KIWI (nuclear reactor program)

KIWI-A reactor

KIWI-A reactor.

Cutaway diagram of a KIKW-A reactor

Cutaway diagram of a KIKW-A reactor, showing the basic design of the graphite core. Credit: NASA.

KIWI was a series of nuclear reactors, designed and built in the late 1950s and 1960s as part of the Rover program, to develop the basic technology of nuclear thermal rockets (see nuclear propulsion). The KIWI-A series of tests developed the technologies of instrumentation and control, fuel element design and fabrication, and structural design. The KIWI-B series was designed to increase power 10-fold while maintaining the same size. It faced a problem first encountered with KIWI-A: internal vibrations caused by dynamic flow instability fractured portions of the fuel elements. This problem was finally overcome in KIWI-B4. The KIWI-TNT was a test reactor for the effects of sudden explosion and excursion. Other reactors developed during the Rover program were Phoebus, Pewee-1, and Nuclear Furnace 1.


KIWI series summary
project date max. power
burn time
KIWI-A Jul 1, 1959 70 300
KIWI-A' Jul 8, 1960 88 307
KIWI-A3 Oct 19, 1960 112.5 259
KIWI-B1A Dec 7, 1961 225 36
KIWI-B1B Sep 1, 1962 880 several
KIWI-B4A Nov 30, 1962 450 several
KIWI-B4D May 13, 1964 990 40
KIWI-B4E Aug 28, 1964 937 480
  Sep 10, 1964 882 150
KIWI-TNT Jan 12, 1965 n/a n/a


KIWI-B4E performance parameters
reactor power (MWt) 937
flow rate (kg/s) 31.8
fuel exit temp (K) 2330
chamber temp (K) 1980
chamber pressure (MPa) 3.49
core inlet temp (K) 104
core inlet pressure (MPa) 4.02
reflector inlet temp (K) 72
reflector inlet pressure (MPa) 4.32
periphery & structural flow (kg/s) 2.0