ML19317E847
| ML19317E847 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 02/01/1978 |
| From: | Shao L Office of Nuclear Reactor Regulation |
| To: | Eisenhut D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML19317E846 | List: |
| References | |
| NUDOCS 8001031011 | |
| Download: ML19317E847 (2) | |
Text
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. /...M ar.k' IJUCLEMI DLGULATORY COM..ilSSION.
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D. Eisenhut, Assistant Director for Operational i
MEMDPJdiD'J!4 l'OR:
Technology, DDR L. C. Shao, Chief. Engineering Branch, DDR TP.0M:
OCO' EE U!i1T 2 STEA. GENERATOR LEAK
SUBJECT:
I On October 7,1977 Oconee Unit 2 was shut down to locate a 0.
tube leak in stectr. generator B.
to locate the leak and the unit was returned to 70% power.on October.
After returning to power operation,.the leak dcveloped again nt a stable rate of 0.03 GPM until November 3,1977 when the 27, 1977.
lect rcle increased to 0.65 GP" during cn atte:r.pt to incrcase power.
The unit uts coain shut down end a second unsuccessful inspection On I ovtr.:ber 11, 1977 the unit returned to for the leLL was rce.de.
28,1977 when power nd operated it reduced ;;ower until Decer.berit un it was reported that the source of the leak was 10, 1975 On Janacry The crack was discovered to be a crack in lane tube C77-T25.
inspectcf using fiber optics imd was described by the licensee e.s The e 50 cirtur.ferentir.1 crack incr.r.ed at th? upper tube no detectable leaki.ge in the unit.
A similcr occurrence in July 1577 involved tube C77-T2 in generator.3-B.
Although this crcck had not propt-to 9:l' circumfere.titi crack.
gated fully around tr.e tube in a short tine as ucs the case in cther lane tubes it was feit tMt this was a phenomenon aff ectint; only peripher.1 tuucs where lor:er cross flow. velocities supplied less kinetic energy for crcck prop:s tion.
The recently plugg:.d tube, C77-T25;however, is not a peripheral t ut is lon.t e:' nct.r ti.e rr:ddle oi' the open tube lare in en Ho.iever, since the unit m s tub:
area 'of higher cron flow velocity.
operating et reduced power levels (less than 70'/) the flow velo and in turr, ti.e e:.9rgy tvtilLblTna efore.the'crati. s.ould tend to stabilir R
decreated.
this recent event is consistent with lie believe tht:
Further-
. power levels.
past experience for lane tubes and is not a new phenomenon.
more, close manitoring of the leakage rate in confonr.ance with the 90
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2 FEB 011973 D. Eisenhut 4
technical specifications will continue to ensure safe operation of the unit.
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A L. C. Shao, Chief
- Engineering trar!ch Division of Operating Reactors
Contact:
J. Strosnider 49-20050 cc:
V. Stello J. Guibert R. Cudlin R. V.ntisen J. Kr.ight S. Pawlici:i R. Dosnal:
B. Turovlin R. Stuart B. D. Liau l
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