed and installed before the imposition of the inservice inspection requirements by Section XI and are not designed for performance of ultrasonic and surface examination. The small diameter of the vessel and nozzles of the Regenerative Heat Exchanger makes a meaningful ultrasonic examination very time consuming and dose intensive. The physical limitations would substantially diniinish the ability to discriminate flaw indications from geometry existing around the joint. Referring to the Residual Heat Exchangers, interference with the! lower support and interference with inlet and outlet pipes leads to only partial coverage for examination of the head and shell circumferential welds.
Furthermore, these components are located in high radiation fields. The estimated personnel dose to perform interval Code inspections on the Regenerative Heat Exchanger is 12.0 man-rem, and it is estimated that 4.5 man-renn would be required to meet the inspection requirements per interval for the Residual Heat Exchanger. In view of the significant dose required to be expended for limited examination providing questionable results, the value of performing the Code required examinations is minimal.
Two other factors presented in the Westinghouse report for these components were considered by the ASME committee - flaw tolerance and risk assessment.
Fracture evaluations were performed for the components using finite element models and fracture calculations. It was concluded that the heat exchangers have a large flaw tolerance and that significant leakage would be expected long before any failure occurred. Fatigue crack growth was determined to be extremely slow even in the most highly stressed region. Thus, detailed inspections are not required to ensure heat exchanger integrity.
Page 3 of 11
Serial No.06-585 Docket No. 50-281 Attachment A risk evaluation was performed using the accepted methodology applied for Risk Informed IS1 piping inspection programs. The following conclusions were made:
Safety equipment required to respond to the potential event is unaffected.
Potential for loss of pressure boundary integrity is negligible.
No safety analysis margins are changed.
Leakage before full break is expected (no core damage consequences associated with leakage).
Thus, elimination of the subject inspections would not be expected to result in a significant increase in risk.
There have been no through-wall leaks on these components or components of similar design as reported in industry and as discussed in the Westinghouse report. The only related leak in the United States occurred in January 2004 at San Onofre Unit 3 on the letdown line exiting the Regenerative Heat Exchanger.
This failure was caused by excessive vibration on the piping line and is not an indlication of failure on the actual heat exchanger.
All of these welds and the nozzle inner radius section have received some type of nondestructive examination during inservice or preservice inspection. The pressure retaining welds on the Regenerative Heat Exchanger received preservice volumetric examinations as outlined in the attached table. Since the prcservice exams, visual VT-2 examinations have been performed in accordance with NRC approved relief requests. Some examinations were limited in coverage but these limitations would again create reduced coverage todlay. See Table 1 for Examination History.
V. PROPOSED ALTERNATIVE In accordance with the provisions of IOCFR50.55a(a)(3)(ii), approval is reqluested to use an alternative to the requirements in Table IWB 2500-1 for Categories B-B and B-D pertaining to the Regenerative Heat Exchanger and Table IWC 2500-1 for Categories C-A and C-B pertaining to the Residual and Relgenerative Heat Exchangers. Complying with the code required examination woluld result in hardship without a compensating increase in quality and safety due to excessive personnel radiation exposure and geometric examination difficulties. Specifically, a VT-2 examination will be performed as an acceptable alternative to the Code required examination.
Page 4 of 1 1
Serial No.06-585 Docket No. 50-281 Attachment VI. DURATION OF PROPOSED ALTERNATIVE The use of this relief request is for the duration of the Surry Unit 2 Fourth Inservice Inspection Interval.
VII. PRECEDENTS Sirnilar requests for relief were submitted and approved by the Nuclear Regulatory Commission for the Joseph M. Farley plant under TAC No. MA3449; North Anna Power Station Unit 2 under TAC No. MB07050; Surry Power Station Unit 1, third inservice inspection interval, under TAC No. MB1998; and Surry Power Station Unit 2, third inservice inspection interval under TAC No. MB1999.
Page 5 of 11
Serial No.06-585 Docket No. 50-281 Attachment SECTION A-A L ~ W E RSUPPORT 's'mFEmF, SECTION 8-8 UPPER SUPPORT I ,
' ,2$F4a OJILEI DETAIL 1 '"5cH TUBE SDI -E WELDS
,875 THICKNESS .--/
EYIPlI8:LIL HEAO 4I. OD ASTM I-21. 1P 381
,875' T M I C W f S S -/ O~r)l~ COUUECTIONS 1311' P B B . L Y .
S E E Y C l l m A-A FOR NIRILSI FLlL COlPLlUGl Figure 1 " A Residual Heat Exchanger Page 6 of 11
Serial No.06-585 Docket No. 50-281 Attachment I ¶F -
INLET SECTION B-B UPPER SUPPORT prusr r m OUTLET DETAIL 1 'w5CH
TUBE SIWELOS OEE
/
rillPllClY SSE SECTION L-h H E 0 42'00 ilSrH 6-248 TP 384 ' \ L D . ~ , ~ CDX(ECI,DYS Fa) WT.ILLI all).W I C < Y F S I -
' W1, 1BDB. 5 1 FLLL CDUPLlNGl Figure 2 "B" Residual Heat Exchanger Page 7 of 1 1
Serial No.06-585 Docket No. 50-281 Attachment ELEVATION LOOKING WEST SECTION 'B' SECTION 'A' A
Figure 3 Regenerative Heat Exchanger Page 8 of 11
Serial No.06-585 Docket No. 50-281 Attachment Table 1 Examination History Component 1 I
I Weld 1 I
I Catlltem I I
I Description I I
Exam Date Results!
Comments 2-RH-E-1A 1-A01 C-NC1.20 Head Circumferential Weld 03/06/1995 0" to 44" lndications dispositioned as geometrical.
44" to 88" No indications.
88" to 0" 91OO/ coverage obtained, no indications.
2-RH-E-1A 1-A02 C-NC1.10 Shell Circumferential Weld 03/6/1995 0" to 44" lndications dispositioned as geometrical.
44" to 66" No indications.
10/06/2003 88" to 0" No indications.
2-RH-E-1B 1-B01 C-NC1.20 Head Circumferential Weld 10/1411986 0" to 44" No indications.
44" to 88" No Indications.
88" to 0" No indications, partial relief request SR-021 approved by
~.
NRC letter 94-271.
2-RH-E-1B 1-B02 C-NC1.10 Shell Circumferential Weld 10/14/1986 22" to 44" No indications.
1011 1/2000 44" to 88" No indications.
0411811993 110" to 0" No indications.
2-CH-E-3 1-04 B-WB2.51 Circumferential Head Weld 11/30/1971 No indications.
2-CH-E-3 1-17 B-BlB2.51 Circumferential Head Weld 12/01/1971 No indications.
2-CH-E-3 1-19 B-BlB2.51 Circumferential Head Weld 12/01/1971 No indications.
2-CH-E-3 1-03 B-BlB2.80 Tubesheet-to-Shell Welds 12/01/1971 No indications. No coverage from 157" to 202" due to support bracket I I I I and nozzle configuration.
2-CH-E-3 11-18 1 B-BlB2.80 ( Tubesheet-to-Shell Weld 1 12/01/1971 No indications. Limited coverage upstream due to pipe hanger.
2-CH-E-3 1-22 B-BlB2.80 Tubesheet-to-Shell Weld 11/30/1971 Baffle plate indication noted due to ID geometry.
Page 9 of 11
Serial No.06-585 Docket No. 50-281 Attachment Component I Weld Catlltem Description Exam Date Results/
I Comments B-DlB3.150 Nozzle-to-VesselWeld 12/01/1971 Indications due to ID geometry.
6-DIB3.150 Nozzle-to-Vessel Weld 12/01/1971 Indications due to ID geometry.
B-DlB3.150 Nozzle-to-VesselWeld 12/01/1971 Indications due to ID geometry.
B-DlB3.150 Nozzle-to-Vessel Weld 12/01/1971 Indications due to ID geometry.
6-DlB3.150 Nozzle-to-Vessel Weld 11/30/1971 Indications due to ID geometry.
B-DlB3.150 Nozzle-to-Vessel Weld 11/30/1971 Indications due to ID geometry.
C-NC1.20 Head Circumferential Weld 12/0111971 No indications. No coverage upstream side from 135" to 225"and downstream from 120" to 240" due to brace.
C-NC1.20 Head Circumferential Weld 12/01/1971 No Indications. No coverage upstream side from 135" to 225" and downstream side from 120" to 240" due to hanger.
C-NC1.20 Head Circumferential Weld 11/30/1971 No indications. 8OoA of downstream side could not be examined due to interference with support clamp and brace.
C-NC1.30 Tubesheet-to-Shell Welds 12/01/1971 No indications. No coverage on downstream side due to pipe hanger.
C-NC1.30 Tubesheet-to-Shell Welds 12/01/1971 No indications. No coverage downstream side from 157" to 202" due to support bracket.
C-NC1.30 Tubesheet-to-Shell Welds 11/30/1971 Indications due to ID geometry.
- Preoperational baseline UT examinations performed between November 1971 and November 1972.
Page 10 of 11
Serial No.06-585 Docket No. 50-281 Attachment The following are Nozzle Inner Radius Sections and are not pressure retaining welds. All received satisfactory VT-2 exams in accordance with Relief Request SR-018 for the 2nd Interval and in accordance with Relief Request SR-029 for the 3rd Interval as shown.
Component Mark # Catlltem 2nd Interval Exam Date 3rd Interval Exam Date 2-CH-E-3 NIR-06 B-DlB3.160 0311911995 0610411996 2-CH-E-3 NIR-08 B-DlB3.160 0311911995 06/04/1996 2-CH-E-3 NIR-09 B-DlB3.160 0311911995 1012912000 2-CH-E-3 NIR-11 B-DlB3.160 0311911995 1012912000 2-CH-E-3 NIR-13 B-DlB3.160 0311911995 0411812002 2-CH-E-3 NIR-15 B-DlB3.160 0311911995 0411812002 The following are reinforcing plate welds for the nozzle to vessel on the Residual Heat Removal Heat Exchanger and received surface examinations (liquid penetrant) as required by code on the dates shown:
Component Mark # Categorylltem Method Exam Date Results 2-RH-E-1A 1-A05 C-BlC2.31 PT 03/06/1995 No Indications 2-RH-E-1A 1-A06 C-BlC2.31 PT 1012312003 No Indications 2-RH-E-1A 1-A07 C-BlC2.3 1 PT 1011412003 Initial indication removed within acceptable grinding limits for grooming. No repair necessary. Evaluated by ET-CM-03-0025.
2-RH-E-1A 1-A08 C-BlC2.31 PT 1011512003 Initial indication found acceptable by volumetric acceptance criteria.
2-RH-E-1B 1-B05 C-BlC2.31 PT 1012212003 No indications 2-RH-E-1B 1-B06 C-BlC2.31 PT 1012212003 No indications 2-RH-E-1B 1-807 C-BlC2.31 PT 1012412003 1 lnitial indication removed within acceptable 1 grinding limits for "grooming". No repair necessary. Evaluated by ET-CM-03-0025.
2-RH-E-1B 1-B08 C-BlC2.3 1 PT 1012412003 Initial indication removed within acceptable grinding limits for "grooming". No repair necessary. Evaluated by ET-CM-03-0025.
Page I 1 of 11