Strategic Successor Submarine (Future British SSBN)
Notes: On 4 December 2006, the UK Ministry of Defense published a report to Parliament "The Future Of The United Kingdom’s Nuclear Deterrent" which outlined a need to design new SSBNs to replace the Vanguard class in the future. The option for new SSBNs was weighed as one of four options, namely 1) Abandoning nuclear weapons 2) Developing a semi-strategic, long range aircraft-launched cruise missile 3) Basing existing Trident SLBMs on surface ships or ashore at Royal Navy bases 4) Building new SSBNs.
On 14 March 2007, Parliament voted to accept the report and proceed with designing new SSBNs for the Royal Navy. In May 2007, a Future Submarines Management (FSM) team was established to run the effort.
On 22 May 2012, the UK Ministry of Defense awarded approximately $700 million to begin the design of a SSBN class to succeed the Vanguard class. The bulk of the funding went to BAe Marine Systems (hull design), with smaller portions going to Babcock (in-service support programme) and Rolls-Royce (reactor design).
Requirement issued: May 2011
Begin design study: May 2012
Next round of design funding ("Main Gate" phase): July 2015
Completion of "Main Gate" design phase): early 2016
Design completed: late 2020
Long-lead items ordered for first submarine of class: mid 2023
Keel laid of first submarine of class: late 2024
First submarine of class launched: early 2026
First submarine of class commissions: mid 2028
Second submarine of class commissions: early 2030
Third submarine of class commissions: 2032
Fourth (if ordered) submarine of class commissions: 2034/2035
It should be noted that Britain has never had a land-based ICBM force, and both the Royal Air Force and Royal Navy have now discarded nuclear bombs meaning the UK’s entire deterrence rests with the SSBNs.
The first of the four-ship Vanguard class was completed in 1985 and is (tentatively) scheduled to decommission in 2022, with the second in 2024. It’s questionable how much more life can be squeezed out of them, as the first (HMS Vanguard) has already had it’s lifespan extended five years to meet the 2022 date. There would seem to then be a slight lag period then between these ships leaving service and the "SSS" entering service in 2028.
One factor regarding the "SSS" timeline is the timeline of the Astute class SSNs now in production. Britain is now facing a pickle similar to that which the United States faced some years ago as the Seawolf class was wrapping up and the Virginia class starting. Since nuclear submarine construction is such a specific art, at least one hull needs to be under construction at all times to keep at least a minimum of trained shipyard workers employed. For the UK, the problem is more acute than faced by the USA. A break in continuity in the American line would have resulted in one of the two remaining submarine yards (Electric Boat or Newport News) going bankrupt. But since Britain has only BAe left, loss of submarine continuity there would leave a choice between the government paying shipyard workers to wait at home doing nothing; or; Britain losing the ability to build submarines. Neither choice seems particularly palatable for a democracy.
The number to be built has not been determined. To guarantee at least one SSBN on patrol at all times, a minimum of four (one on patrol, one at sea transiting to/from patrol, one in port for minor upkeep, and one in refit/drydocked), and an optimum of five, units will be needed. As the Royal Navy has made-done with only four Vanguard class SSBNs as it stands now, it’s almost impossible that five "SSS" class will be built, and given the Royal Navy’s budgeting woes, it’s quite possible that only three will be built which would mean that conceivably, there would be times when no British SSBN would be patrolling.
A consideration is that a three-SSBN force is quite risky, in that a catastrophic disaster (sinking of one of the three due to a peacetime accident, or, a shipyard fire during refit) would mean a loss of credibility for the UK’s survivable nuclear deterrence as with only two SSBNs, one would be on patrol only sporadically, and there would be periods when both were not only inport but unavailable at all due to repair/refit rotations.
The Royal Navy stated in 2006 that, with refurbishment, the existing UGM-133 Trident SLBM’s can be kept flightworthy until about 2040-2042. The December 2006 parliamentary report stated that the then-administration of George W. Bush had given positive feedback to British involvement with either the UGM-X SLIRBM or alternate systems which will eventually replace UGM-133 Trident II in the US Navy.
The number of missiles per submarine has not been decided. The Vanguard class carries 16 SLBMs. However the British government passed legislation in 2010 capping each SSBN to 40 MIRVs each. As each Trident II can carry up to 8 MIRVs, this would mean that each $32 million missile would go to sea with 3/4ths of it’s capacity empty; or; fewer missiles would be carried. The latter seems much more logical and an estimate of 8 missiles per "SSS" class SSBN is realistic. This would also result in a smaller submarine lowering construction costs.
There are currently (June 2012) two loose concepts as to what the "SSS" will look like. Both concepts are by BAe.
1) The Concept 35 (pictured at the top of the page) is conservative and based on a stretched Astute class hull. The advantages would be obvious in hastening the design and cost savings. For the "SSS" class, the Royal Navy has mentioned some changes.
While the Rolls-Royce PRW2-Core H reactor (as on the Vanguard and Astute classes) could be used with no problem, the Royal Navy wants a new reactor similar to the USN’s proposed Transitional Technology Core (see the DB Encyclopedia entry for the Virginia class). Similar to the TTC, this new reactor would use highly-potent uranium fuel and would (depending on the proposed lifespan of the "SSS") either never need to be refueled, or, would be "modularly replaced" one time mid-life, in that instead of the rods being exchanged, the entire reactor vessel would be swapped out with a fresh one.
The most extreme proposed feature is the submarine shaftless drive (SSD). Instead of the normal nuclear propulsion arrangement, where steam turns turbines are linked to reduction gears and a shaft rotating the PJP, the SSD would be all-electric and have an external motor. Steam would drive electric turbogenerators which would be wired to a non-penetrating electric junction at the aft end of the pressure hull, with a watertight electric motor and PJP being faired into the external hull. This concept is not entirely new, it was first examined in the "Tango Bravo" study by the USN for possible use on late hulls of the Virginia class SSN. The advantage of SSD would be huge cost savings in elimination of the reduction gears, shaft bearings, and shaft seal. Additionally there would be hull construction savings as the engine room could be significantly shortened, saving steel. The most obvious drawback is that if a submarine with SSD encountered an engine breakdown, there would be no way for the crew to repair it.
2) The Advanced Hull Form is much more revolutionary. It has a broad, deep hull with no traditional rudder and the SLBMs to be arranged in a staggered-single file format instead of in pairs as on existing SSBNs. The AHF would be powered by "Directional Waterjet Propulsion Pods" which are basically a pair of electric PJPs inside the external hull casing, fed by conformal intake slits.
Regardless of which option is chosen, the "SSS" will have to be compatible with existing facilities at the Devonshire Dock Hall construction yard at Barrow-in-Furness, England and existing piers at Clyde Naval Base in Scotland.
A factor mentioned already is that the "SSS" may well be fitted out as a full SSN in addition to carrying ballistic missiles. The Royal Navy may one day task SSBNs on active missile patrol with unrelated missions such as SIGINT collection, merchant ship tracking, etc. This would seem outrageous in Russian or American naval thinking but due to the down-sizing of the Royal Navy is not unthinkable.
Future of programme
The whole effort rests on the UK government remaining committed. As of the present (mid-2012), the next twelve years will be critical.