05000302/LER-1983-018, Updated LER 83-018/01T-1:on 830413,preliminary Repts Received from B&W Indicated 51 of 120 Upper Core Barrel Bolts W/Ultrasonic Flaw Indications.Caused by Intergranular Stress Corrosion Cracking.Bolts Replaced

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Updated LER 83-018/01T-1:on 830413,preliminary Repts Received from B&W Indicated 51 of 120 Upper Core Barrel Bolts W/Ultrasonic Flaw Indications.Caused by Intergranular Stress Corrosion Cracking.Bolts Replaced
ML20077A253
Person / Time
Site: Crystal River Duke Energy icon.png
Issue date: 07/12/1983
From: Bufe J, Thompson R, Westafer G
FLORIDA POWER CORP.
To: James O'Reilly
NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION II)
References
3F-0783-09, 3F-783-9, LER-83-018-01T, LER-83-18-1T, TAC-51556, NUDOCS 8307220254
Download: ML20077A253 (5)


LER-2083-018, Updated LER 83-018/01T-1:on 830413,preliminary Repts Received from B&W Indicated 51 of 120 Upper Core Barrel Bolts W/Ultrasonic Flaw Indications.Caused by Intergranular Stress Corrosion Cracking.Bolts Replaced
Event date:
Report date:
3022083018R00 - NRC Website

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. , UPDATE REPORT - LAST REPORT DATED 0h/27/83 NRC FORM 3s4 U.S. NUCLE AR REGULATORY COMMISSION LICENSEE EVENT REPORT EXHIBIT A CONTROL . SLOCK: l l l l l .l lh IPLE ASE PRINT OR TYPE ALL REQUIRED INFORMATION) lF l LlC l R lP l 3 l@ul0 l 0l- l uca=sa uca=ses coot is 0 l 0lnuM.ea 0 l 0l 0l -l0 l 2$0 lg[ a h uca~sa l 1l 1]Tves 1lao1lg u A e.g CON'T E M.Ol 0 l 5l0 l -l0 l 3 l0 l 2 lgl 0 i hl1 6 occKEY hum.ER 13l8 l 3 l@l0 l 7l1 l 2l 8l 3.0 lg EVENT .A TE 34 75 RE POR T . AT E EVENT DESCRIPTION AND PROSASLE CONSEQUENCES o lSince April 13, 1983, FPC rece ved preliminary reports from B&W indicatinq

, , , , ,that 51 of 120 upper core barrel bolts showed ultrasonic flaw indications.

o . lFPC embarked on a testing program for those reactor vessel bolts listed ing

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fi SUPPI'L INTARY INFORMATION REPORT NO.: - 50-302/83-t48/0lT-1 FACILITY: Crystal R'.ver Unit 3 REPORT DATE: July li,1983

' OCCURRENCE DATE: . April 13,1983 IDENTIFICATION OF OCCURRENCE:

Florida Power Corporation has received a preliminary report from Babcock & Wilcox (B&W) indicating that numerous. reactor vessel internal bolts may be defective. The possible failure of these bolts is being reported as required by Technical Specification 6.9.1.8.1.

CONDITIONS PRIOR TO OCCURRENCE:

Mode 6 (Refueling)

DESCRIPTION OF OCCURRENCE:

On April 13, 1983, Florida Power Corporation received a preliminary report from Babcock &

Wilcox Indicating 25 of 61 upper core barrel bolts ultrasonically tested may be defective. Since April 13, as a result of extensive ultrasonic testing, Florida Power Corporation has found

. additional defect indications on reactor vessel internal bolts. The results of the tests are described on the attachment.

DESIGNATION OF APPARENT CAUSE:

A preliminary study by B&W has indicated tha't defects in the upper core barrel (UCB) bolts were caused by intergranular stress corrosion.

ANALYSIS OF OCCURRENCE:

The integrity of the core -was maintained because the number of UCB- bolts which passed ultrasonic (UT) inspection was much higher than the number of bolts needed to hold the core barrel (with the' core) in place. There was no effect upon the health or safety of the general public. -

CORRECTIVE ACTION:

The following corrective action was taken:

1.. All 120 UCB bolts were replaced with bolts which:

A. Were machined out of a single piece of A-286 material.

B. Had a redesigned transition region between the head and shank to minimize local

' stress.

C. Were peened in advance to reduce surface stress in use. .

D. Were installed with . torque values and pre-stress methods that resulted in a pea!:

stress of 78,000 psi which is well below the measured yield stress of 100,000-134,000 psi for the A-286 material.

2. All 96 lower thermal shield bolts were replaced with . stud / nut fasteners made of Inconel X750.

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. 3. Surveillance specimen holder tube (SSHT) bolts which showed UT flaw indications were replaced with stud / nut fasteners made of Inconel X750 such that were at least three (3) good (no UT flaw indications) fasteners per upper and lower bracket.

4. None of lower core barrel bolts, flow distributer bolts, guide block bolts, and upper thermai shield bolts were replaced. At Refuel V the lower core barrel bolts will be reinspected and their status reevaluated.

FAILURE DATA:

This is the 18th event reported under Technical Specification 6.9.1.8 i.

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REACTOR VESSEL INTERNAL BOLTS RESULTS OF ULTRASONIC TESTS 1

BOLT LOCATION TOTAL NO. OF BOLTS 'NO. OF BOLTS TESTED NO. OF INDICATIONS NO. OF BOLTS REPLACED i

Upper Core Barrel 120 120 51 120

Lower Core Barrel 120 108 4 0 Flow Distributor to Lower Grid 120 114- 0 0 Upper Thermal Shield (Upper Restraint Block) 60 60 0 0

, Lower Thermal Shield 96 96 74 96 i

Surveillance Holder Tube '72 72 20 17 Guide Block Bolts 24 24 0 0 1

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M Power C O n P o n a t e n eu July 12,1983 3F-0783-09 Mr. James P. O'Reilly Regional Administrator, Region II Office of Inspection & Enforcement U.S. Nuclear Regulatory Commission 101 Marietta Street N.W., Suite 2900 Atlanta, GA 30303

Subject:

Crystal River Unit 3 Docket No. 50-302 Operating License No. DPR-72 Licensee Event Report No. 83-018/0lT-1

Dear Mr. O'Reilly:

Enclosed is Licensee Event Report No. 83-018/-01T-1 and the attached supplementary information sheet, which are submitted in accordance with Technical Specification 6.9.1.8.i. This report supplies suppleinentary information to our initial report dated April 27, 1983.

Should there be any questions, please contact this office.

Sincerely, o

G. R. Westafer Manager Nuclear Licensing and Fuel Management RTimm Enclosure cc: Document Contrcl Desk U. S. Nuclear Regulatory Commission Washington, D.C. 2055

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