ML20076K950
| ML20076K950 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 10/22/1994 |
| From: | Hill W NORTHERN STATES POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| GL-94-03, GL-94-3, NUDOCS 9411020209 | |
| Download: ML20076K950 (5) | |
Text
A Northem States Power Company 414 Nicollet Mall Minneapohs. Minnesota 554011927 Telephone (612) 330-5500 October 25,1994 NRC Gen Ltr 94-03 U S Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 MONTICELLO NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22 Supplemental Response to NRC Generic Letter 94-03, "Intergrannular Stress Corrosion Crackina of Core Shrouds in Boilina Water Reactors" The purpose of this letter is to provide the results of the inspections of the Monticello core shroud as required by Reporting Requirement 3 of NRC Generic Letter 94-03, dated July 25, 1994. The inspection results are provided in Enclosures 1 and 2.
The inspection results have been eva!uated and dispositioned in accordance with the ASME Code and the guidance developed by the BWRVIP. Through this analysis, which is considered extremely conservative, we have determined that the Monticello core shroud is structurally adequate to withstand all design basis accidents and transient conditions and poses no operational or safety concems.
This letter contains no new NRC commitments.
Please contact Terry Coss, Sr. Licensing Engineer, at (612) 295-1449 if you require any additional information concerning this submittal.
$7)/
'I
>s William J. Hill Plant Manager Monticello Nuclear Generating Plant cc: Regional Administrator-Ill, NRC NRR Project Manager, NRC Resident inspector, NRC State of Minnesota, Attn: Kris Sanda J Silberg Dl(
9411020209 941022 PDR ADOCK 05000263 P
PDR L
4 USNRC NORTHERN STATES POWER COMPANY October 21,1994 Page 2
Attachment:
Affidavit to the Nuclear Regulatory Commission
Enclosures:
(1)
Summary of Monticello 1994 RFO Core Shroud UT Inspection Results (2) Summary of Monticello 1994 RFO Core Shroud VT inspection Results i
4#
UNITED STATES NUCLEAR REGULATORY COMMISSION NORTHERN STATES POWER COMPANY MONTICELLO NUCl. EAR GENERATING Plf.NT DOCKET NO. 50-263 Supplemental Response to NRC Generic Letter 94-03, "Intergrannular Stress Corrosion Crackina of Core Shrouds in Boilina Water Reactors" Northern States Power Company, a Minnesota corporation, hereby provides the Monticello core shroud inspection results as required by Reporting Requirement 3 of NRC Generic Letter 94-03, dated July 25,1994.
This letter contains no restricted or other defense information.
NORTHERN STATES FOWER COMPANY By Mdhdn h
b William J. Hilf Plant Manager Monticello Nuclear Generating Plant On this Jfkay of O!fkt
, /9 9Y before me a notary public in and for said County, personally appeared William J. Hili, Plant Manager, Monticello Nuclear Generating Plant, and b?ing first duly sworn acknowledged that he is authorized to execute this document on behalf of Northem States Power Company, that he knows the contents thereof, and that to the best of his knowledge, information, and belief the statements made in it are true and that it is not interposed for delay,
~
l
$ika A. $mNit f
L 7~,
y-I f NOTARY B
A s
-7 January 31,
_ 3 a
. ~
~
Summary of Monticello 1994 RFO Core Shroud UT Inspection Results (See Note 1)
WELD LENGTH OF WELD INSPECTION RESULTS INSPECTED (% OF TOTAL VELD LENGTH)
(See Notes 2 and 3)
H1 143'(25%)
No relevant indications H2 237'(42 %)
One (1) relevant IGSCC/lASCC indication,107.9* Azimuth, 3.9' long, <0.5T deep, lower side of weld, ID connected H3 302"(54 %)
Five (5) Relevant IGSCC/lASCC indications:
1) 76.5* Azimuth,3.85* long, <0.5T deep, lower side of weld, ID connected
- 2) 235.8 Azimuth. 2.85* tong, <0.5T deep, lower side of weld, ID connected
- 3) 239.6* Azimuth,7.59' long, <0.5T deep, lower side of weld, ID connected
- 4) 260.8* Azimuth,9.88' long, <0.5T deep, lower side of weld, ID connected
- 5) 288.2* Azimuth,3.53' long, <0.5T deep, lower side of weld, ID connected H4 165.5'(32 %)
No relevant indications HS 195"(37 %)
No relevant indications H6 Inaccessible (See Note 4)
N/A H7 Inaccessible (See Nute 4)
N/A H8 Inaccessible (See Note 4)
N/A H9 Inaccessible (See Note 4)
N/A Notes:
1.
UT inspection performed using 45 shear wave, OD creeping wave, and 60* refracted longitudinal (RL) wave search units.
2.
All accessible areas inspected, therefore, % inspected = % accessible.
3.
Major interferences include Core Spray downcomers, Jet Pump Riser Braces, lifting lug guide rods, instrumentation lines.
4.
UT package could not be lowered past interferences.
{
Summary of Monticello 1994 RFO Core Shroud Enhanced VT Inspection Results t
WELD LENGTH OF WELD INSPECliON RESULTS INSPECTED (See Note 1)
H4 Approximately 68* OD (Sum
- 1) One (1) 0.5* knear indication (arc strike) at approximately 45* Azimuth.
total of three examination locations at 45*,70 & 135
- 2) One (1) 5.5* linear indication plus several smaller intermittent indications over 27* of arc at Azimuths) (See Note 1) approximately 75* Azimuth. Indications located on bottom side of weld. See Note 3.
H4 Approximately 32'ID at 49 to One (1) 5* to 6* tong linear indication plus several smaller intermittent indications over 23* of arc at 72* Azimuths (See Note 2) approximately 65* Azimuth. Indications located on top side of weld. See Note 3.
H5 Approximately 60* OD (St.
'ne (1) 1" long, vertically orientated linear indication in forged ring below weld at approximately 73~
total of three examination Azimuth. Located below HAZ.
I locations at 45*,70* & 135*
Azimuths) (See Note 1)
H6 Approximately 80* (Sum total No relevant indications at 0* and 180 Azimuths)
H7 Inaccessible (Backing Bar)
N/A H8 Approximately 80* (Sum total No relevant indications at 0* and 180 Azimuths)
H9 Approximately 80" (Sum total No relevant indications at O' and 180* Azimuths) 140tes:
1.
Enhanced VT was performed to supplement the UT inspections in areas inaccessible to the UT equipment.
M 2.
Specific ID inspection of this area was performed to confirm no through-wall cracking existed.
3.
When calculations were performed to confirm the structural integrity of the shroud the entire arc spanned by the grouping of intermittent indications was conservatively treated as consisting of a single continuous indication.
_ _ _ _ _ _ - _ _ - _.. _ - - -