ML19220C394

From kanterella
Jump to navigation Jump to search
Demonstrates Adequacy of TMI-2 Design Re long-term Cooling Capability After Steam Line Break Accident.App 15B of FSAR Will Be Revised to Incorporate Recent Info
ML19220C394
Person / Time
Site: Crane Constellation icon.png
Issue date: 12/20/1977
From: Herbein J
Metropolitan Edison Co
To: Varga S
Office of Nuclear Reactor Regulation
References
GQL 1741, GQL-1741, NUDOCS 7905010097
Download: ML19220C394 (4)
v • d • e


Text

a

/

f ~Act Y'/ f;3 11 l IU'M

~*rdRY 30Cl(ET FRE CD,0y NETROPOLI TAN EDISON COMPANY f

PCST CFFicE 30X 542 REACING. PENNSYLVANI A 19603 TE LEPHCNE 215 - 9?9-3601

, 9, ec ember o._ n,,,

c G %"

11**1

~6g Directer cf :Tuclear Reacter Regulation Attention:

'r.

Steven A. Varg >

Light 'Jater Reactors 3 ranch :ic. 4

'Q; U. S. ?!ac.1. ear Regula: cry Cc=rissica

'Jashing cn, D. C.

20555

Dear Str:

r,, a_.

c. a. 4.., L.

4... o (_.c__-)

,c

.s

,,,,...v4.,..

m_ a _ a_., a

..m.

License :!c. CFFR 66 Docke No. 50-320 Len: "'e Cccline

  • f'er A Steam line 3-eak Accident In reetings with you staff en September 7,1977, they raised an additienc.'.

ccncarn relating te a steam line break accident at I:C-2.

Se questien of icng tern ecoling capability af'er a steam line break accident was discussed.

~he cenerrn was expressed in the c ntext of the Appendix 153 accident 2nalysis and "leng ter cccling" vac defined as bringing the plant to a stable, het shuticvn condition.

S a attachment to th s letter addresses this cencern and demonstrates the adequacy of the T:C-2 design with respect t; this concern.

Appendix 153 cf the TSAR vill be re'tised to inecrporate recent inferraticn en fuel perfer-aace and icng ter: ccoling pricr to rec eipt of an operating license.

Very truly yours, signed J. G. HerbeiII J. G. Eerbein Vice President g9'0077 a

i /

o Gu... m..e

. b

.s g.

3, u....

Lcng Term Cccling Fc11cving Ste1= Line 3reak 7 Oi^

7~/o^ A600M c-Dr. Ernst Vcigenau, Directcr

n..-# 4 -. c, T,, en. 4, t.s -,,, #.

.e e.~.. _ n..

U. S. :;uclear Reg"latory Cenniscic:

~4ashin g:cn, L. C.

20555

m.,p-ma 9 maa e

9~a,~

,,Gw,

-f;.

.,9

.. *r 1,.11. e.-,,, 1 A.

A nerd. I

,a,l. a f.,-

mg

.w e,

w,,.vn

.* a, + c e -,.av bL W 1. 4 J y m, n uL.4 U

".S.. LvLL.4J l

D.

O. 2 eu 4

Analysis results indicate the pctential fer loss of natural circulation subsequent to blcvdevn fciloving a steanline break accident.

For the verst-case accident scenarios prese.-ted in Appendix 153 of the TMI-2 FSAR, conditiens in the primary syste: l5 seccnds after the accident vculd be:

RCS Pressure: 2 00 psia Average =cderator temperature: ~L20F vith 2-phace liquid in the primary lecp RCS flev: reacter ecolant pump tripped (a verst-case assu=ption for this situatica) due either to less of offsite pcVer, cperatcr actica, or the stea: line break envircnnent.

Pressuricer level:

cero (saturated stes: bubble assumed at the core cutlet plenum).

Main feedvater:

isclated (a vorst-case assumptica vith respect to icng tern ecoling).

E=ergency feedve,er: For the -avi u: core ecold:vn, the pu=ps are assured to be initiated at 2 seccnds. Fcr 1cng ter: cooling, the pumps are assumed in-effective until after the syster has been established in a solid water conditicn.

Energency feedvater is autcratically initiated by less of all fcur reacter ecolant pu=ps or loss of feedvater pumps. Feedvater pumps vculd be lost due either to hydraulic upset of the pu=p as a result of the stea: line break, er icss of main stern to run the pu=ps.

Cnce initiated, energency feedvater flev is between h'O and 500 gp: and is suf-

'a--

  • +

---~

Aaaay heat.

High pressure injeer.icn: 2 pu=ps running at -520 gp: each l based on FSAR Figure 6.3-2).

To credit taken for centributien te establishing natural circulaticn due.to HPI flev.

Syste vould be in a solid water eccdition as a result of HPI additicn in 10-15 =inutes after 'he accident.

Lev pressure injection: running, but not adding fluid due to high ECS pressure.

Maximum heatup rate: =cre than ene (1) hour before syster beccres solid, assu=ing no vater additics after T5 seccnds.

Total power is censervatively estirated as 2LO :Gi frc: 75 seconds through the course cf the event.

U)b$ ~ (33mbh e =ber 2C,1377 llh/s 1751

~4 -"+ es af ter accident, isolating the intact MSI7 eles"" -

steam generator.

Core fleed tankc:

Inventcry added for first 75 seccnds.

Insignif-icant vo'"-a

'ddd**^-

subsequent to this time.

Jo credit for CFT ficv assu=ed in establishing natural circulation ficv.

Based en the above initial conditiens and assuming 2 HPI pu=ps running at 520 gp=, the pressurizar veuld be ec=pletely filled in = 15 =inutes, asst =-

ing the operator did not throttle HPI flow prior to +his ti=e.

(It c an be seen the EFI additica, not heatup, has the dc=inant effect in pressur-icing the systes. )

Assr=ing that natural recirculatica has been lost in the ECS it can be reestablished in several different ways.

First, it can be reestablished assu=ing no operster action until after the ECS is in a sclid water cen-diticn.

Water vill be relieved through the pressurizer cede safety valves, prc-venting overpressurizatica of the pri=ary systen.

By this ti=e, at least ene steam generator has been isolated and e=ergency feedvater is being autc=atically supplied to bcth stea= generaters.

The operator vill then centrol plant ccnditiens by taking -, ual centrol cf the HPI and energency feedvater syste=s to =aintain hot standby conditions or prceeed to ecid shutdevn if desired.

Stes: relief frc= either the at=capheric du=p valves of the stea: generator safety valves vill prcvide secondary systen pressure centrol and a heat sink is provided by the intact stea= generatcr.

On the other hand, if the operater assu=es flev centrol over the EP! syste=,

he can establish natural circulatica vithout putting the RCS in a solid water conditicn. He vculd do this by ccrrelating EC het leg temperature and pressurizer pressure.

Cnce the RCS is pressurized at least 1CO psi above the het leg saturaticn temperature, the operatcr is assured that a solid water condition exists and natural circulation thrcugh the core has been reestablished, because of the heat sink previded by the inclated steam generater which is being supplied with e=ergency feedvater.

This sequence of events dces not result in a violation of Appendix G fer the fir: five years Of renc cr cperatien ( Appa A'-

G li=its have only been calculated fcr the first five years of cperation).

Neither does this sequence prevent adequate core ecoling, Since the fuel is always covered by (at least) a tve-ph se fluid, fuel clad te=peratures never exceed the saturatica temperature of the fluid.

Independent of natural circulatien, HPI injection vill provide fu:":her assurance of adequate'ccre c6 cling.

The analysis of this sequence of events has assu=ed that natural circulaticn flev has been Icst due to voiding in the RC piping.

Ecvever, the folleving censiderations support the judga-a-+ +"at natural circulaticn is never actually lost:

f% $

S,

.r

.n_._-._.,

9~,~

1.

Reacter ecclant p=p ccantdevn vculd continue circulacion ir the RC lecp fer at least 90 seconds.

2.

HP: injection uculd enhance natural circulaticn ficv.

3.

Energency feedvater vculd remove heat frc: the ?rimar7 275te cuch scener than is taken credit fer.

Tnis heat rencval vculd collapse stea= veiCs and enhance the cendency for natu-al cir-

.,3a+.4c

-~

S reality, circulaticn in the RCS syste: vould not be lost and an orderly transitien frc= the stea: line break transient to a stable shuticwn ecn-dition vculd cccur. Regardless of these censiderations, we cenclude thac even the ass =ed accident scenario (in which cnly safety g-ade equi; tent is assumed), results in nc undue risk to the health and safety of the public.

3 3 R3, m

g

u.s. sucuaa aucutar:aw ::

s-Occxa7 suu ss a j

Nac sc'au 195 g

-er" <-C - 3 2 O

12. s
  • its suusam I

~ NRC DISTRIBUTICN pen PART 50 CCCKET MATERIAL PSAR/FsAR x.0 D s.

TC:

FRCM:

1 =ATs cp Occ*autNT Metropolitan Edison Ccepan, l

12/20/77 Mr. Steven A. Varga R. eading, P a.

273,ge 3v g =

J. G. Herbein 12/23/77 m-sa Cucicaiza:

    • cr meuraceu suusem en c:r'as mecsivs:

i C caio.N A 2(NC lag 33 p; g g l

/fdL

rscater:ca suc:,,0su a s Consists of info. concerning Long Term I

Cooling af ter a Steam Line Ereak Accident...

I t

(1-P)

(3-P) ptxr Njeg: 'hree Mile Island Unit No. 2 R3L 12/28/77 i

I FCR AC'ICN/INFC AMATICN 1/A %TA'2 t c I i i

' AS5IGNTD AD:

( LU. )

I 8

I 3FANCH CH~EF-i VM /P l i I

FRCJECT stX!AGIR:

I

//. A u4 4 I I l

/

i t 5 rg rrr; As97 Itp ) l M. S6;d'v/c6 l

l l

i I i

i I p*M-M INTERNA L O!STRI EUTICN i

I LAiAS I

I I

I

{

7 _)

'4RC PDF l

I ~PFCL:!O I i i

i qE I

i 7 ROSA I i i

i

 ? _O ( L7 )

I i GA.50CLL

'2i t

i a

i

?.

CCLL*'iS i

I 70LL'ER ( L'R) i i i

3CNCH t

i i

i urim-t i

i

  • =L n?rr s i

i J. COLL 2iS I

I i

i i

.' CASF ( LU )

i I GF3ER i !

i

'4-~20 fL R)

I K~?JCICC D I i I

r

.Tr 3 7.-- i*7) t i

i i i

i I 3 CS?i AK l

I i

i i

i 5ZJWE!L t !

I i i

i

?X.i! CKI I

1 l

1 i

2053 (LTR)

I i

i i i

i NC'i AK I

l l

i i

1 i

i i ROS;TCCZY i

i t

i CHECK 1

I i

t i

i ZCE5CO lLTal i

i i i i

~2 E?i AROY A i

EXTERNAL OIS ;tSU' iCN I

CONT 9C L NUM EE?

",PD; A///ftrdsfA f+1 bfA.-~oo i

i I

I A

.5 1d 53 3E'IT C A O CR*.

i

Retrieved from "https://kanterella.com/w/index.php?title=ML19220C394&oldid=4905822"