The security of nuclear power plants are published in the Code of Federal Regulations, including the caliber of weapons the guards are carrying, physical fitness standards and tests for guards, standards for fencing construction around facilities, etc, etc.

CHAPTER I--NUCLEAR REGULATORY COMMISSION (CONTINUED)
PART 73_PHYSICAL PROTECTION OF PLANTS AND MATERIALS--Table of Contents
Sec. 73.46 Fixed site physical protection systems, subsystems, components, and procedures.

Also-

Domestic Safeguards Regulations, Guidance, and Communications

* Part 11 - Criteria and Procedures for Determining Eligibility for Access to or Control Over Special Nuclear Material
* Part 25 - Access Authorization for Licensee Personnel
* Part 26 - Fitness for Duty
* Part 70.51 - Material balance, inventory, and records requirements
* Part 73 - Physical Protection of Plants and Materials
* Part 74 - Material Control and Accounting of Special Nuclear Material
* Part 76 - Certification of Gaseous Diffusion Plants
* Part 95 - Facility Security Clearance and Safeguards of National Security Information and Restricted Data
* All current rulemakings


Last time I checked, no nuclear facilities have 'sploded.