Protecting People and the EnvironmentUNITED STATES NUCLEAR REGULATORY COMMISSION
SSINS No.: 6835
IN 86-77
UNITED STATES
NUCLEAR REGULATORY COMMISSION
OFFICE OF INSPECTION AND ENFORCEMENT
WASHINGTON, D.C. 20555
August 28, 1986
Information Notice No. 86-77: COMPUTER PROGRAM ERROR REPORT HANDLING
Addressees:
All nuclear power reactor facilities holding a construction permit or an
operating license and nuclear fuel manufacturing facilities.
Purpose:
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
date.
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
Page 2 of 3
Discussion:
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
50.46.
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
Page 3 of 3
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
office.
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
