United States Nuclear Regulatory Commission - Protecting People and the Environment

Information Notice No. 84-54: Deficiencies in Design Base Documentation and Calculations Supporting Nuclear Power Plant Design

                                                            SSINS No.: 6835 
                                                            IN 84-54       

                                UNITED STATES
                        NUCLEAR REGULATORY COMMISSION
                    OFFICE OF INSPECTION AND ENFORCEMENT
                           WASHINGTON, D.C. 20555

                                July 5, 1984

Information Notice No. 84-54:   DEFICIENCIES IN DESIGN BASE DOCUMENTATION
                                   AND CALCULATIONS SUPPORTING NUCLEAR POWER
                                   PLANT DESIGN 

Addressees: 

All nuclear power reactor facilities holding a construction permit (CP) or 
an operating license (OL). 

Purpose: 

This information notice is provided to alert CP or OL holders to some recent
experiences during Integrated Design Inspections (IDIs) in which a common 
finding was deficiencies in design base documents and calculations 
supporting design of nuclear power plant structures, systems, and 
components. Recipients are expected to review the information for 
applicability to their facilities and consider actions, if appropriate, to 
preclude similar problems from occurring at their facilities. However, 
suggestions contained in this information notice do not constitute NRC 
requirements and, therefore, no specific action or written response is 
required. 

Description of Circumstances: 

Appendix B, "Quality Assurance Criteria for Nuclear Power Plants and Fuel 
Reprocessing Plants," to 10 CFR 50, "Licensing of Production and Utilization
Facilities," establishes overall quality assurance requirements for the 
design, construction, and operation of nuclear power plants. 

Regulatory Guide 1.64, Rev. 2, "Quality Assurance Requirements for the 
Design of Nuclear Power Plants," provides a method acceptable to the NRC 
staff for complying with the pertinent requirements of Appendix B to 10 CFR 
50 with respect to design activities. Regulatory Guide 1.64 endorses 
American National Standards Institute (ANSI) N45.2.11-1974, "Quality 
Assurance Requirements for the Design of Nuclear Power Plants," which 
states, in part, that "Applicable design inputs, such as design bases, 
regulatory requirements, codes and standards shall be identified, documented 
and their selection reviewed and approved." The ANSI N45.2.11 standard 
further states that "Design activities shall be documented in sufficient 
detail to permit verification ...." 

A common finding in IDIs conducted by the Office of Inspection and 
Enforcement has been deficiencies in design base documentation and 
calculations for nuclear power plant structures, systems, and components. In
some instances, the design activities were based on engineering judgments or
assumptions rather than supporting calculations. The problems primarily 
concern the availability of 

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                                                               IN 84-5   
                                                               July 5, 1984 
                                                               Page 2 of 2 

valid up-to-date calculations supporting the design rather than the design 
itself. In some instances, valid, up-to-date analyses were not available and
had to be generated or are being generated to substantiate the judgments or 
assumptions used in developing the final design. 

Examples of deficiencies in design base documentation and calculations 
follow: 

1.   Designers had made judgments that openings in the shear walls of the 
     auxiliary building were not sufficiently large so as to change the 
     distribution of forces in these walls. However, no evidence was found 
     as to how this judgment or other similar judgments were made. The 
     applicant is performing additional calculations to show that 
     redistribution of forces is not a significant effect for various cases 
     of wall openings. 

2.   Certain instrumentation set points associated with the auxiliary 
     feedwater (AFW) system were not supported by a formal calculation. 
     Specifically, the pump suction pressure set points to initiate 
     automatic transfer of AFW system fluid source and to provide protection 
     against pump cavitation were determined from an informal handwritten 
     sketch, which did not consider certain factors that would affect the 
     set points. Subsequently, a documented calculation was performed to 
     verify that the set points were consistent with system design 
     requirements. In addition, the applicant has indicated that it will 
     address the subject of basis for set points, set point accuracy 
     requirements, and basis for reset values on a generic basis for 
     safety-related instruments. 

3.   Independence of the instrumentation and control systems needed for 
     accident mitigation and safe plant shutdown had not been demonstrated.  
     Analyses of the plant design did not sufficiently consider the effects 
     of postulated failures of non-qualified, non-safety-related 
     instrumentation and controls on various plant systems.  The set 
     point/volume allowance calculations for the refueling water storage 
     tank contained many assumptions where justification was not provided.  
     This item is under review by the applicant.

If you have any questions regarding this matter, please contact the Regional 
Administrator of the appropriate NRC Regional Office or this office.


                                   Edward L. Jordan Director 
                                   Division of Emergency Preparedness 
                                     and Engineering Response 
                                   Office of Inspection and Enforcement 

Technical Contact:  H. Wang, IE
                    (301) 492-7226

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