Nuclear pulsed propulsion

[RJMAZ]

• Completing ship design for human mission to Mars.

Nice design. Refueling and shielding will be interesting.

I would instead use the nuclear engine to launch huge Aldrin cyclers. Assemble them in LEO with a capacity of 1,000 people. Spinning to create gravity. No radiation shielding is needed for the engines. Shoot it off without any humans onboard and once it is up to speed jettison the nuclear engine. Humans can board the cycler on the second pass. A methane refueling depot in HEEO will then then allow methane fueled ships to catch up to the cycler.

As most of the payload is one way I would just use "slow" methane fueled rockets for any return trips back to Earth. The delta-V requirements at the Mars end is much higher so it would be hard to use an Aldrin cycler for a return trip to Earth.

This is the perfect long term solution. It will be much easier to make a nuclear rocket engine that is a single use with no humans onboard.

[lamontagne]

• Completing ship design for human mission to Mars.

Nice design. Refueling and shielding will be interesting.

I would instead use the nuclear engine to launch huge Aldrin cyclers. Assemble them in LEO with a capacity of 1,000 people. Spinning to create gravity. No radiation shielding is needed for the engines. Shoot it off without any humans onboard and once it is up to speed jettison the nuclear engine. Humans can board the cycler on the second pass. A methane refueling depot in HEEO will then then allow methane fueled ships to catch up to the cycler.

As most of the payload is one way I would just use "slow" methane fueled rockets for any return trips back to Earth. The delta-V requirements at the Mars end is much higher so it would be hard to use an Aldrin cycler for a return trip to Earth.

This is the perfect long term solution. It will be much easier to make a nuclear rocket engine that is a single use with no humans onboard.

Oh hello, fancy seeing you here!
The proposed engine uses up the entire US supply of enriched uranium for just the first boost to Mars.  As you mention, refuelling is an 'interesting' problem.  The burn up fraction is abyssimal.
The thread contains quite a bit of discussion about a more evolved version of this, that used much less nuclear fuel, desinged by prof.  Winterberg.  Focus on the engine part, rather than the mission part, would be appreciated.  There are plenty of other threads about cyclers vs ships.

[lamontagne]

Not specifically space related, DOE Selects 4 Vendors for $2.7B Uranium Enrichment Contract [Oct 18]

The Department of Energy has awarded four companies spots on a potential 10-year, $2.7 billion contract to procure uranium enrichment services to help establish a domestic supply chain of high-assay low-enriched uranium, or HALEU, used for deploying advanced nuclear reactors.

According to award notices published Wednesday, the HALEU Enrichment contract awardees are American Centrifuge Operating, General Matter, Louisiana Energy Services and Orano Federal Services.

HALEU Enrichment RFP
In January, DOE issued a solicitation for the HALEU Enrichment indefinite-delivery/indefinite-quantity contract, which covers the production, storage and transportation of enriched uranium hexafluoride to deconversion facilities.

Enrichment and storage activities must be performed in the continental U.S. in compliance with the National Environmental Policy Act.

The department noted that establishing a domestic HALEU supply chain supports President Joe Biden’s Investing in America agenda by helping meet net-zero emissions goal by 2050, creating jobs, strengthening U.S. competitiveness and improving energy security.

This fuel is a requirement for the pulsed fission engine.  So there is an interesting synergy there.  However, I beleive the engine is an absolute waste of the nuclear fuel, that costs something like 30 000$ per kg. 

[lamontagne]

From the request for proposal documents:

DOE projects that more than 40 metric tons of HALEU could be needed before the end of the decade, with additional amounts required each year, to deploy a new fleet of advanced reactors in time to supports the Biden-Harris Administration’s goal of 100% clean electricity by 2035.
Well, that's a short time frame!

Anyway, the fuel required for the ship is about the same value.  So that entire stockpile in burned in one trip.  Value of about 2,7 billion? 

[edzieba]

Anyway, the fuel required for the ship is about the same value.  So that entire stockpile in burned in one trip.  Value of about 2,7 billion?

Like with "asteroid worth [some obscene dollar value]" headlines, when you make huge changes to commodity demand the price cannot be linearly extrapolated.
For example, if there is a minimum possible size to make a HALEU plant (e.g. minimum viable process batch size) and the projected demand is near that size, then fixed operating costs dominate over raw material costs and doubling demand may only be an incremental overall process cost increase rather than a doubling - splitting per-unit cost in half. Likewise, that halved per-unit cost may make other projects more viable, further pushing up demand and dropping prices.

[lamontagne]

Anyway, the fuel required for the ship is about the same value.  So that entire stockpile in burned in one trip.  Value of about 2,7 billion?

Like with "asteroid worth [some obscene dollar value]" headlines, when you make huge changes to commodity demand the price cannot be linearly extrapolated.
For example, if there is a minimum possible size to make a HALEU plant (e.g. minimum viable process batch size) and the projected demand is near that size, then fixed operating costs dominate over raw material costs and doubling demand may only be an incremental overall process cost increase rather than a doubling - splitting per-unit cost in half. Likewise, that halved per-unit cost may make other projects more viable, further pushing up demand and dropping prices.

Yes, but the quoted price for the new Haleu is 2,7 billion dollars in the government bid references.  I don't know what it cost before exactly, but it used to be 30 000$ per kg or so.  It seems to be an expensive process to enrich uranium to 20%.  There is some information earlier in the thread about the cost to produce Haleu, and why it is high.

40-60 tonnes is supposed to be for all the US reactors that use that product at the date of 2035.  My understanding is that for the moment the US gets its Haleu from Russia.  Hardly a good strategic situation.  Apparently, it will take three suppliers to deliver the required quantity. 

[InterestedEngineer]

Anyway, the fuel required for the ship is about the same value.  So that entire stockpile in burned in one trip.  Value of about 2,7 billion?

Like with "asteroid worth [some obscene dollar value]" headlines, when you make huge changes to commodity demand the price cannot be linearly extrapolated.
For example, if there is a minimum possible size to make a HALEU plant (e.g. minimum viable process batch size) and the projected demand is near that size, then fixed operating costs dominate over raw material costs and doubling demand may only be an incremental overall process cost increase rather than a doubling - splitting per-unit cost in half. Likewise, that halved per-unit cost may make other projects more viable, further pushing up demand and dropping prices.

I wish you could persuade Congress of this when they go cancel programs that are barely up to production levels (F-22, etc, etc)

[Nomadd]

 I don't go to theaters much, but I'd make an exception for Footfall.

[StraumliBlight]

60 Minutes had an interesting section about Centrus Energy [9:14], which is the only US entity that produces HALU.

Their Ohio site currently has 16 40ft tall centrifuges and they're planning to build 11,000 more in the next 6-7 years as part of the transition away from Russian enriched Uranium imports, that goes into full effect in 2028.

[edzieba]

I don't go to theaters much, but I'd make an exception for Footfall.

Dangit Nomadd, you got my hopes up for seeing ol' Putt-Putt on the big screen!

[lamontagne]

Don't think we'll be fueling up many pulsed propulsion engines with those kinds of numbers...