UPDATE 2-Motiva says Port Arthur refinery running at planned rates

* Two smaller CDUs completed initial restarts April 28 * Return delayed by steam supply problems (Recasts with Motiva confirming restart) HOUSTON, May 6 (Reuters) - Motiva Enterprises said its 600,000 barrel per day (bpd) Port Arthur, Texas,refinery was running at planned production levels on Mondayafter completing a plant-wide restart last week following anApril 14 power outage. Motiva spokeswoman Kimberly Windon declined to disclosefurther details about production at the refinery. Sources familiar with operations at the Motiva Port Arthurrefinery said all units were running at full capacity on Monday. The entire Motiva refinery, the nation's largest, wasknocked out of production by a citywide power outage, which alsoaffected the Valero Energy Corp and TotalPetrochemical's refineries in Port Arthur. The three refineries in Port Arthur account for 6.3 percentof U.S. crude oil refining capacity. The Valero and Totalrefineries, which were only partially affected by the poweroutage, were operational by April 24. The restart at Motiva was delayed when steam and hydrogensupply from a third-party provider was lost following the poweroutage, sources had told Reuters. The steam outage came at atime Motiva was performing maintenance on its own boilers, whichproduce steam needed for the refining process. The refinery was able to restart its largest crudedistillation unit (CDU), the 325,000 bpd VPS-5, on April 21. Therefinery's 205,000 bpd VPS-4 CDU and 80,000 bpd VPS-2 CDU didnot complete their initial restarts until April 28. The CDUs undertake initial refining of crude oil enteringthe refinery and provide feedstock for all other units. Motiva is a 50-50 joint venture between Royal Dutch ShellPlc and Saudi Aramco. (Reporting by Erwin Seba; Editing by Gerald E. McCormick,Sofina Mirza-Reid and Dan Grebler)