Westinghouse LWNP

History

The Westinghouse Light Weight Nuclear Propulsion(LWNP) was an propulsion plant designed to be an drop-in replacement for either the LM2500 or FT4 Gas turbines in marine powerplants. It was based on existing technologies, notably those developed for nuclear rocket reactors. The LWNP consisted of an gas cooled nuclear reactor and an integrally packed gas turbine. In the paper describing this powerplant a few ship installations are proposed, none were ever build.

Used on

• LWNP Spruance class proposal
• LWNP Spruance class proposal

Affiliated systems

• General Electric LM2500

Part description

There are 2 setups drawin in the part image. The setup on the left has a full setup with an foot and gearbox such as would be found when installed on a ship. On the right is just the LWNP drawn. Both have a sideview (bottom) and top view (top). For placements in warships double units are shown in the source image, 1 on 1 replacing the double LM2500 units as found on for example Spruance class ships. In that installation the shielding overlaps (no need for shielding between the powerplants) in which case the shafts are 10' apart.

Alternate arrangements

Other speculative estimates for other possible arrangements.

Approximation of the LM5000 equivalent LWNP shown above the LM2500 equivalent with its known dimensions.

While not specified in detail, the LWNP proposal also included provisions and rudimentary data for a 60,000 SHP variant. This proposed variant approximates an LM5000 engine module's footprint while providing the same benefits and disadvantages as the smaller LWNP unit. Although no data on dimensions are present in the proposal, a claimed specific power of approximately 15.6 lb/HP allows for an estimation of the larger LWNP footprint. Please note that the following data is speculative unless specified.

Single LWNP unit data
Equivalent	Dimensions			Weight	SHP	Specific power
	Length	Width	Height
LM1600	25.5'	10.1'	11.3'	539,706 lbs	20,000	27.0 lbs/HP
LM2500	26.5'	10.5'	11.75'	602,500 lbs	25,000	24.1 lbs/HP
FT4A	27.35'	10.84'	12.15'	663,000 lbs	30,000	22.1 lbs/HP
LM5000	30.7'	12.15'	13.6'	936,000 lbs	60,000	15.6 lbs/HP
LM5000 x 2	34.6'	13.7'	15.35'	1,325,840 lbs	120,000	11.0 lbs/HP

Green represents known data; red represents estimations. LM1600 and LM5000 x 2 units are imaginary; no such plans exist.

Extrapolation method

While estimating the dimensions for the LM5000 equivalent unit, it is assumed that the density of the unit remains identical, representing a pure scaleup of the LM2500 equivalent unit. In practice, this may not have been the case; however, it is assumed to be a perfect scale of the smaller unit due to the limited information.

Known volume of 25kSHP unit given as:
l ⋅ w ⋅ h = v
Where density is constant in scaling up the system, volume is proportional to mass:
v ∝ m
A cube of the same volume has sides equal to:
³√v
Ratio of side lengths given as, where k is equal to a known dimension (l, w, or h) and v_n is the new volume:
(l_n) or (w_n) or (h_n) = ³√v_n/(³√v/k) = k ⋅ ³√v_n/³√v
New dimensions given as l_n, w_n, and h_n give new volume:
l_n ⋅ w_n ⋅ h_n = v_n

See also

• Proceedings of a Symposium Advanced Compact Reactor Systems
• Maritime Applications of an Advanced Gas-Cooled Reactor Propulsion System