ML20086D046
| ML20086D046 | |
| Person / Time | |
|---|---|
| Site: | Diablo Canyon  |
| Issue date: | 04/24/1974 |
| From: | Searls F PACIFIC GAS & ELECTRIC CO. |
| To: | Knuth D US ATOMIC ENERGY COMMISSION (AEC) |
| Shared Package | |
| ML20086D026 | List: |
| References | |
| 10CFR-050.55E, 10CFR-50.55E, ISSUANCES-OL, NUDOCS 8311300085 | |
| Download: ML20086D046 (3) | |
Text
O O
+
PACIFIC OAS AND ' ELECT RIC C O M PANY
@ O "86
'{
77 B E A L E S T R E E T. S A N F R A N C I S C O,' C A L I F O R N I A 94106.(415) 781 4211 P R E D E RIC K T. S E A R LS April 24, 1974
"'.*;*[.":g"' [11 j
"**6 mi m...m
..mm c..m dOHN C. MORRISSEY
,"l,'***
y."'.'g'.,.g.
mwm smm en m
.,u.a
...u
- :.r..";=.w.: sos w,u.a-...
-~:
.s..e e MaLCOLM H. PuneUSM cHanLaa v. van oausaw o.....L......
i uaLeoLu a. uacniLLoP
- ll7;"*f;*,""****
PHILIP a. C RaN E. d N.
Mem.m. v. e.6.
;*;; n =
C"l*.*..*::"".'*'
Dr. Donald F. Knuth "C*Jt%"O Directorate of Regulatory Operations
$3aEj.~~;=
Office of Regulation l';;:::*;100 i
U. S. Atomic Energy Commission
- "*L"C**~
"'"~~"
Washington, D. C. 20545 Re:
Dockets 50-275-OL 50-323-OL
Dear Dr. Knuth:
Friday, March 29, 1974, we notified the Region V Office of the Directorate of Regulatory Operations that a condition discovered on the exterior surface of the Unit 1 steamLgenerator'l-1 unit nozzle was possibly reportable as a discrepant condition under provisions of 10 CFR 50.55 (e) (1) (iii).
A series offerack-like indications extending circumferentially around the nozzle _in the first weld 13yer of the transition from the steel casting to the stainless ;t. mal cladding was discovered during a~ routine NDE dye penetrant examination of the field weld made between the' nozzle.and the coolant loop piping.
Wis con-dition vas discovered on March 19,.1974.
Following this discovery,-we embarked on E program of examina-tion and investigation of the safe ends of the Units 1 and 2 steam' gene-rators, reactor vessels and pressurizers to determine the extent of this.
condition.
Westinghouse Electric Corporation, the designer.and~manu-facturer of the equipment, was notified of the condition and-provided metallographic consultants-to direct the investigation"and analyze the-findings.'
PGandE metallurgists also participated in the investigation.-
.Upon the arrival at the site of' the Westinghouse metallurgists on April 1, 1974 a-program to" investigate the extent of the condition on the' steam generator 1-1 outlet nozzle was established.. Metallogrhphic replication, polishing and etching were used in~the following enquence '
to determine the nature of the indication:
- (1) sThe surface'on which the indications were detected-
'.was replicated.
This' investigative technique.re-
.vealed anfirregular' indication-in;the ASME SA-298E-309-15 :(first layer) weld metal-deposited.on the-carbon steel :(ASME SA' 216 WCC) steam generator casting.-
B311300005 750115
. f ADO
]7D
_.i -
(
..-n.
/
O-O g
Dr. Donald F; Knuth 2
April 24, 1974 (2)
'No representative areas, approximately 2" in length, were metallegraphically polished using fine grinding silicon carbide abrasive paper of successively finer grits.
The surface was polished through 1 micron diamond grit and rep-licated.
A linear indication (crack) was disclosed.
(3)
The polished area was then chemically etched by an application of Marble's reagent.
Etching confirmed the indications to be crack-like, intergranular separations restricted to the 309 weld metal layer.
After determining the characteristics of the indications, the two selected areas were ground using a high speed grinding wheel.
The indications were eliminated in each area by grinding to a depth of approximately one-sixteenth of an inch.
The two sample areas were believed to be representative of the condition and may be representative of the most severe condition as judged by the breadth and intensity of the DP bleed out.
In an effort to assure that the crack-line indication e'isted only on the surface, a 360' radiograph was taken of the nozzle x
in the same plane as the deposited 309 weld metal.
The radiograph clearly showed the exploratory grinding areas and an 1 T Penatrameter sensitivity was obtained.
No linear indications were shown on the film.
L The results of this radiograph will be evaluated as a part of the total examination effort in determining the extent of the discrepancy.
The l
preliminary investigations to date provide a high level of confidence that the indications are surface only.
Dye penetrant examination was performed on the I.D. surfaces on 7 of the 8 steam generator nozzles and no indications were found.
Welding.was not yet complete on the 8th nozzle.
Following this examination, an.NDE dye penetrant examina-tion of each " safe end" on-the reactor vessels, steam generators-and pressurizers at Diablo Canyon was undertaken and is presently in l
progress.
Preliminary results indicate the following:
(1)
Six safe. ends of the 8 nozzles of the' Unit 1 steam generators have.like indications.. None-of the nozzles on the reactor vessel or pressurizer bear i
any indications.
i (2)
No nozzles of the steam generators, reactor ~ vessel or' pressurizer of Unit 2 have indications like those-l
.on Unit 1.
f
. Preliminary findings at this time indicate that the cracking
. on the Unit: 1: steam generator nozzle is' superficial surface cracking i
extending-to a depth of approximately 09".,
Apparently, itlisithe result of a st.perficial: corrosive attack'on the surface resulting-from i
exposure to the marine environment. ' PGandE ' Deviation Report #214, l
initiated March 20,.is)in preparation ~to document this discrepancy.
~
l A final report telling the extent, nature and resolution of the e,
( y i+ - p g
,>pp~.yr,gg._
9*y,*9--gie wrd-M++
p e. J 4 y p -
"or,.M g
D.
1r m
m-
- weus
..--#.s,,.m.y-w--ee-e
,a i.F f=-.i--g-*t9gs-+4r-i-n.1 iy-1--
- ,g+s.nMwn..q - y y w q+.
m
- ry+gg i
9 9
i I
Dr. Donald F. Knuth 3
April 24, 1974 discrepancy is expected to be transmitted before June 1, 1974.
I Very truly yours, I
i 1
i i
}
CC:
Mr. R. H. Engelken, Director Directorate of Regulatory Operations i
Region V I
J l
l 14 e
i i
l t
j