Train-World: Feasibility of radioisotope steam-electric engines

...It's paradox. They left us these technological marvels, yet with all their might and knowledge they failed to prevent their own doom...

Excerpt from a lecture by the High Historian of Berlin Falls

Welcome to a future. Mankind has brought doom upon themselves, their cities have been flattened by war and weather, and most of the northern hemisphere is radioactive badlands.

They've managed to avert revert global warming, in the process creating a global society of an unprecedented scale. Air-travel got reduced to the bare necessities, and the railways underwent a renaissance.

Closed stretches of track & stations all over Europe got reopened. Lines between bigger cities got extended to rail-arteries¹. These arteries expanded to stretch all along the northern hemisphere, even connecting Berlin to Boston.

Arteries:
 - Central Europe, Russia, Kazakhstan, Beijing, Bering-Strait, Chicago, Boston
 - England, Central Europe, Spain, Gibraltar, Morocco
 - Kazakhstan, Afhganistan, India
 - Beijing, Hong-Kong, Thailand, Indonesia, Papua New Guinea, Sidney
 - Beijing, Korea, Japan
 - Chicago, Mexico, Colombia

Due to the lack of electrification of rails on the American, African and Australian continents scientists and engineers spent considerable efforts into advancing emission-free alternatives to diesel-electric engines.

A break-through was achieved in the field of SRG & RTG technology. Taking a hint from space-engineering, Radioisotope Heater Units (RHU) were expanded in size to serve as continuous heating elements in the boilers of steam-electric engines - these engines would then be used for trains and ships.

A typical train-engine would consist of a boiler in which 5 RHUs (~6 tons of Radium per unit²) superheat water or another conductor fluid in a primary fluid-cycle. Through conduction the heat in the primary cycle is used to superheat water to steam in a secondary water-cycle, which is then used to drive a turbine³ producing electricity.

┌─────────────────────┐     ┌───────────────┐
│ ┌─┐ ┌─┐ ┌─┐ ┌─┐ ┌─┐ ╞══╗|╔╡ STEAM TURBINE │
│ │R│ │R│ │R│ │R│ │R│ │  ║|║└──────────────╥┘
│ │A│ │A│ │A│ │A│ │A│ │  ║|║   ┌─────────┐ ║
│ └─┘ └─┘ └─┘ └─┘ └─┘ ╞⛒╝|╚⛒═╡CONDENSER╞═╝
└─────────────────────┘        └─────────┘

Assuming ~168W per kg of Radium⁴ and an optimistic efficiency of ~50% this gets us ~2500kW usable energy. Or about ~500kW per RHU.

Q: Is this concept for an engine workable or are there game-breakers that I missed out on?

A good answer:

• addresses issues with the proposed design
• proposes solutions to the addressed issues

_{¹Lines with sections of up to 8 tracks next to each other in order to facilitate higher throughput. Sort of superhighways but for trains.
²Which results in cylinders of ~1m diameter and ~2m height (assuming we do not have to interleave the radium with too much other metal to get the heat out efficiently)
³Similarly to how a Nuclear Power Plant works, also known as Rankine Cycle.
⁴I've not too much knowledge in the area of nuclear physics, so I designed the described system based on the very helpful explanations I got from @kingledion on the chat.}

posted over 6 years ago

dot_Sp0T‭

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