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Nuclear Class 1E Safety Standards

United States Class 1E:

"The safety classification of the electrical equipment and systems that are essential to emergency reactor shutdown. Containment isolation, reactor core cooling and containment, and reactor core heat removal are essential in preventing significant release of radioactive material into the environment."

Recommended practice for seismic qualification of Class 1E equipment for Nuclear Power Generating Stations.

IEEE 323-1974 and IEEE 323-1983:
Standards for qualifying Class 1E equipment for Nuclear Power Generating Stations for:
  • Aging (Radiation, Thermal)
  • Mechanical Vibration (Seismic IEEE 344-1971)

Defined by IEEE 323 as:
"An environment of normal service conditions where seismic is the only design basic event of consequence."

However, IEEE 323-83, Section 6.2 states the following:
  • Aging analysis done on all devices/components including material makeup
  • Radiation and higher than normal ambient temperature is factored into aging criteria (Station Black-out conditions)
  • Determine qualified life and replacement/maintenance schedule to achieve 40-year design life
IEEE 344-1971:
Recommended practice for seismic qualification of Class 1E equipment for Nuclear Power Generating Stations.
  • IEEE 344-1975
  • IEEE 344-1987
Simulates earthquakes:
Equipment must operate during and after at least five (5) Operating Basic Earthquake (OBE) events, and at least one (1) Safe Shutdown Earthquake (SSE) event.

IEEE 650-1979 and IEEE 650-1990:
Standards for qualification of Class 1E battery chargers and inverters for Nuclear Generating Stations.
  • Specific procedures to meet aging requires of IEEE 323
  • Failure Modes and Effects Analysis (FEMA)
  • Electrical stress analysis
  • Pre- and post-seismic environment stress test
IEEE 944-1986:
  • Design criteria for Inverters and Rectifier/Battery Chargers, Bypass Transformers, and Voltage Regulators
  • Electrical testing criteria
  • Utility type battery chargers
  • Design criteria for rectifier/chargers
  • Electrical test criteria
IEEE 946-1985:
IEEE-recommended practice for design of safety related DC auxiliary power systems for Nuclear Power Generating Stations.
  • Battery charger sizing criteria
  • Distribution systems and equipment
  • Spare/swing battery chargers
IEEE 383-1980:
Standard for the type testing of Class 1E rated electric cables, field splices, and connections for Nuclear Power Generating Stations.
  • Cable must utilize certified insulation system, and must pass vertical and horizontal flame test per IEEE 383.
IEEE 384-1981:
Standard criteria for independence of Class 1E rated equipment and circuits.
  • Physical and electrical separation criteria
  • Non-Class 1E circuits from Class 1E circuits (critical vs. non-critical)
  • May require additional "isolation" devices
IEEE 519-1992:
Recommended practices and requirements for harmonic control in electrical power systems.
  • Newly re-written to include reflected current harmonics from rectifiers and battery chargers
  • Does not recommend the use of 3 SCRs (3-pulse designs) for rectifiers

10CFR50 Appendix B:
Quality Assurance Criteria for Nuclear Power Plants and Fuel Reprocessing Plants.
  • 10CFR50.55a(h), Protection and Safety Systems
Branch Technical Position (BTP):
BTP 7-14
  • Guidance on Software Review for Digital Computer-Based Instrumentation and Control Systems
BTP 7-21
  • Guidance on Digital Computer Real-Time Performance

IEEE 1012-2004:
IEEE Standard for Software Verification and Validation
  • Regulatory Guide 1.152, Criteria for Use of Computers in Safety Systems of Nuclear Power Plants, Rev. 3, July 2011
  • Regulatory Guide 1.168, Verification, Validation, Reviews, and Audits for Digital Computer Software Used in Safety Systems of Nuclear Power Plants,Rev. 2, July 2013

NEMA ABI-1986:
Standard for the testing of molded case switches.
  • Certified testing results that breakers meet specified trip ratings and electrical criteria
Note: Solidstate Controls buys directly from the O.E.M.
  • Breakers are serialized for traceability
  • Certified Test reports are issued for:
    • Complete functional tests
    • Tripping time(s)
    • Dielectric tests
EPRI 102323, Revision 1:
Guidelines for Electromagnetic Interference Testing in Power Generating Plants.
  • EMI/RFI (Conducted, Radiated)
  • Equipment susceptibility