ML20084E062

AO 50-237/75-17:on 750317,main Steam Line Low Pressure Switches 261-30A-D Found to Have Low Trip Setpoints.Caused by Instrument Drift.Switch Setpoints Readjusted

ML20084E062
Person / Time
Site:	Dresden
Issue date:	03/27/1975
From:	Stephenson B COMMONWEALTH EDISON CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
194-75, 3235, AO-50-237-75-17, NUDOCS 8304140037
Download: ML20084E062 (4)

Text

.

,,,,*. , f~

Jr: ' ^

C:m',;writh Edisin  !

~P one FiscNational Ptara. Chicago. Ithnois yby Address Heply to: Post Othce Box 767 7' Chicago. Ilknois 60690 BBS Ltr # 194-75 Dresden Nuclear Power Station R. R. #1 ,

Morris, Illinois 60450 'N Ihroh 27, 1975 '

i

^

s .t. .\

3 Rpg' ,y ' ,;,, .

t. , _fol9y \

lir. James G. Koppler, Regional Director '

Directorate of Regulatory Operation-Region III 9.\ ..,- s.

U. S. Nonlene Femtlatory Cenniction h,\ ' '

799 Roosevolt Road \y Glen Ellyn, Illinois 60137 ' p([.h/

\

SUBJECT:

REPORT OF APNORMAL OCCURRENCE PER SFITION 6.6.A 0F THE TIIHNICAL Sr?EIFICf.TIONS MAIR STEEi LIRE IMW PRESSURE INSTRUN?7P DRIPP Roforencoa 1) Regulatory Guide 1.16 Rev. 1 Appendix A

2) Notification of Region III of U. S. Naclear Regulatory Co:nniosion Tolophones P. Johnson, 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br /> on March 18, 1975 Telegrem: J. Koppler, 1430 hours0.0166 days <br />0.397 hours <br />0.00236 weeks <br />5.44115e-4 months <br /> on thrch 18, 1975 neport namoort 50-2f//19 /5-17 Report Datos Pa.rch 27, 1975 Occurrence Date Parch 17, 1975 Facility: Droeden Nuclear Power Station, Morrio, Illinois 60450 IDB7PIFICATION OF OCCURRE"CE Ihin Steam Lino Low Proscure Switches 261-30A-D wore found to have trip netpoints from 835 to 845. The trip aetting is identified by table 3 2.a of the technical epecification no croater than or equal to 855 pai (includco 5 pai head pressuro).

_CONDITICN PRIOR TO OCCURRDEE Dresden Unit 2 was in the cold shutdown scode with zero power (!Gt and IGo). Routine instrument surveillance was in progrecs. Droeden Unit 2 has been shutdown i since Noycober 2, 1974 for refueling.

DESCRIPTION OP OCCURRD!CE During routine surveillance of the main steam lino low pressure switchen 261-30A, B, C and D on thrch 17, 1975, the cidtch notpoints ware found to exceed the

$4Nd75$N7 PDR ScN  ;] COPY SENT REGION ._ ,

pn f S .

]

---w ..--- .a a .,sa-, .-ww -a - ..a .

n y . . , . - - - - - , . - , .n m 4 %Ir. James G. K r % r March 27, 1975 1

.. U -

A)

Q technical specification limit. The switch setpoints were innediately reset within Dresden setpoint limit of 871 1 4 pai. l DESIGNATION OF APPARENP CAUSE OP OCCURRENCE (Equipment Failure)

The apparent cause of this occurrence is instrument drift which probably occurred between the time Dresden Unit 2 was shutdown on November 2, 1974

for refueling and March 17, 1975 when instrument surveinance was accomplished.

! The most recent instrument surveillance, prior to March 17, 1975, was October 26, .

1974, prior to the Unit 2 shutdown for refueling on November 2, 1974.

i ANALYSIS OP OCCURRDT,E <

i i

The 1\tnction of these pressure switches is to initiate a main steam isolation  ;

(Group 1) in the event of a break in the main stcasa line. Previous surveillance, ,

performed on October 26, 1974 (7 days prior,to start of refueling outage), j showed the switch setpoints to be within Dresden setpoint limits. Evaluation i

of the change in the month to month surveillance readings for the Barksdale j precycled pressure switch typo B27-A12SS (GE) from the installation date on January 12, 1974, to October 26, 1974, indicates the switch has not exceeded a 10 poi drift per month. Using a 10 pai per month drift rate, a setpoint of {

! 871 psi minus 10 pai = 861 psi which is within the Technical specification l i limit of 855 psi. It is concluded therefore, that the switch setpoint had j

) not exceeded technical specification limits between the time of October 26,  :'

1974 and the refueling shutdown date of November 2,1974. Since the Unit has

)

been in the shutdown mode since November 2, 1974 and the present date it is .

c a lal d timt, w wick,im - d io iluu laulullaLiva persvunwl or to the pdulic  !

i resulted from this deviation from Technical Specification.  !

1 i

I CORRECTIVE ACTION l The immediate corrective action was to adjust the switch setpoints within  !

Dresden setpoint limit of 871 i pai.

r

It has been concluded from the data analyzed, that increasing the Dresden '

setpoint in November 1972 and monthly surveillances have prevented Technical {

Specification setpoint violations for the cain steam low pressure switch. i

and that the out-of-specification readings obtained on March 17, 1975, can.  !

, be attributed to instrument drift during the period of reactor shutdown when monthly curve 111ances were not m4ntained.

l  !

r Corrective action taken to prevent repetition of the occurrence will be to l

maintain monthly surveillance during reactor operation until a suitable  !

replacement pressure switch with =4=4m=1 drift characteristics can be obtained.  !

During extended periods of shutdowns, such as refueling outages, infrequent-  !

surveillances will be conducted.

t f

w h

l

- - -- --- - - . ~ , .-... -,.- - .. - . . - , -. - , . . , . - , - - - . . -l

[ Mr.JamesG.Khcr March 27, 1975 FAII)JRE DATA ,

i The instrument which drifted below the technical specification value was Barksdale pre-cycled pressure switch type B27-A12 SS (GE).

Review of the instrument surveillance data shows this occurrence to be the only deviation from Technical specification limits on Dresden Unit 2 Barksdale pressure switchen 261-30A-D frca November 20, 1972, through January 12, 1974, when Barksdale precycled switch was installed, to October 26, 1974, when the j last surveillance prior to shutdown for refueling was accomplished. The latest deviation for the same typo Dresden Unit 3 pressure switch 261-30 A-D, l

(pre-cycled switch installed on June 31,1974) was April 19, 1973.

From the time of 11 April 1972, to the time of installation of the pre-cycled i Barksdale pressure switch there had been 11 times during which similar type

! switches have deviated bolow the technical cpecification limit. Since tho i

installation of the pre-cycled Barksdale pressure switch (January 12, 1974 j for Unit 2 and June 31, 1974 for Unit 3) this has been the first occurrence of this type of switch deviating below the technical specification 1:Imit.

l l

Sincerely, wh &'

l . B. Stophenson i

f Superintendent BBSSTDI:smp File /AEC l

l i

l

I l

(LJ /2 0 O LQL i m - ^ 117 3h9 9

- //1 w<

sam u yegearam' e

{ -

yo ,/ mestem union 3

I? -

v ,.g I VEE 265 ( 155 8) (2-0354 8SE0 77) PD 05 /18/75 1558 ICS IPMBNGZ CSP , {

j 8159424449 TDBN MORRIS IL 124 03- 18 035 8P EST V/

PMS JAMES G KEPPLER, REG IONAL DIRECTOR, DIRECTORATE OF REGULATORY OPERATIONS REG ION 5, WUX $

l US NUCLEAR REGULATORY COMMISSION 799 ROOSEVELT RD d \

I GLEN ELLYN IL 6013 7 i P

SUBJECT:

D PR- 19, DRESDEN N UCLE AR POWER STATION, UN IT 2.

! THIS WILL CONFIRM THE CONVERSAT ION WITH MR JOHNSON OF YOUR OFFICE AT ~

i 1430 HOURS THIS D ATE CONCERNING ITEM 1. DRIFT OF PRESSURE SWITCHES 2-261-50A, B, C, AND D WHICH ISOL ATE MAIN STEAM LINES ON LOW PRESSURE. ALL SWITCHES WERE PRECOND IT 10NED TYPE. SWITCHES WERE 1

IMMEDIATELY RESET TO PROPER VALUES. SWITCHES HAVE SEEN O PRESSURE FOR ALMOST 5 MONTHS AND THIS MAY BE FACTOR IN THE DRIFT. ITEM 2. -

i i 1 FAILURE OF UNIT 2 D IESEL GENER ATOR TO ST ART FOLLOWING MINOR sr mi MAINTEN ANCE WHEN ST ARTING AIR SOLENOID ST UCK. STRUCK SOLONOID AND IT i

j POSITIONED TO START THE D IESEL. SOLON0!D BEING INSPECTED NOW.

l B B STEPHENSON SUPERINTENDENT DRESDEN NUCLEAR POWER STATION l COMMONWEALTH EDISON COMPANY RR I MORRIS ILLINOIS 60450 i NNNN i

l I /],'3 '

W 0}r [;

$58 2 4 h (3

} ll I

l sr.im em l

I l

. . - - - . - - _ - . - - - ___- - -. - . - . -