United States Nuclear Regulatory Commission - Protecting People and the Environment

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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