ML20246L557

Urges That Licensee Position on Exclusion of Drywell Oxygen Concentration for SPDS Be Rejected

ML20246L557
Person / Time
Site:	Perry
Issue date:	08/29/1989
From:	Hiatt S OHIO CITIZENS FOR RESPONSIBLE ENERGY
To:	Colburn T Office of Nuclear Reactor Regulation
References
GL-89-06, GL-89-6, NUDOCS 8909060351
Download: ML20246L557 (2)

Text

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August 29, 1989 Mr.' Timothy G. Colburn, Sr. Project Manager Project Directorate III-3 LDivision' ofL Reactor Projects -

III, IV, EV, and Special Projects.

Office of Nuclear Reactor Regulation U.S.' Nuclear Regulatory Commission Washington, DC. 20555 L

Dear Mr. Colburn:

-Re: Perry Nuclear Power. Plant, Docket No. 50-440 On July 12, 1989 the Cleveland Electric Illuminating Co.

responded' to Generic: Letter 89-06, regarding the Safety Parameter Display System'("SPDS"). (CEI letter attached.) In this letter CEI stated that an SPDS display for drywell oxygen concentration will not be provided because the Perry. Mark III containment is.not inerted.

This is an unacceptable position. Precisely because the Mark III containment is not inerted, it is necessary to monitor oxygen as well as hydrogen concentrations in both the containment and drywell. The need to monitor oxygen is illustrated by a degraded core accident scenario initiated by a reactor coolant system pipe break in the drywell. The initial blowdown will force the drywell air mass through the suppression pool into the containment. The drywell atmosphere will consist of steam, and later, hydrogen produced by the-metal-water reaction in the core. This atmosphere, lacking oxygen,- is inert. However, oxygen will eventually be reintroduced into.the drywell. This will result from operation of the drywell purge compressors (part of the hydrogen mixing system, PNPP USAR Section 6.2.5.2.2), which take suction from the containment. This can also occur if steam in the drywell is condensed, causing depressurization of the drywell and the -

flow of containment air into the drywell through the drywell vacuum' breakers. The Perry USAR indicates that drywell steam condensation will occur during accident recovery, when cold coolant spilling into the drywell will cause the steam to condense (USAR pp. 6.2-10). Drywell steam condensation could also occur from violent suppression pool overflow into the drywell (reverse flow through the horizantal vents) resulting from hydrogen deflagrations in the containment (see NUREG/CP-0038, " Proceedings of the Second International Conference on the Impact of Hydrogen on Water Reactor Safety",

p. 291). In the steam condensation scenarios particularly, the Q Ob 8909060351 890829 PDR ADOCK 05000440 1[ j, P FDC

.; ;> ,e hydrogen concentration will pass through the detonable range.

Whether a detonation occurs (or the strength and resulting overpressure effects of any deflagrations) will depend on the oxygen content.Tation. Drywell oxygen concentration thus becomes a crucial parameter to be monitored during an accident for effective accident management (e.g., the operators may need-to turn off the hydrogen igniter system when the hydrogen l concentration is high and when oxygen is present in the drywell).

I therefore urge that the licensee's position on the exclusion of drywell oxygen concentration for the SPDS be rejected.

Sincerely, m~ /

Susan L. Hiatt Ohio Citizens for Responsible Energy, Inc.

8275 Munson Road Mentor, OH- 44060 (21ti) 255-3158

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Ferry Nuctur Praer Ph.t.t Docket No. 50-440 Ceneric 1.etter 89-06 S&fety Pa r arse t e r D i s o l q S g t,,et.

Cent 1tt.cid The o .ibj e c t a n.ste L4t:cc cequented cut certif;. cat ion t hat the Per:; Saf ety

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-By thits le t t. r , ' The Clevelu.d Ele t ri c 111ascinat ing Cocip ny ce r t i!!2 a that the Perry SPDS ucata ri ferenet.d require:.ec.t s with t he exceptions of prt,viding dryvell hyJtegen a.Y1 a x y g e t. concent rations on an SPDS ac:cen. A display for dryeell hy:tru;;en cencta.tre.t ic.:n will la prc eided bef< re st an top f r o the s e c a..d refuelit.g cut ;,c.  :. di piny far dcruell axygen concentrstica aill r.at be -

provided stuce. : h .: ?ctry Mart III containment is licensed to operste at ne rn. 1 orygen le.als. (1.f. n c,t ia.rena).

Tne f all.,- ...; c? ra t t u t it u i s p r:,vided f or s ect ion 111. A. ? of AUhEC-l M2 s, .;h respect t o 01'.,0 a pl i n; r o t e s . Due to system de.41gn, the i,creen r e t t .: s h r a t e 19 ft.ater Ltui. d.e al.nle r tu; hcwe.ver, the f!'LS saupling reten a4 e Latle:f tegory la providic:: the r..qs.tred resolution. SPDS cuurs will Le trata,d to otiferet.ciate trt-as a screen ref resh rates r.nl astple upacte stes.

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