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 A -o3OP WASHINGTON, D.C. 20555-0001 *4"111"'* . "
March 21,2002 9a NOTE TO COMMISSIONER ASSISTANTS L=,
OCM/RM pCM/GJD OCM/EV -C- -- - -
-Dennis Rathbun cc Brad Jones cc Mike Tschiltz cc Jeff ry Sharkey Cynthia Jones 2.L. Kathryn Winsberg
-Alan Levin Tom Hiltz James Beall
-Jennifer Uhle Joe Olencz Heather Astwood
- Keith McConnell Kerr! Kavanagh Scott Moore
-Christiana Lui Donna Smith Linda Lewis Bob McOsker Noble Green Judy Ledbetter Marian Zobler XKaren Henderson OCM/ND OCM/JM
-Clare Kasputys
-Barbara Gabriel cc Maria Lopez-Otin cc Lynne Stauss Linda Herr Davis Agneu
-Roger SMargie Doane
-Terry X Rick Croteau X2 Brian McCabe Diane Flack John Thoma Vicki Boiling Lorna Kipfer Tojuana Fortune FROM: John W. Craig ons, OEDO L Assistant for Operations, OEDO
SUBJECT:
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) SECY (w/attachment)
C. Paperiello, DEDMRS (w/attachment) OGC (w/attachment)
W. Kane, DEDR (w/attachment) OCA (w/attachment)
P. Norry, DEDM (w/attachment) OPA (w/attachment)
J. Craig, AO (w/attachment) OIP (w/attachment)
S. Morris, OEDO (w/attachment) CIO (w/o attachment)
J. Shea, OEDO (w/o attachment) CFO (w/o attachment)
R. Wessman, IRO (w/o attachment) EDO R/F (w/attachment) rzDo--oot Internal Use Only - Not For Public Disclosure
°NUCLEAR no UNITED STATES 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
[I THE INTERNATIONAL NUCLEAR EVENT SCALE (INES)
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 DJ43ELATE0@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 (IF YES, PLEASE ATTACH IT) n 03 SHORT outage, the DESCRIPTION OF THE EVENT: On 8 March 2002, with the reactor shut down for a refueling 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 nozzles, the licensee noted some deterioration of the base material NRC). During the repair of one of the surrounding vessel head is composed of an approximately 6.5 inch thickness of carbon steel the nozzle. The reactor stainless steel weld cladding applied to the interior surface. After removal of the nozzle base material with a immediate surrounding area, the licensee discovered significant wastage of the carbon and cleaning of the adjacent to the nozzle-boring with a total approximate size of 5 inches x 7 inches. steel matenal material in this area had been reduced to a minimum thickness of less than 0.3 inches, The reactor vessel head 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 LOCA) is considered to be an unlikely occurrence. According initiator (major operability within Operating Limits and Conditions (applicable to Table I1l, this event, with safety function 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 process at this facility and the discovery of the degraded condition occurred only duringinspection specifically required by the regulator. This condition, if not discovered, could have inspections 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 11 PLEASE ATTACH ADDITIONAL INFORMATION ON JUSTIFICATION OF THE EVENT RATING AND DIFFICULTIES ENCOUNTERED. IF NEEDED
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 Approve INES Rating S Inform Commission U Inform the Licensee and NEI 0 Inform OPA and OIP S Post on IAEA Nuclear Events Web-based System (NEWS)
S Post on Davis-Besse Web Page S Coordinate with Jim Blaha Draft - Internal Use Only
tptREG "0
4"a NRC NEWS 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 reactor vessel head. The NRC issued a bulletin last rod tubes which pass through the 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 specialists, will monitor the utility's investigation and of metallurgical and engineering 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 Boric acid is a constituent of the water in the reactor as a result of boric acid deposits.
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 discuss the inspection findings. The meeting to will be open to public observation.
The inspection report, issued about four weeks agency's website and through its Electronic after the inspection, will be available on the Reading Room at http://www.nrc.gov as an Document Access and Management System Agencywide (ADAMS) document. Help in using ADAMS through the NRC Public Document Room is available at 301/415-4737 or 800/397-4209.
The NRC has issued an Information Notice corrosion damage at Davis-Besse. The notice to operating nuclear plants to inform them of will be available online in the Electronic Reading the with the accession number of ML020700556. Room