ML20116F624

Intervenor Exhibit I-171,consisting of 840719 Summary of Util 840620 Meeting W/Nrc & BNL Re Review of Potential welding-induced Sensitization

ML20116F624
Person / Time
Site:	Catawba
Issue date:	10/11/1984
From:	Ferdon S DUKE POWER CO.
To:	DUKE POWER CO.
References
OL-I-171, NUDOCS 8505010154
Download: ML20116F624 (5)

Text

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Minutes of 6/20/84 Meeting CFpg7 Re ,

Review of Potential Welding Induced Sensitization 3R dt h'V/ct."

File No.: 1206.00-02 Meeting Attendees: C.'J. Czajkovski - 3rookhaven Labs, NRC N. Economos - NRC S. E. Perdon - Duke, Design Engineering A. R. Rollins - Duke, Design Engineering B. J. Kruse - Duke, Construction D. R. Llevullyn - Duke, Construction

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Backaround:

This meeting was part of the investigation into the allegation that the inter-pass temperature requirement for welding type 304 stainless steel was violated on several 2" and less socket welds. The implication of the allesation is that the welds may be susceptable to intergranular stress corrosion cracking (IGSCC) due to sensitization.

The allegation was brought forward by ' Wider B",-cna claimed that production pressure by "Forman X" did not allow the subject velas t.o adequately cool between each pass.

The purpo'se of the meeting was on NRC review of the non-destructive technique, developed by Duke's metallurgists, to detezuine if an un-acceptable degree of sensitisation eisted in the subject welds. Also discussed was work done on

aoek-up welds to evaluate sensitisation caused by a worst c,ase violation of interpass temparature requirements.

l I. Introductory Meeting - Review of Work-to-Data and Establishment of Critical Welds.

- After the attendees were introduced, 3. J. Kruse and D. B. Llewellyn *

. presented the work done on acck-up welds. This. work involved l

- comparing the degree of sensitization in 1" & 2", Sch. 40 & Sch 160 socket welds, which were welded using correct interpass temperature and no inta gass temp. control. The comparisons were made using the ASTM A-262 practice A technique and the EPRI EPR technique. (Samples from the cock-up welds had been sent to Mr.' Csajkowski for his indepen-dont evaluation.)

. It was egreed by the NRC representatives that even the worst case mock-up weld with intentional interpass temperaturetviolations was acceptable Per ASTM A-262 practice A evaluation.

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Memo to Fil3: 1206.00-02 July 19,1984 Page '

. EPRI EPR results on the mock up welds were also shared with the NRC representatives. Basically these results agreed with the A262-A evaluations, they indicatad ehnt there was some degree of sensitization but it wasn't d h c M orrelatable to an unaccep- T table structure for a PWR environment. , ,

. The NRC representatives raised questions regarding the carbon content of the materials used for the acek up welds. The direct relationship l between carbon content and sensitization was discussed. J

- The results of Duke's literature search regarding stress corrosion cracking problems in the PWR industry wais' reviewed. V * ~

. Based on reviews of INPO, NUREG & EPRI reports, no evidence of a generic stress corrosion cracking problem similar to the BWR Intergranular stress corrosion cracking problem was found. Nearly

. every case of stress corrosion. cracking in PWR's involved the intrusion of a contaminspef

. The NRC representatives pointed out two incidents, one at THI-l and one at Surrey where .Intergranular stress corrosion cracking (IGSCC) occurred, with no obvious evidence of contamination beyond normal design parameters.

. The TMI-l case was in the fuel pool recirculation lines and the Surry case involved stag f Boric Acid lines.

- Duke's experience with stress corrosion cracking at Oconee was also discussed. The experience was presented as further evidence that the designed ==4 - =ent in PWR type reactors is not aggressive _enough to '

cause generic ICSCC.

. Threg casas of stress corrosion cracking have occurred at Oconee in' 30 net years of operation.for the 3 units. m (1) One was externally initiated and involved conventional insulation and a high chloride containing contaminate.

(2) Another, involved solybdenum-di-sulfate (Holykotel on .

sanway studs (not 304 sal -

(3) The third case involved cracking of core support bolts due to y stressing. w (Not 304 ss)

- The second phase of the Duke investigation, evaluating. welds in the field for sensitization, required identifying'dritical welds." The f

procedure for identifying these welds was presented to the NRC repre-sentatives.

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Memo to File: 1206.00-02 suly 19, 1984 -

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. All welders working under the alleged responsible fohan during the alleged time frame were identified.

All of these welders who could do ASME welds were identified.

. The final list of suspect velds consisted of all of the 2" and smaller sockat velds made by these welders; during the alleged time frame; while working under the alleged forman. '

. This list of suspect welds was evaluated by Design Engineering to determine which were*critica3,'^ based on safe operation criteria. 7

. A final population of 360 critical suspect welds was obtained based on the details of the allegation.

. . The NRC representatives wanted to know how welds were going to be sampled and. whether all of welder B's welds were going to be evaluated. Construction stated that their current plan was to sample between 5-10% of the critical welds, including all of welder B's

accessible welds.

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. The NRC representative from Brookhaven, Mr. Czajkowski suggested that all of welder B's welds should be reviewed based on either the ASTM A-262 A test for sensitization, or based on carbon content of the associated process pipe. To determine the carbon level below which sensitization will not occur, he recommended Harvey Solomon 's work which studied sensitization as a function of carben content.

. Mi. Czajkowski requested that Duke provide him with the ) fir Test Reports of the material used in the mock-up welds, and with the

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1 exact criteria used to establish a critical veld.

- This concluded the introductory portion of the meeting, the group adjourned to the Welding Test' Shack. The field portable technique developed by Duke's Metallurgists to evaluate sensitization 'per ASTM A-262 A was reviewed.

II. Field Portable Technique .

- The NRC representatives were shown the equipment and the materials used to do the metallurgical preparation and replication in the field.

- The technique development, current procedure and future refinements were discussed.

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Memo to File: 1206.00-02 July 19, 1984

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- To deisonstrate the techniques, replicas taken in the lab were shown and compared to actual metallurgical structures.

- The meeting then continued with a field tour of the Unit 1 Reactor nuildins.

III. Demonstration of In-Site Metallography (1530/ Replica Technique ~

- Two (2) welds identified as being critical had been metallurgically prepared through final polish and one through 600 grit sanding. The NRC representatives watched as the final polishing, electrolytic etching and replicating technique were demonstrated.

- Comments were shared on how the procedure could be furthar refined, most notable was the addition of a waste solution bottle to segregate the used etching solution from the unused.

- The replicas from these welds were taken to the construction metal-lurgical laboratory and evaluated for sensitization. It was agreed that the replicas were representative of the material's structure and did not exhibit an un-acceptabid degree of sensitization.

- The NRC representative from Brookhaven pointed out that there 'seened to be a variance in the quality of the replicas, however, even the worst replica revealed enough detail to accurately evaluate the presence of sensitization.

IV. Exit Interview i

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- In the Exit Interview the NRC representatives re-capped the day's meetings and events. Included in their closing coussents were the following points:

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. The emehn4- - being used to evaluate sensitization in the field was acceptable. Although there appears to be a difference in quality, the replicas reveal the necessary metallurgical detail to evaluate sensitization.

l . All of welder B's welds should be evaluated either by ISM ,

t or based on carbon content.

. Nothing in the mockmp welds or the demonstration' welds indicated that a sensitization problem existed.

. Mr. Czajkowski requested that he be provided with. several items:

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Homo to File: 1206.00-02 July 19, 1984 * .

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1. The certified mill test reports of the material used in the nock up and demonstration welds.

2. Details on the criteria used to establish criticality. bl,

3. Copies of the In 4 Leu Metallography proaadues.

- The day's meeting adjourned at 4:00 p.m.

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M Steve Ferdon Engineer Assistant

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