ML19241C099
| ML19241C099 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 04/07/1979 |
| From: | Demars R BABCOCK & WILCOX CO. |
| To: | Tulenko J BABCOCK & WILCOX CO. |
| References | |
| NUDOCS 7907260644 | |
| Download: ML19241C099 (5) | |
Text
.
TH,E BAECOCX & W11.00X CCMPANY POWER GENERATION GROUP To j
J. S. TULENKO - MANAGER, FUEL ENGINEERIN:
(
V, V (w/%
f R.v. OE MARS - C: F LEACER 8 3 *,
- ,.5 CCRE CON 0tTICN TASK FCRCE Cast.
Fil e No.
or Ref.
Suoj.
Date CURRENT ASSESSMENT OF CCRE CONDITICN 4/7/79 (1300) 4 7 i,, <:p, m.
a e
jn..i...................................,
ATTACHE 3 IS THE CURRENT ASSESSMENT OF THE CCRE CONDITION 3ASED ON INFORMATION AVAILA3LE AS OF './7/79 MCST OF THE INFCRMATION USED IN FORMING THis ASSSSS-MENT, 15 STILL PRELIMINARY AND RE;UIRES VERIFICATION AND OCCUMENTATION. THE MOST SIGNIFICANT UNCERTAINTY 15 THE TIME AND TEMPERATURE CONDITIONS PRESENT CURING THE CORE UNCOVERY.
THE CORE CONDITICN TASK FORCE CONSIDERS THIS A ?RELIMINARY CUT REALISTIC
/
ESTIMATE BASED ON VARIOUS SOURCES OF INFORMATION INCLUCING INPUT FROM THE EPRI TASK FCRCE CN PJEL DAMAGE ASSESSMENT.
AS FURTHER INFORMATION BECOMES AVAILASLE THE ASSESSMENT VILL BE UP0ATED AC00R0INGLY, RKK::f w ATTACHMENT CC:
0.H. ROY E. A. VCMACK C.D. MORGAN XC: CORE t.ONDITICN TASK ~CRCE 7907 2 6 0e H t
51911G
INTRCDUCTION I
THE PHYSICAL CONDITICil 0F THE CORE IS SASE3 ON THE FCLLOWING POSTULATE]
SEQUENCE OF EVENTS. THE CORE WAS UNCOVERED sli TT CURING THE FIRST 13 MINUTES FOLLOWING THE SECCND PUMP TRIP. (SEE FIG. 1) Tr3 CORE WAS THEN UNC0 VERE $ r7 FOR IC5 MINUTES.
FOR THE REMAINDER OF THE TRANSIENT, THE CORE WAS ASSUME 3 TO SE QUAS t-COVERED TO THE P0!f47 THAT NC SiONIFICANT OXIDATION OCCURRE3.
CUR:NO THE INITI AL UNCOVERING, THE CLA00tNG VOUL3 Fall NEAR THE TCP CF THE RCD OUE TO STRESS RUPTURE.
CEPENDING CN THE HEAT,1NG RATES, THESE FAILURES WCUL3 HAVE OCCURRED SETWEEN %I200-1650*F. THIS MAY PRECLUCE INIT AL FA: LURE EY EUTECT:C FORMATION SETWEEN INCONEL GRID AND :lRCALOY RC05.
CLA00!NG STRAINS OUE TO fil0H-TEMPERATURE DEFORMATION PR!CR TO RUPTURE COUL3 APPROACH 35%.
CURING THE HCL 3 TIME SUSSEquENT TO THE RUPTURE, THE CLACDING CX101:23 SEVERELY, FORMING ZlRCONIUM 0X10E AND RELEASsNG HYOROGEN GAS.
THE DEGREE OF OXf DATION WILL VARY WITH THE PCWER, HAVING SOTH AXI AL AND RADI AL DI STRI BUTION. THE CEGREE OF OXI-DATICN ALONG THE LENGTH OF A RCD COULD VARY FROM i:ECLIG13LE AT THE 3CTTCM 70 100% AT THE HOTTEST REGION NEAR THE TCP 0F THE RCD.
SASED ON EVALUAT!CN AND INTREPRETATION OF AVAILASLE INFORMATICN AS OF (4/7/79) 17 IS PCSTULATED THAT THE CURRENT CORE CONDITIC!l 15 :
1.
FUEL RCD PRESSURE SCUNDARY APPROXIMATELY 90% OF THE FUEL R005 MAY HAVE PERFORATED CL20 DING, ALL3WlhG RELEASE OF HEllUM AND VCLATILE FISSICN PRCCCCTS.
2.
FUEL RCD STRUCTURAL INTEGRITY MANY O F ~
INTERIOR FUEL ASSEMBLlES MAY VIRTUALLY HAVE NO RECOGNIZA3LE FUEL ROD - W 3ETWEEN THE UPPER END FITTING AND FIRST (TCP) (NTERME3! ATE SPACER ORIDS.
I!! SOME ASSEMSLIES THIS C;!!DIT!CN MAY EXIST TO A LESSER EXTE:IT AS FAR 00'.;!! AS THE SECOND CR THI RO INTERME31 ATE GRl:5. MOST OF THE PERIPHERAL ROOS Ai!D iE LOWER PORTION OF MOST ROCS WILL SE 0XI31:I SUT NOT TO A:1 EXT;ST TO SIG:liFICANTLY AFFECT STRUCTURAL INTEGRITY.
U39117
.j-
/
3 FUEL ASSEPSLY STRUCTURE g
THE INTERMEDIATE INCONEL SPACER GR!OS SHOULD SE CLCSE TO THEIR CalGINAL AXIAL POSITICN. THE UP?ER END GRID AND END FITTING IN MA!1Y Ci: THE If4TER;CR ASSEM3 LIES PAY MAVE LITTLE STRUCTURAL SUPPORT. THE FIRST AND SECOND INTERMEDI ATE SPACER GRIOS IN THESE INTERIOR ASSEMBLIES ARE LlxELY TO 3E SUPPORTED AXIALLY FROM SELOW 3Y 3ADLY OXIDIZE 3 GUICE TUSES AND PC5513LY FUEL R005.
THE ;EMAlNING LOWER ORICS ARE EXP:"E3 TO HAVE STRUCTURAL SUPPORT FRCM THE DEGRADED BUT REMAINING CUIDE TUSES AND FUEL R005.
4 ZlRCALOY COMPCNE'fT MATER!AL CONDITION THE ZlRCCNIUM OX10E (:rC ) PRCOUCEO 3Y THE OX!OATICN OF '.nE ZlRCALOY 2
COMPONENTS HAS RELATIVELY LCV OENSITf AND CAN RANGE IN FORM FROM SMALL PARTICLES OF A FEW MILS IN SIZE, TO IRRICULAR SHAPED FLAKES OF A :EV MILS IN THICKNESS AND UP TO A QUARTER INCH ON A SIDE, 70 V!RTUALLY INTACT TUS-ULAR SUT FRAGILE SE0MENTS OF CLA00!NG. THE PARTICLES AND FLAKES ARE LIXELY TO SE MC31LE IN MOV!NG WATER. THESE PARTICLES CA!i SE EXPECTED TO LOCGE IN THE UPSTREAM SIDE CF ANY FLCW RESTRICTION SUCH AS SPACER ORICS.
~
GRAVITY MAY BE SUFFIC!ENT TO CAUSE THE LARGER llRCALOY AND Zro, FRAGMENTS TO SETTLE OUT ON THE OCWNSTREAM OR UPPER SIDE OF SPACER ORIDS. THE e
QUANTITY OF Zro, AND FRAGMENTED ZlRCALCY PRCDUCEO DURING THE PARTI AL CORE UNC3VERY IS LARGE. EXCEPT FOR SCME R005 IN PERIPHERAL ASSEM3Li ES AND THE LOWER PCRTION OF MOST R005 IN ALL ASSEMBLIES, THE TEMPERATURES PROJECTIO FOR TdE ZlRCALCY ~ FUEL RODS WAS SUFFICIENT TO CAUSE SIGNIFICANT OXICATICN.
THUS, THE M081 LIT /. QUANTITY AND ORIGIN OF Zr0: 15 SUCH THAT LCCAL FLCV BLCCXAGE COULD 3E EXPECTED TO OCCUR IN AL50ST ANY LOCATICN IN THE CORE.
HCWEVER, TdE MCST EXTENS4VE FLOW 3LCCKAGE COULD SE EXPECTED IN THE UPPER CENTRAL PART CF TdE CORE, VMERE THE 2r02 PARTICLES COULJ FURTHER RESTRICT THE GENERAL FLCV RESTRICTlGN CAUSED SY THE HEAVIER FUEL ? ARTICLES AND FUEL RCD FRAGMENTS.
FUEL (UO ) CCNDITICN 5.
2 THE FUEL RELEASO FROM THE DETERIORATED CLAC0 LNG 15 VERY OENSE. THE ORIGINAL SIZE OF PELLETS IS APPROXIMATELY 3/3 INCH IN DIAMETER BY 5/G INCF UNCER IRRACI ATICN, THERFAL STRESSES CAUSE THE PELLETS TO 3REAK a.
UP IwTO FRAGMENTS OENERALLY RANGING IN S!;E FRCM I/16 INCH TO 1/k INCH CN A 510E.
DURING A TPANSIENT AND THE PERICO FOLLCWING, THE FLOVING WATER
.C AND STEAM CAN 5E ;XPECTED TO CAUSE SCME FUEL EROSI CN, WHi d WI LL PRCCUCI VERY t
lit
I, SMALL PARTICLES WHI Ch CA'1 SE SUSPENCED IN MOVIN", WATER.,
14 THE CENTER ASSE.MSLIES, IT 15 LIKELY THAT liCS T CF THE FUCL HAS BEEN RE LE AS E 0 FA",e*-TMMCC5 S ET4EEN ThE EN D F I TTI N",
kl3 TH E S E COND O R TH I RC INTERMEDIATE GRIOS. SASE3 CN THE UN0ERSTAli31 NG THAT THE FLOW IN THE CORE 15 SEVERELY 3LOCKE3, THE FUEL F2ACMENTS HAVE SETTLED ON TO THE INTERFE31 ATE ",RIOS.
LOCAL FLOW PERTURBATICNS CAN NCVE PELLET FRAGME:iTS 3ROUGHCUT THE SYSTE t.
FUEL FRCli THE UPPER LE'.'EL PAY H AVE SETTLE 3 CCWN
. s...,%.J
.n:
..P I4...,
,l..,.;
- . e n w;.R u a, i w.,
.O.. S,.,.,,....,.. c n,,,
,... R i
in:
c
..a
..s
. :. s4..
i iw Li'.~ELS T3 A LES5ER EXTENT, THERE 15 5 CME REr.0TE PCSS I BI LI TY THAT TH E S TRUCTURE SUPPORTING TrtE FI RST T40 INTE??E3I ATE OR105 IN THE CENTE't FEW ma n a, l,5
,..(
c o,.,
.P5,..L.51 6.
ein.
.,P y-ri we evt..
3 c -... - w,1...
.ci.u i :1:
s
.o W
T ail a3 I NTEF#.E DI ATE *.313.
THE FUEL FRAGMENTS 400L3 LIKELY BE MIXED IN VI TH SCitE REPAINI NG !! RCALOY RCD FRACMENT!.
THE SPACE 3ET4EEN FRA0MENTS COULO BE F!LLE3 WITH VATER, STEAM, Ir0,, CR SCHE C3t S INATICN THEREOF.
s ik E '.AR
- E 'L AN TI Tt CF S MLL Zr0, PARTICLEI COUL3 CAL 5E SCFE LCCall:E3 FLOW SLOCG'I TO PREVENT FULL COVERAGE WITH WATER.
'HE PRESENCE OF COME h,5LLA; SE*#ENTS COUL3 ALLOW LOCAL FLOV CHN;NELING AND ATTENDRIT "JETTINO".
t,.
- O ".*?*O tiAllLIT/ CF CONF. CONDITION e?4
.~.
p.. ;3 ; Lg, f o-w......L..e3
- 3.,,. w.,.L
..I 4
r.c.,,L.in,es-
..w w
. :. n n.
e r. R.H. e. r.
-~.mLps.,o s s i v.o..
s r
f. A. !L0 cc0E ! 5 LI r.ILY.i t CH CNi CAUS E LOCALI ZIO 301 LIN*,.
WHEN L*CALIZE3 1 ~,1 Li'.~, Ell 5 75. A FURT!iER REOUCTI ON IN SYSTEM PRESSURE WI LL ltiCREASE THE AREA
- f 3 0 t i! 8. *. Ax3 RAISE THE TErPERATURE CF CLAODING IN THE AFFECTED AREA.
IF U
!a E T EX#E AAT'.8.E CF ANY ZI 8.CALOY C0rPCNENT EXCEE05 1CCO F, ACCELERATE 3 OXI DATICN wit.L AA3 70 Tite CENERATICN CF HYOF.0",EN #iG CAUSE FURTHER OEGRACATION OF THE C0K.I STAUCTURE.
7.
.'. 5 M r UJY t 0*t C F F';t t,Vt 3 C r O,
!N SY3 TEM 4
T !$ YERT LI AELY THAT PARTICLES CF Zr0 440 UO ARE CIRCULATING THRCUCHOUT 2
2 THE PP.f rARY SYSTEM N10 MAY SETTLE CUT IN STACN#1T AREAS. //9
=
'. ~ ~ ~ ~
~~ ~ ~
G V l\\ C
[I Cai IE*' l q.I
[ I
_e'-
s e
D *.
8 9
t
+
cg 9
9 e
'p..
ig 4\\k
.t
\\fN m
=g q
l
_; g-1
.a.**~"*
s
=
Q-m
.-v G~-
~,>
s.
,i n z
5 g
. ---t
- m. *U m
u
/
- g j-
' .'11 *
%,e M
==
'I
,', - 4 ;.
.NI
(-'s y *,7 i
- ?
\\
("";
f p*
\\
g I
('j*
r
\\
a w
.x.u,
,)i
.m.
N.
= aab' H
p r \\.
(,.
,".".'(.,=
....'. \\
~
C, s
^
,. 6
,s
.[
l a,, G ]f.
j,'.'- g
. R./
4 v
z
. i '*"..'.
. ),
3.i
.',,..')
s
~
4.,,.
s g
6..
e, '.5
..".3
="*
g, e
l^.
3 t.;,e c l cs :
! c.-
..., =
is..
.s~.
s n
(.
1 y
.*i
- h.,,
cJ s'.
t
\\
~:..
i
..s I:t I.
.s
- s...
(.
s q.
i i...,
i.
n..
,.)
- =
N
,' {
e--*s --.
"ii I
}
\\..,
. g
.s I
- ' ' ~
,,A
$~.
I. t ** >
l '([ t
< -~
. j D.- '-
I -e.
('"1 j'
5 s
r.
e y
g e.m t
,,.*1 i
\\
i\\.% 1
- . /
l s.
m
- \\
.%,.=
Ls
<=e w
A
\\...
't.
N-x
\\
7.
J L
S49120
. ~/,
m s
c.s g' [me_
ml'r, 61 g_9 t
3
- - f f) r k
.f 3,.. - (- )
_1% -
i w:
(
r-J. (.
l ***1 M
tlc.~,e;5,l V.: a u\\
r'
, c..-
i..
- s. z..,...6 NO. V9
. 'u a r.:.\\ f J C
.v.
T*
' ' ~ -.................
. ~...... - -...-......-....-.-
.,.......u.
....._.a.......a-....c..-..,......
.