IE Circular No. 80-09, Problems with Plant Internal Communications Systems
SSINS No.: 6830 Accession No.: 8002280663 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555 April 28, 1980 IE Circular No. 80-09 PROBLEMS WITH PLANT INTERNAL COMMUNICATIONS SYSTEMS Description of Circumstances at the Kewaunee Power Plant: On January 17, 1980, the Kewaunee Nuclear Power Plant lost offsite power to its 4160V non-safeguards buses. Since the system used for internal communications, paging and evacuation alarm purposes (Gai-tronics) was powered from a non-safeguards bus, plant communications were degraded during the outage. This degraded condition persisted until power was restored to the affected bus thru an emergency safeguards bus. While in the degraded mode, the licensee used two-way portable radios for internal communications. The radios performed satisfactorily, per se; however, when transmitting in the vicinity of certain electronic equipment, they induced false signals into the electronic equipment. Description of Circumstances at the Davis-Besse Power Station: On October 15, 1979, the Davis-Besse Power Station lost all offsite power. During the period when offsite power was not available, the licensee noted that the internal three digit telephones (GTE) would not function. In addition, the NRC "Red Phone" was subsequently reported to have been out of service. Other licensee phone systems (Gai-tronics and the outside four digit Ohio Bell phones) did work. Following this event, the licensee provided emergency power to its phones and the NRC took action through AT&T to provide emergency power to all Red Phones. (Note: Although the communications system at Davis-Besse was not designed to meet the single failure criterion, its FSAR states that the main internal communications system is supplied by two redundant power feeders from the uninterruptable instrumentation distribution panels.) RECOMMENDED ACTION FOR LICENSEES AND HOLDERS OF CONSTRUCTION PERMITS All licensees of nuclear power reactor and holders of construction permits should be aware of the potential problems described above. Because of the generic implications of the above problems, it is recommended that the following actions be considered: 1. Determine the source of power for plant internal communications systems; 2. Upgrade the internal communications systems to assure operability during the loss of offsite power or other foreseeable events; . IE Circular No. 80-09 April 28, 1980 Page 2 of 2 3. Determine whether any plant electronic equipment may be adversely affected by portable radio transmissions. This determination should include, but no be limited to, the computer system, electro-hydraulic system, and nuclear instrumentation system; and 4. Instruct employees on the use radios in areas susceptible to electro magnetic interference. No written response to this Circular is required; however, if additional information regarding these matters is required, contact the Director of the appropriate NRC Regional Office.
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