ML20024C511

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

ML20024C511
Person / Time
Site:	Three Mile Island
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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l rTdi i THE BABCOCK & Wit.COX COMPANY POWER GENERATION GROUP t,}4]%

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

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File No. ,

or Ref. 205 T4.4 PSC 16-79 e

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• Preliminary Report of Safety Concern PSC 16 79 May 31, 1979

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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 '

f B. B. Cardwell D. Mars +

D. W. Berger E. A. Womack D. H. Roy C. E. Parks  ;

1 J. C. Deddens 'B. M. Duna.i R. E. Kostba R. C. Jones d

C. M. Olds J. McFarland ,

E. C. W.ted i

A . II. L a :s r 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. ,

j PSC 16-79 has been assigned to this case.  !

J 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 PRELIMINARY REPORT OF SAFETY CONCERN 5 t>'sc /(. yc;P l[.',[Ol - i satt l> ...

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,p Analysis perforced by ECCS Analysis .

Unit in January.1979 for the 205FA Otts S ee I

4 le sama ama.atau is nas a.ast, Standard plant. \

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' Possibly All (177, 205 & 145 FA plants)

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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 jt i RC pump status during a small LCCA. g3 '

l Small Break Analysis with No loss-of-Offsite power - 3e 0.05 ft 2 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 [.

- 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 the reactor vessel would contain'only $ 55a 3ft 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 it would take several minutes just to Since the RV lower head is s900 ft fill the head with only1 HP! pump. (RC pressure s1300 psia at 10 min) The  !-

L 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 [

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

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

r which currently does not exist.

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

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 - i 1

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

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ATTACHMU4T 2 g* .

HF. SABC0CK & Wit.COX CorWAnY k

T61 F J0WER GENERATION GROUP e I $lL w

" . ' .i j E.R. RANK. f.fCENSINC Jros

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

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Fav 292 1979

Telephone conversation with Zoltan Rosatoczy on 2tay 15,1979 on S gm...

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

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f supply.information on the expected results of stuck Thisopea was toPORY small brea i'

with loss of me auxiliarythe feedvater analyses and provided RC pu

:ps over running.

the weekend which coa-cover the concern that .

sidered case.

the same case with the RC pumps offsp-may not have: bee F that the scenario of events would be altered by the different fpump oonassu 7

tioncalland and themsaid back thac 1 would consider these iriMay with a position. note 15th. detail in the a ternAt

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l with them and actually made the call at I described approxi.ately the analysis as 10:30AM,A NRC, Bei Jones of our staff also listened.in.

folless: A typical small break evaluation of a stuck open FORYiwithout ,

auxiliary feedwater with RC pumps ruening and with one HP1 and realist cThe system Scenario of events:

decay heat power levela (1.0 A:3). involve on a homogoacou's it is as opposed to approach high void fractions; at some time betweenOSI oneisand the two hours conceivable that the void fraction could be as high as 75%. 0 equilibrium seconds.

void fraction at a decay heat power To corresponding t fraction by two to three hours as evidenced by the TM1-2 transient. his allow for the fact that I."1-2 had operating steam senerators whereas t ld be If at that [

obtained within the RCS somewhereldbetween one to two ho 4

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

\ two locations, approximately 50This would create a solid water level in e each to each secan generator.

e 'the reactor vessel of 7 feet or a core mixture d n would level of approxima

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

.be preferentially distributed to the reactor vess i 3-1/2 throughout the RC system and that this flow would fill h thest tenain ngThus k it w feet within the core' region. p uncovery wculd take place even if the reactor lt la core pumps would trip at f wafavorable time.

the damage.

cladding temperature heatup would beThis minimum situation and not resuThe y

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

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• Subj Tolophone Conysrsation with Zoltan Roxstoezy on  ;-v May 15,~1979. on Stuck Open FORV Vith Fumps h y 29. 1979

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.. ;, wI Runntne and No Aux 7eed ould g ',

would last for only about five ($) minutes and af ter that time core covery again be maintained. intention within the operating guidelines i bles. Is to cause an RC w pump transient and that this is true regardless of pump performance var a 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 until void systemsit dies. has shown ce proble: s with their perforsance and that our pump experts indicate no concern in pumping a two-phase fluid. I.

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

• and have follovup telephone calls as necessary. F further* contact on this issue. -

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ces R.C. Jones E.A. Womack C.E. Parks'

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