Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
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
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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
Attachment:
List of Recently Issued Information Notices
