05000266/LER-1980-009-01, /01T-0:on 800728 While in Cold Shutdown & During Hydrostatic Leak Test of Steam Generators,Two Dripping Explosive Plugs & Two Wet End Plugs Noted.Cause Not Stated. Dripping Plugs Weld Repaired

/01T-0:on 800728 While in Cold Shutdown & During Hydrostatic Leak Test of Steam Generators,Two Dripping Explosive Plugs & Two Wet End Plugs Noted.Cause Not Stated. Dripping Plugs Weld Repaired

ML19344A649
Person / Time
Site:	Point Beach
Issue date:	08/11/1980
From:	Fay C WISCONSIN ELECTRIC POWER CO.
To:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION III)
Shared Package
ML19344A644	List: 05000266/LER-1980-009, Forwards LER 80-009/01T-0 05000266/LER-1980-009-01, /01T-0:on 800728 While in Cold Shutdown & During Hydrostatic Leak Test of Steam Generators,Two Dripping Explosive Plugs & Two Wet End Plugs Noted.Cause Not Stated. Dripping Plugs Weld Repaired
References
LER-80-009-01T, LER-80-9-1T, NUDOCS 8008210402
Download: ML19344A649 (8)

LER-1980-009, /01T-0:on 800728 While in Cold Shutdown & During Hydrostatic Leak Test of Steam Generators,Two Dripping Explosive Plugs & Two Wet End Plugs Noted.Cause Not Stated. Dripping Plugs Weld Repaired

Event date:
Report date:
2661980009R01 - NRC Website

text

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NRC FORM 364 U. S. NUCLEAR CECULATORY COMMIS$10N (7 77) '

5 LICENSEE EVENT REPORT

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60 68 OOCK ET NUMSER 68 69 EVENT DATE 74 75 REPORT O ATE 80 EVENT OESCRIPTION ANO PROSABLE CONSEQUENCES h 10121 l With the unit in cold shutdown for a required 90 effective full power i

t g l day steam generator testing program, an 800 psi secondary-to-primary l

[T'IT1 l hydrostatic leak test of the steam gen.trators was performed on 7-28-80. l ITTs 1 1 In the "A" SG two dripping explosive plugs (R31C44 and R29C54) and two 1 0 s l Wet end plugs (R24C37 and R21C49) were noted.

In the "B" SG one l

lTTTlI dripping tube (R21C48) and one wet end plug (R2 3C5 3) were noted.

This l i O is i I event is reportable per T.S. 15.6.9.2.A.3 and similar to others.

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CAUSE OESCRIPTION AND CORRECTIVE ACTIONS h -

m l A previous 1v scheduled eddy current inspection program was performed, l

E I28 tubes with indications in the "A"

SG and 22 includina the leaker in l

, 2 I the "B"

SG were plugged.

In addition, 3 tubes were mistakenly cluqued I g l in the " A" SG.

The two dripoing clugs in the "A"

SG were weld repaired,l l and an 800 psi secondary-to-primary hydrostatie test of both SG's was l

i 4 8, y formed after repair.

. DISCOVERY DISCOVFRY DESCRIPTION 7

80 STATUS 4 POWER OTHER STATUS LGJ@ I o I o I o l@l N/A l

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ATTACHMENT TO LICENSEE EVENT REiORT NO. 80-009/OlT-0 Wisconsin. Electric Power Company Point Beach Nuclear Plant Unit 1 Docket No. 50-266 In accordance with the Nuclear Regulatory Commission's modification of the' November 30, 1979 Order dated April 4,

1980, Point Beach Nuclear Plant Unit 1 was taken out-of-service on' July 25, 1980'for hydrostatic tests and eddy current examinations of the steam generator tubes.

An 800 psig secondary-to-primary leak check of both

. steam generators was performed on July 28.

In the "A"

steam

- generator, two dripping explosive plugs and two wet end plugs were identified in the hot leg with no leaks detected in the cold leg.

In the "B" steam generatoc, one wet end explosive plug and one-dripping tube were identified in the hot leg with no leaks detected in the cold leg.

Pertinent information on the identified leaks is as follows:

'A" Steam Generator R31C44 - 84% defect, explosively plugged 3/75, one drop every 20 seconds.

R29C54 - 75% defect, explosively plugred 4/74, one drop every 90 seconds.

R24C37 - 90% defect, explosively plugged 10/72, less than one drop every five minutes.

R21C49 - 45% defect, explosively plugged 10/72, wet end plug.

"B" Steam Generator R23C53 - 68% defect, explosively plugged 11/75, wet end plug.

R21C48 - Leaking tube, slow drip about one drop every two minutes.

The eddy current inspection program consisted of an examination of 100% of the tubes to the first support plate on the hot leg side and 3% of the tube s inspected over their entire length.

A listing.of all hot leg eddy current indications found during this inspection and a ecmparison to previous-inspections for both the " A" and "B" steam generators are provided in Attachment 1 to this submittal.. A listing of tubes plugged during this inspection 11s provided in Attachment 2.

In the "A" steam generator hot leg, 30 tubes wera identified with eddy current indications.

T'enty-eight '28)

. indications were in the tubesheet crevice region and two tubes, 1

s.

+

K s.

., R10C54 and R33C54, had 34% small volume indications at the top of the tubesheet-and one-half inch above the tubesheet, respectively.

All'28 tubes wifh' indications'in the tubesheet crevice region have been mechanically plugged.. Three additional tubes, R07C58, R07C59, and R07C51, were plugged inadvertently.

The two dripping plugs in the "A" steam generator have been weld repaired and the steam generator was successfully hydrostatically leak checked on August 3, 1980.

- The two tubes with indications at the tubesheet and one-half inch above the tubesheet have been left unplugged since these indications do not exceed the Technical Specification plugging criterion.

Further, review of old tapes revealed a stable condition of these tubes.

These tubes will be re-examined during the next eddy current inspection.

In the "B" steam generator hot leg, 22 tubes were identified with tubesheet crevice indications.

As discussed previously, tube R21C48 had been observed to be dripping during the hydrostatic leak check; however, no through-wall eddy current indication was observable during the inspection.

All 22 tubes identified with tubesheet crevice indications have been mechanically plugged.

A satisfactory hydrostatic leak check of the "B"

steam generator was performed on August 5, 1980.

A review of all the available eddy current tapes from October and December 1979 and March 1980 for each of the tubes with eddy current indicaticus was performed.

A summary of this review is provided in Attachment 1.

For some tubes, we have determined that small volume indications were probably present during one or more previous inspections by reviewing the previous tapes in close detail over the specific region of interest.

Because of the small volume of the defects, the signal-to-noise ratio in previous inspections was so small that the evaluators were unable to identify the indications during their reviews. provides a listing of all cold leg eddy current indications found during the inspection of 3% of the tubes over their entire length.

These results indicate that tube degradation on the cold leg side remains insignificant.

No eddy current indications were found in the tubesheet crevice region, confirming previous experience.

The unit was returned to operation on August 9, 1980 in accordance with NRC authorization dated August 8, 1980.

This event is reportable in accordance with Technical Specification 15.6.9.2.A.3.

ATTACHMENT 1 EDDY CURRENT EXAMINATION RESULTS "A" STEAM GENERA 10R (INLET)

Tube Indication Location March, 1980 De c., 1979 Octobe r, 1979 R22C18 73 6" above ttbe end NT NT NDD R28C26 23 5" above tube end Same

<20 at Detect.

NDD Limit'

<20 20" above tube end Same Same Same

.R07C36 53 3" above tube end NDD NDD NDD R33C37 82 8" above tube end NT NT NDD R30C42 31 15-17" above tube end NT NT NDD' R24C46 79 20" above tube end Same Same NDD 400 and mix; same absolute R08C50

<20 8" above tube end Same NDD NDD R09C50 85 20" above tube end NDD NDD NDD R12C50

<20 7" above tube end Same Same NDD R26C53 83 21" above-tube Same' Same Small change R33C54 34 above~ tubesheet NT NT Same; better S/N ratio in 7-80

'R10C54 34 Top of tubesheet Same 400 KilZ Same 400 KilZ Same 400 KilZ Dif ferent Mix Different Mix Dif ferent Mix R22C55 81 7-15" above tube end NDD NDD NDD R24C55 88 18-21" above tube end Same Same NDD R12C56

<20 11" above tube end NDD NDD NDD R08C58 54 15" above tube end Same NDD NDD R17C58 42 20" above tube end

<20 NDD NDD R27C59 69 8" above tube end NT NT NDD

1 e~

- Attrchment 1 Pcge 2 Tube Indication

. Location March, 1980 D$c., 1979 Oc tobe r, ' 19 79 R05C61 -

92 10" above tube end NT NT Same R23C61 80

.10" above tube end Same NDD R18C62 59 10-15" above tube end PEP NT NDD R27C62 84 15-20" above-tt6e end NT NT Same k smaller amplitude R15C64 36

.13" 'above tube end 33%

35%

NDD R27C64 51 3" above tube end NT NT

NDD, R08C66 78 2 -6" above tube end NT NT 66%

R10C6 8 47 10-20" above tube end NT NT Same R08C70 50 20" above tube end NT NT NDD R09C72 76 20" above tube end NT NT NDD R08C75 89 20" above tube end NT NT NDD R08C76 Unde finable 15-20" above tube end NT NT Same De fect "B" STEAM GENERATOR (INLET)

R09C20 65 21" above tube end NT NT NDD R10C25 57 19" above tube end Same NDD NDD R14C27 42 20" above tube end Same Sane Same R08C31 64 10" above tube end NDD NDD NDD R12C31 79 12-17" above tube end Same Same NDD R25C37 54 15-20" above tube end Same NDD NDD R27C38 48 20" above tube end Same NDD NDD

- R26C43 56 21" above tube end Same Same Same i

L

Pr.ge 3

- Tube Indication:

Location March, 1980 Dec., 1979 Octobe r, 19 79 -

R21C48 4i6 3" above tube end Same Same 24%

.R24C49 85-2 -5" above tube end

.NDD NDD NDD

'R20C50 67 17" above tube end NDD NDD NDD R28C51 82 2 -7" above tube end Same NDD NDD R27C53 75 5" above. tube end NDD NDD NDD

.R24C54 80-11" above tube end NDD NDD NDD

.R29C62 75 2 -11" above tube end NT NT NDD R13C69 49 21" above tube end NT NT Same R13C71 83 20" above tube end NT NT NDD R02C74 90 2 -10" above tube end NT NT NDD R10C76 59 14-17" above tube end NT NT NDD R10C78 76 5" above tube end NT NT NDD 70 8" above tube end R02C80 82 5" above tube end NT NT NDD R04C46 61 10-17" above tube end NT NT NDD NT = Not Tested NDD = No Detectable Defect

o.

ATTACHMENT 2 SUMMARY OF TUBES PLUGGED JULY-AUGUST, 1980-

"A" STEAM GENERATOR R22C18 R05C61 R28C26 R23C61 R07C36 R18C62 R33C37 R27C62 R30C42 R15C64 R24C46 R27C64 R08C50 R08C66 R09C50 R10C68 R12C50 R08C70

.R26C53 R09C72 R22C55 R08C75 R24C55 R08C76 R12C56

- R07C58 Plugged by Mistake R08C58 R07C59 Plugged by Mistake R17C58 R07C51_ Plugged by Mistake Inlet Side Only R27C59 Total Tubes Plugged this Outage:

31 Total Tubes Plugged to Date:

404 "B"

STEAM GENERATOR R09C20 R28C51 R10C25 R27C53 R14C27 R24C54 R08C31 R29C62 R12C31 R13C69 R25C37 R13C71 R27C38 R02C74 R26C43 R10C76 R21C48 R10C78 R24C49 R02C80 R20C50 R04C46 Total Tubes Plugged this Outage:

22 Total Tubes Plugged to.Date:

39 2 l

l l

(

'4 ATTACHMENT 3 EDDT dUlkRENT EXAMINATION RESULTS

" A" STEAM GENERATOR (OUTLET) e Tube Indication Location R28C48 29

" above tubesheet R24C52

<20 1" above tubesheet R20C56

<20 1" above tubesheet R24C56

<20 2" ~above tubesheet R20C60 21 2" above tubesheet

.R20C24

<20 2" above tubesheet B" STEAM GENERATOR (OUTLET)

No eddy current indications observed.

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