ML19338D600
| ML19338D600 | |
| Person / Time | |
|---|---|
| Issue date: | 09/02/1980 |
| From: | Pappas H NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III) |
| To: | Wright G ILLINOIS, STATE OF |
| References | |
| NUDOCS 8009230537 | |
| Download: ML19338D600 (1) | |
Text
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UNITED STATES 8 \\*
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NUCLEAR REGULATORY COMMISSION
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GLEN ELLYN, ILLINOIS 60137 State of Illinois Department of Public Health ATTN:
Mr. Gary N. Wright, Chief Division of Nuclear Safety 535 West Jefferson Street Springfield, IL 62761 Gentlemen:
The enclosed IE Bulletin No. 79-26, Revision 1 titled " Boron Loss From BWR Control Blades" was sent to the licensees listed below for action on August 29, 1980:
Commonwealth Edison Company Dresden 1, 2, 3 (50-10, 50-237, 50-249)
Quad-Cities 1, 2 (50-254, 50-265)
Consumers Power Company Big Rock Point (50-155)
Dairyland Power Cooperative LACBWR (50-409)
Iowa Electric Light & Power Company Duane Arnold (50-331)
Northern States Power Company Monticello (50-263)
Sincerely, A
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O elen Papp s, Chief Administrative Branch
Enclosure:
IE Bulletin No. 79-26, Revision I cc w/ encl:
Mr. D. W. Kane, Sargent & Lundy Central Files Reproduction Unit NRC 20b AE0D Resident Inspectors, RIII Local PDR NSIC TIC 8.000230 6 3 7
SSINS No.: 6820 Accession No.:
UNITED STATES 8006190042 NUCLEAR REGULATORY COMMISSION OFFICE OF INSPECTION AND ENFORCEMENT WASHINGTON, D.C.
20555 August 29, 1980 IE Bulletin No. 79-26 Rev. 1 BORON LOSS FROM BWR CONTROL BLADES l
Description of Circumstances:
The General Electric Company (GE) has informed us of a failure mode for control blades which can cause a loss of boron poison material.
Hot cell examinations of both foreign and domestic blades have revealed cracks near the upper end of stainless steel tubing and loss of boron from the tubes.
The cracks and boron loss have so far been confined to locations in the poison tubes with more than 50 percent Boron-10 (B10) local depletion.
Observed crack sizes range from a quarter to a half inch in length and from one to two mils in width.
GE has postulated that the cracking is due to stress corrosion induced by solidification of boron carbide (B C) particles and swelling of the compacted 4
B C as helium and lithium concentrations grow.
Once primary coolant penetrates 4
the cladding (i.e., the cracking has progressed through the cladding wall and the helium-lithium pressures are sufficient to open the crack), boron is 10 leached out of the tube at locations with more than 50 percent B local depletion (local depletion is considered to be twice the average depletion).
It was further found with similar cracking but with less than 50 percent local 10 depletion of B
, that leaching did not occur even though primary coolant hcd penetrated the cladding.
The cracking and baron loss shorten the design life of the control blade.
According to the GE criteria the end of design life is reached when the reactivity worth of the blade is reduced by 10 percent, which corresoonds to op quarter of the control blade.
10 DUPLICATE DOCUMENT duced the allowance for B deple-nti-ol blade from the 42 percent Entire document previously entered into system under:
ANO b[. hh.__
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