05000000/LER-1950-266-75, /75-18:on 751217,during Cycle 3-4 Refueling, Discovered Section of Fuel Rod Missing.Caused by Water Impingement Through Baffle Plate While Failed Assembly in Cycle 2 Position H-1.Investigation in Progress
| ML20081B675 | |
| Person / Time | |
|---|---|
| Site: | 05000000, Point Beach |
| Issue date: | 12/30/1975 |
| From: | Bobe P, Burstein S WISCONSIN ELECTRIC POWER CO. |
| To: | Rusche B Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20079P656 | List:
|
| References | |
| FOIA-83-368 LER-50-266-75-18, NUDOCS 8310280168 | |
| Download: ML20081B675 (10) | |
| Event date: | |
|---|---|
| Report date: | |
| 0001950266R75 - NRC Website | |
text
.
UC EVENT REPORT v
aoc* [01 l l31%I cmau
=1 au. neeumo meomnarismi
/.
con"ot P: -.
t 6
I
...2
...e m,.
. o -..
8, slivllir 10l# 111 1/>l ol-l olo l o lo lo I-101 ol C
II I / l/ Ir I / I I cl 31 i
/
l u
is es u.
.,o a
u 9' '
J
~,. ; ' ='
i o.., m
, u,.
..,.m,,
cosil.1.1 trl LlJ lo ll' l-101216101 I /la i f 1717lsi l /l.2 l yl o iv i ri o
1 til S/
ties b9 tio et f.,8 69 74
/$
WO t
l 'e t a ti DtSC6mfCN RE l Ih~f - ?? !N F 'n ' 4 G C YC l E ? ~ l'c rart wc y=4 ot.rp re ct.
sv.o.r l
, e..
so i
_ r i : c >,, : o c t v n et A ren z~s n y (>. e 3 N rovo w W.C.
VuCL F'! 4 sn curr I
@ li-r s.
00
@ l re o rga r D u s : t 8 : ' ',0
/\\ t! ! v r t!
T."c v re v e r r' 0 n os tr 4 C. we/G l
, e.a ao a
me 0.
7/ic /4 sta v e t r //A p ) Psrsa,t of 23117 l
_y
@ l A -,, '
,n.-
r 3
iso l
s,/u-j 1, ty;, <
7*.
H fi.s t t e -s o ut'o+ C C Ye tr f' l
t so e,,
~
m. u,
o-u.
i.2 l Kh l W lF1[l71Y!)l V1 h Iw$fd[o1
. o4 v
i 43 44 47 4e f
'~
w.>
_.st.ato.
fi < t
,< ta r: p o r ri.
7 -// s fr.- re r vn% s u /! hTW l
- l
. <9.L, ly,
s v:
e to l f. > -. ;.-
.c th c. - s v w. pet.
tecaco get h e r ri s o n'e-* l
' ^-
u -
,,, s, w
R3 I w _:
I.
~ u 'L a r.: v.
b sc r ros.niss or c a nvuivc.
l "O
[
v,. x,..
.. e..
[jj Ir le Ic I I i 1 l 141J l N'cTiere bor' M be.^'eva l
i m.
s..rs
- - o....
.... ruc-, o.
e
'ir e
/ H 9
'O V ?8 44 45 4b tsO
.. so n O.1.'4,
..' '1 m e o. m i as.
(?J LiJ l
'J,,,,.
+.e.
l I
- 4 I
l 7 6
'e
'O 11 44 45 tsO i-
..t eeu w.i. omsuus r
,. b?
t...
H I CIe ir I til I 9
1 h
I.
7 o3 i,
V o
ao
.wmat moms
- . epen a.
. e q s e. p.
.c E IciclCl l v/
I 5){"
7 89 11 12 00
f OH f.it t NStOupdCES k
@l l
7, 7 8 L*
(90 LOSS 054 DAMAGE TD f ACUTV
,,t.
l
.
- D2 lfj l A3 1
7
.9 to ao if(
1 eum orv I
h i,
@L#4 r -;
2 ee ao 0
a.
ADOrfCNAL FACiOR3 I
D2 i N4 I
i 69 18 0 s4'
$l4 [12 1 l
/[fSN.
//fhd
@)
_ '/9 ? ???.s~
~
g k
2n wtsi uicmc en. unsAuntt, wisconsin 13201 Deceeer 30. 1975
- f %
Hr. Benard C. Rusche. Director 9
Office of Nuclear Reactor Regulation U. S. Nuclear Regulatory Cossaission
(
Washington D. C.
20555 I
e5
Dear Mr. Rusche:
P LICENSEE EVENT REPORT NO. 50-264/76-18 FAILED FUEL IN ASSEMBLY D-03 POSITION K-6. CYCLE 3 m
POINT BEACH NUCLEAR PLANT This letter is to report in detail the discovery and results of se-secuent investigatten of a failed fuel assedly during the Cycle 3-4 refuel-ing of Unit I at Point Beach Nuclear Plant on Decader 17, 1975. An initial report of this event was filed Deceder 23. 1975 to cously with the ten-day reporting reoutrements of the Point Beach Technical Specification Section 15.6.6.A.2.
On Decerter 17, 1975, durire the refueling of Unit 1, the f, ore Load-ing Supervisor noted something protruding from the side of fuel assedly D-03 as it was being lowered into the fuel assedly upender. Fuel novament was stc;Ded irrediately while the Reactor Engineering Group representative moved the underwater TV camera in position to observe the affected area. The pre-lininary inspection indicated that a section of fuel rod was missing. The Reactor Engineer was notified of the finding after which the subject assembly was noved to the fuel inspection periscope in the spent fuel pit where a more detailed examination was sede.
VISUAL EXAMINATION OF FUEL ASSEMBLY D-03. EAST FAfL 12-17-75
(
The results of detailed visual examination of the fuel assedly are sumarized below, starting with the top of the fuel asseely.
Top of the Fuel Assa dly mods 12 and 13 were observed to be slightly below other rods (approxi-mately 1/16") and reduced spacing between rods 12 and 13 was evident.
Top of Grid 1 Rods 12 and 13 showed (Mications of wear adjacent to grid flow vanes.
l The vene at rod 13 was partially worn away.
N
\\
Q Mr. Benard C. Rusche December 30, 1975 At Grid 1 Rust marks were evident on the grid and rods 12 and 13. Clad of rods 12 and 13 worn away to the extent that fuel springs were visible be-hind slots in the grid.
Below Grid 1 A fuel fragment was observed to be lodged between rods 13 and 14.
Geuge marks could be seen in rods 12 and 13 adjacent to grid tab and a hole was visible in rod 12 at grid tab. A tab was touching rods 12 and 13 and a narrow gap exists between rods 12 and 13.
Between Grids 1 and 2 No apparent damage to rods was noticeable at this location but the spacing tetween rods 12 and 13 was reduced.
Too of Grid 2 The cladding of rod 12 was separated near vane with no cladding or fel tehind the upper part of grid. Rod 13 has a cut mark near upper edge of the clad and a hole on the left side. A fuel frapent was visible t?%een rods 13 and 14. The vane near rod 12 was bent in slightly.
At Grid 2 The spring for rod 12 was missing. Fuel fragments and open clad en rod 13 was visible at this location.
Below Grid 2 A two-inch section of clad for rod 12 from behind the grid had slipped down and pinned between the grid and the lower section of rod 12.
This rod has several holes natching the contact points of the grid springs.
No fuel was visible.
Rod 13 has a hole under the grid tab with an outline siellar to the tab.
Between Grids 2 and 3 About a four-inch open split in rod 13 with no fuel visible except at the top end of the split.
Top of Grid 3 Open cut in cladding on rod 12 adjacent to vane. Tr.1 vane is severely worn down on the side near rod 12.
Q%
Mr. Benard C. Rasche December 30, 1975 Coriplete separation of rod 13 at point just above grid with the section of rod between grids 2 and 3 resting on orid 3 between rod 12 and the second rod in from 12.
The section of clad for rod 13 that was behind the grid springs made ccntact. Also a lot of gouge marks are present on that section of clad. No fuel fragnents are visible.
A fuel fragment was visible on top of the grid neer rod 8.
At Orid 3 ftissing grid spring for rod 13.
% clad for rod 13 visible behind grid, 1
Eelow Grid 3 l
Holes visible in rod 11 near grid tab. Large hole in rod 12 with large fuel frag. ent sticking out.
Section of cladding for rod 13 missing from behind grid. Fresh scra e earks en top edqe of the existing rod 13 cladding. No fuel visible at to, edge cf this section of rod 13.
Betvan Grids 3 and c Rub nark on rod 13.
Teo of G.-id 4 Wide gap between rods 12 and 13.
At Grid 4 center of grio spring for rod 12 separated. Many small fuel frao-nents visible behind grid at rods 12 and 13.
Wear in grid spring at rod 13.
Below Grid 4 Gouoe marks and hole in rod 12. Fuel visible in hole. Rod 13 miss-ing coripletely from grid to midway between grids 4 and 5.
Gouge marks on second rod in from rod 13.
Betw>en Grids 4 and 5 Top 11 inches of rod 13 missino. End of rod 13 bent to a horizon-tal condition about two inches long.
+
Mr. Benard C. Rusche December 30, 1975 Top of Grid 5 Wear in rod 11 adjacent to vane. Rod 12 clad worn through at vane with vane worn down also.
Rod 13 has an unusual ragged hole next to but not parallel to the edge of the grid vane. The vane is severely worn and bent.
A piece of clad about one-haIf inch long is lodged between rod 14 and the grid.
Below Crid 5 Roi 12 has a hole with gauge marks around it. A fuel fragment is visible in the hole.
Below Grid 6 Hole in rod 12. Couge narks and hole in rod 13 witn fuel showing.
Botton Grid and Nozzle Rod 12 almost bottomed out and resting on bottom. The normal rods are about 3/4 inch off the bottom.
SL" WRY OF FUEL ASSEMBLY D-03 OPERATING HISTORY A brief summary of the operating history of fuel assembly 0-03 is as follows:
Fuel Asse*1bly Identification: 0-03 Prepressurized low parasitic design with fuel rods off the bottom nozzle.
Fabricated at Westinghouse Nuclear Fuel Division. Cheswick. Pennsylvania.
Date received on site: August 22, 1972 Initial inspection revealed no abnormalities, t.oaded into Unit 1. Cycle 2 at core location H-1 Insert was a thiele plug device. Burnup during Cycle 2 was 7.071 WD/MTU.
Loaded into Unit 1. Cycle 3 at core location K-6.
Insert was a thie le plug device. Burnup during Cycle 3 was 15.306 MWD /MTU.
Total burnup: 23.377 MWD /NTU.
There was no difficulty in the fuel handling ooeration during Refueling 2 which involved D-03 and/or adjacent assemblies.
Y 4
2 3.__
_ m m
1 l
Mr. D:n:rd C. Rusche Q
5-December 30, 1975 OETAILED FUEL HANDLING STEPS LEADING TO DISC 0 KRY OF OCCURREMCE Anomalous behavior was first noted during the fuel reloading se-t quence when fuel assedly E-06 was being lowered into adjacent core position K-5.
The operator noted some deflections of the order of 120 pounds in the load cell which monitors the weight of the fuel assedly and mast. This occurrence is not particularly unusual as the asseely slides into its apening between four other assed11es. He also noted that this assedly was slightly higher in elevatten (1/ f to 1/4") when it was posittened on the louer core so port
^
plate. When it was observed that there wes a sectica of feel red appremiestely' 11 inches long missing from D-03. its former leestian (K-4) uns taspected and nothing abnormal was noted assedly E-33 was then leaded late core positten K-6.
Fuel assembly E-06 was then removed fren een positten n=4 to facilitate 3 an inspection of the core support plate. A portien of feel red. apprest.astely 11 inches long, was observed to be lying diagonally acrees.the K-5 loestion.
Assemeltes in J-5 and L-5 (E-29 and G-24 respectively) were reeved from the core to give clear access to the broken piece of rod.- An air eperated vise grip was utilized to retrieve the rod. Several small piles of debris were also noted and removed by using an underwater vacuum.
Faces and corners of assemblies which could have been'affected either
~
during Cycle 3 oceration of D-03 or during the fuel movements men inspected.
This effort included the southwest corner of F-07; the southeast ~ corner of E-33; the south face of G-24; the north face of E-2g; the west face of F-25;
~
and the west face of D-34. A small plug-like object was noted on top of the botton nozzle of F-07 and this was rencved to the bottom of the refueling cavity where it was vacuumed. On D-34's west face several fuel fragments were observed wedged between the rods and grids. Scratches were also noted on D-34 in the area of the gross failure on adjacent fuel assedly D-03. There was nc apparent failure to D-34 D-34 was later removed pemenently from the core per the preplanned refueling procedure.
PROBtJLE CAUSE OF FUEL CLAD FAILURE The nuclear steam supply system vendor. Westint$euse, has stated that a highly probable initiating factor for the fuel fa91ere was water in-pingement through the baffle plate while the failed asseely was in its origi _
nal Cycle 2 position H-1.
This problem was experienced provicesly at two fer-eign nucleer plants.
Esserience at the foreign plants has indicated that flew through the' stitch weld joining in the baffle plate.'er belted baffle plates as may be the 1
case at point Beach, has occurred at locations steiler to N-1.. This can result' in a water impingement on the corner or near comer fuel rods of the assedly at this position, thus leading to vibration and fretting weer of one or more s
fuel reds.
In the point Seach case, asse dly 0-03 occupied position H-1'during/
Cycle 2 before being moved to position K-4 for the ensuing Cycle 3.
A small-hole in the affected fuel rods due'to fretting from fuel rod vibration is poste lated to have taken place prior to relocation of the asse dly into positian K-6.
The Cycle 3 Position subjected the. assembly to a measurably, higher power rat-o ing than in its Cycle 2 position.
...e-p e
3 4
Q g'
Mr. Benard C. Rusche December 30, 1975 The initial escalation to power at the beginning of cycle 3 was at a rate higher than the present operating guidelines and a sharp increase in reactor coolant activity was noted between power levels of 40 to 50%. It is presmed that the fuel rods containing holes in the clad became water-logged during the shutdown and burst due to steam pressure and/or the lack of suffi-cient time for the Zircaloy to plastica 11y deform during the power escala-tion phase.
SAFETY EVALUATION At3 C01UtECTIVE ACTION l
tial for and e.onsequences of additional fuel failures and (2) (the effect of Two potential safety concerns have been evaluated: ~ 1) 1he poten-loose fuel pellets in the coolant system on the health and safety of plant-4 operating personnel and the public, a
The first item requiring a safety evaluation is the potential for 3
and the consequences of additional fuel failures of a sistlar nature. If baffle imingement at core location H-1 is the problem, a potential problem a
exists in two additional assemblies. Fuel assembly F-M had boen locatad in position H-1 during Cycle 3 and has been moved to position J-3 for Cycle 4 opera tien. r'ew fuel assembly G-07 is presently located in position H-1 for Cycle 4 operation. Both assec611es will be carefully inspected at the end of Cycle 4 oper.
atice.
In reviewing the safety aspects of locating assedly F-36'at position J-3 during Cycle 4, it was confirmed that the assem6ly does not contain a' con-I trol red in this position; therefore no possibility exists of,a damemd fuel rod
~
interferring with a control rod dropping action. ' A notable facter ad tigating the possibility of cladding damage to this assembly during Cycle 4 is that some months ago Westinghouse instigated guidelines governing the rete of pesar escala-tion following a cold shutdown of the reactor. These guidelines will be fol-lowed rigidly during future startups from the cold condition for Unit 1. Cycle 4 The purpose of controlled power escalation _is to allow fuel rods unich might have taken in water via pinhole leaks to expel the waters thus preventing the bursting of cladding due to steen pressure buildup within:the fueltred as appears e:ay have happened in this instance.
p It is considered that careful monitoring of the reacter coolant activ-ity during reactor starte and later operation will provide the necessary informa-tion for monitoring the condition of fuel assembly F.M. as well as the other fuel assemblies in the reacter. Reacter coolant system activity monitoring and alloweble limits will be continued as prescribed by the Technical Specification.,
~
The second item requiring safety evaluation is that of loose fuel pel-lets in the reactor coolant systes during subsequent plant operation. As'de '
y~
scribed previously, all reasonable attempts to' locate and removeloose pellets y
a
_-=
a
\\
s I
s
(..
'41
- - _-(,_
o O
Mr. Benard C. Rusche December 30. 1975 from adjacent fuel asserblies and the lower core support plate were performed.
I No known loose pellets re=*ined in the reactor vessel or on fuel remaining in the core. If there are any xllets or parts of pellets remaining in the reactor vessel they would be small fragments that traveled upward between the adja-cent fuel assettlies during Cycle 3 operation (assembly to asses 61y nominal clearance is.040 inches) or larger fragments that dropped to and through the lower core support plate when fuel was moved during Cycle 4 reloading. Mater-tal on the lower core support plate was removed.
It is not known if pellets below the lower core sgport plate would stay in place or be lifted by the coolant flow. If the pellets are lifted by the coolant flew, they are small enough to pass through the betten nozzls but they would be caught by the fuel assem6ly bottom grid. This might cause some local flow blockage, but it is tolerable at this axial core location.
If pellets remaining in the system retain their integrity, thers should be no significant reactor coolant activity increase because these pel-Icts will not be exposed to core neutron flux and hence cannot generate fission products. Should the pellets disintegrate. it is expected that temporary and minor increases in reactor coolant activity will be detected. The chemical and volure control system purification demineralizers and filters will remove par.
ticulate and dissolved material from this source. It is not expected that opera-tion will result in teactor coolant activity levels oigner than those experi-ecced during Cycle 3.
Therefore, based on the safety evaluation given above, operation of the Unit 1. Cycle 4 core is not considered to pose a hazard to the health and safety of the public. Investigation as to the pxact cause of the fuel failure will continue. Present plans are to remove all fuel and the lower core barrel of the Unit I reactor vessel during its Cycle 4-5 refueling as part of the in-I service inspection program. This will permit a thorough fuel inspection and investigation of baffle plate joints to determine if this is the cause of D-03 failed fuel reds.
Very truly yours.
l j [ N:a ExecdiveVicePresident Sol Burstein i
I i
E cort toaol:r, PATTtra M
PO!!(T BEACH U'l!T 1 CYCLE
't 1
2 3
4 5
6 7
8 9
10 11 12 13 tro
~
PD FD R12 12P16 R33 PD PD F29 C07 D16 D15 D12 D23 D24 EIS F26 PD 4P1 R32 FD R15 PD 205 4P12 PD FIS E16 DOS E01' D04 E02 D30 E03 007 EOS F19
~
PD 4P11 n27 CP34 PD 8P21 PD SP35 R22 4P10 ko F03 D14 Ell D10 E27 D11 E29 D34 E10 D13 F10 FD R20 8P23 R17 4P8 RS4 4P14 A07 OP26 R02 PD 194 E39 D18 D17 E39 540 E23 518 E31 002 D06 E40 F35' F
PD xec PD PD 4Plc RIs sp27 n30 4P2 PD 882 R26 PD T20 F31 D Yi ElC D01 Co E34 E25 025 E24 D35 F23 F27 s.
g l
PD Er6 R13 AF:9 RS3 8P33 R19 8P29 RS2 SP31 R14 SSS TD 1
F36 1 37 D32 D26 E22 A02 E19 D41 E21 D40 D31 E35 F21 I
g '.
PD TG4
~g /
F14 D27 E12 DOB E32 D20 E30 D22 EC4 037 F17
.~
PD R25 BP36 kil 4P15 R51 4F9 R10 SP24 R16 PD
~
FD9 E17 D21 E06 D29 E14 D33 F:28 D38 E09 FC6 j
j PD 4P13 R24 CP22 PD 8P25 PD SP32 R29 4P4
/D K
r11 E20 D24 e03 D19 D28 oss E13 r18 PD 4P3 R31 PD R28 PD ROS 4P6 PD
{
F12 F07 E33 F31 E36 r05.
P24 PD PD R03 12P15 R23 PD PD A
l M
F25 F30 F28 cAttra'
/
- '4F" i
so-Fuel Assembly Ib i
- e Other Device ID #
+
e e
wPatmte otr.ction or retent nw
,8 K
,9 t
g 4
3 5
2_
---T
.~ 1 CORE LOADI!;G PATTER 1, hk POINT BEAcil Uti!T 1
cyggg 4
(
TEST ASSDtBLY
_ FUEL ID #
' N aternu s ef I ranu tatt,
P0 - P'1wt fievice Insert 10 t
E,
. m 4, uintrei.Nos.
2 38 - Activated secondary so-270 RS - RCC Partial Length-Centrol Rod C q GM Gie.
G26 A
7 7
7 ItF'-12BurneblePoison'AC on m2 Pn Reds G3s GIS F05 F32 F07
..Ocs Cl?
(Asfasert'd)
'I e
B 7
.7 6
6 6
7 7
Sf.
PD on n
un18:
R Pn Pn GU F01 E01 E41 E02 E05 E03:
F33 Gi2 7
C 6
5 5
5 5
5
- - 6 7
t-~
pD pn o
en p
Po a
Pn en D
G e t' Fr*
E16 E30 F24 E23 F12 E32 E08 F35 Ge4 7
6 5
5 6
5
- - 6 5
5 6,
7 r0 I rin e,
en pn-on p
aa 80_
' DI.
g_
ElT E21 F29 A83 B51 033 -l F26 E22-E10 G 30 4
y
?
l pf f
jh h
P0 P
l P0
,b D
p Gf F17
' E38 F06 A61 E07 F16 E15 M0 F09 E40 F14 ep6 6
5 6
'(
5 6
5
)
6 6,
to r
'F PD p
pn pg a
pn a
yo p
130 Gay F20 E18 E26 882 F34 E34 F23 875 EZ3 E24 F2I e
5
.5 6
7 0* '
Y 6
5 5
6 5
6 k)
G PD k)
- 56/12 '
R pn Pn R
PD 3,
603 F10 E37 F19 A85 E20 F31 E13-A67-FIS
- E351F03 G 2.6 g
Il 6
5 6
6
(
.6 5
6 7
Ng-PD
, TJ
,5
,5 g
po pg pn pa Pe a
PO '
G '*
I y
E12 E31 Fil A59 801 AM FIS
.139 004 C 20 -
3 PD 5
~5 6
(
{1-)
)-
- - n an -
7 6'
SL 1 9.,
L r*IS' Po m
Of F36 E7 E29 r13 E19 F23 m
m.
m 0 Z3,
- m
'~J
- - 6 5
5 5.
6-5 8
~. 6 7
- 6. -
PD Pa en a'
on '
PO j;>
v PO pn a
en 4f 95 FZ5 E06 (33 E14 E36 us,
ym.
- G02, a
E 5
5 5
5-5
- - 8<
7-
~
, g,
'l l
PD E..
a-en a
pn R
PD pn
~
G)0 64 F02 F30 F0s GZ7 Cr09 7-6 6
6 7 'L' 70 PO e
unic en
- - Pn N
'l4 b2I -
7 y
[
PO _
ss.1 PO
= '
j 90?
V-4
.x
+
a-
- , +
cl
.2
.3l
- 4
f5 I61
^
K
^?
'^
13 -
lY j
Y,T N
))s 19 -
$5 JY0$lY.
" n?n