Information Notice 1979-25, Reactor Trips at Turkey Point Units 3 & 4

Reactor Trips at Turkey Point Units 3 & 4

ML031180174
Person / Time
Site:	05000000
Issue date:	10/01/1979
From:	NRC/IE
To:
References
IN-79-025, NUDOCS 7908220125
Download: ML031180174 (4)

Accession No.: 7908220125 SSINS No.: 6870

UNITED STATES

NUCLEAR REGULATORY COMMISSION

OFFICE OF INSPECTION AND ENFORCEMENT

WASHINGTON, D.C. 20555 October 1, 1979 IE Information Notice 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 condi- tion 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 avail- able. 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.

IE Information Notice No. 79-25 October 1, 1979 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 compo- nents. If plant procedures had been followed, or if the Rod Position Indica- tion 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.

JE Information Notice No. 79-25 Enclosure

October 1, 1979 LISTING OF IE INFORMATION NOTICES

ISSUED IN LAST SIX MONTHS

Information Subject Date Issued To

Notice No. Issued

79-05 Use of Improper Materials 3/21/79 All power reactor

in Safety-Related Components facilities with an

OL or CP

79-06 Stress Analysis of 3/23/79 All Holders of

Safety-Related Piping Reactor OL or CP

79-07 Rupture of Radwaste Tanks 3/26/79 All power reactor

facilities with an

OL or CP

79-08 Interconnection of 3/28/79 All power reactor

Contaminated Systems with facilities with an

Service Air Systems Used OL and Pu Processing

As the Source of Breathing fuel facilities

Air

79-09 Spill of Radioactively 3/30/79 All power reactor

Contaminated Resin facilities with an

OL

79-10 Nonconforming Pipe 4/16/79 All power reactor

Support Struts facilities with a

CP

79-11 Lower Reactor Vessel Head 5/7/79 All holders of Reactor

Insulation Support Problem OLs and CPs

79-12 Attempted Damage to New 5/11/79 All Fuel Facilities

Fuel Assemblies Research Reactors, and Power Reactors

with an OL or CP

79-13 Indication of Low Water 5/29/79 All Holders of Reactor

Level in the Oyster Creek OLs and CPs

Reactor

79-14 NRC Position of Electrical 6/11/79 All Power Reactor

Cable Support Systems Facilities with a

CP

79-15 Deficient Procedures 6/7/79 All Holders of Reactor

OLs and CPs

IE Information Notice No. 79-25 Enclosure

October 1 1979 LISTING OF IE INFORMATION NOTICES

ISSUED IN 1979 Information Subject Date Issued To

Notice No. Issued

79-16 Nuclear Incident at Three 6/22/79 All Research Reactors

Mile Island and Test Reactors

with OLs

79-17 Source Holder Assembly Damage 6/20/79 All Holders of Reactor

• Damage From Misfit Between OLs and CPs

Assembly and Reactor Upper

Grid Plate

79-18 Skylab Reentry 7/5/79 All Holders of Reactor

OLs

79-19 Pipe Cracks In Stagnant 7/17/79 All Holders of Reactor

Borated Water Systems At OLs and CPs

PWR Plants

79-20 NRC Enforcement Policy 8/10/79 All Holders of Reactor

NRC Licensed Individuals OLs and CPs and Production

Licensees with Licensed

Operators

79-21 Transportation and Commercial 9/7/79 All power and research

Burial of Radioactive Material reactors with OL's

79-22 Qualification of Control 9/14/799 All power reactor

Systems facilities with

operating licenses

and construction permits.

79-23 Emergency Diesel Generator 9/25/79 All power reactor

Lube Oil Coolers facilities holding OLs

and CPs

79-24 Overpressurization Of 10/01/79 All power reactor facilities

Containment Of A PWR Plant with a OL or CP

After A Main Stream Line

Break