ML20085M491

LER 75/021:on 751124,during Shutdown & Monthly Surveillance on Reactor Bldg louvers,66 of 94 Louvers Were Sluggish or Did Not Fully Open.Due to Slightly Negative Pressure on One Side of Louvers & Hinges Collecting Dust/Water

ML20085M491
Person / Time
Site:	Fort Saint Vrain
Issue date:	12/23/1975
From:	Franek W, Swart F PUBLIC SERVICE CO. OF COLORADO
To:	Howard E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
References
LER-75-021, LER-75-21, P-75040, NUDOCS 8311080600
Download: ML20085M491 (6)

Text

_ . - - - _ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - _ .---- _

O LI ENSEE EVENT REPg

' ' CONTROL 8 LOCK:l } l l l l l (pLEASE PRINT CLL KEGUIRED INF2RMATION) 1 6 NAME LCENSE NUMBER E TY PE O1 7 89 18101715l \/i / I 14 l0101-10101010101-101Ol 15 25 141/l/IfIOl 26 30 loL51 31 32 CATEGORY T1Y . DOCKET NUMBER EVENT OATE REPORT OATE O 1 CON'T lO l Zl [4_] lL_l l []6l[l-l dl2l hl #[l 68 l/l/l2lMl7l$l 69 74 l l l2 l2.131~I 151 75 80 7 8 57 58 55t 60 G1 EVENT DESCRIPTION se l Whik skmVotun ant / oerGemino g a monil, la wr veilla nm- nni 7 89 f 80 l

@@ l-lhe reasine buildinn 7 89 J Inn ufrs & A et" f/tx M lovvers were- 80Ij' DC islunoish nr r/irl an+ &//u Npen. There are nn redu ndin+ 1 7 89 JJ J '

60 BB l sumtems.1n'seskohion In}n ahL N nS h be AmblPM M2 l

!lG Yh ina 60 n clu Ye=cl . (UlE ~7s/21\"$

7 89 / m

' 80 CE CCMPONENT CODE MANUFACTufER WRA110N ag I z.l z l [ g_]

7 89 10 11 ILiol(LIVIEIR1 12 17 gj 43 1yl919191 44 47 g

CAUSE DESCRIPTION 7

ac I D u e 4 e s I,'e l,+1 o n e e d itte nressuno an one micleP J +ltL 80I 89 32 I inu vers , fItr /dn)aes YnIIeet dusf cand wder_ UJith J

I 7 89 80 as i +i m e +heu he c.0 nme hard 4e c oorde . , I

T 7  % POWER OTHER STATUS O CO E OGCOVERY OESCRWmON 1

[G.] I010101 l u/A _

I LbJ l 9IA I

• 7 8 9 10 12 13 44 45 48 80 l

a mNT.O ACmTv ux: anon Os REtnasE E@ LZ1 LzJ l M //) l I u/A I 7 8 9 10 11 44 45 80 PERSONNEL EXPOSURES NUMOER TYPE DESCRumON

@ I_Ololol Iz] I M/A 1 7 89 11 12 13 80 PERSONNEL INJURIES E 1010101 I w/A 1 30 7 89 11 12 OFFSITE CONSEQUENCES

[@ l N/A I 7 89 '

80 LOSS OR OAMAGE TO FACIUTY TYPE DESCRfmON l

8 LzJ l M/A I 7 89 10 80 PUGUCITY

> 05 I Lt/A I 7 89 1 80 0600 7S1223 ADDITIONAL FACTORS S 5000267 D: I u/A I 7 89 80 0: I - , 1 umE. $2bN v -$Y . .m sW 7M1. Ed Z46.. 5 . . . . .,

r ,

o .

. .  ; o public service company *e conomde P. O. Box 361, Platteville, Colorado 80651 4 5 AEct?vtg a December 23, 1975 N j*/f = 7f sg Fort St. Vrain Unit No. 1 g

• P-75040 Mr. E. Morris Howard, Director lif -

I Nuclear Regulatory Commission Region IV Office of Inspection and Enforcement Suite 1000 Arlington, Texas 76012 REF: Facility Operating License No. DPR-34 Docket No. 50-267

Dear Mr. Howard:

Enclosed please find a copy of Unusual Event Report No. 50-267/75/21, Preliminary, submitted per the requirements of the Technical Specifi-cations.

Very truly yours,

()

C Frederic E. Swart Superintendent, Nuclear Production Fort St. Vrain Nuclear Generating Station FES/alk cc: Mr. Roger S. Boyd i

yes

o .

O REPORT DATE: December 23, 1975 UNUSUAL EVENT 75/21 OCCURRENCE DATE: November 24, 1975 FORT ST. VRAIN NUCLEAR GENERATING STATION PUBLIC SERVICE COMPANY OF COLORADO P. O. BOX 361 PLATTEVILLE, COLORADO 80651 REPORT NO. 50-267/75/21 Preliminary IDENTIFICATION OF OCCURRENCE: .

A number of the reactor building pressure relief louver sections did not func-tion as required. This is identified as an unusual event per Fort St. Vrain Technical Specifications AC 7.6, Non-Routine Reports, (C) 2.

! CONDITIONS PRIOR

, TO OCCURRENCE: Steady State Power Routine Shutdown Hot Shutdown Routine load Change i

X Cold Shutdown Other (specify)

Refueling Shutdown -

Routine Startup The major plant parameters at the time of the event were as follows: -

Power RTR 0 Weh .

f ELECT 0 We

Secondary Coolant Pressure N/A psig

! Temperature N/A *F i

Flow N/A #/hr.

L i Primary Coolant Pressure 267 psig -

i i

. Temperature 144 . *F Core Inlet i 144 *F Core Outlet i

l Flow 1 circulator at 2,500 RPM -

l l .

{

s e

m

., , . , , , - - . . , ,...,y - q.

o

• o UNUSUAL EVENT 75/21 Page 2 of 4 APPARENT CAUSE OF OCCURRENCE: X Design Unusual Service Cond.

Including Environment, Manufacture Component Failure Installation /Const. Other (specify)

Operator Procedure The apparent cause of this occurrence is the system environment, and a weak actuating spring.

ANALYSIS OF OCCURRENCE:

The louvers normally have atmospheric pressure on the outside and -1/4" H,,0 with respect to atmospheric pressure on the inside. They also have rubber seals on all sides of each vane. Due to wind, dust, and water vapor, the surfaces on which the rubber seals slide deteriorates, and'the rubber seals become hard.

This requires additional force for louver operation. The installed spring is too weak to overcome the combined resistance of seventeen vanes in each louver section. See attached sketch.

The system is composed of 94 louver sections. Twenty two of them opened 100%;

35 opened between 75% and 100%; 29 opened between 50% and 75%, and, 7 opened between 25% and 50%. Although louver opening was not 100% for all louvers, it is believed that the partial opening was sufficient to safely relieve potential reactor building internal pressure.

, At no time was there any danger to the safety of the plant or the public. -

1 i

CORRECTIVE ACTION:

Corrective action is under investigation.

j FAILURE DATA /SIMILAR REPORTED OCCURRENCES:

None

, PROGRAMMATIC IMPACT:.

None CODE IMPACT:

None ,

I l

l.!

- t. . .

1

.O

- - -~

s

. i ,

Soft,Rubb r Ssala

. .O - -

J Hing2

/

. S. oft Rubbar Stalo

-' - Rubber Seal '

• 14 - - / / ~Al l

- - - - --M. k Hinge .y'- 4 ,,, 5: Nut g / ./ IJL. 4s

\ .

7  ; .

M.. . . . . . . . . . . . _ . . _ . ._ .. .

'ltm

_ _ . . . Vane r

_g 43.75'! pActuating

' 17/ Louver i TOP VIEW Arm

. . . _ . . .. . . a  ! i I, ___L . . .

, , i. . .

- -UNUSUAL EVENT 75/21 - - - - -

i ' '

! 1

_,._ Page 3 .of .4  :

.,--_r.

, i .

I  ; i i i i i i  !  ! l i , } l t i i  ! I

_.. _ _ . . _ . . . _ . _ _i_ .-

H-- r - - - * -- - -

' t i i .

l .

l f__ _l , q__._ _

l

. .J _ . _.. _ _i .__ t i 9 _ } __

i i

i j _

- I .

' I

i

_ . . . . . _li . . i. . j . .!- j . .! . , . . .

_{' . _ 7. . . # 4 i

t i

i i f -

. i i i  ;

,  !. )

_ i. .. ...e t ,

._s. .s . . .. . . . +_ . . . . . . . . . ,

! , , i t i

i

. . . . .. _ . . . . ., . . . . . . . . . . .....p._ . -

t

. . ....'_/.. . ._

l , . . . _..._____.c. . _t._..... .

...t . . _ . .

Van'e . _ ' ;. . '

!  ! l l . ._1_. f _ I...._! '

i . Hinge _.,/ ,

! , f

!~ i Vane

. i . ,

- ;'~ T

. Ac'tuating

..._.._.'.._l.___}___.' '

.{

Arm , , . i l

. ! . . l .. .

L _ . . L_._ r ._

.._-.r...-__.

l .. _.

l '._,___ ..

I h l

_i I  !. /4_ l __ _

Direction of i

i ,

1 i l _! lcfaveltoopen.

_ _ . . _ . _ . i louvers-  :.- .._-

i _\i (,

i

' ' ' A- ' ' ' _.

! I I I I I'  ! I I l l l l l l

~. _a _. . ___

__4.__. . _; ___ ., . __,l. . .._.. -. ._ ___

i .. ._ _ I ___ + . i

.r. t. _ . _i __

l .  ; -

l I

i [ e I

1

' ' i  !' .s

p. ,

i

. _- ._ _._.__ a._. r [  : .

j. .' .

t i

I I  ; i

~

l

._+___+ __

l h.

- f._gt ! . . . ._ _ . . _ _ ._ .__ _ _ _ . _ .

EanesL__f M. :tuating Cylindert -- - . * --

l l l l

, , _.3 - . . _ .

._9 - = . _ . _ _ . _ . _ _ .

l l t , l SIDE VIEW .

L I

I UA.NE ACTUATING ._

- j ._ _ . . __. -

i MECHANISM i .

l i

_ -e.._ . - . -

i . I, .. _ . . . . . . . __. . . _

l _1__________ l _l _ _l

O . .

o UNUSUAL EVENT 75/21 Page 4 of 4 Submitted by: _

[t< ,___ f

/M W. 'Hillydrd, Jr.' / '

Technical Services Supervisor Reviewed by: 1 N Frank M. Mathie Superintendent, Maintenance d

Approved by: ' L 'W Ffederic E. Swart Superintendent, Nuclear Production OO t

4 1

l l

1

.g*

I t'

'I m