ML19332C816
| ML19332C816 | |
| Person / Time | |
|---|---|
| Site: | Haddam Neck File:Connecticut Yankee Atomic Power Co icon.png |
| Issue date: | 11/17/1989 |
| From: | Wang A Office of Nuclear Reactor Regulation |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8911290037 | |
| Download: ML19332C816 (38) | |
Text
,,
,J 6 J /,tii UNITED STATES
~
, r !"
~ ' ' ~
' NUCLEAR REGULATORY COMMISSION l
n 7.5 l.
WASHINGTON, D. C. 205$5 f
hy * * * * +,/
November 17, 1989
{
p ' Docket;N'o. 50-213 i
i LICENSEE:
Connecticut Yankee Atomic Power Company i
i FACILITY:
Haddam Neck Plant
SUBJECT:
MID-0UTAGE STATUS MEETING y
j 25,(?1989,CYAPCO)'todiscussthestatusoftwomid-outageconcerns:
l the NRC staff met with the Connecticut Yankee Atomic-On October 4
Power Company 1eaking fuel pins and thermal shield damage. CYAPCO provided a background on the cleaning and testing of.the fuel pins. CYAPC0 believes 88 assemblies of the 109 assed11es which are to be reused have degraded pins. At the time-
)
of the meeting, the number of degraded pins was 286. This is based on-ultrasonic testing with a threshold of about 20% thru-wall. CYAPC0 assumed t
that any fuel pin with a detectable flaw is a leaker and will be replaced.
In addition, each assest>1y was visually inspected for degradation. Any pins with visual damage will also be replaced. CYAPC0 discovered a significant amount of' debris (metal flakes) in the fuel assemblies. Ninety nine percent l~
-of the debris was between the bottom nozzle and the first. spacer grid. CYAPC0
' believes a11' fuel pin damage was debris induced. The debris is believed to have been left over from the milling work done to the thermal shield during the last outage.
CYAPC0 is mapping the debris in the core against the fuel pin failure sites.
L There seems to be a reasonable correlation, and therefore where heavy debris sites exist without fuel pin degradation, CYAPCO it performing additional
'J examinations of the fuel pins in that area. One observation has been that E
- coolant activity was not' indicative of the large amount of _ degraded pins r
discovered. CYAPCO expected about 6-12 leakers based on increased coolant i
activity.-.CYAPCO believes the failures are pin hole failures and the fission product gases lcould not readily leak out. -Normally, fuel failures are due to pellet clad interaction, which results in axial cracks.
CYAPCO.is scavaging previously used fuel for fuel pins to be used as donor pins..CYAPC0 hopes that enough donor pins can be found with similar burn-up to match the degraded pins. CYAPC0 plans to demonstrate that the reload
. analysis will be bounding'for the reconstituted fuel so that the reload analysis will not need to be reperformed.
1 9
gn88am@r P
L i-7......-.g.. g. ; --
phn" I,f *
+ ;co :
(l ?
Erch F,
4"
[,
Midi 0 stage ' Status Meeting ^
e t
l CYAPC0'provided several handouts regarding the thermal shield. A summary of The damage is provided in the handout..ISI is currently being performed and CYAPC0 has not drawr. any conclusions regarding.the thermal shield degradation.
CYAPCO noted, however, that the wear in the space limiter keyways is greater than expected. The gaps in the keyways were 1-3 mils after installation and have grown to 5-10 mils. The NRC requested CYAPC0 to keep the staff. informed
- t 1
of the fuel reconstitution and thermal shield work.- Attached are CYAPCO's
}
handouts and the attendance list, j
i.
i
/s/.
Alan B. Wang, Project Manager Project Directorate I-4 Division of Reactor Projects - I/II j
Attachments:' 1 - CYAPCO's Handouts
{
2 - Attendance List
-1 cc: w/ enclosures See next page j
s l
-i 1
-i LA L:
PM:PDI '
4 I-4 SNorris AWang:- [
JStol
.11/li/89 11//q/69
,11/}/89 1
f
.....r a
m.r.
, u-ps ::;1
- 7)l;f...
4
--t y:7
'4 DISTRIBUTION FOR MEETING
SUMMARY
DATED: November,17, 1989 g
mn s
Plant File?
L, -
'J. i Stolz b-S.i Norris:
A. Wang-0GC
-E. Jordan (MNBB3302)I
.e-
.NRC Participants-Richard Lobel
?--
. C.D.-Sellers Larry Phillips Shih-Liang Wu.-
fACRS(10)
- JDyer(17G21).
l I
i
..t:
- i I
- +
I e
i,.
t 0
l C
1
., i -
,,.m.-......,,_.,
.3j+ H 2+~,
u
. ~..
n y
I, 4 W
,a.
Mr. Edward J. Mroczka Connecticut Yankee Atomic Power Company Haddam Neck Plant J
-cc:
1 Gerald _ Garfield, Esquire R. M. Kacich, Manager c
Day, Berry and Howard_
Generation Facilities Licensing Counselors at Law Northeast Utilities Service Company City Place Post Office Box 270 Hartford, Connecticut _06103-3499 Hartford, Connecticut 06141-0270-W. D. Romberg, Vice President D. 0. Nordquist-i' Nuclear Operations Director of Quality Services Northeast Utilities Service Company Northeast Nuclear Energy Company
' Post Office Box 270 Post Office Box 270 Hartford, Connecticut 06141-0270.
Hartford, Connecticut 06141-0270 Kevin McCarthy, Director Regional Administrator Radiation Control Unit Region 1.
Departnent of Environmental Protection.
U. S. Nuclear Regulatory Commission State Office Building 475 Allendale Road Hartford, Ccnnecticut C6106-King of Prussia, Pennsylvania 19406
- Bradford S. Chase, Under Secretary Board of Selectmen Energy-Division Town Hall Office of Policy and Management Haddam, Connecticut 06103 80 Washington Street Hartford, Connecticut 06106 J. T. Shedlosky, Resident Inspector Haddam Neck Plant D. B. Miller, Station Superintendent c/o U. S. Nuclear-P9 ulatory Commission Haddam Neck Plant Post Office Box 116
-Connecticut Yankee Atomic Power Company East Haddam Post Office RFD 1, Post Office Box 127E East Haddam, Connecticut 06423 East Hampton, Connecticut 06424 G. H. Bouchard, Unit Superintendent Haddam Neck Plant RFD #1 Post.0ffice Box 127E East Hampton, Con.necticut 06424 O
- 3_-
p-4
>v
- c ATTACHMENT 1-La-e.+,
u px i
1 l:
^:
i t
-s l:
r.
l-
. *^
- y n
L CONNECTICUT: YANKEE ATOMIC POWER COMPANY ~
\\;
HADDAM-NECK PLANT L
~
u MID-00TAGE STATUS MEETING l
WITH NRC STAFF
)
p k
OCTOBER 25, 1989 c
'T*'
?*"*
- O
=r e
e, e s em e,
,o y
rees..,,,-,g, g%, c
.. w...-.
-..4
. _.. - _.,. _. ~. _,, - - - -. _ _. _ _ ~, - - -
._,--__---_-__._--m___
.------m
b
- L
's I
- w
- 2 c ;v ATTENDEES y
4
'0L C. J.JGLADDING l
L ENGINEERING SUPERVISOR
'i a
L HADDAM NECK PLANT l
l CYAPC0 o
e 0,
. W. M. HERWIG-SENIOR ENGINEER.
j REACTOR ENGINEERING BRANCH NUSCO 0-E. P. PERKINS'
- )
SENIOR LICENSING ENGINEER
' GENERATION FACILITIES LICENSING
-NUSCO
~
i o
i ih.t
.t
. -.:: :: : ~' ~:.. :. :.-. r..
......2*~---..-. L.
~-
-__i_mde 4
I~
AGENDA I.
FUEL ASSEMBLY INSPECTION AND CLEANING II.
CORE SUPPORT BARREL / THERMAL SHIELD WITHDRAWAL AND INSPECTION P
III. STEAM GENERATOR TUBE PLUG INSPECTION UPDATE J
l:
. _,, -. ~ '., -.,.. _...., _,,.
' $ 1'..- ~..[1_._.,_..I _..l.. $ _._ [$.... _ _._,._. _ _. -
[
s
--.Aa, d.s,
. A f
...m,4ae
.w
.ama J&A6 e.aa-
,a-6xm4m4, Am g
4
.a 4
p k
~
i
+
e l..
6 F
l' I
i :.
5 I
L:
- I.
FUEL ASSEMBLY INSPECTION AND CLEANING l.
6 VIDE 0 PRESENTATION
~
a I
l?
O e
t 1
0
- ~_L,.-
..-,.-..-.T.
-, ~.n w---r-y4
.-r-
.w,s,,2am ay v
4 4
eM
- m m.
&--6,-
4
,sta-A e
4 A
5 4
.J
+
sabL pf E
T
s w,.'
y Y
f.
nP' j
I l... 4.
- l }".
l 1
,\\
.1 r
7 1'
'4
- II.
CORE SUPPORT BARREL / THERMAL 1 SHIELD l
1, l.
f
'I l
- DIAGRAMS L<
u, PHOTOGRAPHSL a
i
'.o,
3 i
I e
I
- 1 4
B
.I -
1 i
4 up
- I}
t 1L J
, h,.\\
+
0 i
'g.
..,...s r
,. - -... -.. - - - - -... ~ -.... _..... -.. ~.., - ~,. _ _ - _ - -. _ _ _ _ _ _ _ - _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ - - - - - - _ _ _ _ - _ _ _.
t
- 14 91 w*
a
{
1989. Core Support Barrel Disual Inspection Results f
nermal Shield Displacement Limiter 128
- I.ower Block All 3 dowel pins backed out Dermal Shield Support Block 210' CenterDowel backedout.
upper right bolt backed out 1/4" to 1/2" post T.S.
Thermal Shield Suppon Block 270' upper right bolt, lower suppon block, missing RPV near 128' gouge in cladding
. Bottom Head Misc. pieces found 1 bolt,18" metal strip, rod Inspections Completed:
6 displacement limiters examined with an overhead camera and a 90' lens.
.5 Thermal Shield Suppon Blocks lower blocks examined with an overhead camera and a 90' lens.
330' Thermal Shield Suppon Block lower bolt not examined. Overhead camen t apection r
- of upper bolts revealed no damage.
All Six Support Blocks examined from the ID of Con Barmi using a 90' lens.
I Thennal Shield Lower Suppon Blocks from ID l:
30*
All 3 dowel pins meessed 90 All 3 dowelpins meessed 150 All 3 dowel pins recessed, lower center bolt, upper right bolt recessed m
210 All 3 dowel pins recessed, upper right bolt recessed r
270' All 3 dowel pins recessed, upper right bolt missing 330 Lower 2 dowel pins and lower bolt appear recessed J
s l
7.
y #; u ?
.i g y
- ...e,,
v-
-l.)n t
- 1
%:=.
m 1
u L
)i s
t
{
L im 1
i i
i l
)
l StCTcN A.A --
f
\\
o i-11SPLActMt*
I twAER KtY
/
WIACM) h S
A
!== A f
c j
StCTOW 8 8:
l I
l ggyt s
i
[
i
=8
- 90WELPas t
\\
1 90170MIUPPORT
. SLOCKS i.3 SEACH3 i
C S!CTONC4 Figure 2-1.
Thermal Shield Support Details Without Flexures
===mie 2-3 t
9
+-
,.ec
,er,
--,.w, se-
,r...,.,-.
4
,e
.-..-e._.,..,#,..e.,.
-. - =. - -. -,.. - - - - - -... -
.--.--..-.m.
1
=
.~._.
- g, 4
s,.
~
j I '~, s '. t'.
westmonouss enomerany ouss a
'(
j i
\\
1.20s.1 c
T Elput SNIELD i_
L L
l
/f l
\\
?%
/
N
/
- ' a l,'Q(AIl i
/h4 W f
\\
%p\\
\\
Q
~
/
- THEIDEL SHIELS BLOCK ORIGINAL BLOCK N
Figure 3.2-1 Thermal Shield Lower Support Relative to Original Block
- .: 2.
~
A.
e e.
8
(-ly)&
l
'Q j
.(
]
()
@y e
1
@s a-Y u
f F
4 d!7 O
j
,/
e h
Ai k Y/'
l
/ /.- /
Y
- ,5::
V'i,i<//
/
/
/,/l' i
n /,
z
'hNh'
+
m S'N'\\\\\\NNN x
~
0
.L
.,.p. i 4-
-. - - - -.~- -.... ~
-N:. _.
"L
-- z.g masvuosovos enomrvaav esass :
,.t
. r s-
- l
[:h 7
A h j
- 1 I
)
h L
4 4
3 f
- l l6 bd d
L @e@
f h
O Oj s
Figure 6-2 CYW Thermal Shield Repair Displacement Limiter Assembly 0
16-10 s-l.
---..E E.
_.,.s..
-,_-,w,...,.-,__.,,,.,,,,,.,,,_,,,,,,m,,,,r._,n,.,,,,
_,,--ge,,,w,,,_,.,
n.pw.g,.wp.,v..,
.,,,p-y-
(.p.x m
..{
'III.. STEAM GENERATOR-TUBE PLUG-INSPECTION UPDATE INSPECTION AND REPAIR WORK IS: COMPLETE SUM ERY OF RESULTS:.
- 0F PLUGS
- 0F. PLUGS
- 0F PLUGS *-
SS INSPECTED UNACCEPTABLE PAP'D 1
394-3 (HOT LEG) 69 2
602 52 (HOT' LEG) 169-3' 170 11 (HOT LEG) 58 4
632 33 (HOT LEG) 292 L
- ALL HOT LEG SIDE PLUGS FROM HEAT-#3513 WERE PAP'D; L
J
-ALL " UNACCEPTABLE" PLUGS WERE FROM HEAT #3513.
SLIDES
,y,
(%
s I
\\. '
3 1
- ' I,.;
270' N
I L yn m:5r
-210'p
(
t i
m.
i 4.
8 i,
LacAfl0R$
i
/
\\
d
(
SEL MATERIAL IRMDIATIC s
genvEI1ANCE SAMPLE CEUTE!-
/
\\
o uci>
q TOP VIEW 90ZZ12 IDCATIONS u,.wi ar L'
o
- v. : c x
w
{
h TEEAKA enun.
l f
SE* H lW k
/
{<g/A g ggyyg
-4 V
J 4
l 6
gggy 3 3 a
~ s pH er enum seus F
f 1
4
')
s E
8 8,
pH EP 8 mm l-I TIEW E-E O
/
war.noeouss paoenirre mass a f.,
. i
<\\
,i
.r I
).-
?
1a f-l
~
I
-q.
l
(
' N f
. SECTON A A.
hispggggg.
LW.IttR K!Y j
WIACN1 -
l
=\\
f, k#
A i
t
<=A ShM l
SDLT van 5g DOWELPall I
ttmenterner -
,f Stocrs
. L,,.
J, 8IA8KI
<=C sitfewt c l
l
[-
Figure 2-1. Thermal Shield Support Details liithout Flexure:
(
o
. srame.
2-3 cd
.... - ~..
~. ~. -. -
c,,,
~
i N FROPRIETA!aY EASS 3 1
% : m -.
-C i
,9-
- s e.
a 1
370*
i ettest essesses, esammtem gy= m men.
gggf
'+
L, :
see m t..r.
' O mo' h
.v j.
L it'-
h
,1 o
l-
+,
L-N
...n
_ S_E\\
/
- o J
ee' Figure 2-2.
Plan View Core Barrel and Thermal Shield l
O M:10 2-4 g
',"I OiP'*4'd E
....a.
.. _..... _... _. _... ~...., _ _.. _ _.. _... _
b% d g g.g g. q g g
- ~ - -.
j
'g' y
westwoonouss anomrrany ouss -
,g,4
.o c.
t 370' 70 *slock 4
t 1
i 330*. Block 210' 51ock
,_. 1g o. -
g1 8
l.
=
- 30* Block l
150* Slock t
90*B,iock 1 p
.v l-90*
i.
Figure 2-4.
Thermal shield Support Block Locations 0
spmanas:w g.6 Y'
A
_.._.__....,,-..._.,......_._......_.._..._.._,_..___.._,.,__...~..m.
Jl.M.' %
wastmonossa encenstany otAss a
- ).
g7.
o.
i Q
QP y
~
L-s s
1 N V L;
L, e
i t
- =
3, j
1:n:t
?
c 3
e l l g-y I
i
>i s'[.
l A_.-
s s
l,4 g
.ss I;
' s s
1%,
ti X
i
. g s
j s
t J5 ss
?
I.
e ggf m
. s l'
h k (l' s
.I,s' E
l N
E i
1 1
g t
= s
\\
N N
k 1
Figure 2-8.
Irradiation Specimen Holder Tube Assembly 4
w 7
f ve
= === = = =.
x
mestusanovos peopsustany e6 ass a UPPER.DISPLACEE NT LIMITER - TOP VIEW N
%s. marbg9
\\
s x x n
T5 l
4
(\\
\\
L
-'u THERMAL SHIELD Q
l CORE BARREL 6 -
- ~
u. ~,,,
SIDE VIEW UPPER DISPLACEENT LIMITER L
w A-([
[
c 6
,L.it 1
r*
5
,) <
[l W
gf CORE BARREL As e
THERMAL SHIELD t
Ab 9
Figure 2-9.
Upper Displacement Limiter
[
2-11 L.
-,,,,,,,,,,, guse s :
'9, y p;y
&T'
'l
- 4. * '
l}
R l
y b,a
'j
\\ UPPER D!$ PLACEMENT N
~
m LIMITERS (4).
.g'
,* p' ki, CORE BARREL i
N1 N
k N
N J
NNN J
N
. THERMAL SHIELD-k N
+
N N
A
'\\NN
' N 3
N THE10RL SHIELD HUPPORTSLOCKS(6) i
(
a g
g I
1 Figure 2-3.
Thermal SMeld and Lower Core Barrel Fit-Up 1^
Q 2-5
)
..,.7
.7..
, W,,. "?g' '
"o wasmonousa enomrrany mass r
g.[
<.o.
^
f.
j
-j l.
fz t
-r
\\-w-3 rx s
ex Me
(
Nxggw.n
_r_.
=
1 1[M hi#
l M,
I l-
.\\
3 9,
r u
o 6
- N i
A (f
(f%
7
%O L
e.,
~
/
-s-s, m
=
4 p.
8 d
4 1
g:
90 Fu k,g 3
g w
4 i
t 3
Figure 2-7.
Support Block Dimensions 1
armaram =
g.g f
^
1
>:s4-t.:
1:
bl&
I 1.202.1.
s TIENEL SHII18 N -
N r
ML i
,/
-i m.
hYNY
(
.i
/ k%W aN x\\ /
4 f THDBEL SHIELD BLOCK WISIRAL BLOCK 1
K-
i Figure 3.2-1 Thermal Shield Lower Support Relative to Original Block o
-ne 3.g f
= = = = = = = = =
-+
.,y e.
~..; ; 1.W m many gA33 3
_y; l:[ -sh, '
].[
{j M 02 ?A -
t
/WMXg j
[
'F
-q h
k
$ ;M
~
PJJ l
' f
/
\\.
/
?
y
/
T l/
\\
., pw x
~
s d
l rf Q I
l W M
@f
+'
Figure 6-1 CYW Thermal Shield Repair Displacement Limiter Assembly
(
- ae 6-9
/O
1.,,.[L;~
~~
~'
~ ~ ~~~ "
~~ ~ ~~~
~
e uomsonouse momstany stass s p
m:
s-s s o
i r
1:
D r
RV p
l f
L 7
F 1
k N
h i
l 3
U)
Figure 6-2 CYW Thermal Shield Repair Displacement Limiter Assembly 16-10 y
.3%.--*-
e
/;..,;, r p : g, wastusonousa peopawrany auss :-
q, l
- 3
..l:...
L t
u O
i e
l W
o I
l l"
l 2
l I
1 I
e
,..J.
i 1
l I
.([h 1
8
,- -,,. l g-e.
I-. - +
l..
-l l
.i t.%
t.g.
I g
U 147* % die se-s g
- %se,m4 6 b4 t i
l l
/
0 1
p eX/
N
%.t hi, ie we 6
s
[ %
-s y
=
Figure 6-4 90 Degree Dowel Pins. Radial View m.=
$=12 42
.m c% r
--~wse-e+eew vee-e-w,*+,-w-ttw ur-
'w wen **e-'ww*ae+-se*+vr-wwwww-----=--w--=--=wiv-e--====-------w
=
v-
-w
\\; [is; a;'o n WESTWeeMouts pnergurTARY enAss 3 -
1.K '
e b
{
.I
,l i
i i
4
/
l 4
..___.1 d-Q L
M \\\\\\Nyr L
\\
.. f : /
' [umud j/
- 8 tesmenerses ENLARGED IN-
=
FIGURE 9F i.'
l i
. Qumye / f f--l s{s.
l Figure 6-5 90 Degree Dowel Pins. Elevation View c
mm 5-13.
2
...a... _ : _ _ _
c
.r h 1" r
,e-
!r j
- 1989 Core. Support Barrel Visual Inspection Results-
- with Core Suppon Barrelin RPV Thermal Shield Displacement Limiter 128 *
. Lower Block-. All 3 dowel pins backed out s
~
\\
- Thermal Shield Support Block 210' CenterDowel backed out -
upper right bolt backed out 1/4" to 1/2" past T.S.
. Thermal Shield Su Block 270*.
upperleft missing l
RPV near 128*- Hot Leg Nozzle-gougein cladding
. Bottom Head
- Misc. pieces found 1 bolt,18" metal strip, rod i
Inspections Completed:
6 displacement limiters examined with an overhead camera and a 90 lens.
5 Thermal Shield Suppon Blocks lower blocks examined with an overhead camera and a
.90* lens.
330 Thermal Shield Suppon Block lower bolt not examined. Overhead carnera inspection of upper bolts revealed no damage.
All Six Suppon Blocks examined from the ID of Core Barrel using a 90 lens.
Thermal Shield Lower Suppon Blocks from ID J
30 All 3 dowel pins recessed 90*
All 3 dowel pins recessed 150
- All 3 dowel pins recessed, lower center bolt, upper right bolt recessed 210 All 3 dowel pins recessed, upper right bolt recessed 270 All 3 dowel pins recessed, upper right bolt missing r
330' I.ower 2 dowel pins and lower bolt appear recessed i
/y'
p)&.
j
- 1.,
POTENTIAL ROOT CAUSES 1.
Loose Dowels At 128 degree Limiter Inserts Backed Out
. A. Degradation of the 128 degree Limiter Insert Results in increased Vibratory L.. ads at the Lower Support Blocks
- 1. Preliminary Vibratory Evaluations Show Highest Loads
]
at:
- a. 210 degree block
- b. 90 degreu block
.2. : Analysis Results Show That For A 10 mil or Even A 27 1
mil Limiter Key Gap, Lower Support Top Bolts Should i
Not Crack due to High Cycle Fatigue During One Cycle of Operation
.B. If Lower Support Top Dowel Fin Backs Out, The Top Bolt Loads are Expected to increase
- 1. The Visual Inspection of the 210 degree Block Shows:
- a. Top Dowel Pin Out
- b. Top Right Bolt Could be Out Slightly
- 2. Some Degradation at 90 degree Block Appears to be 4
Present ie, Shims have Rotated C. Assuming the 210 Degree Block Degraded as Well as the 128 degree Limiter Vibratory Evaluations Were Performed-1.. Loads at the Lower Support Blocks increased Only Slightly Over the Case Assuming Only the 128 Limiter i
was Degraded y
(
j L: ~P 1
=== :2
= :
- =:: ::::::
Scen:ris I Ccnclusi:ns For this Scenario the Degradation of the 128 degree Limiter has' the Greatest influence on the Lower Support Block Loads.
However, the Resulting Loads, by themselves, are Not Large Enough To Produce Cracks in the Lower Suppiort Block Bolts for Limiter Key Gap Sizes Up to 27 mils for One Cycle of Operation.
The Top Bolts at the 210 degree Lower Support Block may be t
Cracked due to the Movement of the Top Center Dowel Pin Coupled with the increase in Loads The Results of this Scenario do not Provide Any Conclusions on Why the One Bolt is Missing from the 270 degree Block Location.
?
l 1.
i l
0
/4
- I II, D w;l Pin Bccked Out ct the 210 degrco Lower Supptrt BI:ck l
A. The Degradation of the' 210 degree Lower Support Block was Considered in the Vibratory Evaluations
- 1. Compared to an Undegradated Case
- a. At the 270 degree Block:
- Radial Loads increased by ~ 26 %
l
- Vertical Loads increased by < 5 %
-b. Displacements at the 128 degree Limiter Location Increased Only Slightly in the Radial Direction Conclusion The increased Loads at the 270 degree Block do not Appear to be
. Sufficient Enough to Cause a Bolt to Crack.
l l.-
1
/7 1
. -. ~.. - -..... -. -... -. -
[
\\
)
7-lit.
A Top Bolt is Missing from the 270 degree Block A. Vertical Gap Between Shield / Support Block' and Support Block / Core Barrel May Be Larger Than Initial As-Built Value of.000/.002 inch
- 1. A Larger Gap will Reduce the Effective Preload Needed i
for a Tight Joint and increase Top Bolt Loads.
Using the Nominal Torque Coefficient (c=.177) the Calculated Preload may not be Sufficient to Close a Gap of 14 mils or Greater j
- a. Previously (last outage) Bolts Were Missing from i
the 270 degree Block and Wear may have Occurred at the Interfaces Conclusion increased Radial Loads at the 270 degree Block Coupled with an increased Vertical Gap Between the Shield / Block / Core Barrel Could Degrade a Top Bolt a
l 1
l l
//
r
~.
ALLOWABLE VERTICAL GAP vs TORQUE COEFF.
GAP BETWEEN SHIELD /8 LOCK / CORE BARREL 16 i
15 t i
x\\
e i4
\\x 2. -....
g I I t
13 coefficient range 4
e
.144 to.231 i
\\ \\\\
i i?
N NN 5
\\ \\\\
g
\\ \\h o
N NN i
i
>E 6
L e
\\
5
+
L N
N' N
d l
3 N
N' 2
N N
[N 1
1 N
71 O
O.12 0.14 0.16 0.18 0.2 0.22 0.24
'O.26 0.28 0.3 TORQUE COEFF., C O 10 MIL UMITER
+
17 MIL UMITER 0
27 MIL UMITER i
- ~
y T
IV.
Loose Dewal Pins At 128 Limiter Ins rts Bceked Out
- A Top Bolt may be Missing from the 270 degree Block Based on the in-Vessel Internals Visual Inspection 1
A. A Vibratory Evaluation was Performed Assuming the Above
. Conditions i
- 1. Lower Support Loads were not Significantly Different for this Case than for the Case With Only the 128 j
degree Limiter Degraded i
L V. _
Bolt Over Torque During Installation A. Bolt Over Torque could Initiate a Crack in the Bolt that could Propagate During Operation and Lead to Bolt Failure u
l
?
t 9
4
4 POTENTIAL ROOT CAUSES 4
s
- 1. The Degradation of the 128 Limiter, due to Dowel Pins Backing Out, increased the Loads At the Lower Supports
- 2. The Higher Loads At the 210 degree Block Helped in j
Backing Out the Dowel Pin.
- 3. The Decreased Capacity of the Dowel Pin Probably Caused the 210 degree Top Right Bolt to Start to Back Out, Which Degrades this Block Even Further.
j L
- 4. The Degradation of the 128 Limiter and 210 degree Block increased the Loads on the 270 degree Block l
- 5. The Bolt at the 270 degree Block may have Degraded if One j
j.
of the Following Conditions Exists Coupled with the L
Predicted increased Loads from Condition 4:
j l
- a. A Large Vertical Gap Between the Thermal Shiel' and d
Support Block and/or Between the Support Block and Core Barrel.
l
- b. Over-Torque of the Bolt initiated a Crack i
l.
- c. The Banana Pin was not Securely Engaged into the Base Metal f
- 6. If Significant Wear Occurrs at the Limiter Keys then Cracking of the Bolts at the Lower Supports may Occur O
d/
~.... h
-z --
=:2.: =--. :-
c.
10
-. =
t' d:
I I
CONNECTICUT YANKEE ATOHIC POWER COMPANY DOCKET NO. 50-213 Meeting of October 25, 1989 STATUS OF DEGRADED FUEL F
(l l
Attendance List-Name Company Phone Alan Wang NRC 301-492-1313 Bill Herwig NUSCO 203-665-3198 E.P. (Chip) Perkins NUSCO 203-665-3110 Clint Gladding Conn'. Yankee 203-267-3628 Richard Lobel NRC 301-492-1157 C. D. Sellers NRC 301-492-0930 Larry Phillips NRR/ DST /SRXB 301-492-3235 Shih-Liang Wu NRR/ DST /SRXB 301-492-1065 I
1 e
li c
.a
- -e e
~
h o;[$$!Ii o,.
rc,:
.Docume t Namet
,*>m
MID-0UTAGE STATUS MEETING Requestor's'ID:
MITCHELL Author's Name:
Wang,A-Document Coments:
Haddam Neck - re. Leaking Fuel Pins & Thermal Shield Damage Y
t 4
i e
e e
4
-'l 1
r l
i-.
4 1,
1.
i l.
i
-.47-
-- - - - - ;y- - - - - - -
_