ML17252A297

LER 77-014-00 for Dresden Unit 3 Regarding an Occurrence of the Differential Pressure (D/P) Across the Off Gas High Efficiency Particulate After Filters (HEPA) Increasing to Approximately 13-Inches of Water

ML17252A297
Person / Time
Site:	Dresden
Issue date:	06/14/1977
From:	Stephenson B Commonwealth Edison Co
To:	James Keppler NRC/RGN-III
References
BBS Ltr. #77-530 LER 77-014-00
Download: ML17252A297 (3)

Text

Commonwealt9dison Dresden Nuclear Power Station R.R. #1 Morris, Illinois 60450 Telephone 815/942-2920 BBS Ltr. #77-530 June 14, 1977 Mr. James G. Keppler, Regional D'irector Directorate of Regulatory Operations - Region III u.: S. Nuclear Regulatory Commission 799 Roosevelt Road Glen;Ellyn, Illinois 60137

~nclosed please find Reportable Occurrence report number 50-249/77-14.

This report is being submitted to your office in accordance with the Dresden Nuclear Power Station Technical Specifications, Section 6.6.B.

. ~ oYl. fUe;;t:

~. B. Stephenson r . Station Superintendent Dresden Nuclear Power Station BBS:sm Encloi;mre cc: Director of Inspection & Enforcement Director.of Management Information & Program Control File/NRC.

/

77174Q02~*

JUN l 7 1977

coNi"Ro_ L *a_LOCK *. _ l *.. j * *.

e*llL'C:M:>d: *. I *I I I

'f::VENi HEPO'Rf'

• [P19iE

_.A. .PAINT

• ALL*RE~UIRED,INFOAMATION:

.. .. 1 *.* .. "".*: 6 ' .

.LICENSEE .. '.

• NAME * .. ** *

.. . .... *.* ..... * *. LIC;ENSE** NUMBER. . . *' ... UCF"'SE.

1"*.'E '. <. EVENT TYPE ... ' :-.*>* .

T~ITJ*: I: *-r,I *L l. . DI* *Rl.s . ,_3~. -1 Io ;:~I ct I.~ I a*I a I 0-1 a I a I ~l al at *f 41.1 1* ~- 11 J 11 I a I 3 J" 1 ..*e.*9. * *14 . 15 .* 25'. : 26 . . 30 31 32 ;

. ~TEGORY . REPORT TYPE. SROEPU~RCTE . OOCKe-f NUMBER *'* . . . *~*OATE. ... *

• REPORT> DATE *

@IT) CoN"T I I I L!J LlJ

• I o I s I a 1- I *a12 I 4 I 9 I I a 1* s I 1 I s I 1 I 1 *I I ti I 6 I 1 I 4 I 1 I 1* f 7 *8 . 57 . '.58 ' 59 60 61 . . .' '. 68 - 69 . '. 74 75 .* aa*

EVENT '1 OESCRIPTIOl\.I}: *:

10(21 I Duririg n9rmaL* operation* on May 1.5, 1977 at .approxiinc:itely 18aa hours the differential J

7 8 9 ... 80

• . ~l I pressure .(D/P). across the** off .gas 'higheffisienc~ part~~ulat~. afte~filters (HEPA) .

I 7 * .. a 9 ** *. 80

• lal41: I increased to* approximately inches *of water.*

• The normal p/P across the filters  !

7 . Br9 80 fol51 I is less than a. 2-iriches *of water at* rated* power. Both A and*B HEPA filters were in-.

I 7 8 9 ' ,.-* ~:.._ ... v80 lofsl *I .. service at the time of* the'°:P.~Eu.rE~Ei!~ (continued) .. I 7 8 9 FAME 80 SYSTEM . : CAUSE . COMPON811T . COMPONENT I:.. . *. COOE ' * * .. CODE. COMPONENT COOE sul'Puel=I MANUFACTl..R:A . VDl.ATDN 10171 IM r BJ l.!..l _* r F 1 r 1L 1T 1E 1R 1 .* . lEJ . IM I 3~ 13.l 5.J. WJ -.

7 8 9 10 ' ' 11 12 *. ... ' .. 17 .43 . *. 44.* 47 . 48 . ** ..

CAUSE DESCRIPTION ,. . .. . .

• .. ~*. ~ .1 The .increase ln D/P. acros~ .the HEPA filtets*:*was attributed .,~o an<increase gf Wqter .,

fo1si:j 'yapor 8 1

• I

• in the. off gas h~ldup: li~e ... The wa~_e r* ~apoi, -~ncre:;:ise. was du~ .to .. ~pcreased flo~. ~

.* 7 8*9

(!El I incurred b:Y abnormal condenser air-inleakage and the inability of* the holdup* line 8

j I 7 8 9 .. . 80

~ Desc~1P~10N (continued

• FACIUTY' . METHOO OF ' )

.... STArus. POWER*. OTHER STATUS 01scovERY . orscovERY

.. *.'*' .*711_1_1*~'***  ;*' 9.lLJ.' I a I. 7. I a12JI..__* _N_A_ _~...;.*..;.i' LAI 46I ' NA I 10 13 .* . 44:":' 45 ..*

. FORM OF 80 ACTlVlTY * . CONTENT .

• ' .. I!IB 1 a AEl..EASEO * . OF RELEASE

.9

~. w '~*._ . . .

10 11 AMOUNT OF ACTIVITY N.;,;;,;,A.._,.'---~'

1

• NA .

LOCATION OF .RELEASE.

44**<* . 4*':=5~-;_.,~~--;..._.-.,..----__;o...,.;...-------------~....---. ~.8*.Jo;:

• I l

• . PEJ=ISONNEL EXPOSURES , . ,. */_;_b.*. ,: *. **"***** .. ".

.*.:

• NUMBER"t * . TYPE. :* " OESCRIPTION . * ... : . *:: ..

':* ..<[!EJ l al al oI W NA

.';;-~_;.;;.:.....~--:---~-----_;_--~.....;.;.~.;..._--~_;_~~~~---~--.;_.;.__J 7

8 9 .. .

11 '12 13 80

..

• PERS.ONNEL INJURIES .

"NUMBER ,  :

• DESCRIPTION

• 7 .a

~ . sI.ala la~I .. 1.1 12 .

~:_N_A_ _~--~~---~~-~-~~~~-~-~1 eo

... OFFSITE CONSEQUENCES

• • . . 1. tillLa .s .* ..

• NA 80 LOS$ OR.* DAMAGE TO FACILITY

. . . TYPE DESCRIPTION

EID 7 .B. 9~ *: . . . NA I

10~-------...;.;..----:~--...,;,,;.---~...;._----~."'t:--:..~.*_--. . . _.,...,,...._;__ _.,....._..:.._.....__-:__ _ _ _ _ _ _ _ i.~U~ J ..

PUBLICITY .

.. [!Ej

• NA l.'

• • .. 7 . 8 9 .. 80 ADDmONAL FACTORS IT@* . J 1** a e~---.-,_.-:-..~---...':'.".,,.~------:-------------....;...--.....;.~----....;...,.;.__.:.___ _,:... _e!J

• J*~hn 'w. W_uJ* ciga Ext. 421 *

• .. NAME:-.*- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - PHONE: _ _ _ _ _ _ __

~ *J .

.-:.-.~ ..

EVENT DESCRIPTION (continued)

On May 21, 1977 the unit was brought off system and the reactor was maintained in the hot standby mode of operation to replace the deteriorated HEPA filters.

The initial DOP efficiency test prior to removal of the filters indicated 0%

efficiency. New HEPA filters were installed and *satisfactorily DOP tested. The efficiencies obtained for both sets of filters were gr:.eater than 99. 97% which is the design efficiency of the filters as eva*luated in the ff,1inal ,Saf.ety-;Analysis '.Report.

• Continued unit operation was recommended as a result of an on-site review for the period be.tween May 1.5, 1977 and May 21,. 1977 (unit* outage). This recommendation was based on the following:

1. On May 16~and )))7 the efficiency of the "B" HEPA filters were determined to be approximately 60% on both days when analyzed for CS-138 (32.2 min.

Half-Life). *

2. A S!Jilllllation of t.he release rates of halogens and particulates with half

t*f:iv;~~*)onger than eight (8) days was determined to be considerably less

- than the limit as specified in Section 3.8.C of the Technical Specifications.

3. The major gamma particulate contributors were determined to be BA-'140, I-131 and C0-60 (<1%'of the Technical Specification Limit). These isotopes are normally present in the Dresden -2/3 ventilation system which dis-charges to the -Dresden -2/3 chimney.

4. The I-131 as sampled by the CESCO "B" ch~rcoal absorber unit was determined to be 2. 8% of the Technical Specification Limit.

5. A daily sampling program was established to assure ho gross radioactivity releases occurred which would exceed Teeh. Spec. Liinits during the period in question *.

An additional consideration was the increased off gas flow rate from the design of 250 CFM as described in the FSAR to approximately 400 CFM. As a result, the designed holdup time was reduced from 30 min. to.approximately 17.2 min. During the period of increased flow the off gas isolation timer was set at 15 min. which is sufficient time to isolate the holdup line for off standard conditions. No Technical Specification release limits were exceeded for the unit or station during this period of qperation. This is not a repetitive occurrence. (50-77-249-15)

CAUSE DESCRIPTION *,(continued) to properly drain. While the unit was off system the drain was cleared of the deteriorated filter media which had broken loose and a drain trap located in the drain line was repaired. Following the repair the unit was ~gain brought on the line with nq further significant moisture problems.