Berkeley's public library will face a showdown with the city's Peace and Justice Commission tonight over whether a service contract for the book check-out system violates the city's nuclear-free ordinance. The dispute centers on a five-year, $63,000 contract the library wants to sign with 3M, an international technology company based in Minnesota, to service five scanner machines library patrons use to check out books.But 3M, a company with operations in 60 countries, refused to sign Berkeley's nuclear-free disclosure form as required by the Nuclear Free Berkeley Act passed by voters in 1986.As a result, the library's self-checkout machines have not...