Nuclear Infrastructure Security Act of 2003

Nuclear Infrastructure Security Act of 2003 - Amends the Atomic Energy Act of 1954 to require the Nuclear Regulatory Commission (NRC), in coordination with the Department of Homeland Security, to study and report to Congress on threats and vulnerabilities targeting nuclear facilities. Directs the NRC to: (1) revise design basis threats; (2) establish a system for the determination of threat levels; (3) require each licensee or certificate holder of a designated nuclear facility to revise its security plan and make necessary upgrades; (4) review the emergency response plan for each facility; (5) assign a Federal security coordinator to each NRC region; and (6) require fingerprinting of nuclear facility personnel for criminal history record checks.

Amends the Energy Reorganization Act of 1974 to establish in the NRC the Office of Nuclear Security and Incident Response.

Directs the NRC to establish a security response evaluation program to assess the ability of each designated nuclear facility to defend against threats in accordance with the facility's security plan.

Amends Federal criminal law to authorize NRC licensees and certificate holders guarding nuclear facilities, equipment, or material to: (1) transport short-barreled shotguns or rifles; (2) accept imported firearms or ammunition; (3) transport and possess firearms; and (4) possess semiautomatic assault weapons and large capacity ammunition feeding devices.

Amends the Atomic Energy Act of 1954 to: (1) redefine byproduct material to include accelerator-produced radioactive material; and (2) direct the NRC to promulgate requirements and standards for its acquisition, possession, transfer, use, or disposal.

Amends the Energy Reorganization Act to extend whistleblower protection to a contractor or subcontractor of the NRC.