ML19339B341
| ML19339B341 | |
| Person / Time | |
|---|---|
| Site: | Trojan File:Portland General Electric icon.png |
| Issue date: | 10/10/1980 |
| From: | Engelken R NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION V) |
| To: | Withers B PORTLAND GENERAL ELECTRIC CO. |
| References | |
| NUDOCS 8011060767 | |
| Download: ML19339B341 (1) | |
Text
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UNITED STATES p,
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,g NUCLEAR REGULATORY COMMISSION g
s REGION V O[
o, 1990 N. CALIFORNIA BOULEVARD o
SUITE 202, WALNUT CREEK PLAZA so,*
WALNUT CREEK, CALIFORNIA 94596 1
October 10, 1980 t
Docket No. 50-344 3
Portland General Electric Company 121 S. W. Salmon Street 4
Portland, Oreaon' 97204 Attention: Mr. Bart D. Withers Vice President Nuclear Gentlemen:
This Infomation Notice is provided as an early notification of a possibly significant matter.
It is expected that recipients wil review the infor-mation for possible applicability to their facilities.
, a specific action or response is requested at this time.
If further NRC evaluations so indicate, an IE Circular or Bulletin will be issued to recommend or request specific licensee actions.
If you have questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
Sincerely, l
u.isee u.
.4, t R. H. Enc elken Director
Enclosures:
1.
IE Information Notice No. 80-36 2.
List of Recently Issued IE Information Notices cc w/ enclosures:
C. P. Yundt, PGE J. W. Durham, Esq.
Senior Vice President and Corporate Counsel 8011060 M Q
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,u J SSINS f!o.:
6835 Accession No.:
8006190085 IN 80-36 UflITED STATES flUCLEAR REGULATORY COMMISSI0tl OFFICE OF INSPECTION AND ENFORCEMENT WASHINGT0ft, D.C.
20555 October 10, 1980 1
IE Information ?!otice No. 80-36:
FAILURE OF STEAM GENERATOR SUPPORT BOLTING Description of Circumstances:
4 a
On September 4,- 1980, the NRC staff was informed by the Northern States Power Company that extensive cracking of the bolting for the supports attached to i
bottom of the steam cenerators on Prairie Island Unit I had occurred. The i
licensee initially discovered the boltinq problem when two bolts failed during detensioning. The licensee was attemptino to remove the pre-load on the bolting-(specified at 1400 ft-lbs) to minimize the potential for stress corrosion cracking of the high strength 1-1/2 in, dia.
250 ksi maraging steel bolting (Vascomax 250).
J Ultrasonic examination of the support bolting revealed cracks or breaks in 47 l
of 48 support bolts for the two steam generators at the Prairie Island Unit 1 facility. The licensee subsequently shut down the Prairie Island Unit 2 facility and performed ultrasonic examinations of the same steam generator support bolting, that failed on Unit 1.
The results of the UT examinations revealed cracks in three of the 48 steam generator support bolts.
The licensee attempted to remove the cracked bolts from the steam generator supports. Two cracked bolts were
.:cessfully removed while the third failed during removal.
Two bolts that were. Judged as defect free by the ultrasonic examination were also removed. Iagnetic particle examinations confirmed the results of the i
ultrasonic examinations on the bolts which were removed. As part of the short term corrective actions taken, the licensee has unloaded and retensioned the bolting at approximately 50 to 100 ft.-lbs.
Inservice ultrasonic examination of the affected bolting had been performed i
previously.
In the case of Unit 1 a significant number of the bolts were j
examined at the last refueling outage 14 months ago.
flo cracks were found at that time.
The susceptibility for stress corrosion cracking was identified in NUREG-0577 (for comment). The NUREG identifies those facilities which have utilized 3
maraging steels for reactor coolant pump and steam generator support bolting.
Further the NUREG recommends augmented inspections for the facilities included l
in Group I.
Licensees are ecouraged to review the bolting materials used at their respective facilities and consider inspection of maraging steel bolting that are either pre-loaded or significantly loaded during operation.
This Inforr tion flotice is provided as an early notification of a possibly significant matter that is still under review by the NRC staff.
It is' expected that recipients will review the information for possible applicability to their facility.
flo specific action or u; nse is requested at this time.
If you have any questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
l l
Ir1 80-36 w
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October 10, 1980 RECEi!TLY ISSUED IE INFORMATION i;0TICES Information uate of
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flotice t!o.
Sub.iect Issue Issued to 80-35 Leakino and dislodged 10/10/80 All categories G and Iodine-124 inplant seeds G1 nedicai licenrees 80-34 Boron dilution of reactor 9/26/80
' All pressurized water coolant during steam reactor facilities generator decontamination holding power reactor OLs 80-33 Ceternination of teletheracy 9/15/80 All teletherapy tirer accuracy (G3) licensees 80-32 Clarification of certain 8/12/30 All NRC and agreement recuire ents for Exclu-state licensees sive-use snipments of radioactive materials 80-31 t'aloseration of Gould-3/27/80 All light water reactor Ercwn Boveri Type 480 facilities holding OLs volt type K-600S and or cps K-CnN 600S circuit breakers 80-30 Fotential for unaccept-3/19/80 All boiling water reactor able interaction between facilities holding power the control rod drive scram reactor OLs or cps.
function and non-essential control air at certain GE BUR facilities 80-29 Croken studs on Terry 8/7/80 All light water reactor turbine steam inlet facilities holding flange power reactor OLs or cps
- Supplement to notification of 7/29/30 All holders of reactor 80-06 significant events at and near-term OL operatinq power reactor applicants facilities 80-28 Prorpt reporting of 6/13/80 All applicants for and reauired infornation holders of nuclear power to MPC reactor cps l
80-27 Degradation of reactor 6/11/80 All pressurized water coolant pump studs reactor facilities holding power reactor l
OLs or cps
- Operating Licenses or Construction Permits