NOC-AE-11002705, Request for Relief to Apply an Alternative to the ASME Section Xl Code Requirements for Examination of Class 1 and Class 2 Piping Welds (Relief Request RR-ENG-3-04)

From kanterella
Jump to navigation Jump to search

Request for Relief to Apply an Alternative to the ASME Section Xl Code Requirements for Examination of Class 1 and Class 2 Piping Welds (Relief Request RR-ENG-3-04)
ML11250A170
Person / Time
Site: South Texas  STP Nuclear Operating Company icon.png
Issue date: 09/01/2011
From: Ruvalcaba M
South Texas
To:
Document Control Desk, Office of Nuclear Reactor Regulation
References
NOC-AE-11002705
Download: ML11250A170 (13)
v • d • e


Text

Nuclear Operating Company South Te-xs Pro/eel Electric Cenerating Station P.. Box 289 Wadsvorth. Texas 77483 -

September 1, 2011 NOC-AE-1 1002705 File No.: G25 10 CFR 50.55a U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852-2746 South Texas Project Units 1 and 2 Docket Nos. STN 50-498, 50-499 Request for Relief to Apply an Alternative to the ASME Section Xl Code Requirements for Examination of Class 1 and Class 2 Piping Welds (Relief Request RR-ENG-3-04)

In accordance with the provisions of 10 CFR 50.55a(a)(3)(i), the South Texas Project requests relief from the ASME Section Xl code examination requirements for inservice inspection of Class 1 and Class 2 piping welds. As an alternative to the Code requirements, a Risk-Informed process will continue to be applied in selecting Class 1 and Class 2 piping welds for examination during the third inspection interval. The proposed alternative provides an acceptable level of quality and safety as required by 10 CFR 50.55a(a)(3)(i).

There are no commitments in this letter.

STPNOC requests NRC review and approval of this relief request by March 1, 2012, to support implementation of the Unit 1 and Unit 2 ten-year Inservice Inspection Plan during the third inspection interval, ending September 24, 2020 (Unit 1) and October 18, 2020 (Unit 2).

If there are any questions, please contact either Mr. Philip L. Walker at (361) 972-8392 or me at (361) 972-7904.

Marco Ruva aba Manager, Testing and Programs Engineering PLW/

Attachment:

Request for Relief to Apply an Alternative to the ASME Section Xl Code Requirements for Examination of Class 1 and Class 2 Piping Welds STI: 32905093

NOC-AE-1 1002705 Page 2 of 2 cc: (paper copy) (electronic copy)

Regional Administrator, Region IV John Ragan U. S. Nuclear Regulatory Commission Catherine Callaway 612 East Lamar Blvd., Suite 4004 Jim von Suskil Arlington, TX 76011-4125 NRG South Texas LP Balwant K. Singal A. H. Gutterman, Esquire Senior Project Manager Morgan, Lewis & Bockius LLP U.S. Nuclear Regulatory Commission One White Flint North (MS 8B1) 11555 Rockville Pike Balwant K. Singal Rockville, MD 20852 U. S. Nuclear Regulatory Commission Senior Resident Inspector Richard Pena U. S. Nuclear Regulatory Commission Ed Alarcon P. 0. Box 289, Mail Code: MN1 16 Kevin Polio Wadsworth, TX 77483 City Public Service C. M. Canady C. Mele City of Austin City of Austin Electric Utility Department 721 Barton Springs Road Peter Nemeth Austin, TX 78704 Crain Caton & James, P.C.

Richard A. Ratliff Texas Department of State Health Services Alice Rogers Texas Department of State Health Services

Attachment NOC-AE-1 1002705 Page 1 of 11 SOUTH TEXAS PROJECT UNITS I AND 2 REQUEST FOR RELIEF TO APPLY AN ALTERNATIVE TO THE ASME SECTION XI CODE REQUIREMENTS FOR EXAMINATION OF CLASS I AND CLASS 2 PIPING WELDS (RELIEF REQUEST RR-ENG-3-04)

1. REFERENCE CODE: ASME Code Section XI, 2004 Edition, No Addenda
2. COMPONENTS AFFECTED: Class 1 and Class 2 Piping Welds
3. APPLICABLE CODE REQUIREMENTS:
  • Table IWB-2500-1, Examination Category B-F and Category B-J ASME Section Xl ExaminatiOn Categories B-F and B-J contain the requirements for nondestructive examination of Class 1 piping components. Category B-F applies to pressure-retaining dissimilar metal welds in vessel nozzles. Category B-J applies to pressure-retaining welds in piping.
  • Table IWC-2500-1, Examination Category C-F-1 and Category C-F-2 ASME Section Xl Examination Categories C-F-1 and C-F-2 contain the requirements for nondestructive examination of Class 2 piping components. Category C-F-1 applies to pressure-retaining welds in austenitic stainless steel or high alloy piping.

Category C-F-2 applies to pressure-retaining welds in carbon or low alloy steel piping.

4. BASIS FOR RELIEF FROM CODE REQUIREMENTS:

ASME Section Xl code requirements do not allow for selection of inspection locations using consideration of degradation mechanisms that are potentially active, the relative severity of each degradation mechanism at an inspection location, and the inspection methods to be applied. Focusing inspection activities on risk-significant piping segments enables reduction of pipe leak and rupture frequencies, reducing core damage frequency (CDF) and large early release frequency (LERF).

5. ALTERNATIVE EXAMINATION:

The alternative risk-informed inservice inspection (RI-ISI) program for piping is described in Electric Power Research Institute (EPRI) Topical Report TR-112657, "Revised Risk-Informed Inservice Inspection Evaluation Procedure," Revision B-A. TR-112657 provides the requirements for defining the relationship between the risk-informed examination program and the remaining unaffected portions of ASME Section Xl. The risk-informed ISI program applied during the second inspection interval was submitted in references 8.1 and 8.2, and approved by the NRC in references 8.3 and 8.4.

Review of the current RI-ISI program in accordance with NEI 04-05, "Living Program Guidance to Maintain Risk-Informed Inservice Inspection Programs for Nuclear Piping Systems," led to the following proposed changes:

Attachment NOC-AE-1 1002705 Page 2 of 11

  • During the third ISI interval, the ISI program is in accordance with the 2004 Edition of ASME Section XI. One of the changes in the new edition and addenda of the Code is that the exemption size for Class 2 auxiliary feedwater piping is decreased from 4" NPS to 1 1/2" NPS. As a result, the 4" NPS Class 2 auxiliary feedwater lines from the outboard isolation valves to where they connect to the four main feedwater lines were added to the ISI program and consequently added to the RI-ISI program.
  • The South Texas Project (STP) probabilistic risk assessment model revision used to evaluate the consequences of pipe rupture for the RI-ISI assessment for the second inspection interval was the Level 2 Probabilistic Safety Assessment and Individual Plant Examination submittal, dated August 1992, supplemented by PRA model STP_1997. The current PRA Model of Record is STPREV6. Segments in the following systems changed their consequence ranking:

o CVCS: consequence rank from Low to Medium o RCS: consequence rank from Low to High o SIS: consequence rank from Medium to Low.

  • Replacement of the steam generators and other repair/replacement activities resulted in numerous welds being deleted, added, or re-designated.

In accordance with the guidance provided by NEI 04-05, Tables 3 and 4 identify the number of welds added to and deleted from the originally approved RI-ISI program.

Table 5 defines the risk categories assigned to the systems listed in Tables 3 and 4.

6. JUSTIFICATION FOR GRANTING RELIEF 6.1 Consequence Evaluation The consequences of pressure boundary failures are ranked based on their effect on core damage and containment performance (isolation, bypass, and large early release).

Consequences considering both direct and indirect effects were considered using TR-1 12657 as guidance.

6.2 Degradation Mechanism Evaluation Failure potential estimates were generated utilizing industry failure history, plant-specific failure history, and other relevant information. These failure estimates were determined using TR-1 12657 as guidance. Tables 3 and 4 summarize the failure potential assessment by system for each potential degradation mechanism.

6.3 Risk Characterization As a risk-informed application, this submittal meets the intent and principles of Regulatory Guide (RG) 1.174, "An Approach for Using Probabilistic Risk Assessment in Risk-Informed Decisions On Plant-Specific Changes to the Licensing Basis," and RG 1.178, "An Approach for Plant-Specific Risk-Informed Decisionmaking Inservice Inspection of Piping."

Attachment NOC-AE-1 1002705 Page 3 of 11 Each run of piping within the scope of the program was evaluated to determine its impact on core damage and containment performance (isolation, bypass, and large, early release) as well as its potential for failure. Piping segments are then defined as continuous runs of piping potentially susceptible to the same type of degradation and whose failure will result in similar consequence. Segments are then ranked based upon their risk significance as defined in TR-1 12657.

The base core damage frequency (CDF) from the STP_1997 model is 1.17E-05 per year. The original RI-ISI program represented a negligible increase of 1.06E-07 for Unit 1 and 1.11 E-07 for Unit 2 in regards to CDF. A new risk impact analysis found that the revised program represents a risk reduction when compared to the last deterministic Section Xl inspection program. The revised program represents a reduction of 7.OE-1 1 for Unit 1 and 6.OE-1 1 for Unit 2 in regards to CDF. A risk-informed ISI program does not have an impact on LERF.

6.4 Inspection Location Selection and NDE Selection Tables 1 and 2 list the systems included in the RI-ISI program and the number of affected locations. The risk-informed evaluation boundaries are defined consistent with the system boundaries established in the plant ISI program previously approved by the NRC.

The intent of the inspections mandated by ASME Section Xl for piping welds is to identify conditions such as flaws or indications that may be precursors to leaks or ruptures in a system's pressure boundary. Currently, the process for picking inspection locations is based upon structural discontinuity and stress analysis results. As depicted in ASME White Paper 92-01-01 Rev. 1, "Evaluation of Inservice Inspection Requirements for Class 1, Category B-J Pressure Retaining Welds," this method has been ineffective in identifying leaks or failures. TR-1 12657 provides a more robust selection process founded on actual service experience with nuclear plant piping failure data.

This process has two key independent components: determination of each location's susceptibility to degradation; and secondly, independent assessment of the consequence of the piping failure. These two ingredients assure defense-in-depth is maintained. First, by evaluating a location's susceptibility to degradation, the likelihood of finding flaws or indications that may be precursors to leaks or ruptures is increased.

Secondly, the consequence assessment effort has a single failure criterion. As such, no matter how unlikely a failure scenario, it is ranked "High" in the consequence assessment, and at worst "Medium" in the risk assessment (i.e., Risk Category 4) if, as a result of the failure, there is no mitigative equipment available to respond to the event.

In addition, the consequence assessment takes into account equipment reliability, and less credit is given to less reliable equipment.

In-scope piping components, regardless of risk classification, continue to receive Code-required pressure testing as part of the current ASME Section Xl program. VT-2 visual examinations are scheduled in accordance with the station's pressure test program, which remains unaffected by the RI-ISI program. The STP RI-ISI Program was subjected to an internal evaluation at the end of the second period of the ISI second interval. An additional RI-ISI program periodic evaluation was conducted in accordance

Attachment NOC-AE-1 1002705 Page 4 of 11 with the recommendations of NEI 04-05. This review evaluated any possible changes that could affect the RI-ISI Program from September 2007 through October 2010, which corresponds with the third period of the second interval for the two units. The updated program resulting from these reviews is the subject of this proposed alternative.

6.5 PRA Quality The NRC has reviewed STP's program for implementation of risk-informed Technical Specifications for compliance with RG 1.174, RG 1.177, "An Approach for Plant-Specific, Risk-Informed Decisionmaking Regarding Technical Specifications," RG 1.200, "An Approach for Determining the Technical Adequacy of Probabilistic Risk Assessment Results for Risk-Informed Activities," and NEI 06-09, "Risk-Informed Technical Specifications Initiative." The NRC safety evaluation dated July 13, 2007, "South Texas Project, Units 1 and 2 - Issuance of Amendments Re: Broad-Scope Risk-Informed Technical Specifications Amendments," (ML071780186), in addressing the risk-informed program implemented during the second inspection, stated the following:

" Staff Findings and Conditions The staff finds that the licensee's proposed implementation of RMTS for the identified scope of TS LCO action requirements is consistent with the guidance of the staff-approved NEI 06-09, Revision 0. The licensee's methodology for assessing the risk impact of extended CTs, including the individual CT extension impacts in terms of ICDP and ILERP, and the overall program impact in terms of CDF and LERF, is accomplished using a full-scope PRA model of sufficient technical adequacy as described in NEI 06-09, Revision 0, and based on consistency with the guidance of RG 1.200, Revision 1. The assessment of configuration-specific risk to support the extension of CTs, and the RMTS program requirement to reassess configuration changes in a timely manner, and to implement compensatory measures and RMAs at the appropriate risk thresholds, are acceptable. The licensee's proposed implementation of RMTS is consistent with Tier 1, Tier 2 and Tier 3 guidelines of RG 1.177. The licensee has not proposed to use any conservative or bounding analyses in lieu of quantitative PRA models. The implementation of the RMTS program will therefore use the full-scope plant-specific PRA models, maintained to reasonably reflect the as-built, as-operated plant, and will conform to the guidance of RG 1.200, Revision 1.

  • Conclusions of Technical Evaluations The potential risk impacts for STP implementation of the RMTS program are determined consistent with the staff-approved NEI 06-09, Revision 0, methodology, and are reasonably expected to be small and consistent with the guidance of RG 1.174 and RG 1.177. The licensee's CRMP is consistent with NEI 06-09, Revision 0, guidance with regard to its scope and technical adequacy, and therefore satisfies RG 1.177 CRMP guidelines. The application of the CRMP for the RMTS program will assure timely identification of any risk-significant configurations, and prompt implementation of appropriate compensatory measures and RMAs, satisfying Tier 2 and Tier 3 of RG 1.177.

The staff therefore concludes that the proposed changes satisfy the key

Attachment NOC-AE-1 1002705 Page 5 of 11 principles of risk-informed decision making identified in RG 1.1 74 and RG 1.177, and therefore the requested adoption of the broad-scope risk-informed TS license amendments request by STP is acceptable.

6.6 Conclusion The RI-ISI program, as a substitute for the ASME Section Xl Code 2004 Edition examination program for Class 1 and Class 2 welded piping in accordance with 10 CFR 50.55a(a)(3)(i), provides an acceptable level of quality and safety.

7. IMPLEMENTATION The alternative will be applied for the STP Unit 1 and 2 third ten-year ISI program inspection interval, subject to the review and update guidance of NEI 04-05. The third inspection interval is currently scheduled to end September 24, 2020 for Unit 1 and October 18, 2020 for Unit 2. STPNOC requests NRC approval of the proposed alternative by March 1, 2012, to support continuation of risk-informed inservice inspection practices.
8. REFERENCES 8.1 T. J. Jordan, STP Nuclear Operating Company, to NRC Document Control Desk, "Relief Request for Application of an Alternative to the ASME Boiler and Pressure Vessel Code Section Xl Examination Requirements for Class 1 Piping Welds (RR-ENG-2-16)," dated December 30, 1999 (ML003676903) 8.2 T. J. Jordan, STP Nuclear Operating Company, to NRC Document Control Desk, "Relief Request for Application of an Alternative to the ASME Boiler and Pressure Vessel Code Section Xl Examination Requirements for Class 1 Socket-Welded Piping and Class 32Piping Welds (RR-ENG-2-23)," dated February 27, 2001 (ML010650285) 8.3 Robert A Gramm, NRC Office of Nuclear Reactor Regulation, to William T. Cottle, STP Nuclear Operating Company, "South Texas Project, Units 1 and 2 - Request for Relief From ASME Code Requirements for the Second 10-Year Interval Inservice Inspection Program Based on Risk-Informed Alternative Approach (Relief Request RR-ENG-2-16)

(TAC NOS. MA7789 AND MA7790)," dated September 11, 2000 (ML003749167) 8.4 Robert A Gramm, NRC Office of Nuclear Reactor Regulation, to William T. Cottle, STP Nuclear Operating Company, "Approval of Relief Request for Application of Risk-Informed Inservice Inspection Program for American Society of Mechanical Engineers Boiler and Pressure Vessel Code Class 1 and 2 Piping for South Texas Project, Units 1 and 2 (TAC NOS. MB1277 AND MB1278)," dated March 5, 2002 (ML020390041)

Attachment NOC-AE-1 1002705 Page 6 of 11 TABLE I UNIT I - SYSTEM SELECTION AND SEGMENT I ELEMENT DEFINITION System ASME Code Class Number of Segments Number of Elements RCS - Reactor Coolant System Class 1 13 21 SIS - Safety Injection System Class 2 56 736 RHRS - Residual Heat Removal System Class 2 29 364 CSS - Containment Spray System Class 2 9 126 AFW - Auxiliary Feedwater System Class 2 23 167 FWS - Feedwater System Class 2 20 144 MSS - Main Steam System Class 2 40 197 SLS - Sludge Lancing System Class 2 1 12 CVCS - Chemical and Volume Control System Class 2 0 0 Total: 191 Total: 1767 TABLE 2 UNIT 2 - SYSTEM SELECTION AND SEGMENT I ELEMENT DEFINITION System ASME Code Class Number of Segments Number of Elements RCS - Reactor Coolant System Class 1 11 30 SIS - Safety Injection System Class 2 55 693 RHRS - Residual Heat Removal System Class 2 28 361 CSS - Containment Spray System Class 2 9 118 AFW -Auxiliary Feedwater System Class 2 24 162 FWS - Feedwater System Class 2 20 120 MSS - Main Steam System Class 2 40 201 SLS - Sludge Lancing System Class 2 1 8 CVCS - Chemical and Volume Control System Class 2 0 0 Total: 188 Total: 1693

Attachment NOC-AE-1 1002705 Page 7 of 11 TABLE 3 COMPARISON BETWEEN ORIGINAL APPROVED AND UPDATED RI-ISI PROGRAMS BY RISK CATEGORY - STP UNIT I Systm~ Risk 1

~Consequence Failure Potential Original Interval 3 Update Category Rank Rank Degradation Mechanism Rank Weld Count RI-ISI OtherP2 ) Weld Count RI-ISI Other RCS 2 High High TASCS Medium 30 8 RCS 2 High High TASCS, TT Medium 39 9 RCS 2 High High TASCS, TT Medium 2 High PWSCC Medium 152 46 RCS 2 High High TT Medium 71 17 RCS 2 High High TT Medium 1 1 2 High PWSCC Medium RCS 4 Medium High None Low 199 19 4 Medium None Low 198 10 RCS 2 High High PWSCC Medium 12 2 RCS 5a Medium Medium TASCS Medium 3 1 RCS 5a Medium Medium TASCS, TT Medium 8 1 2 RCS 5a Medium Medium TT Medium 3 RCS 6a Low Medium None Low 18 0 18 RCS 6b Low Low TT Medium 2 RCS 7a Low Low None Low 8 8 SIS 5a Medium Medium TT, IGSCC Medium 3 1 3 1 SIS 6a Low Medium None Low 704 447 SIS 6b Low Low TT, IGSCC Medium 3 3 SIS 7a Low Low None Low 88 345 RHRS 5a Medium Medium TT Medium 12 2 12 2 RHRS 6a Low Medium None Low 413 413 RHRS 7a Low Low None Low 26 26 CSS 6a Low Medium None Low 126 106 CSS 7a Low Low None Low 47 20 1 1 AFW 5a Medium Medium TASCS Medium 14 3 26 2 3 High FAC High

Attachment NOC-AE-1 1002705 Page 8 of 11 TABLE 3 (continued)

COMPARISON BETWEEN ORIGINAL APPROVED AND UPDATED RI-ISI PROGRAMS BY RISK CATEGORY - STP UNIT I Risk System~1 lRan ConsequenceWedthr Failure Potential Original Interval 3 Update 2 Category Rank Rank Degradation Rank Weld RI-ISI Other 2 Weld RI-ISI Other Mechanism Count Count AFW 5a Medium Medium TASCS, TT Medium 4 4 1 3 High FAC High AFW 5a 3 Medium High Medium TT FAC Medium High 8 8 1 6a Low None Low AFW Medium 141 335 3 High FAC High FWS 5a Medium TASCS Medium 16 2 18 2 3 High FAC High FWS 6a Low Medium None Low 128 128 3 High FAC High MSS 6a Low Medium None Low 197 197 SLS 7d Low None None Low 12 12 CVCS 5a Medium Medium -r Medium 0 2 1 CVCS 6a Medium Low TT Medium 0 2 CVCS 6b Low Low TT Medium 0 j 7 CVCS 7a Low Low None Low 0 47 TOTAL NUMBER OF WELDS 2328 65 2548 68 change from original: 220 3 Notes 1 System designations are defined in Table 1.

2 This column is generally used to identify augmented inspection program locations that are credited beyond those locations selected per the RI-ISI process, as addressed in Section 3.6.5 of EPRI TR-1 12657. This option is not applicable for the STP RI-ISI application. The "Other' column is retained in this table solely for uniformity purposes with other RI-ISI application template submittals.

PWSCC = pressurized water stress corrosion cracking TASCS = thermal stratification, cycling, and striping TT = thermal transient FAC = flow-accelerated corrosion

Attachment NOC-AE-1 1002705 Page 9 of 11 TABLE 4 COMPARISON BETWEEN ORIGINAL APPROVED AND UPDATED RI-ISI PROGRAMS BY RISK CATEGORY - STP UNIT 2 Risk Failure Potential Original Interval 3 Update System~l) Consequence Category Rank Rank Degradation Rank Weld RI-ISI Other(2) Weld RI-ISl Other(2)

Mechanism Count Count RCS 2 High High TASCS Medium 30 8 RCS 2 High High TASCS, TT Medium 38 9 RCS 2 High High TASCS, TT Medium 2 High PWSCC Medium 147 46 RCS 2 High High TT Medium 67 16 RCS 22 High TT Medium Medium 1 1 High High PWSCC RCS 4 Medium High None Low 203 20 4 Medium None Low 202 11 RCS 2 High High PWSCC Medium 12 2 RCS 5a Medium Medium TASCS Medium 5 2 RCS 5a Medium Medium TASCS, TT Medium 0 0 2 RCS 5a Medium Medium TT Medium 5 RCS 6a Low Medium None Low 20 0 35 RCS 7a Low Low None Low 10 0 10 SIS 5a Medium Medium TT, IGSCC Medium 0 0 3 1 SIS 6a Low Medium None Low 553 0 348 SIS 6b Low Low TT, IGSCC Medium 0 0 3 SIS 7a Low Low None Low 140 0 401 RHRS 5a Medium Medium TT Medium 12 2 12 2 RHRS 6a Low Medium None Low 328 0 393 RHRS 7a Low Low None Low 21 0 264 CSS 6a Low Medium None Low 118 0 97 CSS 7a Low Low None Low 0 0 21 AFW 5a Medium Medium TASCS FAC Medium High 17 3 28 2 3 High

Attachment NOC-AE-1 1002705 Page 10 of 11 TABLE 4 (continued)

COMPARISON BETWEEN ORIGINAL APPROVED AND UPDATED RI-ISI PROGRAMS BY RISK CATEGORY - STP UNIT 2 Risk 1 Failure Potential Original Interval 3 Update Systm~ ~Consequence Rank Rank Degradation Weld RI-ISI Other(2 ) Weld R2)

Category Rank Count Count RI-ISI Othe Mechanism AFW 5a Medium Medium TASCS, T1 Medium 4 4 1 3 High FAC High AFW 5a Medium Medium TT Medium 8 8 1 3 High. FAC High 6a Low None Low AFW 63 Hig High Medium FAC FAC Hig High 133 0 337 5a Medium Medium TASCS Medium High 13 2 18 2 3 High FAC FWS 6a Low Medium None Low High 107 0 133 3 High FAC MSS 6a Low Medium None Low 201 0 201 SLS 7d Low None None Low 8 0 8 CVCS 5a Medium Medium TT Medium 0 0 2 1 CVCS 6a Medium Low TT Medium 0 0 2 CVCS 6b Low Low TT Medium 0 0 8 CVCS 7a Low Low None Low 0 0 36 TOTAL NUMBER OF WELDS 2042 64 2498 69 change from original: 456 5 Notes 1 System designations are defined in Table 2.

2 This column is generally used to identifyaugmented inspection program locations that are credited beyond those locations selected per the RI-ISI process, as addressed in Section 3.6.5 of EPRI TR-1 12657. This option is not applicable for the STP RI-ISI application. The "Other' column is retained in this table solely for uniformity purposes with other RI-ISI application template submittals.

PWSCC = pressurized water stress corrosion cracking TASCS = thermal stratification, cycling, and striping TT = thermal transient FAC = flow-accelerated corrosion

Attachment NOC-AE-1 1002705 Page 11 of 11 TABLE 5 DEFINITION OF RISK CATEGORIES (ASME CODE CASE N-578-1)

RISK CATEGORY RISK RANK PIPE RUPTURE POTENTIAL CORE MELT POTENTIAL 1 HIGH HIGH HIGH 2 HIGH MEDIUM HIGH 3 HIGH HIGH MEDIUM 4 MEDIUM LOW HIGH 5a MEDIUM MEDIUM MEDIUM 5b MEDIUM HIGH LOW 6a LOW LOW MEDIUM 6b LOW MEDIUM LOW 7a LOW LOW LOW 7b LOW HIGH NONE 7c LOW MEDIUM NONE 7d LOW LOW LOW

Retrieved from "https://kanterella.com/w/index.php?title=NOC-AE-11002705,_Request_for_Relief_to_Apply_an_Alternative_to_the_ASME_Section_Xl_Code_Requirements_for_Examination_of_Class_1_and_Class_2_Piping_Welds_(Relief_Request_RR-ENG-3-04)&oldid=2113007"