ML19296C026
| ML19296C026 | |
| Person / Time | |
|---|---|
| Site: | Maine Yankee |
| Issue date: | 01/31/1980 |
| From: | Grier B NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| To: | Groce R Maine Yankee |
| References | |
| NUDOCS 8002250075 | |
| Download: ML19296C026 (1) | |
Text
ffv
+
o, UNITED STATES E'
NUCLEAR REGULATORY COMMISSION e
g e
REGION 1 0
631 PARK AVENUE
,e KING OF PRUSSIA, PENNSYLVANIA 19406 w
Docket No. 50-309 JAN 311980 Maine Yankee Atomic Power Company ATTN: Mr. Robert H. Grace Senior Engineer - Licensino 25 Research Drive Westborough, Massacnusetts 01581 Gentlemen:
This Information Notice is provided as an early notification of a possibly significant matter.
It is expacted 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 this office.
Sincerely,
~
Boyce H. Grier Director
Enclosures:
1.
IE Infonnation Notice No. 80-03 2.
List of Recently Issued IE Information Notices CONTACT:
D. L. Caphton (215-337-5339) cc w/encls:
E. Wood, Plant Superintendent E. P. Thurlow, President
/
4002350 09s
ENCLOSURE 1 UNITED STATES SSINS No.:
3870 NUCLEAR REGULATORY COMMISSION Accession Ni..:
OFFICE OF INSPECTION AND ENFORCEMENT 7912190666 WASHINGTON, D.C.
20555 IE Information Notice No. 80-03 Date:
January 31, 1980 Page 1 of 1 MAIN TURBINE ELECTR0 HYDRAULIC CONTROL SYSTEM 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).
Techniciaps 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 permis-sible 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 systea 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 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 MK 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 ')ffice.
"GEK Instruction Book 11381-D, " Speed Control Unit", Maintenance Section, Page 4.
ENCLOSURE 2 IE Information Notice No. 80-03 Date:
January 31, 1980 Page 1 of 1 RECENTLY ISSUED IE INFORMATION NOTICES Information Subject Date Issued to Notice No.
Issued 79-28 Overloading of Structural 11/16/79 All Power Reactor Faci-Elements Due to Pipe Support lities with an Operating Loads License (OL) or Construction Permit (CP) 79-29 Loss of Nonsafety Related 11/19/79 All Power Reactor Faci-Reactor Coolant System In-lities with an OL or CP strumentation During Operation 79-30 Reporting of Defects and 12/6/79 All Power Reactor Faci-Ncocompliances, 10 CFR lities with an OL Part 21 or CP 79-31 Use of Incorrect Amplified 12/13/79 All Power Reactor Faci-Response Spectra (ARS) lities with an OL or CP 79-32 Separation of Electrical 12/21/79 All Power Reactor Faci-Cables for HPCI and ADS lities with an OL or CP 79-33 Improper Closure of Primary 12/21/79 All Power Reactor Faci-Containment Access Hatches lities with an O' or CP 79-34 Inadequate Design of Safety-12/31/79 All Power Reactor Faci-Related Her*, Exchangers lities with an OL or CP 79-35 Control of Maintenance 12/31/79 All Power Reactor Faci-and Essential Equipment lities with an OL or CP 79-36 Computer Code Defect in 12/31/79 All Power Reactor Faci-Stress Analysis of Piping lities with an OL or CP Elbow 79-37 Cracking in Low Presssure 12/31/79 All Power Reactor Faci-Turbine Discs lities with an OL or CP 80-01 Fuel Handling Events 1/4/80 All Power Reactor Faci-lities with an OL or CP 80-02 8X8R Water Rod Lower 1/25/80 All BWR Facilities with End Plug Wear an OL or CP