ML20002C596
| ML20002C596 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 01/17/1974 |
| From: | Sewell R CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Oleary J US ATOMIC ENERGY COMMISSION (AEC) |
| References | |
| NUDOCS 8101100540 | |
| Download: ML20002C596 (8) | |
Text
@i-(
1 P,egd2.,: Udd File
'f, L. g*[$b Y COnSumC[S h/p 1 e
. #ph, (/ A 9
W Y
4eggg4 P0Y.'Cr s
[ f' b g E,
I;
^
A
,, J.t c.n.,.i ome..: :na seca.oa. wcw.n 492oi. 4,.. coo. si7 vss.osso o
p w,W 's U
sg!g January 17, 197h O
r:,
Mr. John F. O' Leary Re: Docket 50-155 Director of Licensing License DPR-6 US Atomic Energy Commission Washington, DC 20545
Dear Mr. O' Leary:
letter of December 21, 1973 reported two problems found 6 s,ne Big Rock Point Emergency Condenser (condenser) and identified corrective action that was being taken. This letter is written to provide an updated description of the corrective action taken and also describes one further problem that was discovered and corrected concerning the condenser.
Weld repairs have been completed on the three tube-to-tube sheet velds that were determined to be leaking due to porosity.
These repairs were made using properly qualified welding procedures and welders. Further inspections revealed indications of porosity on ten additional tube-to-tube sheet velds, although no signs of leakage were detected. Weld repairs were made to these ten velds.
The original water box divider plates were replaced with a redesigned divider plate. The redesign, depicted in the attached drawings, consists of replacing the center section of the baffle plate with a bolted panel and the Flexitallic gasket with a narrow plate velded to the tube sheet. This design was selected to reduce thermal stresses, resultant plate bowing and subsequent loss of the seal provided by a Flexitallic gasket. Seven 1/2-inch bolts in 9/16-inch holes, initially torqued to one-half yield strength, vill permit slippage between the baffle plate sections and limit fixed end moment to bolt yield stress. This design vill significantly reduce baffle plate stresses as compared to the original design.
The bolting is ductile, and, after an initial cycle, the plate and bolting vill come to suitable alignment for service without over-stressing the baffle plate and bolts.
The condenser operating conditions and original baffle plate design were studied to determine the cause of deformation. The original water boxes survived many cycles of loading and vere still 8101100540
,Mr. John F. O' Leary 2
Dock:t 50-155 License DPR-6 January 17, 1974 performing satisfactorily when it was determined that the baffle plate was pennanently deformed and fillet velds were cracked. The permanent deformation is the result of buckling in response to thermal stress.
The cracks are apparently strees corrosion cracks which developed in response to high tensile rasidual stresses which would develop during cooldown and the standby environment. An elaborate thermal stress analysis was not performed on either the orib;r.a1 or redesign.
In-stead, the mechsnics of the two designs were ecmpared to demonstrate the stress reduction of the redesign compared with the original which should ensure a much longer service life. Also, the new design will not be subjected to furnace stress relief which contributed to the stress corrosion susceptibility of the original construction.
Operating conditions of the condenser are:
a.
Standby condition - tube side flooded and at 100 F.
b.
Transient condition - condensate side valve opens, tube side drains and 600 F (maximum) saturated steam is drawn into the in-let side of the water box as 100 F condensate flows out.
c.
Steady-state operating condition - steam flow up to 13,450 lb/h (max rated), 600 F steam in and 600 F condensate out.
The transient consists of bringing the water box up to tem-perature as condensate temperature increases to 600 F.
Operating condition is 13,h50 lb/h flow of 600 F steam in and 600 F condensate out.
There were two sets of loadings to consider: Flov induced and thermal response. The maximum flow induced forces, from steam impact on the upper surface of the baffle plate and from negative velocity head on the lower surface, were found to be of small magnitude. The thermal stresses for the original design were found to be excessive.
These are alleviated in the redesign by reducing constraint at the plate edges.
A detailed safety analysis of this facility change was per-formed in accordance with the provisions of 10 CFR 50.59 This safety analysis included an evaluation of the cause of the deformation to the original baffle plate and corrective action taken in the redesign, the failure of baffle plate bolting and a bypass flow comparison of the redesign to the original design. It was concluded that this change did not involve a change in the Technical Specifications or an unreviewed safety question.
As a quality assurance overcheck on the material certifica-tions for the divider plate bolting material, samples of bolting material were analyzed metallographically.
These overchecks which were completed about the time the plant was being returned to l
l
t Mr. John F. O' Leary 3
- ~
Dockst 50-155 License DPR-6 January 17, 1974 service (1/11/74), showed evidence of cold working including several slight cracks _ in the lands of the bolt threads (as opposed to the I
roots). As these residual stresses and slight cracks are not a con-cern over the near term, the return of the plant to service was con-tinued. This bolting material will be replaced at the first refueling after suitLble bolting material is obtained (and prior to July 1975) to insure that no long-term corrosion problems develop.
During the period of time that the channels were removed from the condenser, the studs were inspected to fulfill in-service inspection program requirements. These inspections revealed that 23 of the 48 studs had axially oriented indications which vere later determined to be due to cold working during the manufacturing pro-cessing.
It was concluded that these indications had existed since the studs' manufacture and had not progressed since that time. All 48 studs were replaced.
Yours very truly, l
1 wT RBS/mel Ralph B. Sewell Nuclear Licensing Administrator CC: JGKeppler, USAEC
'T 4
u
-,m.
-r r,.., -
%y, e
N k.
, N L4 3 03 N
1 CO k
"' N
-b c'...c6 5
G
?$
I:
fl., b s
!I Ly l
_ y [@5 48 E
sm i
E'W
.I l
2D E
- l
- s. Lo s sm n
sib E I' 5 5 m
7 E#
.a i
i; g
m l
I to E
}*I
- = =
f I
??
i-s f
.!!!i. 8 2r I
un 3
W E
m
=
h
- E h
a
)
}
2 Es se
-- J i
bd F
s !" '
8 dw OW qa 5
b d@
4W 5
s'!
t
- 4. R q
+
Wy
- l g AN
%^ "b :D
.J m k ~a lj
- i
~N N
id N ; !'
l N
5 il !d! P
\\
\\
4_
g l
~ i, r
O 1
I H
PDDR OR GINAL I.
35 f.n
--m&-f I ["
11 "
- II "
=-
ci l
33 DIA.
.__L_L t
s
~
[
.f...__._._____._......._____._______.___.
3 7
r.
g--
p
/
N 3"
g
__f g _._
/
5 i
i
/
/
l n
\\
l-s\\
\\
l
\\
\\
i i
j
- b-18 "
l j
k
/
I
\\
s
/
i
\\
/
/
3( '
l o
.._..__.o.
o_
/
t
's i
T.
I t
/',
_}
i
/
./
l
~_ _
- /
HORSE SHOE PL A TE -
O-
-yA75p gox WELDED TO WATER BOX
- cs in. l j o... l., l.,, f,- },g,l l
- .~c.
E f VISIONS PART5 LIST c:::)
7:h",.s
~
=,:~=.-~
HORSE SHOE PL A TE -
- C3
- 7 p, ma
" ;r'~"
WATER BOX
'2~2 7 -7 3 I " '/"
Cl""3
~"*5(n 0'.
SOUTHWEST RESEARCH INSTITUTE g
y;",(u Ca
";? B 2882 905
$^"^*'"'
" " ^
- 3::=
r---
0 0
O 5O C)
N O
CD CD (TJ in m
h 2~ 2 0
j Yo 3
N
!?
s k
a al fT Qm 5}
- l0
- (
E m'
e
'Q 3
la 35 i
5 I
i o
55 a
g
- -O-
-O-
-O-y Q
R o'
i m,z w
i.
_ / _.____
s t;; r i
3_
ik) m5m i-g; 22 E
- it o
Ei!I m
i
.,*-l
-O-
_v-.
_O:
f N
+
4 i
N i
N
)
e a
i e
l i
E F
e o
a s
q 3 h II I If !
l $
t i
5E k
'cr p' 0
g%
O i
I v
cK e
- "4 r :s' j
=
. q
\\*y,
s l
y ti p.
.I.._...... %-
-_ o.
f, t
fA l~' s\\
i g.._,
i dl 4
1l,f D
e 4 l-
'jN I
I __
f I
l P00R DIG NA'.
G I
s
{
b f))
OJ O
d,
.A I ($!
g lm E
~
U) o t.'
7 4
E U) i:
X
~<
O O2 F ca
[ III
=>
~
W O
u e
m
=,
e E
a8 e
a i
s m
m C?
8
(
,e W
T f
M3 m
er W
e Q'
W b-i I 3:
7
> (i x
O*
8
=
o o
=
n* a ? E O
~~
ir ieri
/
/
7
's./
s'
, x
/e\\
,/ %
7 o
/
'/
g 5
/
5 I
', t 5
b
\\
3-W
(
5
\\
,'e s
4
\\
.%,.--s-c:.
- e..-
f
.f,f.
.?
\\
\\,
- s e
s, O l,,
g g
i, g
i-
=
\\
s s
N s
.\\
s s
s\\
\\
N
\\
s\\
/ h.).
N
,\\
\\
/
r 0\\s e
6
/
\\\\
,/
/
,/
ss l
l
,/
\\\\
j
/
'Y<
/
/
/
i i
/
/
0
-\\
i p
,/
/
\\1
\\
,o 9
/-
s
-J
~,
300R ORIG NAL
AEC DIST 'UTION FOR PA!T 50 DOCRET MATEP L,
(TDiPORAdY FORM)
CO:; TROL NO:
559 FILE: bl$ b I
FRCM:
DATE OF D00 DATE Pdd'D LTR l'I2:0 RPT OTliEE Consumers Power Company J ckson, Michigan 49201 1-17-74 1-21-74 X
R. B. Sewell 10:
ORIG CC OT!I' R SCf;T l.EC PDR__
X J. F. O'Imary 1 signed SEtiT LOCAL PLR X
CLASS UUCLASS PROP Ilir0 INPUT NO CYS REC'D DOCKET 1:0:
XXX 40 50-155 DESCR!PIIO;;;
ENCLOSURES; Ltr re their 12-21-73 ltr....... furnishing T
t
.mV 1 iM.,, c. VE en updated description of the corrective cetion taken 6 one further problem that was discovered & corrected concernings the condanser..............w/a tch drawings B-2882904, 05, 05, 07...............
ACKN077E'rTD FLANT UAME: Big Rock Point YCF. ACTIO::/1:'FORAT1dN BUILER(L)
SCCE ;CCR(L)
/ZIC:!4iN(L)
RECAN(E)
U/ Copico W/ Copies W/ 7 Copics U/ Copics CLALK(L)
S'WLZ (L)
DICirCR(E)
W/ Copic W/ Ccpics U/ Copies U/ Copics CCLLCR(L)
VI.SSALLO(L) 1211GiCC:'(E)
W/ Ccpies W/ Ccpics W/ Copies W/ Copiec IS;IEL(L)
SCHE'EL(L)
YOUUGI-LCOD (E)
U/ Copies W/ Copics W/ Ccpice U/ Copics I'TEP::AL DIS 1RIEUTION SWYu TEC1: PEVIi7 DE:;10:1 A/T T: 3 LIC ASST ppg 9.g.
2 EC PDR 4Ic1:LRIE GRIliES f
- 0GC, R00'1 P-506A ScrRGED:R GA"!ILL dIGGS (L)
SALTZMld!
ADJNTZIi;G/ST/.FF A!ACCARY KASTSER GEt. RIM (L)
B. liURT CASE Ja:ICllT r.ALLARD GOULBOURNE (L")
PLIJ'S y
GIAtiLUSSO f/.ULICKI SPASGLER LEC (L) liCDONAT.D BOYD fila 0
!!AICRET (L) pg3gyf7pp3e ENVIRO SERVICE (L)
POORE (L)(B7R)
/TELLO MULLER SEPPARD (E)
INTO DEYOUI;G(L) (Pi'R) j!!OUSTON
/SKOVi!OLT (L) jNOVAK DICKER SMITn (L)
C. MILES P. COLLIUS unCSS 101IGHTON TEC1S (L)
/d. KING (RO)
DEUISE 4 Pr0LITO Y0l'NGSLCOD W/.EE (E)
A EG OPR d CDSSCO REGid:
UILLI!.MS (E)
ILE & REGION (3)
/1.ONG PROJECT LDR UILSON (L) l l
l l{
l l
1:0RRIS
/LAIUAS
~
/STEELE p'.E'.:AROYA IIARLESS I'
VOL111ER EXTER" *.L DISTRTIMION
~~
1 - LCOAL PDR
/1 - DTIE(AT2k:;ATilY)
(1)(2)(10)-UATIont.L LAB'S 1-PDR-S AU /Lt./NY
/1 - USIC(TUCE'J:Mi) 1-ASLBP(E/W Sidn.Rm 529) 1-CEI ALD LELLCUClis 1 - ASLB(YO"?./SAYRE/
1 '.l. PE:::I::3Tod,1:= E-201 GT E'100KH!.vEN MAT. L;E j
UCCDARD/"l" ST.,
1-CONSULTAUT' S.
1-ACMED(Rath Cussman)
- 16 - CYS ACRS EX:DITJ SENT TO LIC. ASST.
NUiT.ALK/ELnir/AGEAFIAn D1-B-12 7. GT.
~
1-21-74 DIGGS 1-GElRLD UIRIKNON..ORNL 1-RD..!?ULLER..r-309 GT