ML20073F722
| ML20073F722 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 04/25/1991 |
| From: | Creel G BALTIMORE GAS & ELECTRIC CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9105030008 | |
| Download: ML20073F722 (4) | |
Text
- _ _. _ _ _ _. _ _ _ _ _ _ _ _ _
-- J
-t
+
B ALTIMORE.
G AS - AND -
ELECTRIC 1
l CHARLES CENTER
- P.O. BOX 1475 e BALTIMORE, MARYLAND 21203 1475 l
b GEOROC C CREEL VICt PntSIDEh?
Nvettan Entnov (JOO 240 4 465 April 25,1991 U. S. Nuclear. Reg' 2 tory Commission Washington, DC _0555 i
ATTENTION:
Document Control Desk..
J y
SUBJECT:
Calvert Cliffs Nuclear Power Plant -
Unit No.1; Docket No. 50-317.
Reauest for Relief from ASME Reauirements j
REFERENCE:
^
Gentlemem
-Baltimore Gas -and Electric Company received verballinterimLapproval from 'the NRC Staff on -
April 20,' 1991 for relief from ASME:Section?XI requirements. cThis: letter requests final relief approval.
n-4 y
u t
s m
COMPONENT FOR' WHICH RELTEF IS REOUESTED"
'x
.y.
- A small through wall flaw (hole) exists in the weld attaching a six-inch weld o let inspection port toi the 30-inch Unit 1 Saltwater System. header just downstream of NoT12 Service Water / Saltwater heat
-exchanger. This piping is classified as Class 3-for Insarvicc inspection purposes;JThe hole is'
-approximately one-quarter inch diameter and was caused by corrosion.
CODE REOUIREMENT FROM'WHICH RELIEF IS REOUESTED >
'In accordance with Referened (a), relief is requested from ASME Section XI IWd 4130(1)(2), whi5h -
requires that when repairing an item the flaw must be removed.; This requirement is a hardship. We :
prefer an alternative. Interim NRC approval was granted for that ahemative.
~
3 y
4
+
j i
4 I;
t
.A O OO 7
-- p p
~
m.
a e
Document Control Desk April 25,1991 Page 2 e
PROPOSED ALTERNATIVE An evaluation of the hole in the six-inch weld o-let weld was performed to determine whether the flaw was stable or likely to propagate.
The configuration was modeled using significant 4
conservatisms. The resultant stress due to a combination of deadweight, pressure, thermal expansion, and seismic was determined to be less than 500 psi. The Code allowable stress is 12,750 psi. It is concluded that stress levels are too low to cause an increase in the size of the existing hole.
We have installed a branch connection to provide a pressure boundary replacement around the six-inch weld.o-let. The branch connection was designed in accordance with the original construction code ANSI B31.1 - 1967. The requirements of ASME Section XI IWA 7200 were met.
A drawing is attached showing the details of the branch connection. Calculations were performed to support the design. The branch was evaluated for deadweight, pressure, thermal expansion, and seismic stresses. A conservative corrosion rate was incorporated into the analysis. The stress analysis demonstrated that the branch connection stresses are well below the Code allowable values.
This alternative clearly provides an acceptable level of quality and safety.
JMSIS FOR HARDSHIP Compliance with the specified requirements would result in a hardship without a compensating-increase in the level of quality and safety. Due to isolation valve leakage, repair of the small hole in the saltwater header would require securing the entire Saltwater System, which in turn would require off loading the entire core from the reactor vessel.-
IMPLEMENTATION SCHEDULE The proposed alternative has already been implemented.
i Should you have any further comments regarding this issue, we would be pleased to discuss them with yuu.
Very truly yours, GCC/DLS/ dis /dtm Attachment 4
i
. m r.
., - +
Document Control Desk April 25,1991 i
Page 3 cc:
D. A. Brune, Esquire J. E. Silberg, Esquire R. A. Capra, FRC D. G. Mcdonald, Jr., NRC T. T. Martin, NRC L E. Nicholson, NRC R. I. McLean, DNR J. H. Walter, PSC h
__m
___m.m_m.__m2------m-a.--m--=--------------^------------^-----------"-"'---------'""-
^--
A'lTACIIMENT lillANCil CONNECTION CALVEltT CLII'FS UNIT 1 NO.12 SAL'lh'ATEll SYSTEM llEADEll SEE DETAIL B PL 5/e5--THK.
A516 GR.E 12" e, SCH. 40 PIPE
+A' N
AIO6 GR.B 5/ 7 8
4 PL 1/z' THK.
A516 GR.70 E'
'I h
h 6" t Vf 5
-o
~
~
S N
o*
vzV
'+
' 5" + Vz _~S [3 j $
y 3
g/
g r
?
S S
'S M (
) I V
. x usuuu rsuuuuss
[
$ w /,V
[h b
G
)
ORILL Vi!'$31 VENT HOLE Y'
PRIOR TO WELDING.
A 3/4" TmEACED CAP 3000* SA105 3/4" SCH.80 A1068 PIPE l
MAX. LENGTH = 4" W4* SW HCPLG d b[
3000* SA 105 5
I I I
DETAIL B SECTJ_ON 'A-A' -
l
- _