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Information Notice No. 79-25, Reactor Trips at Turkey Point Units 3 and 4
IN79025 UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 September 28, 1979 MEMORANDUM FOR: B. H. Grier, Director, Region I J. P. O'Reilly, Director, Region II J. G. Keppler, Director, Region III K. V. Seyfrit, Director, Region IV R. H. Engelken, Director, Region V FROM: Norman C. Moseley, Director, ROI, IE SUBJECT: Information Notice No. 79-25, REACTOR TRIPS AT TURKEY POINT UNITS 3 AND 4 The subject document is transmitted for issuance on October 1, 1979. The Information Notice should be issued to all power reactor facilities with an operating license or a construction permit. Also enclosed is a draft copy of the transmittal letter. No inspection followup is necessary since no action by the licensee is requested. Norman C. Moseley, Director Division of Reactor Operations Inspection Office of Inspection and Enforcement Enclosures: 1. Draft Transmittal Letter 2. Information Notice No. No. 79-25 CONTACT: J. W. Craig, IE 49-28019 . (Draft letter to all power reactor facilities with an operating license or a construction permit) Information Notice No. 79-25 Addressee: This Information Notice is provided as an early notification of a possibly significant matter. It is expected that recipients will review the information for possible applicability to their facilities. No specific action or response is requested at this time. If further NRC evaluations so indicate, an IE Circular, Bulletin, or NRR Generic Letter will be issued to recommend or request specific licensee actions. If you have questions regarding the matter, please contact the Director of the appropriate NRC Regional Office. Sincerely, Signature (Regional Director) Enclosures: 1. Information Notice No. No. 79-25 2. List of IE Information Notices Issued in Last Six Months . Accession No.: 7908220125 SSINS No.: 6870 UNITED STATES NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C. 20555 October 1, 1979 Information Notice No. 79-25 REACTOR TRIPS AT TURKEY POINT UNITS 3 AND 4 Background On August 3, Turkey Point Units 3 and 4 tripped while operating at full power. A voltage spike on a second protection channel caused Unit 4 to trip during surveillance testing on the reactor protection system. This resulted in a loss of offsite power and subsequent shedding of non-essential loads. Unit 3 tripped as the result of high coolant pressure caused by a turbine runback. Discussion While performing a periodic test on channel "C" of the T-Average and Delta T Protection Channels, a spurious signal on channel "A" completed a 2 out of 3 trip logic: tripping Unit 4. This resulted in a loss of offsite power condition for Unit 4. At this time, the Unit 4 startup transformer was out of service due to performance of periodic maintenance. This condition caused the initiation of the emergency diesel generator load sequencer which resulted in the shedding of non-vital loads. Among the non-vital loads shed, were those on Motor Control Center (MCC) "D" which is common to both units. Since the Rod Position Indication System for both units is powered by the non-vital portion of MCC-D, a turbine runback on Unit 3 was initiated upon loss of rod position indication. This resulted in a reactor trip on high pressurizer pressure. At the time, neither of the two pressurizer spray valves was available. One was considered inoperable prior to the transient and the other, temporarily powered by the non-vital portion of MCCD, had become unavailable earlier as a consequence of the Unit 4 trip. A subsequent review disclosed inadequacies in the administrative controls over the correction of operational problems exhibited by spray valve PCV-3-455B. The original Hagan controller for spray valve PCV-3-455B had been disconnected and was replaced by another manual controller which was plugged into the valve control circuit and which had been taped to the top of a console in the main control room. The actual installation of the manual controller was not performed under established guidelines. Additionally, no temporary procedure had been issued to ensure consistent understanding between shifts of the operational control of this unusual component configuration. . Information Notice No. 79-25 October 1, 1979 Page 2 of 2 Thus, failure to establish guidelines and procedures resulted in unnecessary challenges to the reactor protection system. The subsequent transient resulted in needless thermal stress cycles on the reactor coolant system and its components. If plant procedures had been followed, or if the Rod Position Indication System had been a vital load this transient would have been prevented. All holders of operating licenses or construction permits should ensure that temporary procedures for plant changes and modifications are established and followed as required.
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