ML023570266
| ML023570266 | |
| Person / Time | |
|---|---|
| Site: | Davis Besse  |
| Issue date: | 03/21/2002 |
| From: | Jocelyn Craig NRC/EDO/AO |
| To: | Beall J, Croteau R, Henderson K, Hiltz T, Mccabe B, Tschiltz M NRC/OCM |
| References | |
| Download: ML023570266 (6) | |
Text
iniernal use Only - Not For Public Disclosure UNITED STATES NUCLEAR REGULATORY COMMISSION OCM/RM
-Dennis Rathbun cc Mike Tschiltz
-Alan Levin
-Jennifer Uhle Keith McConnell
-Christiana Lui Bob McOsker Marian Zobler XKaren Henderson
-Clare Kasputys
-Barbara Gabriel Linda Herr
-Terry Agneu FROM:
SUBJECT:
cc Brad Jones Cynthia Jones Tom Hiltz Joe Olencz Kerr! Kavanagh Donna Smith Noble Green OCM/ND cc Maria Lopez-Otin
-Roger Davis X
Rick Croteau Diane Flack Vicki Boiling John W. Craig
- ons, OEDO L Assistant for Operations, OEDO cc 2.L. Jeff ry Sharkey Kathryn Winsberg James Beall Heather Astwood Scott Moore Linda Lewis Judy Ledbetter OCM/JM cc Lynne Stauss SMargie Doane X2 Brian McCabe John Thoma Lorna Kipfer Tojuana Fortune INES RATING OF DAVIS-BESSE REACTOR HEAD DEGRADATION 'EVENT" Attached please find the staff's rating of the Davis-Besse "event" in accordance with the INES user's manual. The event rating form provides the basis for a rating of "3," the most significant rating NRC has made for a reactor since full participation in the INES program began. The staff intends to inform the IAEA of this rating by March 27, 2002.
Attachment:
As stated cc: W. Travers, EDO (w/attachment)
C. Paperiello, DEDMRS (w/attachment)
W. Kane, DEDR (w/attachment)
P. Norry, DEDM (w/attachment)
J. Craig, AO (w/attachment)
S. Morris, OEDO (w/attachment)
J. Shea, OEDO (w/o attachment)
R. Wessman, IRO (w/o attachment)
SECY (w/attachment)
OGC (w/attachment)
OCA (w/attachment)
OPA (w/attachment)
OIP (w/attachment)
CIO (w/o attachment)
CFO (w/o attachment)
EDO R/F (w/attachment)
Internal Use Only - Not For Public Disclosure A -o3 OP WASHINGTON, D.C. 20555-0001
- 4"111"'*.
March 21,2002 9a NOTE TO COMMISSIONER ASSISTANTS L=,
-C-pCM/GJD OCM/EV rzDo--oot
UNITED STATES no
°NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-.0001 Mr. Dominique Delattre 00 INES Coordinator Division of Nuclear Safety International Atomic Energy Agency Wagramerstrasse 5 P.O. Box 100 A-1400 Vienna Austria
Dear Mr. Delattre:
Enclosed is a completed Event Rating Form for an event at the Davis-Besse Nuclear Power Station. The event involved the discovery of significant unexpected deterioration of reactor vessel head material in the vicinity of a penetration during an inspection conducted on March 8, 2002. This event was rated in accordance with Section IV-3.2.3 of the 2001 INES Users Manual. The event was assigned a rating of level 3.
Sincerely, Joseph J. Holonich, Deputy Director Incident Response Operations
Enclosures:
INES Rating Form Press Release
THE INTERNATIONAL NUCLEAR EVENT SCALE (INES) 11 SHORT DESCRIPTION OF THE EVENT: On 8 March 2002, with the reactor shut down for a refueling outage, the licensee discovered a significant loss of reactor vessel head base material adjacent to a penetration nozzle that was being inspected. The licensee was performing an inspection of control rod drive nozzles in the reactor vessel head as required by the regulator (US NRC). During the repair of one of the nozzles, the licensee noted some deterioration of the base material surrounding the nozzle. The reactor vessel head is composed of an approximately 6.5 inch thickness of carbon steel base material with a stainless steel weld cladding applied to the interior surface. After removal of the nozzle and cleaning of the immediate surrounding area, the licensee discovered significant wastage of the carbon steel matenal adjacent to the nozzle-boring with a total approximate size of 5 inches x 7 inches. The reactor vessel head material in this area had been reduced to a minimum thickness of less than 0.3 inches, which is the thicknes.,
of the cladding.
JUSTIFICATION OF THE RATING: This event was rated in accordance with Section IV-3.2.3 of the INES User's Manual "Potential Events (including structural defects)". The potential initiator (major LOCA) is considered to be an unlikely occurrence. According to Table I1l, this event, with safety function operability within Operating Limits and Conditions (applicable due to normally scheduled outages of safety equipment during long periods of operation of the unit) results in a base rating of 2/3.
The rating of 2/3 was confirmed to be level 3 based upon the size of the degraded structural area. In addition, the inspection revealing the condition was not part of the normal surveillance inspection process at this facility and the discovery of the degraded condition occurred only during inspections specifically required by the regulator. This condition, if not discovered, could have directly led to an accident. Thus, the rating of level 3 is appropriate.
CONTACT NAME Joseph J Holonich PERSON ADDRESS USNRC, Washington, DC 20555 FOR FURTHER PHONE (301) 415-7482 INFORMATION FAX (301) 816-5151 PLEASE ATTACH ADDITIONAL INFORMATION ON JUSTIFICATION OF THE EVENT RATING AND DIFFICULTIES ENCOUNTERED. IF NEEDED
[I EVENT RATING FORM (ERF)
TO BE SENT TO THE IAEA INES CO-ORDINATOR BY
- FAX. + 431 2060 29723 IAEA. WAGRAMERSTRASSE 5. P.O. BOX 100. A-1400 VIENNA, AUSTRIA E-MAIL DJ 43ELATE0@AA2ORG EVENT VY ECTED DETERIORATION OF REACTOR EVENT DATE TITLE HEAD MATERIAL IN VICINITY OF PENETRATION 08.03.02 RA IG RATING OUT BELOW ON SCALE SAFETY DEGRt DEFENVCE IN DATE OF SCALE ATTRIBUTE DEPTH PROVISIONAL SCALE2 1 2 3
5 6 7 ON-SITE IMPACT S5.03.0 OFF-SIEIMPACT COUNTRY USA FACILITY DAVIS-BESSE NUCLEAR POWER FACILITY PWR NAME STATION TYPE ASPECTS OF SIGNIFICANCE TO THE PUBLIC:
YES NO ACCIDENT 0 INCIDENT U DEVIATION 0 RADIOACTIVE RELEASES OFF-SITE 0
U RADIOACTIVE RELEASES ON-SITE 0
[
WORKERS INJURED BY RADIATION 0
B WORKERS INJURED PHYSICALLY 03
.0 PLANT SAFETY IS UNDER CONTROL U
E3 THE EVENT REPORTED IS A DISCOVERY OF A DEFICIENCY BY ROUTINE SURVEILLANCE 0 :
A PRESS RELEASE WAS MADE n
03 (IF YES, PLEASE ATTACH IT)
Davis-Besse Rating Flowchart:
- 1) Section IV-3.2.3 (page 37) Potential events (including structural defects)
Assume the defect leads to a failure, if it could also lead to an initiator (refer to page 86, in this case a Major LOCA (unlikely))
- 2) Go to Page 33, Table III, to determine upper bound of rating Unlikely, with safety function operability within Operating Limits and Constraints = Level 2/3 Safety Function Availability: Within OL&C due to time of existing condition (i.e., the LOCA could have occurred during a normally scheduled outage of safety equipment during an operating cycle)
- 3) Page 39 - Consideration of additional factors Level 3 (upper value) based on the size of the degraded structural area Additionally, the inspection revealing the condition was not part of the normal surviellance program, and was revealed only as a result of Bulletin inspections If not disdovered, could have led to an accident Actions:
S S
U 0
S S
S Approve INES Rating Inform Commission Inform the Licensee and NEI Inform OPA and OIP Post on IAEA Nuclear Events Web-based System (NEWS)
Post on Davis-Besse Web Page Coordinate with Jim Blaha Draft - Internal Use Only
tptREG 4"a NRC NEWS 0
U.S. NUCLEAR REGULATORY COMMISSION OFFICE OF PUBLIC AFFAIRS, REGION III 801 Warrenville Road Lisle IL 60532 Web Site: http://www.nrc.gov No. 111-02-002 March 12, 2002 CONTACT:
Jan Strasma (630) 829-9663 E-mail: opa3@nrc.gov NRC TO CONDUCT AUGMENTED INSPECTION OF DAVIS-BESSE REACTOR VESSEL DAMAGE The Nuclear Regulatory Commission has begun a Augmented Team Inspection into damage to a small area of the top of the reactor vessel, apparently caused by corrosion, at the Davis-Besse Nuclear Power Station. The plant, located at Oak Harbor, Ohio, is operated by FirstEnergy Corporation.
The plant has been shut down since February 16 for refueling and maintenance.
The cavity in the top of the reactor vessel was discovered during inspection and repair activities in the outage. It is about 4 inches by 5 inches and approximately 6 inches deep. The reactor vessel head, fabricated of carbon steel with a stainless steel liner, is about 6 1/2 inches thick.
During the outage, plant personnel inspected 69 control rod tubes which pass through the reactor vessel head. The NRC issued a bulletin last August requiring the detailed inspections at Davis Besse and other sites after cracking problems were found at several other nuclear plants.
Using ultrasonic techniques, FirstEnergy workers found cracks through the tube walls in three tubes, and lesser cracks in two additional tubes.
During repairs to one of the tubes with through-wall cracks, workers discovered the void adjacent to the tube.
The NRC's Augmented Inspection Team, comprised of metallurgical and engineering specialists, will monitor the utility's investigation and evaluation of the cavity and its determination of the conditions causing the damage. The inspection is being conducted to better understand the circumstances surrounding the corrosion and damage and to consider whether similar conditions might exist at other plants.
The preliminary cause of the damage appears to be corrosion as a result of boric acid deposits.
Boric acid is a constituent of the water in the reactor cooling system and was apparently deposited on the reactor vessel through the leaking crack in the control rod tube or some other source.
The utility is developing its plans for repair of the reactor vessel head. The NRC will review
the utility's plans.
Following completion of the inspection, the NRC will hold a meeting in the plant vicinity to discuss the inspection findings. The meeting will be open to public observation.
The inspection report, issued about four weeks after the inspection, will be available on the agency's website and through its Electronic Reading Room at http://www.nrc.gov as an Agencywide Document Access and Management System (ADAMS) document. Help in using ADAMS is available through the NRC Public Document Room at 301/415-4737 or 800/397-4209.
The NRC has issued an Information Notice to operating nuclear plants to inform them of the corrosion damage at Davis-Besse. The notice will be available online in the Electronic Reading Room with the accession number of ML020700556.