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UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C. 20555 January 3, 1992 NRC INFORMATION NOTICE 92-02: RELAP5/MOD3 COMPUTER CODE ERROR ASSOCIATED WITH THE CONSERVATION OF ENERGY EQUATION Addressees All holders of operating licenses or construction permits for nuclear power reactors. Purpose The U.S. Nuclear Regulatory Commission (NRC) is issuing this information notice to alert addressees of an error in the RELAP5/MOD3 computer code associated with the conservation of energy equation. The computer codes in the RELAP5 Series are general purpose, thermal hydraulic system codes used to simulate the response of systems such as the reactor coolant system (RCS) to transients and accidents. 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 On November 25, 1991, Northeast Utilities forwarded the enclosed 10 CFR Part 21 initial notification to the NRC Operations Center, regarding an error in the RELAP5/MOD3 simulation of the response of the Haddam Neck Plant terry turbine room to a postulated steam line break. The equipment environmental qualification (EEQ) profile for the room would have been nonconservative by approximately 100�F had the simulation been accepted. Although the error in determining the environmental conditions could be significant, the effect of the error on the evaluation of the nuclear steam supply system (NSSS) response to a loss-of-coolant accident (LOCA) and steam line break has been determined to be negligible. Appropriate corrections in the code are the responsibility of the Idaho National Engineering Laboratory (INEL). Codes in the RELAP5 Series are not intended to be used as containment analysis codes. Containment analysis specific codes exist for that purpose. The primary purpose of the RELAP5 codes is analysis of the response of the NSSS to accident and transient conditions. 9112270227 . IN 92-02 January 3, 1991 Page 2 of 2 This information notice requires no specific action or written response. 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. Charles E. Rossi, Director Division of Operational Events Assessment Office of Nuclear Reactor Regulation Technical contact: Nancy Campbell, NRR (301) 504-2836 Attachments: 1. Northeast Utilities 10 CFR Part 21 Notification 2. List of Recently Issued NRC Information Notices .
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