05000295/LER-1978-078-01, /01L-0:on 780818:possible Use of Atypical Weld Metal Discovered in Loop 4 of Reactor Pressure Vessel. Interim Heatup & Cooldown Curves Calculated & Used to Provide Adequate Conservatisms Until Issue Resolved

/01L-0:on 780818:possible Use of Atypical Weld Metal Discovered in Loop 4 of Reactor Pressure Vessel. Interim Heatup & Cooldown Curves Calculated & Used to Provide Adequate Conservatisms Until Issue Resolved

ML20147E607
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Site:	Zion File:ZionSolutions icon.png
Issue date:	09/15/1978
From:	Shannon R COMMONWEALTH EDISON CO.
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ML20147E594	List: 05000295/LER-1978-078, Forwards LER 78-078/01L-0 05000295/LER-1978-078-01, /01L-0:on 780818:possible Use of Atypical Weld Metal Discovered in Loop 4 of Reactor Pressure Vessel. Interim Heatup & Cooldown Curves Calculated & Used to Provide Adequate Conservatisms Until Issue Resolved
References
LER-78-078-01L, LER-78-78-1L, NUDOCS 7810170189
Download: ML20147E607 (3)

LER-1978-078, /01L-0:on 780818:possible Use of Atypical Weld Metal Discovered in Loop 4 of Reactor Pressure Vessel. Interim Heatup & Cooldown Curves Calculated & Used to Provide Adequate Conservatisms Until Issue Resolved

Event date:
Report date:
2951978078R01 - NRC Website

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60 LVkNT OATE 14 lb HLPOHT 0A1E NO EVENT DESCRIPTION AND PROUAOLE CONSEQUENCES h 1 O I 21 l On Aug. 24, 1978, the station was advised of the possible use of I O Ia I ; atypical weld metal in the manuf acture of Unit 1 and 2 reactor vessels.

io i4i l This would result in the change of the initial RT(NDT) from 27F to

_ l O I 51 l 125F and NDTT from 15F to 70F in Table 3.3. 2-1 of the Tech Specs.

The i o,g i ; pressure and temperature limits of Tcch Spec.

3. 3.2 may therefore have i o,,; ; been non-conservatively calculated.

Observation and evaluation show

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40 di 42 43 44 47 CAUSE DESCRIPTION AND CORRECTIVE ACTIONS h Ii10i l The possible use of atypical weld wire in 4-loop PWR Reactor Vessels, l

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Board Nos. N-184 and N-185 as part of West.

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ATTAC3 MENT TO LER NO. 78-078/01 L - 0 COMMONWEALTH EDISON CO.

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Description of Event

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On August 14,J1978, Conunonwealth Edison was advised by the NRC that j

Babcock and Wilcox hadL determined from chemical analysis of archive reactor vessel weldment.. that the nickel and silicon-content of the weld material was outside the specified range.

It has been determined that the weld filler wiro used for that particular we?.d was atypical.. As of -this date it is not known whether or not this atypical weld wire was' used in the manufacture of Zion ' reactor vessels.

It is possible that this atypical weld metal may have been used in the circumferential girth weld of the Zion Unit i vessel and the lower shell longitudinal' weld of the Zion Unit 2 vessel.

Review of the records avallable to date has not enabled the station to discount the possibility that these vessels contain weld metal having an 0

initial RT of 1250F and an initial T of 70 F.

This compares withaninfNal'RT of270FandaninYNa1T 0

of 15 F-as found in Table 3.3.2-1.ogDIhe Technical SpecificatioE The-pressure and temperature limitations' described in Technical Specification 3.3.2 may therefore have been non-conservatively calculated.. No affect to the integrity of the reactor coolant pressure boundary has been observed in-relation ~ to Unit 1 and 2 having operated 2.8 and 2.4 Effective Full Power Years respectively, based on the less conservative limitations.

l Consequences of Occurrence 1

No~ effect to the integrity of the reactor coolant systems has. been

- observed.

In addition,. evaluations conducted.by Westinghouse Electric,. based oni ASME Section III, Appendix III, has shown that no adverse effects on the integrity or safety of the plant has occurred due to operation using the possibly less conservative limitations.

Additionally, ultrasonic inspections following the Minitial hydrostatic test = indicated the absence of any flaws.

The.

health and safetyf of the : plant and public was unaf fected by this occurrence.

Cause of Occurrence.

The cause of the occurrence is the possible use of atypical weld i

filler. wire in' the, manufacture 'of. Zion Unit 1 and 2 4-loop PWR

Reactor Vesseis National Board Numbers N-184 and N-185, designed by.

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l-e Westinghouse Electric Co. and manufactured by Babcock and Wilcox.

It is unknown at this time how the atypical weld metal could have been introduced. or if it was, in fact, used in these vessels.

Corrective Action

The Unit' l and 2 reactor vessel pressure and temperature limitations have been re-evaluated assuming the atypical metal was included during fabrication.

These limitations were calculated in.accordance with 10 CFR 50, Appendix G and are valid for heatup and cooldown during the first eight Effective Full Power Years of operation.

Interim operating curves representative of-these limitations were implemented as.of August 18, 1978, and will remain in use.until this issue is resolved.

.Use of these curves will ensure continued vessel integrity in the event the atypical weld wire' was used.

If future investigations demonstrate the absence of the atypical weld metal, then the interim curves will have provided excess cons erva tism.

If the metal is in fact present, then the interim curves will continue in use and be periodically updated as necessary to provide adequate conservatism.

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