- About NRC           - The Commission
      - Statutory Authority
      - Strategic Plan
      - Budget &  Performance
      - Organization & Functions
      - Locations
      - History
      - Values
      - Policymaking
      - Radiation Protection
      - Fire Protection
      - How We Regulate
      - Grants
      - Civil Rights
      -     
    - NuclearReactors           - Operating Reactor Locations
      - Reactor Quick Links
      - Power Reactors
      - Research and Test Reactors
      - Operating Reactors
      - Operator Licensing
      - New Reactors
      - Operator Licensing for New Reactors
      - Reactor Safety Research
      - Advisory Comm (ACRS)
      - Decommissioning of Nuclear Facilities
      -     
    - NuclearMaterials           - Fuel Cycle Facility Locations
      - Uranium Recovery Locations
      - Materials Quick Links
      - Special Nuclear Material
      - Source Material
      - Byproduct Material
      - Med, Academic & Ind Uses
      - Source Materials Facilities
      - Uranium Recovery
      - Fuel Cycle Facilities
      - Materials Transportation
      - Materials Research
      - Advisory Comm (ACMUI)
      - Decommissioning of Nuclear Facilities
      - Materials Environmental Reviews
      -     
    - RadioactiveWaste           - Waste Quick Links
      - Low-Level Waste
      - Waste Incidental to Reprocessing
      - Incidental Waste Criteria
      - High-Level Waste
      - Uranium Mill Tailings
      - LLW Disposal
      - HLW Disposal
      - Spent Fuel Storage
      - Spent Fuel Transport
      - Waste Research
      -     
    - NuclearSecurity           - Security Spotlight
      - NRC Responsibilities
      - Domestic Safeguards
      - Radioactive Material Security
      - Facility Protection
      - Nuclear Material Control
      - International Safeguards
      - Information Security
      - Emergency Preparedness
      - &;   
    - Public Meetings& Involvement           - Public Meeting Schedule
      - Commission	    Schedule
      - Conferences & Symposia
      - Documents for Comment
      - Brochures & Fact Sheets
      - Involving Stakeholders
      - Info Quality Guidelines
      - Rulemaking Process
      - Licensing
      - Enforcement
      - Hearing Process
      - Hearing Applications
      -     

**UNITED STATESNUCLEAR REGULATORY COMMISSIONOFFICE OF NUCLEAR REACTOR REGULATIONWASHINGTON, D.C. 20555-0001**

December 1, 1998

**Addressees**

All holders of operating licenses for nuclear power reactors.

**Purpose**

The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert addressees to certain aspects ofrequesting relief from American Society of Mechanical Engineers Boiler and Pressure Vessel Code (ASME Code)examinations that received less than "essentially 100 percent" coverage. ("Essentially 100 percent" examination is definedas more than 90 percent of the specified examination volume.) It is expected that recipients will review the information forapplicability to their facilities and consider actions, as appropriate, to avoid similar problems. However, suggestionscontained in this information notice are not NRC requirements; therefore, no specific action or written response is required.

**Description of Circumstances**

It became evident to the NRC staff while it was conducting inservice inspections (ISI) reviews of licensees' 90-day ISIreports that some licensees were unaware of, uncertain of, or had misinterpreted the Title 10 of the Code of FederalRegulations 50.55a(g)(4) (10 CFR 50.55a(g)(4)) requirements regarding the examination of components to the extentpractical within the limitations of design, geometry, and materials of construction of the components. Licensees should becognizant of 10 CFR 50.55a(g)(5)(iii) which requires submittal of requests for relief from paragraph 50.55a(g)(4) whencomplete examination coverage(s) is impractical. Because of the scope and extent of ISI examinations, significant planningis necessary to address the technical and regulatory issues associated with the examinations required by the ASME Code, tothe extent practical, of Class 1, 2, and 3 systems and components.

This information notice contains a discussion of certain areas of misinterpretation that the NRC staff has dealt with in theimplementation of the 10 CFR 50.55a(g)(4) rule.

**Discussion**

In 10 CFR 50.55a(g)(5)(iii), it is requested that requests for relief from limited examinations be submitted when it isimpractical to complete the examination coverage requirements of Section XI of the ASME Code. Recent NRC reviewsfound that several licensees did not submit requests for relief from examinations of less than essentially 100 percentcoverage. The licensees correctly interpreted 10 CFR 50.55a(g)(4) for Class 1, 2, and 3 components to mean that they wererequired to perform the ASME Code examinations to the extent practical. However, the licensees misinterpreted therequirement to mean that they were not required to submit requests for relief from examinations that received less thanessentially 100 percent coverage because they had examined the component to the extent practical.

At least one licensee quoted 10 CFR 50.55a(g)(4) as a basis for not seeking relief when unable to obtain the requiredexamination coverage. In 10 CFR 50.55a(g)(4) it is stated, in part, that "components. . . must meet the requirements. . . tothe extent practical within the limitations of design, geometry and materials of construction of the components." However,when incomplete or partial ISI examination coverage required by the ASME Code is obtained, NRC relief is requiredpursuant to 10 CFR 50.55a(g)(5)(iii).

During discussions with the NRC staff regarding its review of a 90-day ISI summary report, it was determined that alicensee had obtained "essentially 100 percent" coverage for most examinations but had obtained coverage of 90 percent orless on several components. Contrary to the requirements of the rule, the licensee did not submit requests for relief to theNRC on the basis of impracticality before 1 year after the end of the effective interval as required by 10 CFR50.55a(g)(5)(iv), until the NRC pointed out this omission.

**"Essentially 100 Percent" Examination Standard**

After many inquiries and interpretations, ASME issued ASME Code Case N-460, "Alternative Examination Coverage forClass 1 and 2 Welds," Section XI, Division 1, dated July 27, 1988. ASME Code Case N-460 states, in part, that "when theentire examination volume or area cannot be examined. . . a reduction in examination coverage . . . may be acceptedprovided the reduction in coverage for that weld is less than 10 percent. The NRC has adopted and further refined thedefinition of "essentially 100 percent" to mean "greater than 90 percent" in 10 CFR 50.55a(g)(6)(ii)(A)(2) for requiredexamination coverage of reactor pressure vessel welds. This standard has been applied to all examinations of welds or otherareas required by ASME Section XI.

Most licensees are finding that although the overall average examination coverage for all welds may be more than 90percent, examination coverage for other individual welds may be substantially less than 90 percent. When a licensee isunable to examine "essentially 100 percent" of each weld, it must seek relief from the NRC in accordance with 10 CFR50.55a(g)(5)(iii).

This information notice requires no specific action or written response. However, recipients are reminded that they arerequired to consider industry-wide operating experience (including NRC information notices), where practical, whensetting goals and performing periodic evaluations under 10 CFR 50.65, "Requirements for monitoring the effectiveness ofmaintenance at nuclear power plants." If you have any questions about the information in this notice, please contact thetechnical contact listed below or the appropriate Office of Nuclear Reactor Regulation (NRR) project manager.

Attachment:  List of Recently Issued NRC Information Notices

----