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NRC Section XI Report - September 2004

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Presented By: Mr. Wally Norris, United States Nuclear Regulatory Commission


NRC Report
Section XI
September 2004

1. Amendments to 10 CFR 50.55a

 

The final amendment to 10 CFR 50.55a incorporating the 1997 Addenda through 2000 Addenda by reference was published on September 26, 2002 (67 FR 60520) and is available at the Office of Federal Register website: http://www.access.gpo.gov/su_docs/fedreg/a010803c.html.

 

A proposed rule to amend 10 CFR 50.55a to incorporate by reference the 2001 Edition through 2003 Addenda of the ASME Code was published in the Federal Register on January 7, 2004 (69 FR 879).  The public comment period ended on March 22, 2004.  Fifteen comment letters were received.  The NRC staff has developed responses to the comments and modified the proposed rule based on some comments.  The final rule is scheduled to be published in September 2004.

 

2. ASME Code Cases - Rulemaking/Regulatory Guides

 

Three draft regulatory guides were published for public comment on August 3, 2004: Proposed Revision 33 to Regulatory Guide 1.84, “Design, Fabrication, and Materials Code Case Acceptability, ASME Section III [ADAMS Accession Number ML040850299]; Proposed Revision 14 to Regulatory Guide 1.147, “Inservice Inspection Code Case Acceptability, ASME Section XI, Division 1 [ML040850346]; and Proposed Revision 1 to Regulatory Guide 1.193, “ASME Code Cases Not Approved for Use [ML040850236].”  The guides address Code Cases in Supplement 12 to the 1998 Edition through Supplement 6 to the 2001 Edition.  The Proposed Rule incorporating the Section III and Section XI regulatory guides was also published on August 3, 2004 [69 FR 46452].  The public comment period for the regulatory guides closes on September 2, 2004, and on October 18, 2004, for the proposed rule.  The “Evaluation of Code Cases,” that is attached to the proposed rule, discusses the staff’s basis for any proposed conditions to Code Cases.

 

The NRC staff has completed its review of the Code Cases in Supplement 7 through Supplement 12 to the 2001 Edition.  Draft Revision 34 to RG 1.84, Draft Revision 15 to RG 1.147, and Draft Revision 2 to RG 1.193 are presently being reviewed by the cognizant NRC offices.  These guides would be published for public comment shortly after the guides discussed in the above paragraph are published final.

 

3. Risk-Informed Activities

 

Plan for Phased Approach to PRA Quality Drafted

 

On December 18, 2003, the Commission issued a Staff Requirements Memorandum (SRM) (COMNJD‑03‑2003) that directs the staff to develop an action plan for implementing a phased approach to PRA quality.  An attachment to the memorandum outlines the Commission's expectations for each of the four phases.  On July 13, 2004, the staff forwarded SECY‑04‑0118, "Plan for the Implementation of the Commission's Phased Approach to Probabilistic Risk Assessment Quality," and an attached Action Plan, "Stabilizing the PRA Quality Expectations and Requirements," to the Commission.  The SECY and Attachment are available on the public web site and in ADAMS under ML041470505 and ML41530099 respectively.  In the plan, PRA quality is defined as having three aspects:  the scope of risk contributors addressed (full power, low power and shutdown modes of operation, internal initiating events, and external initiating events), the level of detail, and the technical adequacy of the model.  PRA of sufficient quality to support an application need only have the scope and level of detail sufficient to support that application, but it must always be technically adequate.

 

The plan covers the first three phases defined in the SRM, and identifies the activities required to support implementation.  The feasibility of a fourth phase will be assessed following achievement of Phase 3.  The phases are achieved for specific risk‑informed activities when guidance documents are available to support those activities, and in particular to address the issue of the quality of PRA necessary to support the activities.  Phase 1 represents the current situation, where guidance on PRA quality is general.  Phase 2 takes advantage of the work that has been performed to develop PRA standards.  Phase 2 occurs when there are PRA standards and the associated regulatory guides in place to address those PRA scope items that are significant to an activity.  To be in Phase 2, the PRA is expected to be in conformance with the published standards.  The PRA standards are being developed on different schedules.  As a result, the risk‑informed activities will transition to Phase 2 on different schedules according to which scope items are significant to the decision.  Phase 3 provides a regulatory framework for the development of a PRA that will be of sufficient quality to support all current and anticipated activity.  Phase 3 will be completed by December 31, 2008.

 

The NRC website contains information at http://www.nrc.gov/what-we-do/regulatory/rulemaking/risk-informed/reactor-safety.html relative to risk-informed activities in the Reactor Safety Arena.

 

IMPORTANT NOTE:  The appropriate level of quality of the PRA's used to support the applications envisioned by ASME Code Cases should be consistent with RG 1.200 as necessary to support the phased approach to PRA quality outlined in COMNJD-03-0002.  PRA quality considerations unique to ASME Code Cases arise from the ability of licensees to implement staff approved Code Cases without prior staff review and approval of the proposed change.  The ASME is encouraged to provide comments to the staff on the draft plan.

 

Risk Management Coordinating Committee (RMCC)

 

The formation of this committee is jointly proposed by the ASME, American Nuclear Society, and the NRC.  The committee will coordinate codes and standards activities associated with risk management for current and new nuclear power plants, nuclear facilities, and the transportation and storage of nuclear material.  Since the organization meeting on February 20, 2004, the Committee has assembled a draft charter, begun the process of nominating members of the committee, and has started to prioritize potential risk informed standards development projects.  On May 20, 2004, NRMCC held its second meeting by telephone conference.  At the May 20 meeting discussions included the Committee Charter, Draft Strategic Plan, and the concept of a single standard or "framework" that would include requirements for all PRAs; i.e. Level 1, 2 , and 3 PRAs.  NRMCC agreed to form a small Task Group to study the single standard concept.  The Task Group will be charged with having a first draft of the results of its study by the next meeting to be held on  September 9, 2004, at the ASME Washington D.C. Headquarters.

 

4. Generic Activities on PWR Alloy 600/182/82 PWSCC

 

On August 6, 2004, a Staff Requirements Memorandum was issued on SECY-04-115, “Rulemaking Plan to Incorporate First Revised Order EA-03-009 Requirements into 10 CFR 50.55a.”  The Commission approved Option 3 of the rulemaking plan - evaluate the anticipated ASME reactor pressure vessel inspection requirements for incorporation into 10 CFR 50.55a.

 

On July 30, 2004, NRC staff met with representatives from NEI, EPRI, MRP, and industry to discuss the industry’s Safety Assessment for Alloy 82/182 Butt Welds including a review of actions recommended by MRP for industry and results of field inspections.  The information is provided in MRP-113 which has been submitted to NRC for information.  The industry presentation included an overview of the content of MRP‑113, a summary of butt weld locations, a description of field experience, safety assessment calculations, safety assessment conclusions, leak before break strategy, and status of development of the butt weld inspection and examination guidelines.  The MRP has concluded that there is not an immediate safety concern, and that “Needed” actions for visual inspection of Alloy 82/182 butt welds have been issued under NEI 03-08 (“Needed” is an NEI 03-08 category).  Inspection and examination guidelines are being developed.  Industry plans to meet with NRC to review their approach and obtain feedback in the Fall of 2004.  NEI\MRP plans to issue “Mandatory” requirements under NEI 03-08 when the inspection and examination guidelines are ready.  The NRC staff is reviewing the MRP-113 information provided in detail.

 

On July 19, 2004, NRC staff held a teleconference with representatives of EPRI, MRP, NEI, and industry to discuss the status of the industry’s safety assessment and recommendations for the detection and control of leakage and corrosion of the bottom reactor vessel head and nozzle penetration areas.  The slides provided by industry are in ADAMS under accession number ML042020010.

 

The industry presented information on the bottom mounted nozzle (BMN) nondestructive examination (NDE) demonstration program, the BMN safety assessment plan, the integrated inspection plan, and the BMN strategic plan.  Industry reported it was continuing to develop the elements of the safety assessment plan for BMN and provided details of the ongoing efforts of the Westinghouse and the Babcock and Wilcox Owners Groups.  Industry presented a list of plants that plan to conduct BMN volumetric examinations during upcoming outages through the Spring of 2005 outage season.  Regarding BMN repair techniques, industry indicated that commercial techniques were available and it was not necessary to develop new techniques.  Industry expects to have its final BMN inspection strategy and final BMN safety assessment completed in the Spring of 2006.

 

On April 14, 2004, NRC staff met with representatives of NEI, MRP, and industry to discuss the industry’s safety assessment for reactor vessel upper head penetrations.  The viewgraphs from the meeting may be accessed through the NRC ADAMS document management system via Accession Numbers ML041060132, ML041060166, ML041060218, ML041060234, ML041060249, ML041060396,  ML041060402, and ML041060407.  Industry indicated it would be submitting proprietary and non‑proprietary versions of MRP‑110, "Reactor Vessel Closure Head Penetration Safety Assessment for US PWR Plants," and MRP‑111, "Resistance to PWSCC of Alloys 690, 52, and 152 in PWRs," for NRC staff review.

 

MRP‑110 conclusions were that: (1) nozzle ejection and head wastage are the major potential safety concerns; (2) a third concern is the generation of loose parts which helps to set the required inspection area for periodic nonvisual inspections; (3) axial cracking leading to nozzle rupture is not a credible failure mechanism; (4) significant margin exists against nozzle ejection; (5) periodic bare metal visual examinations provide assurance against significant vessel head wastage; (6) a program of nonvisual nondestructive examination (NDE) and bare metal visual examination would provide adequate protection against safety‑significant failures; (7) PFM analysis (MRP‑105) shows a low probability of pressure boundary leakage; and (8) the MRP inspection plan under development will define appropriate inspection intervals, coverage, and characteristics.

 

Regarding the resistance to PWSCC of Alloys 690, 52, and 152 compared to Alloys 600, 82, and 182, laboratory test results and recent industry experience all indicate significantly superior resistance to PWSCC for Alloys 690, 52, and 152.  Analysis of laboratory test data indicate an improvement factor for time to initial failure of 26.5 relative to Alloy 600 mill annealed and 13.3 relative to Alloy 600 thermally treated.  Field experience with Alloy 690 and its weld metals have shown no indication of degradation from PWSCC in over 10 years.  Industry concluded that the data indicates it is very unlikely that Alloy 690 and its weld metals would develop PWSCC during extended plant life (60 plus years).

 

5. Examination Requirements for Cast Austenitic Piping Welds Greater Than 2 inches Thickness

 

Efforts to develop qualification requirements for Appendix VIII, Supplement 9, “Cast Stainless Steel,” have been hindered by the current difficulties in volumetrically examining cast austenitic stainless steel (CASS) piping from the outside diameter (OD).  Under sponsorship of the NRC, Pacific Northwest National Laboratory (PNNL) has been conducting a series of studies on twenty  PNNL and Westinghouse Owners Group (WOG) specimens using eddy-current examination (ET) from the inside diameter (ID) of the specimens.  This has been shown to be quite successful as all of the cracks were detected and length sized to standards contained in Appendix VIII.  Thus, preliminary tests indicate that this surface examination method may prove to be very effective at detecting surface breaking cracks.

 

PNNL has begun conducting Low Frequency (LF) Synthetic Aperture Focusing Technique (SAFT) and phased array examination of the WOG specimens from the OD.  ET scans on CASS surge line piping has been conducted to assess the background noise level of this pipe material.  It is not as “noisy” as the worst CASS in the WOG specimens but is noisier than the quiet WOG CASS material and the PNNL material.  A ring specimen cut off a pipe (on loan from the EPRI NDE Center) from a canceled plant is being polished to etch the grain structure and photograph to document the microstructure.  This pipe specimen will then be examined using both LF-SAFT and phased array.  ET scans of the ID of the pipe specimen will be conducted to determine the noise properties and to perform UT scans to assess the coherent noise properties for UT.  Based on these measurements, a determination will be made as to the best path forward.  PNNL staff will be making a presentation to the Section XI Working Group Procedure Qualification and Volumetric Examination and Working Group Personnel Qualification and Surface Visual Examination and Eddy Current Examination at the September 2004 meetings in New Orleans.


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