ML030980322
| ML030980322 | |
| Person / Time | |
|---|---|
| Issue date: | 04/11/2003 |
| From: | Barrett R Division of Engineering |
| To: | Marion A Nuclear Energy Institute |
| Wichman K, EMCB/DE, 415-2785 | |
| Shared Package | |
| ML030980327 | List: |
| References | |
| +KBR1SISP20050517, EA-03-009 | |
| Download: ML030980322 (8) | |
Text
April 11, 2003 Mr. Alex Marion, Director of Engineering Nuclear Energy Institute 1776 I Street, N.W., Suite 400 Washington, D.C. 20006-3708
SUBJECT:
FLAW EVALUATION GUIDELINES
Dear Mr. Marion:
to the letter from Jack Strosnider to you dated November 21, 2001, contained flaw evaluation guidelines for control rod drive mechanism (CRDM) penetrations. These guidelines were developed by the Office of Nuclear Reactor Regulation (NRR) staff and were needed since no guidance or rules existed in the American Society of Mechanical Engineers (ASME)
Code,Section XI to evaluate flaws found in the CRDM pressure boundary. While these guidelines have fulfilled a need, subsequent interactions with the industry and further information from multiple sources have rendered these guidelines obsolete. This situation was recognized in Footnote 1 to the February 11, 2003, NRC Order EA-03-009 establishing interim inspection requirements for reactor pressure vessel heads at pressurized water reactors.
Footnote 1 states in part,...The NRC has issued guidance to address flaw evaluations for RPV head penetration nozzles (see letter from J. Strosnider, NRC, to A. Marion, Nuclear Energy Institute) and will, as necessary, issue revised guidance pending the updating of the ASME code and related NRC regulations.
Attached to this letter as Enclosures 1 and 2 is revised guidance that is generally consistent with the recently approved action by Section XI at their meeting in San Francisco on February 27, 2003. That action consisted of a Code addition and an enabling Code Case to establish rules for flaw evaluation for PWR reactor vessel upper head penetration nozzles. The NRR staff, through their representation on the cognizant Section XI groups and committees, participated in the development and approval of these new flaw evaluation rules. Publication of the Code addition and Code Case and subsequent formal approval by the NRC will take time.
In the interim, the staff intends to reference these guidelines in interactions with licensees during the current and future outage seasons. Note that we have modified the flaw acceptance criteria of Table 1 in Enclosure 1. Any plant specific considerations can be discussed with the staff as appropriate.
As additional information becomes available, further development or changes to these guidelines can be anticipated. The staff contact for flaw evaluation issues is Keith Wichman who can be reached at (301) 415-2785. Your continued cooperation is appreciated.
Sincerely,
/RA/
Richard Barrett, Director Division of Engineering Office of Nuclear Reactor Regulation
Enclosures:
As stated cc: See next page
April 11, 2003 Mr. Alex Marion, Director of Engineering Nuclear Energy Institute 1776 I Street, N.W., Suite 400 Washington, D.C. 20006-3708
SUBJECT:
FLAW EVALUATION GUIDELINES
Dear Mr. Marion:
to the letter from Jack Strosnider to you dated November 21, 2001, contained flaw evaluation guidelines for control rod drive mechanism (CRDM) penetrations. These guidelines were developed by the Office of Nuclear Reactor Regulation (NRR) staff and were needed since no guidance or rules existed in the American Society of Mechanical Engineers (ASME)
Code,Section XI to evaluate flaws found in the CRDM pressure boundary. While these guidelines have fulfilled a need, subsequent interactions with the industry and further information from multiple sources have rendered these guidelines obsolete. This situation was recognized in Footnote 1 to the February 11, 2003, NRC Order EA-03-009 establishing interim inspection requirements for reactor pressure vessel heads at pressurized water reactors.
Footnote 1 states in part,...The NRC has issued guidance to address flaw evaluations for RPV head penetration nozzles (see letter from J. Strosnider, NRC, to A. Marion, Nuclear Energy Institute) and will, as necessary, issue revised guidance pending the updating of the ASME code and related NRC regulations.
Attached to this letter as Enclosures 1 and 2 is revised guidance that is generally consistent with the recently approved action by Section XI at their meeting in San Francisco on February 27, 2003. That action consisted of a Code addition and an enabling Code Case to establish rules for flaw evaluation for PWR reactor vessel upper head penetration nozzles. The NRR staff, through their representation on the cognizant Section XI groups and committees, participated in the development and approval of these new flaw evaluation rules. Publication of the Code addition and Code Case and subsequent formal approval by the NRC will take time.
In the interim, the staff intends to reference these guidelines in interactions with licensees during the current and future outage seasons. Note that we have modified the flaw acceptance criteria of Table 1 in Enclosure 1. Any plant specific considerations can be discussed with the staff as appropriate.
As additional information becomes available, further development or changes to these guidelines can be anticipated. The staff contact for flaw evaluation issues is Keith Wichman who can be reached at (301) 415-2785. Your continued cooperation is appreciated.
Sincerely,
/RA/
Richard Barrett, Director Division of Engineering Office of Nuclear Reactor Regulation
Enclosures:
As stated cc: See next page Distribution:
EMCB R/F SDuraiswamy JLarkins BWSheron WDTravers WFKane SJCollins Athadani TChan JAZwolinski GMHolahan DBMatthews BABoger SBloom MEMayfield NCChokshi AHiser PCWen WCullen WDLanning, R1 CCasto, R2 CPederson, R3 DChamberlain, R4 Package ML030980327; Letter ML030980322; Attachment ML030980333 OFFICE EMCB:DE EMCB:DE D:DE NAME K Wichman W Bateman R Barrett DATE 4 / 2 / 03 4 / 8 / 03 4 / 11 / 03 OFFICIAL RECORD COPY
cc:
Marvin Fertel, Senior Vice President and Chief Nuclear Officer Nuclear Energy Institute Suite 400 1776 I Street, NW Washington, DC 20006-3708 Leslie Hartz, Chair, MRP Vice President - Nuclear Engineering Dominion Energy 5000 Dominion Blvd.
Glan Allen, VA 23060 Larry Mathews, MRP Southern Nuclear Operating Company Manager, Inspection and Testing Services P. O. Box 1295 Birmingham, AL 35201 Craig Harrington, Technical Chair RPV Head Working Group TXU Corporation Comanche Peak Plant PO Box 1002 Glan Rose, TA 76043 - 1002 Frank Ammirato, EPRI Inspection Manager EPRI NDE Center P. O. Box 217097 1300 W. T. Harris Blvd.
Charlotte, NC 28221 C. Thomas Alley, Jr., Technical Chair Inspection Working Group Duke Power Company Nuclear General Office 526 South Church Street Mail Code EC09O PO Box 1006 Charlotte NC 28201 David Steininger, EPRI MRP Manager Chuck Welty, EPRI MRP Manager Christine King, EPRI MRP Manager Electric Power Research Institute P. O. Box 10412 3412 Hillview Ave.
Palo Alto, CA 94303 John Wilson, Technical Chair Repair/Mitigation Working Group Exelon Corporation Cornerstone II at Cantera 4300 Winfield Ave.
Warrenville, IL 60555 - 4012
ENCLOSURE 1 FLAW EVALUATION GUIDELINES AND ACCEPTANCE CRITERIA FOR PWR REACTOR VESSEL UPPER HEAD PENETRATION NOZZLES PWR reactor vessel upper head penetration nozzles containing flaws may be evaluated to determine acceptability for continued service in accordance with the evaluation procedure and acceptance criteria specified herein. Application of the evaluation procedures shall be subject to review and approval by the U.S. Nuclear Regulatory Commission (NRC).
Scope This evaluation procedure is applicable to upper head penetration nozzles with eight inch (200 mm) nominal outside diameter and less. This procedure shall not be used for J-groove welds.
Evaluation Procedure The acceptance standards of IWB-3500 of Section XI of the ASME Code (herein after referred to asSection XI) shall not be used to accept flaws in this region.
A flaw growth analysis shall be performed on each detected flaw to determine its maximum growth due to fatigue, stress corrosion cracking or both mechanisms, when applicable, during a specified evaluation period. The minimum time interval for the flaw growth evaluation shall be until the next inspection.
All applicable loadings shall be considered, including weld residual stress, in calculating the crack growth.
The flaw shall be characterized in accordance with the requirements of IWA-3400 of Section XI including the proximity rules of Fig. IWA-3400-1 for surface flaws.
The flaw shall be projected into both axial and circumferential orientations, and each orientation shall be evaluated. The axial orientation is the same for each nozzle, but the circumferential orientation will vary depending on the angle of intersection of the penetration nozzle with the head. As illustrated in Fig. I, any flaws within +/-10 of the plane formed by the J-groove weld root shall be considered pure circumferential flaws.
The location of the flaw, relative to both the top and the bottom of the J-groove attachment weld, shall be determined.
The flaw shall be evaluated using analytical procedures, such as those described in Appendix A (Enclosure 2), to calculate the following critical flaw parameters:
af = the maximum depth to which the detected flaw is calculated to grow at the end of the evaluation period lf = the maximum length to which the detected flaw is calculated to grow at the end of the evaluation period.
2 Acceptance Criteria The calculated maximum flaw dimensions at the end of the evaluation period shall be compared with the maximum allowable flaw dimensions in Table I.
Table I Reactor Vessel Upper Head Penetration Nozzle Acceptance Criteria(1) (3)
Location Axial af lf Circumference af lf Below Weld (ID)(2) t No Limit t
0.75 Circ.
(4)
At and Above Weld (ID) 0.75 t No Limit repair repair Below Weld (OD) (2) t No Limit t
0.75 Circ.
(4)
At and Above Weld (OD) repair repair repair repair Notes:
(1) Surface flaws of any size in the attachment weld are not acceptable.
(2) Intersecting axial and circumferential flaws in the nozzle are not acceptable.
(3) t = wall thickness of head penetration nozzle (4) 75 percent of the circumference
3
+10
-10 Fig. I Definition of Circumferential Orientation for Flaw Characterization Note: Planar flaws within +/- 10° of the plane formed by the J-groove weld root, shown as the dashed line, shall be considered circumferential flaws.