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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