ML20024C511

Advises That Preliminary Rept of Safety Concern PSC 16-79 Will Be Provided Upon Completion

ML20024C511
Person / Time
Site:	Crane
Issue date:	05/31/1979
From:	Taylor J BABCOCK & WILCOX CO.
To:	Jackie Jones, Karrasch B, Klein S BABCOCK & WILCOX CO.
References
TASK-*, TASK-03, TASK-06, TASK-3, TASK-6, TASK-GB 205-T4.4, GPU-0262, GPU-262, PSC-16-79, NUDOCS 8307120727
Download: ML20024C511 (7)

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i THE BABCOCK & Wit.COX COMPANY t,}4]%

POWER GENERATION GROUP

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From ll3 J. H. Taylor, Manager, Licensing (2817) ses **.s

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File No.

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PSC 16-79 e

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Preliminary Report of Safety Concern PSC 16 79 May 31, 1979 g..........-

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i S. H. Klein E. R. Ksne B. A. Karrasch J. D. Agar I

J. P. Jones G. O. Geissler W. A. Cobb H. A. Bailey B. B. Cardwell D. Mars f

D. W. Berger E. A. Womack

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D. H. Roy C. E. Parks 1

J. C. Deddens

'B. M. Duna.i R. E. Kostba R. C. Jones C. M. Olds J. McFarland d

i A. II. L a :s r E. C. W.ted K. R. Ellison Record Center In accordance with Procedure NPG-1707-01, " Processing of Safety Concerns," I sm forwarding herewith a reported concern on a small break LOCA should the RC pumps go off the line by any means such as by operator sction or loss of offsite power.

PSC 16-79 has been assigned to this case.

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When my staff has completed its evalustion ss to whether a reportsble concern exists, I will communicate their findings to you. The point of contact within 1.icensing on this matter y'.

is H. A. Bailey, Ext. 2678.

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MAY 2 91979 l-

- i PRELIMINARY REPORT OF SAFETY CONCERN 5 t>'sc /(. yc;P kto: RAsiaGtt. LICthsthE. hPGll Q 8t&sesitaat $ttstetett satt l>

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,p Analysis perforced by ECCS Analysis Unit in January.1979 for the 205FA I

Standard plant.

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v-ATTACINCHT 1 M II 961 In the ECCS Analysis Unit's and Plant Cesign's progress report for January.

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1979. the following item was reported as re,olution of a concern over the j

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RC pump status during a small LCCA.

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Small Break Analysis with No loss-of-Offsite power - 3e 0.05 ft break was stuaiec cn tne 205 f.A. Plants to determine the impact of keeping the R.C. pumps on. Results show a much rore rapid loss of R.C. inventory relative to a case with tripped R.C. pumps. While it has been determined that the liquid Inventer / situation is worse s

for a pumps running case, hand calculations have been performed 4 -

which show that, due to the pu.ps running. 4. forced flow, steam cooling situation will exist in the core and will result in cladding

'i temperatures of less than 67CF. Thus, the pumps tripped case remains a worse situation for small LCCA evaluations. This position will be documented during February.

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Examining this case from the standpoint of being able to withstand c:ultiple

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failures brings about this concern. While the statement above may be true p

if the RC pumps remain in operation, the case that was run also shows that, l

3 the reactor vessel would contain'only $ 55a ft of water in 10 minutes after the break should the RC' pumps go off line by any means such as by operator action or loss of offsite power.

3 Since the RV lower head is s900 ft it would take several minutes just to fill the head with only1 HP! pump. (RC pressure s1300 psia at 10 min)

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core teeperature transient would probably be unacceptable. Rough hand cales 5

predict a temperature rise of 300-400. F/ min for the hot pin. Assuming a I

starting cladding temperature of 7CCF and a 300 F/ min rise clad temperature

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would reach 22C0 F in 5 minutes. The lower head cannot be filled in 5 minutes.

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One solution to this problem is to develop a signal to trip the RC pumps such as a low system pressure signal or some, new signal such as a low level signal s

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In any case, sheuld a trip signal be installed a great deal of safety ind 4

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ECCS analyses would have to be perforced or re-examined. On the other hand.

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if the pumps are not tripped, unacceptable results would probably cecur if

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1 the RC pumps should go off line. Further study of this situation is warranted.

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3.M. DUNN MANacER. ICcs ANALYSIS (2138)

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gw Telephone conversation with Zoltan Rosatoczy on 2tay 15,1979 on S r

Fav 29 1979 2

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Mr. Rosatotsy phoned on the afternoon of the 14th with a request that R&V k

supply.information on the expected results of stuck opea PORY small brea f

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This was to with loss of me auxiliary feedvater and RC pu::ps running.

i the analyses provided over the weekend which coa-sidered the same case with the RC pumps off may not have bee cover the concern that F

sp-that the scenario of events would be altered by the different pump assu

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f oon tion and said thac 1 would consider these iri note detail in the a ternAt

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and call them back with a position.

May 15th.

with them and actually made the call at approxi.ately 10:30AM,A I described the analysis as l

NRC, Bei Jones of our staff also listened.in.

A typical small break evaluation of a stuck open FORY without i

auxiliary feedwater with RC pumps ruening and with one HP1 and realist cThe system folless:

Scenario of events:

decay heat power levela (1.0 A:3). involve on a homogoacou's as opposed to it is approach high void fractions; at some time between one and two hours OSI is the conceivable that the void fraction could be as high as 75%.

0 equilibrium void fraction at a decay heat power corresponding t To fraction by two to three hours as evidenced by the TM1-2 transient.

seconds.

his allow for the fact that I."1-2 had operating steam senerators whereas t ld be obtained within the RCS somewhere between one to two ho If at that

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ld fall inte time the RC pumps are tripped, the available, 25%, water wouAnto the RC vessel and ap i

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two locations, approximately 50This would create a solid water level in e

'the reactor vessel of 7 feet or a core mixture level of approxima each to each secan generator.

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that in my opinion the HF1 flow occurring during the pump coast owel rather than dispersed 8-1/2 feet.

.be preferentially distributed to the reactor vess i

3-1/2 throughout the RC system and that this flow would fill the tenain ngThus it w h

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uncovery wculd take place even if the reactor pumps would trip at feet within the core' region.

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lt la core wafavorable time.

the cladding temperature heatup would be minimum and not resuThe y

This situation sulting peak temperature could not be in excess of 1300*y.

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BM Dunn to ER Kane Tolophone Conysrsation with Zoltan Roxstoezy on Page he jyt.

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May 15,~1979. on Stuck Open FORV Vith Fumps h y 29. 1979

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.. w I ould would last for only about five ($) minutes and af ter that time core covery g ',

again be maintained. intention within the operating guidelines to cause an RC pump i bles. Is transient and that this is true regardless of pump performance var a w

other words, I restated our position that at least one pump per loop will rus I confirned that my experience with RC pu:sps running in high void systems has shown ce proble: s with their perforsance and that our pump until it dies.

experts indicate no concern in pumping a two-phase fluid.

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Our phone call ended with Mr. Norlan to pass this information on to Mr. Rozzteca I have not, at this time, had

• and have follovup telephone calls as necessary.

F further* contact on this issue. -

gy IMD/lc Y

t ces R.C. Jones E.A. Womack C.E. Parks' L

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