JFC Fuller

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Apr 22, 2012
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I have found three readily available sources referencing this reactor, either directly or indirectly:
  • Rickover and the Nuclear Navy, Francis Duncan, 1990
  • American destroyers and Frigates, Norman Friedman, 1982
  • Deciding to Buy: Civil-military Relations and Major Weapons Programs, Quentin E. Hodgson, 2010
Stitching those three together I get the following timeline for the design:

June-August 1960: D1W program is started, the aim is to provide a more cost effective, single reactor, nuclear plant for destroyers (F. Duncan), generally described at this stage as a 60,000 SHP plant suitable for ships below 8,000 tons displacement

June 1961: Director of Op-93 (Long Range Objectives Group), T.H. Moorer, writes that the Navy has committed itself to using a single reactor plant with the Bainbridge power output [60,000 SHP, this can only be the D1W], the plant may be available for FY65 destroyers but there are no destroyers in the LRO and Typhon DLGs require more power (N. Friedman)

Fall 1961: The D1W program was in trouble, it was providing no advantage over the twin D2G plant and has a higher than desirable centre of gravity. A task force is set up that manages to produce a configuration with less length and weight than the Bainbridge plant. (F. Duncan)

November/December 1961: Rickover directs that the D1W be designed as a more powerful plant “half again that originally planned” (F. Duncan) [I interpret this as 90,000 SHP, 50% greater than the two reactor D2G plant, this appears to be Rickover responding to the issue Moorer identified in June 1961]

April 1964: A D1W two-reactor plant briefed to McNamara and described as being able to power a carrier larger than a Midway but smaller than a Forrestal (F. Duncan) [This size description, based on the various small CVAN and CVSN studies described by Friedman suggests to me a total of c.180,000 SHP, which could be achieved with two D1W's that were each 50% more powerful than the Bainbridge plant]. However, such a plant couldn't be ready for the FY67 CVA [then CVA-68], only a plant suitable for an Essex size ship could be ready by then (Q. Hodgson) [This implies that the D1W design is still stuck at 60,000 SHP and therefore 120,000 SHP for a twin reactor arrangement]

Which leaves me with some questions:
  1. What was going on with the D1W design between Fall 1961 and Spring 1964, it seems that very little progress was made?
  2. How mature was the twin reactor plant briefed to McNamara, was it as crude as Ellis T. Cox proposing that a doubled D1W configuration would give twice the power and might be enough for a carrier? Or was it an arrangement that had been tentatively conceived during some of the 1960-63 CVS studies?
  3. Were any DLGs ever designed around a single D1W plant? Friedman doesn't mention any in the early editions of his books? Newport News and Electric Boat are stated to have been designing a ship displacing about 2,000 tons more than Bainbridge but its not clear that this was a single reactor vessel? (F. Duncan)
  4. Was there any relationship between the D1W and the A3W for the four reactor plant proposed for CVAN-67, the SHP outputs of both are close?

Grey Havoc

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Oct 9, 2009
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[This implies that the D1W design is still stuck at 60,000 SHP and therefore 120,000 SHP for a twin reactor arrangement]
Alternatively, it could mean that two different cores were under development.

A Tentative Fleet Plan

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Apr 9, 2018
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From Norman Friedman's US Submarines since 1945, Revised Edition

On p165 he describes D1W as a "60,000-SHP reactor".

1968: The Naval Reactors Division begins work on a submarinized D1W. A submarine with a D1W might be ready for the FY74 program.

April 1971: An SSGN design (APHNAS) is designed around a D1W (requiring a 40ft diameter pressure hull).

September 1971: Zumwalt orders his systems analysis division (Op-96) to begin a study of future submarine employment over the next decade.

Late 1972: APHNAS is cancelled, and the development of the UGM-109 Tomahawk, to be placed on a existing Los Angeles class SSNs, begins.

It was believed by some that the size of the UGM-89 STAM missile used by APHNAS (34in x 336-340in, requiring a 40in x 360in tube, which precludes the use of a torpedo tube) was an attempt by Rickover to require a large submarine, thus justifying the cost of the development of a submarinized D1W.

April 1975: As part of SSNX an "Advanced SSN" is presented in a with a variety of other designs including a pair of improved Los Angeles designs and pair of smaller designs powered by S5Ws (improved Sturgeons?). At the time it was a summer the new reactor would complete development in FY82, enabling installation in a new large submarine in the mid 1980s.

May 1975: CNO directs that SSNX would be no larger than the Los Angeles. As a result no other D1W designs were considered.
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Feb 11, 2007
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[This implies that the D1W design is still stuck at 60,000 SHP and therefore 120,000 SHP for a twin reactor arrangement]
Alternatively, it could mean that two different cores were under development.
Or they had the early 60,000 SHP iteration of the D1W available to revert to, but the 90,000 SHP iteration wasn't ready yet. I don't think it implies 'stuck' so much as 'not ready', which covers a much wider set of potential issues, from 'stuck' right down to 'conceptual design is complete but we just can't have the engineering drawings ready in time'.

If a D2G is also 60,000 SHP, then it could even mean two D2Gs.

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