The following comment by a (probably French) Anonymous on January 12, 2022, got me to thinking.
I’ve bolded the parts that most strike me. Anonymous commented:
“To Gessler
Sorry to come back again to the HEU/LEU
perspective..so many time exposed
your views are not correct as the LEU choice in
France is fundamentally an economical and N safety issue to piggyback on the
civilian N industry..BTW it take a few weeks to change the fuel (2 has been documented)
in the military harbours of Toulon and Brest using hatches and specialized
robot. Not in Cherbourg yard.
LEU reactors as seen in the 2,500 tonne Rubis class can be very compact..
Military PWR are subject to the same safety
standards as civilian (inspection of the inner part of the reactor..) and
audited by the same independent people. This contributes to the political
acceptance of having N reactors in the middle of large cities. The spent fuel
can be treated nearly in the same processes as well. In the French view it is
the HEU which is perceived as problematic...Sealed for life..?
Once the glut of bomb grade HEU due to the SALT treaties will be exhausted in the middle of the century in the US this question will be probably revisited as well in the US.
As far as the number of SLBM tubes this has
nothing to do with LEU ..Each M51 carry up to 10 MIRV at above 8,000 km (everywhere
on Earth if you remember loxodrome vs orthodrome including China from the North
Sea)..160 X 100 KTon in each sub... 500 Hiroshima..! France successive Governments
believe in "just sufficient deterrence"...Having 2 sub at sea , even
partially loaded (they are in fact at least in the public domain in the UK..)
is a much better deterrent.."
I plan to write a Report to Donors around this tomorrow.
5 comments:
Hi Pete
some comments from "the french anonymous"
The HEU/LEU debate is not about which system is better,as they are equivalent in term of operations (the life time "advantage" vs 10 year is highly debattable)in most experts opinion
HEU is not produced any more since 30 to 40 years in the US, Russia ,France ,UK ,China.This is public.Only in India and Pakistan small facilties seem to operate to fullfill their programme.It is too costly an not needed for deterrence above a certain amount of devices(a bomb in every day parlance..).(A nuclear device needs 15 to 25Kg of HEU ,about a liter ,while a sub "life time" about 600kg...)
The US and Russia have huge inventories (in the hundreds of tons...) of bomb grade HEU due to the dismantling of thousands of nuclear devices.This "glut" is used in "downblending" back for civilian reactors and for marine propulsion , subs and aircfraft carriers.The US has put aside 110 Tons of HEU for the USN needs and this is expected to last typically to 2050 / 2070
The US started their nuclear sub 70 years ago and have accumulated a tremendous learning curve (hundreds of of boats)including in safety. In the 2030/2040 the US will havre to ask the question of sticking to HEU (huge cost to restart or further security or arsenal dismantling) or switching to LEU (Billions of USD and 20years to have the right experience)This debate is public in the US among the specialists
LEU was initiated in France in the 65/70 time with 3 constraints:
-get rid ot the HEU operation,
-uses civilian grade produced by commercial operator in Fr , US, Russia, Japan ,Holland, UK, China.. ect..that are allowed to 6%
-have reactors inside completely inspected every 10 years by independant civilian, alegal Fr requirement
The system has been completely reingeneered with plate fuel vs rod (X4 in U density) , compact reactour with the heat exchanger within the reactor and the control plates horizontally positioned..This is possible because the system is designed also to be inspected and the plates removed by robots through removable hatches
This LEU route has accumulated over 50 years , and 20 boats, a significant learning curve including in the dismantling /recycling steps, is future robust as civilian LEU is here to stay this century..Unlikely to change
Pls find a useful link
https://fissilematerials.org/library/rr15.pdf
Anonymous again
2 points for added "clarity" for the curious technically trained mind
-the power density (KW/cubic meter), critical for a sub operation performance , is essentially identical for LEU and HEU and dependant of the density of fissile material(the fuel) per unit time (roughly).The decrease from 93% to 6 % is compensated by a life time of 10y vs 35/40 years and a gain in U density in the planar route of X 4.11(so called "caramel")
-One the most critical element in a N plant is the steam generator (having pressurized water heated by the Zr cladding on one side and steam for the turbine on the other side). Because it is a critical safety barrier it needs to be changed typically every 10 years in civilian plants.These is why in the US design it is located outside the reactor..
Conversly if you have a system engineered for simple (relatively)access to the reactor , you can locate these heat exchanger within the reactor and have highly compact design
So you have fundamentally different philosophies in reactors design
Thanks Anonymous
1. For your two French reactor comments. I'll turn them into an article soon.
You provide useful summarised information on subjects rarely raised in the Anglosphere.
In lengthy, sometimes unwieldy form, the American, Peter Lobner, in "Marine Nuclear Power 1939 - 2018, Part 4: Europe & Canada"
concentrates on France in pages 159 to 304 https://lynceans.org/wp-content/uploads/2018/07/Marine-Nuclear-Power-1939-2018_Part-4_Europe-Canada.pdf
but I can't say I have time to read those 150 pages.
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2. What do you think of my theory here https://gentleseas.blogspot.com/2018/11/frances-barracuda-delayed-existing-k15.html that one reason for the delay in France completing the Barracudas was the need to further reduce the height of the K15 reactor?
My theory further being - the K15 in preceding larger form - fitted into carrier Charles de Gaulle and the Triomphant SSBNs - but the K15 needed to be smaller to fit into the Barracuda/Suffren SSNs.
Regards Pete
Hi Pete
Yes the Barracuda programme was delayed by about 3 years and the Suffren was launched in 2019
In a public hearing in the Fr Parlement Defense Commission of the DGA Director, Mr Collet Billon,in 2016 the delay was attributed to "technical problems"and the Suffren was launched only in 2019 after an 11 years construction time. No further informations were released
However it is very unlikely the the size of the reactor was the problem..The delay occured very late in the programme ..
Interestingly the Russian believe that the delay was due to efforts to correct the problems with the Virginia and Astute noise reduction coating and tiles, "childhood disease"..
The Suffren has dual propulsion: a turbine for the high speed and electric generators for the silent mode where it is similar to AIP with the reactor working at low power, may be in a natural cooling mode
This russian article compare the noise to be on par with the most recent AIP German and Japanese subs in "sneaking" mode and really innovative for a nuclear sub.Likely to be very hard to detect
Even more interesting the ability to launch the Mica AA missile while submerged is seen as a real challenge for the Russian Naval Aviation especially with link16 network where the detection could be far appart
read://https_topwar.ru/?url=https%3A%2F%2Ftopwar.ru%2F160189-podlodka-sjuffren-brosaet-vyzov-morskoj-aviacii-vmf-rossii-kovarnyj-ohotnik-s-vozmozhnostjami-pvo.html
To note that French press rumour indicates that the Suffren has a hard time to achieve its top speed due to a steam turbine problem that could be potentially corrected only in the following subs and during the next sub major overhaul
Thanks French Anonymous for your comments [at Jan 16, 2022, 7:02:00 AM]
I'm still of the belief that even early on at the computer generated design stage the K15 reactor was too large to fit in the Barracuda/Suffren's image space.
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The Germans have also experimented with a torpedo tube launched anti-aircraft (AA) missile system. This is https://en.wikipedia.org/wiki/IDAS_(missile)
"Four missiles will fit in one torpedo tube, stored in a magazine. First deliveries of IDAS for the German Navy and operational service were planned from 2014 on."
I don't know whther IDAS was actually deployed.
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The interesting Russian article to which you refer is at https://topwar.ru/160189-podlodka-sjuffren-brosaet-vyzov-morskoj-aviacii-vmf-rossii-kovarnyj-ohotnik-s-vozmozhnostjami-pvo.html
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Re: "French press rumour indicates that the Suffren has a hard time to achieve its top speed due to a steam turbine problem" I also understand HMS Astute after launch its top speed proved a few knots too slow - but this was later rectified.
Regards
Pete
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