ML20134G968

Suppl 2 to Preliminary Equipment Survivability Rept

ML20134G968
Person / Time
Site:	River Bend
Issue date:	08/31/1985
From:	GULF STATES UTILITIES CO.
To:
Shared Package
ML20134G952	List: ML20134G961 ML20134G968 RBG-21-900, Forwards Revised Stuck Open Relief Valve Base Case & Suppl 2 to Preliminary Equipment Survivability Rept, Per 850812 Meeting.Analysis of Wetwell Hydrogen Igniters for Revised Thermal Profiles Will Be Submitted by 850821
References
NUDOCS 8508280180
Download: ML20134G968 (10)

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Attachnent II River Bend Station Preliminary Equipnent Survivability Report Supplanent 'Am Gulf States Utilities Ccrnpany River Eend Station - Unit 1 August, 1985 3

I-i B508280190 850819 PDR ADOCK 05000458 A PDR

Introduction The previously subnitted preliminary equignent survivability report (Ref.1) was based on the original CIASIX-3 analysis of the pressure and tmperature response of the River Bend Station following a hydrogen generation event (Ref. 2) . We thermal p7ofiles predicted by CLASIX-3 for the wetwell and intar=vliate volume were used to determine equipnent response to deflagration burns. mis analysis determined that no deflagration burns would occur in the intermediate volume although a single burn was forced to occur concurrently in the wetwell, intermediate volume and upper containment to deplete the renaining hydrogen inventory after hydrogen release was coupleted. 'Ihe equipnent survivability analyses based on this thermal environment indicated that with the exception of the hydrogen igniters located in the wetwell all analyzed equipnent was capable of surviving the hydrogen generation event.

Although the intarwvliate volume thermal environment predicted by CLASIX-3 is consistent with the design of the hydrogen ignition system which is based on maximizing hydrogen burning at low concentration which would occur primarily below the HCU floor, there is a possibility that sane burns could occur above the HCU floor. Consequently, at the request of the NBC staff, GSU subnitted a supplanent to the preliminary equignent survivability report (Ref. 3) which evaluated the thermal response of equignent located in the intermediate volume assuming that i the equipnent was exposed directly to the burn environment predicted for

m-= ,

a the wetwell region below the HCU floor. his was an extremely conservative approach since the CIASIX-3 results are very conservative and the intamadiate volume equipnent will not be exposed to the wetwell thermal enviroment.

To provide a more realistic upper bound for the in+amadiate volune thermal envirorsnent, a revised Stuck Open Relief Valve (SOW) CLASIX-3 analysis has been performed (see Attachment I of this subnittal) . This repvrt. evaluates the ability of equipnent located in the intermediate volume to survive this thermal envirornent.

2.0 Sermal Environment he revised SOW base case CIASIX-3 analysis is presented in f

Attachment I. %is analysis was based on a more detailed nodalization of the intamadiate volune and more realistic hAwen burn parameters for all con +aimant regions except -in the wetwell

• volume. : The CLASIX-3 model used in the revised SOW analysis split the previously defined intermediate volume into two separate volumes to- provide a better definition of the thermal environment to which the equipnent would be caevsed. %ese new volumes were termed the lower in+amadiate volune (HCU floor to El.141') and the upper intamadiate volume (El.141 ft to refueling floor). @e thermal

profiles used in this analysis.are shown in figures 1 through 3 for i

the wetwell, lower intermediate volume and upper intermediate volume respectively. Equipnent located in the lower intermediate volume L

L

o .

near the HCU floor will be directly exposed to deflagration burns occurring in this voltme. Evaluation of the thennal loading to equipnent in the lower ini-arnviiate volume due to deflagration burns in the wetwell indicates that the thermal radiation contribution should be minimal cmpared to the intermediate volume deflagrations.

%is is based on the physical location of the equignent relative to the wetwell burns. For example, the Rosanont transmitters are effectively shielded fran the wetwell burns by the floor plate upon which the panels are mounted and by the HCU floor grating. Since the grating has a blockage function of 0.3 and the view angle is relatively small for these transmitters, the radiative heat flux due to wetwell burns was judged to be of minor importance. Inspection of the lower intermediate volume thermal profiles shows that the flow of hot gases fran the wetwell due to burns in the wetwell has been included in this profile.

-3.0 Equipment Modeled The equignent- modeled in this analysis are a Rosanont transmitter and a Reliance motor. h e HEATING 6 models used in this analysis are the same as the models previously subnitted (References 1 and 3) . anphasis was placed on these pieces of equipnent since these are the only equipnent, other than cable, required to survive a hydrogen generation event which are located in the lower inter =vliate volume. Inspection of the thermal profile for the upper intermediate volume indicates that the maximum tanperature

reached in this volume is 320 F, since these tanperatures are only slightly higher than the tenperature profiles previously analyzed (Referen m 1). All equignent located in the upper intarnvH ate voltzne is expected to survive the hydrogen generation event.

Further analysis of the survivability of equipnent located in this voltane is not judged to be necessary at this time.

4.0 Results/ Conclusions The results of this evaluation are sunnarized in Table 1 which shows the t.w g z.tures reached by the casing and the most thennally limiting sutHxxuponent when exposed to the lower intennediate volume deflagration burn envirorrnent predicted by CLASIX-3.

For the Rosemont transmitter, the case temperature at the end of the transient was below the equipnent qualification tenperature.

Therefore, the survivability of these transmitters is assured.

Although the case tenperature of the Reliance motor was slightly above the equipnent qualification tenperature at the end of the transient, the sensitive conponent, the motor coil, was well below the qualified temperature.

These results show that the essential equipnent located in the lower intarwaiate volume is capable of surviving the hydrogen generation event.

tezueNCES

1) RBG-21,423 dated July 1, 1985 fra Gulf States Utilities (J. E. Booker) to Nuclear Regulatory Ccunission (H. R. Denton)

2) RBG-21,218 dated June 7, 1985 frm Gulf States Utilities (J. E. Booker) to Nuclear Wp.datory Cmmission (H. R. Denton)

3) RBG-21,771 dated August 5, 1985

-frm Gulf States Utilities (J. E. Booker) to Nuclear Regulatory Cmmission (H. R. Denton)

Table 1 Stenary of Results Equipnent Predicted Tenperature Qualification Sersitive Unit Tenperature Casing Component Rosemont Transmitter

- 320 F 311 F 290 F Model 1154 Reliance Motor on 345 F 347 F 311 F Limitorque Operator-

e 4 g ,

FIGURE 1 GSU/ RIVERWETWELLBEND 5 VOL. AUG.85 TEMPERATURE 2.4 2.2 -

2-1.8 -

p 1.6 -

vm talj 1.4 -

1.2 -

0 US 1-I o.a -

0.6 -

O.4 -

, ((((( @ (LLb4bb400UU o , , , , , . . . . . i i i O 4 8 12 .16 20 24 28 TIME (1000 SECONDS)

A-

. FIGURE 2 l

l GSU/ LOWER RIVER BEND 5 VOL. AUG.85 INTERMEDIATE VOLUME TEMPERATURE 1

' O.9 -

O.8 -

0.7 -

C

[9 0.s -

2 5

g l 0.5 -

0 .4 -

I O.3 -

A' '

Js6 '

6-

• 6 L W 0.2 - (y(( ( 5 ( 5 O.1 -%

0 , , , , , , , , , , , , ,

O 4 8 12 16 20 .'44 28 -

TlWE (1000 SECONDS)

FIGURE 3 GSU/ RIVER BEND 5 VOL. AUG.85 UPPER INTERWEDIATE VOLUWE TEMPERATURE 320 -

300 -

280 -

260 -

Q 240 -

]

p 220 -

200 -

160-p 140 -

l i l 1 20 -

g s LLL a uN

)

V t L. /

l J 'lh[l I 100 - .

A U M i i a e a i i e i a i e i O 4 8 12 16 20 24 28 TlWE (1000 SECCHDS) i

._ _ _ . _ _ . , . _ _ _ _ _ . _