Information Notice No. 86-77: Computer Program Error Report Handling

                                                            SSINS No.: 6835 
                                                            IN 86-77       

                                UNITED STATES
                           WASHINGTON, D.C. 20555

                               August 28, 1986



All nuclear power reactor facilities holding a construction permit or an 
operating license and nuclear fuel manufacturing facilities. 


This notice is to alert addressees that errors are being identified in 
computer programs used during safety-related design activities. These design
activities, including facility modifications and reload calculations, may be
invalidated by errors found in computer programs used to support 
safety-related design calculations. While these errors are contained in 
error reports prepared by computer service bureaus, licensees using the 
program as a basis for safety-related activities may not be aware that a 
significant number of errors are being identified. It is expected that 
recipients will review the information for applicability to their quality 
assurance programs 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; therefore, no 
specific action or written response is required. 

Description of the Circumstance: 

During reviews of the implementation of computer program error report 
handling procedures at various architect engineering companies (A/Es), 
nuclear steam supply system companies (NSSS), and nuclear fuel manufacturing
facilities, the NRC has learned that there are a significant number of 
errors being gound in computer programs used for safety-related design. 
Further users (Licensees, A/E's) may not be implementing appropriate 
measures to ensure that these errors do not invalidate safety related 
calculations already completed, in progress, or to be conducted at a further 

The computer program errors have usually been found by individual program 
users and reported to the computer service bureaus which subsequently report
these errors to all customers using the program, provided that the 
requirements of 10 CFR 21 are specified in contracts between the service 
bureaus and affected customers. 

                                                           IN 86-77       
                                                           August 28, 1986 
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A computer program is a basic component use in 10 CFR 21 when used in a 
safety-related design activities. In addition, control measures are required
to prevent the use of incorrect or defective material, parts, and components
as discussed in Criterion VIII of Appendix B to 10 CFR 50. Similarly, 
measures are required to ensure that conditions adverse to quality, such as 
deficiencies and nonconformances, are promptly identified and corrected as 
discussed in Criterion XVI, appendix B, 10 CFR 50. 

Utilities holding a CP or OL have the primary responsibility to ensure that 
computer code errors are adequately reviewed and their impact on past and 
present safety-related design calculations are evaluated. 

As an example, a recent 10 CFR 21 report to the NRC identified an error in 
the Rayleigh frequency calculation contained in the GT STRUDL computer code 
which resulted in numerous safety-related systems having to be reanalyzed. 
The error was found during performance of an analysis check on a previously 
completed Duct Support and was related to the method used by the program to 
select seismic design loads. The code, marketed by the Control Data 
Corporation (Service Bureau) and technically supported by its author, 
Georgia Institute of Technology, is used throughout the nuclear industry, 
primarily in the analysis and design of pipe supports and general building 
structural design. A thorough review and evaluation of affected designs, in 
addition to applicable vendors that may have used GT STRUDL in 
safety-related applications, is currently being performed by several CP 
holders. One CP holder recently reported that this error affected 960 
calculations. However, program users and Service Bureau subscribers such as 
Licensees, A/E's and NSSS organizations who did not specify the requirements 
of 10 CFR 21 in their contract with the service bureau may not be aware of 
this error. 

Another example involved the discovery by a nuclear fuels manufacturer of an 
input error in a loss-of-coolant-accident (LOCA) code used to calculate the 
effects of fuel rod heatup. This computer code error was identified during 
performance of a fuel reload analysis. The error resulted in the value of 
fuel rod decay heat generation being too low, causing the calculated peak 
cladding temperature (PCT) to be unconservative. Corrected calculations 
showed that the value of PCT exceeded 2200F, resulting in several 
licensees having to reduce power to comply with the provisions of 10 CFR 

Several documents are available which may be useful to licensees when 
reviewing computer code control used by vendors engaged in safety-related 
activities. NUREG-0040, "Licensee Contractor and Vendor Inspection Status 
Report," published quarterly by the NRC provides a detailed, technical and 
programmatic review of organizations engaged in supplying safety-related 
equipment or services to licensed facilities. This NUREG discusses important
plant safety elements, including computer code usage, maintenance, and error
report handling, for firms such as NSSSs, AEs, and nuclear fuel suppliers. 
Documents that also may be 

                                                           IN 86-77       
                                                           August 28, 1986 
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useful include IE Information Notices Nos. 85-52, "Errors In Dose Assessment
Computer Codes and Reporting Requirements Under 10 CFR Part 21" (July 10, 
1985) and 83-31, "Error in the ADLPIPE Computer Program" (May 19, 1983). 
These two notices focus primarily on computer code errors and 10 CFR 21 
reporting responsibility. 

No specific action or written response is required by this information 
notice. If you have any questions regarding this matter, please contact the 
Regional Administrator of the appropriate NRC regional office or this 

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

Technical Contact:  R. Pettis, Jr., IE
                    (301) 492-9039

Attachments: List of Recently Issued IE Information Notices

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