ML19261F300

Abnormal Occurrence 50-289/74-13:on 740706,1B Emergency Diesel Generator Tripped During Testing Prior to Reaching Rated Speed & Voltage.Caused by Design Deficiency.Design & Application of Pressure Switch to Be Reviewed

ML19261F300
Person / Time
Site:	Three Mile Island
Issue date:	07/16/1974
From:	Arnold R METROPOLITAN EDISON CO.
To:
References
GQL-0171, GQL-171, NUDOCS 7910250763
Download: ML19261F300 (5)

Text

AEC DIF **I3tMC?I FOR pac? 50 DCCET VAMRIAL

/ '

CONTROL NO: 6548 (TEltPORARY FO?}i)

FILE:

FRCH: DATE OF DOC DATE REC'D LTR 7% RPT CT:~IR Metropolitan Edison Company Reading, Pa. 19603 Mr. R.C. Arnold 7-16-74 7 18-74 X To: c ORIG CC OTHER SENT AEC PDR W-SENT LOCAL PLR ^^^

" CLASS UNCLASS PROP INFO INPUT NO CYS RIC'D DOCKET NO:

XXX 1 50-289 DESCRIPTION: ENCLCSURES:

Ler reporting an abnormal occurrence No. A0-50-289/ -

^

j

-)

74-13...conecrning Trip of the IB Emergency g,,q ~ ~ '[,,,.

~ ~ ~

Diesel Generator Pript to reaching rated spedd and ,[ N Power....

, . - 75 PLANT NA.v.": r Three Mile Island DO EU ~ 1-i FOR ACTIC:!/IN7C ".ATIC:' 7-18-74 JB BUTLER (L) SCHWENCER (L) ZIEMANN (L) REGAN (E)

W/ CYS W/ CYS W/ CYS W/ CYS CLARK (L) STOLZ (L) DICKER (E) y Lear W/ CYS W/ CYS W/ CYS W/7CYS

• a" 'a'IC."0!'

t'J "a?Ya.LLO iLl (El W/ CYS W/ CYS W/ CYS W/ CYS KNIEL (L) PURPLE (L) YOUNGBLOOD (E)

W/ CYs W/ CYS W/ CYS W/ CYS e m INTERNAL DISTRI3CTICN G FILE j JECH REVIEW DENTON LIC ASST A/T IND v r -.s #HENDRIE GRDIES DIGGS (L) BRAITMAN C fSCHROEDER GAMMILL GEARIN (L) SALTZMAN

• MJNTZING/ STAFF J CCARY KASTNER COUL300RNE (L) B. h13RT

/ CASE IGHT BALLARD KREUTZER (E)

GIAMBUSSO AWLICKI SPANGLER LEE (L) PLANS BOYD HA0 MAIGRET (L) MCDONALD MOORE (L)(LWR-2) TELLO ENVIRO REED (E) CHAPMAN DEYOUNG (L)(LWR-1) CUSTON MULLER SERVICE (L) DUBE w/ input SKOVHOLT (L) OVAK DICKER SHEPPARD (L) E. COUPE

/GOLLER (L) OSS KNIGHTON SLATER (E)

? COLLINS /PPOLITO YOUNGELCCD SMITH (L) /D. THOMPSON (2)

'1ENISE v EDESCO REGAN V TEETS (L) /KLECKER

'C OPR ONG PROJECT MGR WILLIAMS (E) /EISENHUT

c. & REGICN (3) INAS WILSON (L)

"S BENAROYA HARLESS

/VOLDidR 1AO9 00l ""'

A EXTERNAL DISTRI3CTIC:. I "I J '

N PDR Harrisburn.'Pa. _(1)(2)(10) . ATIO::AL U.2 5

'ASERNATHY) 1-FDR-S A': / Ls. .

[

"CHANAN) 1-ASLEP(E/W Bid;, Fa 529) 1-ERCCKF.AVI:, 4 D.2 1-W. PENNINGTC: , R:n E-201 GT 1-G . ULRIKSC'. , C 7.'. ~

1-B&M SWI::E3 ROAD, R:n E-201 GT 1-AGMED (RUT: 0 " I I:'_ .

, LIC ASST Teets 1.CONSULTA'. TS R:n B-127 CT 7-18-74 33,3Ap;.cf 3tg 3,;,c3a3 m; i.gn,,gu~ T r- - :_-

791025076h 3

" ~

. . ~

v$*Mds"d g: n -

na. ,-n-m METROPOLITAN EDISON COMPANY DC2T cFFICE ScX 542 RE ADING, PENNSYLVANI A 19603 TELEPHCNE 215 - 923-26T JUL 161974 .

iI g /

hj . '^ ,Y h 't

/ h/s4,

'/~te 4 b dj W r.

' & s,i Director c/

l 2' q

+f:..,

h, Q* *F- I \n +.*f;qN.8

-s 1,

~ '.'%

\v Ql ls Directorate of Licensing C q,vp

1. 4N c / "g ' 'TGl# D

i

• ^ ,. I S M.Q)

U. S. Atomic Energy Oc==issicn 'A 4 -

'a'ashingten , D. C. 205h5 i.' h -

2 ,-

Dear Sir:

Operating License DFR-50 Dec.tet No. 50-289 In acecrdance with the Technical Specificaticns for Three Mile Island Nuclear Station, l' nit 1, we are reporting the following abnormal occur-rence:

(1) Report Number: A0 50-289/7L-13 (2a) Report Date: July 16, 197h (2b) Occurrence Date: July 6, 197L

( 3) Facility: Three Mile Island Nuclear Generating Station, Unit 1 (h) Identificatien of Occurrence:

Title:

Trip of the 13 Energency Diesel Generator prier to reaching rated speed and power.

Type: An abncr=al cecurrence as defined by the Technical Speci-fications, paragraph 3.8d, in that the tripping of the 13 Energency Diesel Generater threatened to cause an Engi-neered Safeguard feature or syste= to be incapable of perfer=ing its intended functicn.

(5) Ccnditions Prior to Occurrence:

Pcver escalaticn test with the reactor at hC,# of rated power and

=ajer plant para =eters as follevs:

m, -

1482 002

. , s Directorste of Licensing JUL 16 1974 Power: Core: 101h M4T Elec: 319 K4E 0

RC Flow: 136 x 10 lbs./hr.

RC Pressure: 2155 psig RC Temp.: 579 F PRZR Level: 220 in.

PRZR Temp.: 650 F (6) Description of Occurrence:

During the performance of the quarterly Engineered Safeguards System (ESAS) Test, the 13 E=ergency Diesel Generater tripped pricr to reaching rated speed and voltage. A second attempt at initi-ating the ESAS Test resulted in a successful start of the generator in questien. An i= mediate investigaticn was conducted to determine the cause of the trip.

The diesel generater is equipped with an cil pressure limit switch (CPLS) which senses engine speed as a function of cil pressure.

The CPLS vorks in ccmbination with a timer, which is set for about 10 seccnds. When the diesel receives a start signal, the timer is energized. If the diesel does nct start and ccce up to running speed within 10 seconds, the timer vill " time out" and energize a "Shutdevn Relay," which causes the engine to trip. In the present case the speed sensing CPLS failed to pick up in less than 10 seconds and the diesel engine tripped.

(7) Designatien of Apparent Cause of Occurrence:

The investigatien which folleved the diesel trip revealed that the CPLS will net always ,f ck up in less than 10 seccnds, even thcush the engine is running. This same proble= had been noted en both Energency Diesel Generator OPLS's during precperaticnal testing, at which time an increase in the disseter and a reduction in the length of the scnsing lines to the pressure switches had appeared to have solved the problem.

It has been cencluded that the apparent cause of this occurrence is tne desien of the OFLS for reasons as fcilows:

a) the 13 Energency Diesel Generator CPLS settings and " Start Failure" tirer setting were subsequently verified to te in accordance with the manufacturer's recctmendaticns; b) the cil pressure sensing lines were checked for air binding and no binding was found ; and

, }hb-

~

Directorate of Licensing JUL 16 37.;

c) the above-referenced previcus pressure sensing line design

=cdificatica (to enable the CPLS to better functicn) failed.

(8) Analysis of Cccurrence: It is believed that the tripping cf the 13 Emergency Diesel Generator did not represent a threat to the health and safety of the public for the folleving reasons:

a) During an actual energency requiring actuation cf the ESAS, the 13 Emergency Diesel Generator vculd have started and pro-vided the necessary emergency pcver in that the circuit which shutdevn the diesel engine is bypassed in an actual ESAS situatien.

b) Unit 1 is provided with several redundant scurces of emergency electrical pcwer. Consequently, the failure of a single source does not hinder the effective operation cf the ESAS.

(9) Ccrrective Actic"- hediately fc11cving the occurrence, the redundant 1A Emergency Diesel Generator was successfully tested; and the 13 Emergency Diesel Generator was retested, and this time it did not trip. Also, the CPLS settings and the " Start Failure" timer settings fer the affected 13 Emergency Diesel Generator were verified to be in accordance with the =nufacturer's reccc-mendations .

The Plant Operaticns Review Cc==ittee (PCRC) met prc=ptly after the occurrence and recc== ended to the Station Superintendent that :

a) the design and application of the pressure switch be reviewed te determine if the switch should be replaced by a switch of a different design, and b) the pessibility of a faulty CPLS be corrected by replacing the questicnable CPLS with a new switch and by ensuring after its installaticn that

1. the CPLS settings and start failure timers be checked to ensure they are in acecrdance with the manufacturer's latest recc= endaticns ,

2. the cil pressure sensing line be checked fer air binding, and 3 a test be run to ensure that a sufficient targin exists between the CPLS actuaticn time and the " Start Failure" tirer setting.

The Station Superintendent has cencurred with PCRC's ra:ctmendatiens; the Architect - Engineer is in the process of reviewing the design and applicatien of the pressure switch; a new CPLS has been crdered; and step 9b above vill be ec=pleted after receipt cf the new CPLS.

1482 004

irectorate of Licensing _4_ JUL 16 1974 (10) Failure Data

a) Record of Previcus Failures:

None, b) Equipment Identificaticn:

Censolidated Centrols Pressure Switch, 0-25 psi, Part No.

21A13L 0253-3.

Sincerely,

/

f;

/

)k(l ';1 :

R. C. Aracld N

Vice President-Generaticn RCA:JFV:sh cc: Directerate of Regulatory Operations, Region 1 U. S. Atenic Energy Ccc=issicn 631 Park Avenue King of Prussia, Pennsylvania 19h06 File 20.1.1 77351

} klb2.