ML20128B096

Forwards Eccs,Loca & Containment Design Analyses for Plant, for Inclusion in Rept to ACRS

ML20128B096
Person / Time
Site:	Monticello
Issue date:	10/29/1969
From:	Rosen M US ATOMIC ENERGY COMMISSION (AEC)
To:	Boyd R US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 9212030559
Download: ML20128B096 (8)

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[ i R. S. Boyd, A/D for RP, DEL TERUt S. Levine, A/D for RT, DEL MONTICELLO - ECCS, LOCA, COIffA1 MENT DESIGN REVIEWS Enclosed for inclusion in your report to the ACRS are the ECCS, LOCA, and containment design analyses for the Monticello reactor.

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RT-799A Morris Rosen, Chief DRLINTB BS/RJC Huclear Technology Branch Division of Reactor 1.icensing Enclosure Monticello Review cc:

D. Vassallo, DRL D. Huller, DRL bcct H. Specter R. Colmar M. Rosen R. DeYoung S. Levine

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i R. S. Seyd, A/D for RF, DEL THRUt S. Levine, A/D for RT, DEL N0HTICELLO - ECCS, thCA, CONTAINME!U DESIGH REVIEVS Enclosed for inclusion in your report to the ACKS are the ECCS, LOCA, and containment design analyses for the Monticello reactor.

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e Horris Rosen, Chief RT-799A DRLINTil:HS/RJC Nuclear TechnoloFy Branch Division of Reactor 1.icenslag Enclosures Monticello Review cc D. Vassallo, DRL D. Huller, DRL i

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.I ECCS AND LOCA AMALYSIS f

k'c have con.pleted our review of the ECCS and LOCA analysis for the a

The ECCS is of the same concept as those approved i

I Monticello reactor.

I for all recent B W s.

The coolant delivery capacitics of the several l

ECC subsystems are appropriate to the comparatively cr.nller size and thernal output of this plant.,Recent design changes in auto-relic!

4 1:ater:1ght Permissives have been incorporated in the Monticello design, compartments for redundant sets of ECCS pumps have been provided for post-LOCA ficoding protection.

l The LOCA analysis for this plant was performed by CZ vith codes and This modeling assumptions which were the same as for the Dresden 3 plant.

i analysis includes Moody's level suc11 model which vc find acceptabic, but it also includes the controversial transient MC11FR calcul tion which vc

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consider as unsubstantiated with experi-ontal data at this time and which l

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vc regard as less conservative than the previous codels as used, for t

example, in the Duane Arnold analysis. liovever, a recalculation of the t

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Monticello plant was submitted in Amendment 017 on the basis of the more conservative "dryout" model which indicates a change in clad temporaturc only in the first 16 seconds of the blowdown, but virtually no difference On this' in the calculated peak clad temperatures which occur later on.

basis as well as on the basis of the similarity to the Dresden 3 plant I

which we found acceptable as a result of our evaluation using the coro

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,'s conservative nodel, vc conclude that the predicted perfor::.ance of the 4

LCCS for the Monticello plant is within our bounds on met:.1-water reac-J i

tion, clad damage, and peak clad toeperature.

1 With regard to the probicms of fuel failure and the associated potential blocking of channels resulting from the " ballooning" of the clad, recent preliminary tests have-indicated that relatively large I

clad deformations have been observed for conditions approximating the d

However, cooling tests on simulated fuel bundles wfth substcntial 1,0CA.

flow blockage have indicated that the clad temperatures arc turned down with only a relatively small increase in temperature over the case with i

an unblocked channel.

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~t rc."Its are not yet definitivo, 1

the findings are very encoura;,, e icg wu la chis arca is continuing.

The present tentative results indicate that no new difficulties have been

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' identified and that effective cooling appears to be possibic even with relatively severe deformations of the cladding.

4 We have identified one area of conectn on which a firm DRL position should be given to the applicant. This concern is with possible dt. mage to the hPC1 turbine due to very low quality two-phase flow ( 20%) fol-loving a main steam line break.

Because the turbine is designed to operate i

at steam qualities greater than 95% because gross failure of the EPCI i.

turbine could potentially create a large leakage path from the_contain-ment, and because the HPCI steam supply isolation capability is relatively 1

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slov acting, vc believe that a design chen;;e in this subsyster is i

3 Such a change should be required to precludo dce.cgo to the varranted.

HPCI turbine for the cobpicte spectrum of breaks over which the subcystem i

is actuated, not just over the spectrum of breaks for which the subsystem

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is needed for vessel depressurization and emergency-core cooling.

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i CONTAINMENT DESIGN REVIt" i

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The Monticello Nuelect Cencrating Picnt has a " torus cnd light-

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l bulb" primary containment confir,uration. A comparison of tha signifi-

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cant characteristics of this containuent to that of sever:1 other Mt.I's is shown in Table 1.

The drywell and the suppression chambcr are both l

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Since the designed to accom:aodate internal pressures of +56 psig.

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calculated maximum blowdown pressure for the drywell and supprection j

chamber is 41 psig and 25 psig, respectively, t,he primary containment I

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is designed with adequate pressure margin and is acceptabic.

The calculated peak containment blowdown pressures are based on an analytical model that has been shown to be conscrvative when ec pared i

to experimental measurements made at Humboldt Bay and Bodega Ecy pressure i

suppression tests.

The drywell and suppression chamber pech pressures are dependent J

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1 upon parameters such as the vent pipe submergence, the vent flow resis-tance factor, the reactor blowdown area to vent area ratio. and by the To a lesser degree drywell volun.c to the suppression chamber air volume.

i' the volume ratios Vd/Vr, Vp/Vr, also influence the design, where Vd. Vp, i

and Vr are the volumes of the drywc11, suppression pool and reactor, t

i The design of the Monticello nucicar Cencrating Plant respectively.

I has climinated several of these variables by utilizing-a configuration that has features that are the same as the Podega Bay test configuration, l

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nancly, each had a 4 foot vent pipe subscrgence, ar.d the vant resictance The suppressf or, chanber air volu;c ves sized a; c factors are equal.

3 and has dryvell to vetvell air volume ratio minimum volume of 98,300 f t k

of 1.37 vhich is close to the 1.42 volume ratio used in nany todcr.c Lay f

tests.

is determined by keepir.g a brcsh in addition, the total vent area l

This arca ratio is tha ca=0 as arca/ total vent area ratio of 0.0194.

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that used in Oyster Creek and other ma designs and is the sat.e as

_ Bodega Bay tests B-17 and D-30.

Co:parisons between the analytical model 1

and experiments at this break arca/ vent area ratio show a 10 psig over-i I

The Monticello 4

f prediction of the peak pressure for the analyticci model.

break total area is 5.6 it'2, which is the sum of one face of a 28 inch f'

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cach, diameter recirculation lino (3.57 f t ), ten jet pumps at 0.057 f t a

2 Under normal operating

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i and 1.48 ft from the equalizer line valve port.

conditions the equalizer line valve is-closed and the bresh area.is only '

The dryvell peak pressure is about 3 to 5 psig higher for':he f

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1 5.6 ft case than the 4.2 ft case.

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1 COMPARISON OF SEVERAL L'JP. CONT /INMI" TS i

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a Drywc11 Free Volu:ao, f e 132,400 146.400 147,000 180,000 i

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108,250 113,600 110,000 127,400 j

volume, (caximum), it i

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f volume, (maximum), it 77,970 90,800 92,000 91,000 l

Vent pipe submergence, i

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4-4 4-a Vent flow resistance factor 6.2 6.2 6.2 6.1 i

Design break area, ft*

5.6 4.2 5.5 6.22 3

break arca/ total vent

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.0194

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area Volume dryvell/suppres-

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sion chamber air volume 1.37 1.29, 1.25 1.42 4

Calculated peak pressure during blowdown, psig i

Drywell 41 45 41 37 i

Suppression Chamber 25 28 26 19.4 l

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