A defense attorney conceded Tuesday that his engineer client took software from the nation's largest nuclear plant and used it while in Iran, but said he did it only so his Iranian relatives could see what he did for a living.

Prosecutors said in opening arguments Tuesday that Iranian-born Mohammad Reza Alavi, a former software engineer at the Palo Verde nuclear plant, broke the U.S. embargo on trade with his native country in 2006 when he took the training software from the plant and later downloaded codes in Iran that allowed him to open it.

Authorities don't believe the 50-year-old Alavi, who worked at the plant from 1989 until August 2006, intended to provide details of the plant to terrorists.

Defense attorney David Laufman said Alavi, a naturalized U.S. citizen, never intended to break the law and opened the program only to show it to his relatives out of pride.

The training software was used to simulate the control room at the plant and contained detailed plant information, such as the schematics of its design.

Plant operators said the unauthorized use of the software didn't pose a security risk because it contained no information on plant security.

Alavi, who was arrested more than a year ago in Los Angeles when he arrived on a flight from Iran, pleaded not guilty to charges of exporting in violation of trade sanctions, transporting stolen goods and computer-related fraud.

Authorities said that plant operators shut down Alavi's access to the software after he resigned but that the engineer later used his logon to get onto a Web site run by the vendor of the software. Plant operators failed to notify the vendor that Alavi had resigned.

Prosecutor David Pimsner said Alavi was aware of the restrictions on doing business with Iran because the Treasury Department sent him a letter in 2001 saying payments he received from a company in Iran were a violation of regulations.

Laufman said the money was repayment of a loan involving Alavi's brother in Iran.

The defense attorney also said plant operators permitted certain employees to put the simulator software on their personal computers.

The Palo Verde Nuclear Generation Station, about 50 miles west of downtown Phoenix, supplies electricity to about 4 million customers in Arizona, New Mexico, Texas and California.