ML19338G295
| ML19338G295 | |
| Person / Time | |
|---|---|
| Site: | Clinton  |
| Issue date: | 10/10/1980 |
| From: | James Keppler NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Gerstner W ILLINOIS POWER CO. |
| References | |
| NUDOCS 8010290026 | |
| Download: ML19338G295 (1) | |
Text
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GLEN ELLYN, ILLINolS 60137
. OCT 101980 Docket No. 50-461 Docket No. 50-462 Illinois Power Coepany ATIN:
Mr. W. C. Gerstner Executive Vice President 500 South 27th Street Decatur, IL 62525 Gentlemen:
This IE Information Notice No. 80-36 is provided as an early notification of a possibly significant matter.
It is expected that recipients will review the information for possible applicability to their facilities.
No specific action or response is requested at this time.
If further h3C evaluations so indicate, an IE Circular or Bulletin will be issued to recommend or request specific licensee actions.
please contact this office. If you have questions regarding this matter, Sincerely,
{
James / WYh G. Keppler Director
Enclosure:
IE Information Notice No. 80-36 j
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Central Files i
Director, NRR/DPM i
Director, NRR/ DOR
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Local PDR NSIC TIC Mr. Dean Hansell, Office of Assistant Attorney General Mr. Gary N. Wright, Chief Division of Nuclear Safety 4
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SSINS No.:
6835 Accession No..
8006190085 IN 80-36 UNITED STATES NUCLEAR REGULATORY COMMISSIOM OFFICE OF INSPECTION AND ENFORCIMENT WASHINGTON, D.C.
20555 October 10, 1980 IE Information Notice No. 80-36:
FAILURE OF STEAM O2NERATOR SUPPORT BOLTING Description of Circumstances:
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 bottom of the steam generators on Prairie Island Unit 1 had occurred.
The licensee initially discovered the bolting problem when two bolts failed during detensioning.
The licensee was attempting 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).
Ultrasonic examination of the support bolting revealed cracks or breaks in 47 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 successfully removed while the third failed during removel Two bolts that were judged as defect free by the ultrasonic examination were also removed. Magnetic particle examinations confirmed the results of the 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 previously.
In the case of Unit 1 a significant number of the bolts were examined at the last refueling outage 14 months ago.
No 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 utilizet maraging steels for reactor coolant pump and steam generator support bolting.
Further the NUREG recommends augmented inspections for the facilities included in Group I.
Licensees are encouraged 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 Information Notice a 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.
No specific action or response is requested at this time.
If you have any questions regarding this matter, please contact the Director of the appropriate NRC Regional Office.
i IN 80-36 October 10, 1980 i
RECENTLY ISSUED j
IE INFORMATION NOTICES i
Information Date of Notice No.
Subject Issue Issued to 80-35 Leaking and dislodged 10/10/80 All categories G and Iodine-124 impiant seeds G1 medical licensees 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 Determination of teletherapy 9/15/80 All teletherapy timer accuracy (G3) licensees 80-32 Clarification of certain 8/12/80 All NRC and agreement requirements for Exclu-state licensees sive-use shipments of radioactive materials 80-31 Maloperation of Gould-8/27/80 All light water reactor Brown Boveri Type 480 facilities holding OLs volt type K-6005 and or cps K-DON 6005 circuit breakers 80-30 Potential for unaccept-8/19/80 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 BWR facilities 80-29 Broken 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 7/29/80 All holders of reactor 80-06 significant events at and near-term OL operating power reactor applicants facilities 80-28 Prompt reporting of 6/13/80 All applicants for and required information holders of nuclear power to NRC reactor cps 80-27 Degradation of reactor 6/11/80 All pressurized water coolant pump studs reactor facilities holding power reactor OLs or cps
- Operating Licenses or Construction Permits