ML20087P669
| 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
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.k di UNION ELECTRIC' COM PANY 1901 GRATioT STREET sT. Louis. Missouns.
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. March.28,_1984 s
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'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 Cho'illes - of the NRC were :co atacted and 'it. wasi agreed that a 2
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 eft?theicontrol room and subsequently recovered without; seeking 1
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- medical assistance..Another individual. indicated that=he was' o
L"lightTheaded" but-he.did.not:become'111.= A third person in
~
- the. control room' revealed'that the odor.was unpleasant but it
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_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~
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-Lexh'ibited 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
~
1 symptoms may be' caused.by either a. physiological _ reaction or by s
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
~
- of.these gases, as defined
- by OSHA, are reached.
7
.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.
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In summary,.we believe. thati necessary steps are being-
.ta en to-assure con rol room habitability.
The addition of t
lCO/CO : monitors coupled withothe= smoke detector and human detection 2
'of. malodors _provides a; Control Room ventilation ~ system design which c.M,
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3 assures that control room occupants have adequate warning of these potential environmental. conditions.
This is our final report regarding this matter.
i 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
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