ML20087P669

Final Deficiency Rept U-71 Re Induction of Auxiliary Boiler Exhaust Gases Into Control Room.Initially Reported on 840224.CO/CO2 Monitors Coupled W/Smoke Detector & Human Detection of Malodors Provides Control Room Ventilation

ML20087P669
Person / Time
Site:	Callaway
Issue date:	03/28/1984
From:	Schnell D UNION ELECTRIC CO.
To:	James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
References
U-71, ULNRC-782, NUDOCS 8404090260
Download: ML20087P669 (3)

Text

7

.k di UNION ELECTRIC' COM PANY 1901 GRATioT STREET

, sT. Louis. Missouns .

l-s

. March.28,_1984

a. .. "9 T.* *,"."'

.~~,.w

. .co ... ..... .......

'Mr. James G. Keppler Regional-Administrator

U.S.. Nuclear. Regulatory. Commission Region III 799' Roosevelt Road Glen Ellyn', Illinois 60137.

DeariMr. Keppler r ULNRC- 78 2 FINAL-: 10CFR50.55 (e) REPORT U-71

~ , ' INDUCTION OF ~ EXHAUST GASES INTO CONTROL ROOM CALLAWAY PLANT

.On February 24, 1984 Union Electric informed the NRC Region III office of a potential significant deficiency under 10CFR50.55(e) Lregarding the induction of auxiliary boiler

' exhaust gases into the:Callaway Plant Control' Room. This deficiency was reported as.a;significant deficiency on March 2, 1984.. Subsequently, on March.22, 1984,. Messrs. Pelke and 2

Cho'illes - of the NRC were :co atacted and 'it. wasi agreed that a final report would be: transmitted to the NRC on or'before

! March 30,.1984.

The event-occurret on December 30,_1983 when exhaust

~

. gases from-the plant auxiliar; boiler stack apparently entered

the; control building' air ' intake' as . a result of a temperature linver,sion"or a downdraft condition. As:a point of. reference, the' control building. air intake penthouse is-located'approximately L70 feet' below and 90 feet southeast of .the' stack. Control ~. room A . operators noticed the' smell.of exhaust. fumes'for approximately

, thirty minute's.to an' hour. During the event, our constructor's

. , safety.personnelLanalyzed.the control room' atmosphere and' deter-minedithat-the _ oxygen-level was adequate, and there were no.

measurable combustible' gases present. The ventilation system

. was .then ' switched to the recirculation mode to alleviate the

~

condition.Z Subsequently, one individual indicated he was naus-

' .,eated and.could:not> complete:his1 work shift. .This individual 1

1 eft?theicontrol room and subsequently recovered without; seeking W' - medical assistance. .Another individual. indicated that=he was' L"lightTheaded" but-he.did.not:become'111.= A third person in

~

o -

the. control room' revealed'that the odor.was unpleasant but it

• f -

_did'not;cause himytofbecome ill. =Othertpersonnel-were in the control room ats the. -. time, L and they experienced little discomfort.

From tihe .information' available L regarding the event,-

lit 11slindeterminate'which combustion gases or concentrations

'of' gases'affected the operators. The operator.who became.ill~

9  :.

S..

Q~ y e4o4o9o260 84032s . "~ APR 2' - M PDR ADOCK 05000403 p.

1 e., ,,9

-. 7 q3 ,

pon y , pi

?? / .-

A E.. ,

v - 2 -

-Lexh'ibitedl symptoms similar to.that of carbon monoxide and carbon dioxide exposure. . Carbon monoxide is the predominant cause of E Jillness'from the inhalation of exhaust' fumes due to its inter-ference.with:the transfer of oxygen to the blood. Carbon dioxide has.the same effect, but to a much lesser' degree. Exposure to these gases is' difficult.for humans to detect because the gases

are= colorless and. odorless.

Other predominant gases in the exhaust fumes, such as unburned hydrocarbons and sulfur dioxide, produce a characteristic malodor thatxindicates their presence. These gases can produce

~

.the'same discomforting effect on an individual; however, the s 1 symptoms may be' caused.by either a. physiological _ reaction or by ca psychological. response to aLdisagreeable, but benign odor.

For example,=the pungent smell._of sulfur dioxide produces a repugnant response from'most individuals at a concentration well below that which is_ considered harmful. It-is not known what stimulus caused the reaction in some of the individuals in the controlLroom as-they recovered shortly thereafter without requiring medical attention. Regardless, fumes were detected by the occupants of.the. control room and'it did prompt them to take necessary corrlctive~ action.

! Regulatory Gu'ide 1.78. addresses the use of human detection as a mechanism'for identifying. hazardous chemical (buildup although we recognize this means.is not_ appropriate for carbon dioxide and carbon monoxide. Therefore, redundanc i non-IE; monitors for'these gases are being installed in the control

building air. intake duct to alarm operators if unacceptable levels

~

7 ;of.these gases, as defined:by OSHA, are reached.

.Our A/E, Bechtel Power / Corporation ~ considered the ilocation of the. control building' air intake duct relative to che auxiliary boileriand diesel ~ generator exhaust stacks in their foriginal design. . Based cnt engineering judgement, they determined 4that.the system design would meet 7the requirements of Regulatory

. Guide ~l.781for controlaroom habitability. In addition, the original' design provides an ionization-type smoke detector for

thecair intake duct-to alarm the operators of-the presence of

~

smoke. .However,.this detector'was not operational at the time

~

' of? the' event and: it :is : indeterminate 'if its sensitivity can be equated to levels of fumes'that would-impair operator performance.

The smoke detector.will be. operational' prior.to fuel-load while the gas.monitorsEare expected <to be installed and operational

.priorsto ascension,above 5%_ power. If the. permanent gas monitors

' ' are noE operational at that time, . port'able detection equipment twill;beiutilized within--the control room.

In summary, .we believe. thati necessary steps are being-

.tak. en to-assure cont rol room habitability. The addition of lCO/CO 2 : monitors coupled withothe= smoke detector and human detection

'of. malodors _provides a; Control Room ventilation ~ system design which c.M , s a

L

[

i ~' < _f ,f-

.o . d*

3 -

assures that control room occupants have adequate warning of these potential environmental. conditions. This is our final i report regarding this matter.

Very truly yours, Donald F. Schnell JJS/JJM/glp cc: B. L. Forney,-NRC Region III Richard DeYoung, Director, I&E

. NRC Resident Inspectors, Callaway Plant (2) 12 " Missouri Public Service Commission I

i't,.

9 1

k -v -

.1.

': N. - _