Information Notice 1980-03, Main Turbine Electrohydraulic Control System

Main Turbine Electrohydraulic Control System

ML031180116
Person / Time
Issue date:	01/31/1980
From:	NRC/OI
To:
References
IN-80-003, NUDOCS 7912190666
Download: ML031180116 (3)

UNITED STATES

SSINS No.: 6870

NUCLEAR REGULATORY COMMISSION

Accession No.:

OFFICE OF INSPECTION AND ENFORCEMENT

7912190666 WASHINGTON, D.C.

20555

January 31, 1980

IE Information Notice No. 80-03

Description of Circumstances

On September 6, 1979, while performing a routine startup of the Trojan Nuclear

Plant, a speed control problem was encountered during warmup of the General

Electric turbine and increase of turbine speed to normal operating speed

(1800 RPM). Technicians were notified and trouble shooting in accordance with

the technical manual was commenced to resolve the apparent oscillation between

the primary and backup speed control circuits which was hindering normal turbine

startup operations. The technical manual indicates that it is permissible to

remove either the primary or backup low value gate circuits which contain speed

and acceleration error amplifiers.

Upon removal of the primary low value gate

circuit card, the backup card amplifiers, coming from a saturated condition, became the controlling circuit. During the shift in control circuits (primary to

backup), the speed/acceleration error signal went to maximum which resulted in

a full open signal to the turbine control valves.

Under existing plant conditions

this appeared to the safety injection system as a major steam break downstream of

the main steam isolation valves which resulted in a safety injection system

actuation and reactor trip.

The Electrohydraulic Control System (EHC) technical manual indicated that slight

load changes are likely when a low value gate card is removed. The effect on an

unloaded turbine appears to be much more significant and tests conducted by

• GEK Instruction Book 11381-D, "Speed Control Unit", Maintenance Section, Page 4.

IE Information Notice No. 80-03 January 31, 1980 Trojan personnel indicate that the transient is initiated whether the turbine is

at a set speed or in an acceleration mode to a set speed. Discussions with General

Electric personnel by the licensee have been initiated in an attempt to verify

the phenomenon observed and, if applicable, alert other facilities which operate

a turbine with a M1K 1 EHC System regarding the potential operation of the control

valves when trouble shooting the speed control unit in accordance with existing

instructions.

This information is provided as an early notification of a possible 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 or Bulletin

will be issued to recommend or request specific licensee actions.

If you have

questions regarding this matter, please contact the Director of the appropriate

NRC Regional Office.

Enclosure:

List of Recently Issued

IE Information Notices

IE Information Notice No. 80-03

January 31, 1980

Enclosure

RECENTLY ISSUED

IE INFORMATION NOTICES

Information

Notice No.

Subject

Date

Issued

80-02

80-01

8X8R Water Rod Lower

End Plug Wear

Fuel Handling Events

Cracking in Low Pressure

Turbine Discs

1/25/80

1/4/80

Issued To

All BWR Facilities

holder power reactor

OLs or CPs

All holders of power

reactor OLs and CPs

79-37

12/28/79

All power reactor OLs

and CPs

79-36

79-35

Computer Code Defect in

Stress Analysis of Piping

Elbow

Control of Maintenance

and Essential Equipment

12/31/79

All power reactor

and CPs

12/31/79

All power reactor

with an OL or CP

OLs

facilities

79-34

79-33

79-32

79-31

79-30

79-29

Inadequate Design of

Safety-Related Heat

Exchangers

Improper Closure of

Primary Containment

Access Hatches

Separation of Electrical

Cables for HPCI and ADS

Use of Incorrect Amolified

Response Spectra (ARS)

Reporting of Defects and

Noncompliance, 10 CFR Part 21.

Loss of NonSafety-Related

Reactor Coolant System

Instrumentation During

Operation

12/27/79

All holders of power reactor

OLs and CPs

12/21/79

All power reactor facilities

holding OLs and CPs

12/21/79

All power reactor facilities

holding OLs and CPs

12/13/79

All holders of power reactor

OLs and CPs

12/6/79

All power reactor facilities

holding OLs and CPs and

vendors inspected by LCVIP

11/16/79

All power reactor facilities

holding OLs or CPs