ML19209C899

Final Deficiency Rept Re Invalid Heat Treatment of Reactor Pressure Vessel Pedestal Studs.Studs Fabricated by Acimet Mfg Co in Lots Exceeding ASME Requirements.Caused by Error on Purchase Order in Specs for Heat Treated Matl

ML19209C899
Person / Time
Site:	Hartsville, Phipps Bend
Issue date:	10/11/1979
From:	TENNESSEE VALLEY AUTHORITY
To:
Shared Package
ML19209C889	List: ML19209C888 ML19209C899
References
NUDOCS 7910180453
Download: ML19209C899 (2)

Text

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ENCLOSURE HARTSVILLE AND PHIPPS BEND NUCLEAR PLANIS, ALL UNITS INVALID HEAT TREATMENT OF REACTOR PRESSURE VESSEL PEDESTAL STUDS 10CFR50.55(e) REPORT NO.1 (FINAL)

NCR S-10 On September 12, 1979, TVA notified NRC-0IE Region II, Inspector W.

B. Swan, of a potentially reportable 10CFR50.55(e) conditien involving heat treattent of the reactor pressure vessel (RPV) pedestal studs in lots exceeding ASME Section III, Subsection NF 2345 requirecents. This is the final report on the subject reportable deficiency.

Descriotion of Deficienev The 756 three inches in diameter by 23 inches long reactor pressure vessel pedestal studs (126 per unit) for TVA's Hartsville and Phipps Bend Nuclear Plants, f abricated by ACIMET Manufacturing Cocpany (ACIMET) under subcontract from Lakeside Bridge and Steel (Lakeside) were heat treated by Addison Heat Treating Company, Cleveland, Ohio (Addison), in lots having weights from 9,000 to 13,000 pounds, exceeding the 6,000-pound maximum required by ASME Section III, Subsection NF 2345. These studs were fabricated from ASME SA-540, Grade B23, Class 4 material and are to be used to hold the reactor pressure vessel to the RPV pedestal.

ACIMET tested additional samples of the =aterial in question af ter discovery of the deficiency and a large percentage of the samples failed the Charpy-V-notch test, indicating unacceptable notch sensitivity.

The first shipment of 126 studs was received at the Hartsville Nuclear Plant to be used on the unit Al reactor pressure vessel support before discovery of the deficiency. These studs had not been installed at the time of discovery of the subject deficiency.

Cause of Deficiency When ACIMET wrote the purchase order for the heat treatment of this material they mistakenly specified 10,000-pound maximum lot sizes in lieu of the 6,000-pound requirement. A subsequent internal review by ACDET QA personnel discovered the error before the heat treatment and a correction to the purchase order was sent to the ACIMIT canager of purchasing for transmittal to Addison. This correction was never officially transmitted to Addison as requested.

Addison, on the v _r b'nd, did not follow the requirements of the original pr - te v  : der which specified five 10,000-pound taxi =um heat lots - -: seen from the 9,000- to 13,000-pound heat lots reported. tan ACu 2T asked for verification of the 6,00n. pound maximum heat lots, Addi;.On indicated the actual heat lot weights. ACIMET then generated their noncenfornir.g =aterials report No. 170 to docucent this problem and informed Lakeside, who in turn infor ed TVA.

1176 169 7910180 53

Safety Imolications Additional testing of the deficient material shewed unacceptable notch sensitivity. Unacceptable notch sensitivity indicates reduced resistance of the studs to crack propagation, which would increase the probability of brittle failure of the studs which could degrade the structural support of the reactor pressure vessel.

Corrective Action TVA has returned to ACIMET the 126 deficient studs which were shipped to the Hartsville Nuclear Plant. ACIMET is in the process of having all 756 studs reheat treated at Nettleton Steel Co=pany in 6,000 pounds maximum heat treat lots. Each lot of the materials thus reheat treated will be retested to a level equal to or greater than applicable ASME requirements. This reheat :reatment will be complete by November 1, 1979.

Action Taken to Prevent Recurrence _

ACIMET quality assurance personnel has informed appropriate engineering and purchasing personnel to be aware of the 6,000-pound lot requirement for future ASME purchase orders. ACEKET has deleted Addison from their approved vendors listing. Also, the ACIMIT manager who failed to inform Addison of the corrected heat treatment requirement was discharged.

Lakeside audited ACIMET on September 26, 1979, and determined that ACUET is qualified to provide material to ASME NCA 3800 requirements. their audit indicated that this deficiency appears to be a "one time occurrence" and that corrective actions taken by ACIMET should prevent recurrence of this problem in the future.

1176 170

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