If you want your first choice of dates for Hanford tours this year, better plan on staying up late tonight.

Registration opens at 12:01 a.m. Tuesday for sitewide tours of the nuclear reservation, which usually is closed to the public. The tours will be offered at 7:30 and 9:30 a.m. on 30 weekdays starting April 13 and ending Sept. 15.

Registration is offered only on the internet at www.hanford.gov and is on a first come, first served basis. Last year registration for all tour seats for 2009 filled within a little less than 12 hours.

However, anyone who waits too long to register or doesn't get their first choice of dates can keep checking back at hanford.gov. When cancellations are received, registration reopens for newly available seats.

This year the tours will leave from the B Reactor Tour Headquarters, 2000 Logston Blvd., Richland. Tours last at least five hours, which includes an hour and 15 minutes at Hanford's historic B Reactor.

During World War II and the Cold War the Hanford nuclear reservation produced plutonium for the nation's nuclear weapons program. Now work on the 586-square-mile site is focused on a massive effort to clean up environmental contamination left from wartime production.

New this year on the tour is a focus on the Hanford tank farms, where 53 million gallons of radioactive waste are stored in underground tanks.

The tour will include a stop at the Cold Test Facility, where technologies are tested in a safe environment for retrieving radioactive waste from leak-prone underground tanks. Later, visitors will stop outside one of the tank farms and also will see the outside of the $12.2 billion vitrification plant being built to treat the tank taste.

Visitors will stop at the huge landfill being expanded in central Hanford, which is planned to hold 30 million tons of debris and waste from Hanford cleanup. The bus also will stop at a project to treat contaminated ground water.

Tours of the site are offered only on weekdays so visitors can see cleanup work being done. Participants must be at least 18, U.S. citizens and carry valid photo identification on the tour that exactly matches the name they registered under. A dress code appropriate for an industrial setting will be enforced, including no open-toe shoes, short shorts, skirts or sleeveless shirts.

People who want to see just B Reactor may sign up for a separate set of public tours with registration starting at 12:01 a.m. March 16. Tours are offered on 36 weekdays and Saturdays from April 6 to Sept. 25. Saturday bus tours will start at 8 a.m. and 12:15 p.m. and weekday minibus tours will start at 9 a.m.

Internet registration also is done at www.hanford.gov. But to help those who don't use the internet, 10 seats on each weekday tour will be reserved for those who register by telephone or in person at the B Reactor Tour Headquarters.

Phone and in-person registration also starts March 16 and may be done when the tour headquarters are open 8 a.m. to 4 p.m. Mondays through Thursdays. Call 373-2774. In addition, there typically are one or two cancellations or no shows, leaving empty seats on the days of the tour. Those will be available to walk-ins.

Visitors must be at least 18, but are not required to be U.S. citizens. Valid photo identification and appropriate clothing for an industrial environment are required.

The B Reactor tours include two hours at the reactor and a 45-minute bus ride each way.

B Reactor was the world's first full-scale production reactor. Part of the Manhattan Project, it produced the plutonium for the world's first atomic explosion and the atomic bomb dropped on Nagasaki, Japan, helping end WWII. It looks today much as it did during WWII.