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UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF NUCLEAR REACTOR REGULATION WASHINGTON, D.C. 20555 April 27, 1992 NRC INFORMATION NOTICE 92-31: ELECTRICAL CONNECTION PROBLEM IN JOHNSON YOKOGAWA CORPORATION YS-80 PROGRAMMABLE INDICATING CONTROLLERS 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 inform addressees of a potential electrical connection problem in the read only memory (ROM) chip sockets of Johnson Yokogawa Corporation (JYC) YS-80 programmable indicating controllers (controllers). It is expected that recipients will review the information for applicability to their facilities and consider actions, as appropriate. However, no specific action or written response is required. Description of Circumstances In July 1991, Yokogawa Electric Corporation (YEC), parent company of JYC, issued engineering service note (ESN) 102E, "Troubleshooting of User ROM Socket for YS-80 Programmable Instruments." In ESN-102E, YEC stated that YS-80 controller models SLPC*E, SLMC*E, SCMS*E, and SPLR*B had ROM sockets that did not properly engage ROM pins when the ROM was installed in the socket. YEC stated that the problem was caused by the material of the ROM socket wear plate blades. This material did not exhibit sufficient spring pressure to adequately engage the ROM pins when the ROM was mounted in the socket, which could cause an intermittent or inadequate electrical connection when the ROM was mounted and locked in its socket. JYC has distributed a letter to its sales representatives to inform them of the concern. The YEC design staff in Nakacho, Musashino-Shi, Tokyo, Japan, discovered this problem while redesigning and improving the YS-80 controller. YEC determined that any of its YS-80 controllers could exhibit this problem. In ESN-102E, YEC listed the following symptoms of the problem: (1) the fail lamp illuminates and the controller displays check codes "10," "00," and "04" and (2) the digital input is not being sent to the controller, but the instrument is operating as if receiving input. YEC stated that the symptoms of the problem could differ depending on the program in the ROM. 9204210362 . IN 92-31 April 27, 1992 Page 2 of 2 Discussion The NRC staff was informed of this problem in a December 23, 1991, letter from Spectrum Technologies USA, Incorporated (Spectrum), and a January 7, 1992, letter from Nutherm International, Incorporated (Nutherm). Nutherm supplied a total of 22 YS-80 controllers (models SLPC-271*E and SLPC-281*E) to the Commonwealth Edison Company, and Spectrum supplied 26 YS-80 controllers (model SLPC-281*E) to the Tennessee Valley Authority. Both vendors informed the affected licensees of the problem. JYC recommended that users not make any field changes to the ROM socket because this action could damage the interfacing printed circuit board. Instead, JYC suggests that applicable NRC licensees contact Mr. John Jerman, Manager of JYC's Technical Assistance Center, at (404) 254-0400, extension 137, for further assistance and information. This information notice requires no specific action or written response. If you have any questions about the information in this notice, please contact the JYC staff member listed above, one of the technical contacts 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 contacts: Randolph N. Moist, NRR (301) 504-2981 Joseph J. Petrosino, NRR (301) 504-2979 Attachment: List of Recently Issued NRC Information Notices .
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