BELL SYSTEM NUCLEAR DESIGN CRITERIA (1969)




EXTREMELY HARD DESIGN (50 PSI)

Design Assumptions:
- 2 1/2 miles from 20 megaton blast
- 1000 Miles per hour wind
- 40 G shock wave
- high velocity debris
- Intense radiation, heat and electromagnetic effects

Design Criteria
- Below grade construction with 2 ft concrete walls and a minimum of 4 ft of earth over cover
- Shock mounting on communications equipment to reduce excelleration to 8 g's
- Metal shield completely enveloping structure (-80 db at freqs above 10 Khz)
- Provisions for flexing of incoming cables at entrance points
- Above ground structure (microwave and troposcatter antennas) require at least two thirds of the
structure to be below grade to prevent tilting or rotation
- Microwave antennas require tilting to shed debris, beryllia window to resist over pressure, flame sprayed
aluminum finish to reflect heat and concrete filling for weight.

Typical structures:
- Buried cable 4 ft deep i.e.: L-4
- Military locations with troposcatter and line of site microwave
- L-3 and L-4 main stations less than 5 miles from a potential target
- L-3 and L-4 repeater and equalizing stations (18" earth over cover)

MODERATELY HARD DESIGN (10 PSI)

Design Assumptions:
- 5 miles from 20 megaton blast
- 800 Miles per hour wind
- 8 G shock wave
- moderate velocity debris
- Moderate radiation, heat and electromagnetic effects

Design Criteria
- Below grade construction with 2 ft concrete walls and a minimum of 2 ft of earth over cover
- No or little shock mounting on communications equipment.
- Metal shield completely enveloping structure (-80 db at freqs above 10 Khz)
- Provisions for flexing of incoming cables at entrance points
- Blast valves on air intakes
- Escape hatches to proved exit when expendable entrance building is destroyed
- Three weeks of food , fuel and emergency provisions
- Air shafts with protective caps or debris pits

Typical structures:
- L-3 and L-4 main stations more than 5 miles from a potential target

REINFORCED DESIGN (2 PSI)

Design Assumptions:
- 13 miles from 20 megaton blast
- 70 miles per hour wind
- negligible shock wave
- no debris
- Little radiation, heat and electromagnetic effects

Design Criteria
- Current antenna structures will withstand 2 PSI
- Horn antennas require standard modification equipment for reinforcing
- Fallout protection must be provided for manned facilities
- Reduce vulnerability by utilizing topography

Typical structures:
- Conventional microwave relay station with minor modifications
 
 
 

Reference: Bell Labs Record, January 1969