The ORNL X-10 reactor (CC-SA Ɱ)

Hanford B plutonium-production reactor (LOC)

• In 1946, Walter Zinn designed a proof-of-principle for breeding
• It was thought that uranium was very scarce, so breeders would be the only option for economical civilian power.
• EBR-1 was hooked to a generator and made the first significant amount of nuclear electricity
• It also proved that a conversion ratio >1.0 was possible
  • They didn’t consider it a true breeder because it used U-235
• Had a core melt in 1955, repaired and ran for another 9 years

The EBR-I (AEC)

The LITR, the 1st water-cooled/moderated reactor (CC-BY-2.0 ORNL)

The 40 MWt MTR (AEC)

• Experienced and extremely hard working submariner
• Worked in engine rooms, on electrical systems, and in logistics/supply
• Sent to ORSORT in 1946, took charge of Naval Group
• Ridiculed by AEC leadership for thinking sub could be built quickly
• Maneuvered politically to get authorization
• Developed Zirconium industry
• Later built Shippingport, chose UO₂ fuel
• Famously mean, but also famously revered by sailors
• See Rickover on 60 Minutes at age 84

Admiral Rickover, 1955

Prototype submarine in Idaho

Launch of USS Nautilus (1955)

• Intended to be 1st industrial/commercial power reactor
• Sodium-cooled, beryllium-moderated: intermediate-speed neutrons
• Supposed to breed and make commercial power
• On April 15, 1950, was repurposed as a submarine prototype because:
  • Technical challenges
  • Darkening relationships with the USSR
• Ended up as the S1G, the prototype for the USS Seawolf SSN-575
• Large dome at Kesselring site, West Milton, NY remains (KAPL)
• Made USA’s first commercially distributed electricity

The Knolls Intermediate Power Breeder (AEC)

APEX-901

An actual test of a nuclear-powered jet engine in Idaho, called HTRE-2

Aircraft Reactor Experiment

The NB-36 (NTA) with ASTR onboard

The ASTR and flight cabin sans airframe

Intended to power remote areas

• SM-1 at Ft. Belvoir
• PM-1 in Wyoming
• PM-2A in Camp Century ice base
• PM-3A in Antarctica
• ML-1 Truck-mounted mobile
• SL-1 in Idaho
• SM-1A Fort Greely, Alaska
• MH-1A floating barge in Panama

ML-1 field test in Idaho

PM-1 being sent to Wyoming

• 1 MWe portable PWR
• Manufactured and tested in a factory,
• Disassembled into 16 modules,
• Air-lifted to the closest airfield by C-130
• Trucked to site, re-assembled
• Direct air cooling, (no water supply)
• No field welding was needed for re-assembly.
• Could be operated by a crew of 2.
• Awesome film summarizing it

PM-1 fully assembled in Wyoming

• The reactor was difficult to perform maintenance on because of its compactness. The operators recommend designing the next microreactor with maintenance requirements satisfied first, and then compactness requirements
• The conventional steam plant cause roughly half of the unplanned outages and required a lot of maintenance, leading the authors to suggest that perhaps a non-steam approach is needed at this small scale (e.g. other energy conversion systems).
• The nuclear instrumentation system was oversensitive and overcomplicated for a field plant.
• The HVAC system and building design were wholly inadequate
• It was difficult to maintain qualified staff to operate and maintain the reactor
• The reactor was used as a training reactor for crews headed to Antarctica to operate the sister plant PM-3A, which reduced PM-1’s overall performance.

PM-1 Final Summary Report

• Offset 21 million liters of diesel for electricity and water distillation
• 434 malfunctions
• 221 health physics reports, 14 needing outside medical attention
• 99 plant modifications made
• 2 officers and ~20 enlisted to operate/maintain is too many!
• Chloride stress corrosion cracking found, decision to remove reactor
• Shielding with local backfill can be a problem due to activation
• Couldn’t compete, even in the most remote of areas

See Final Operating Report for PM-3A

PM-3A in operation at McMurdo Station (Source)

• Minimal assemblage of fuel/coolant/moderator/control
• Used to check basic nuclear characteristics against theory
• Room temperature
• Very low power (<10 W)
• Often reconfigurable
• Often used to support final design (e.g. rod worth curves)
• Diminished need due to robust nuclear data and radiation transport codes

• Facilities in which most public research on radiation occurred
• Over 800 built, listed in the RRDB
• Swimming pool type
• Aqueous Homogeneous (L-77s)
• Teller-inspired TRIGA became popular

A batch of AI L-77s, ready for crating

• Fluid fuel: uranium sulfate
• Ran at ORNL in 1952
• Expected to be simple and compact
• Kept burning holes in containment
• Holes were repaired, but concept was abandoned
• Incredible 1961 film of how they repaired the hole

• Is it possible to operate a core with boiling water?
• Experiments ran at National Reactor Testing Station, starting in 1953
• BORAX-I exploded at end of life (to test limits)
• After small success with BORAX-1 larger BORAX-2 was built.
• Re-designated BORAX-III with the addition of a turbine
• Powered town of Arco, ID
• Formed basis for BWRs
• Some destructive test film

• Molten salt fluid fuel
• Ran at ORNL in 1954
• Expected to be compact and very high power density
• Intended for nuclear-powered bomber
• Ran for 4 days
• Got leak, they blew fission products into the forest to the south
• I wrote the Wikipedia page on it (inspired by Prof. R. Fleming)

• High temperature reactors coupled to jet engines in 1956
• Developing nuclear-powered flight for long-range bomber
• Ran in Idaho
• Never flew
• Can be seen in parking lot of EBR-1 museum
• See APEX-901

• Sodium metal coolant, graphite moderator
• Started in 1957
• Expected to make economical power
• Low pressure, high temperature, LEU fuel
• Near LA
• Prototype for Hallam reactor
• Suffered core melt
• Very cool construction photos

• Terphenyl coolant/moderator
• Low pressure, high temperature, low corrosion, chemically inert
• Ran at the NRTS in 1957
• Expected to lead to low-cost commercial power
• New film coming soon!

• Helium gas-cooled reactor with UC₂ fuel coated with 3 layers of pyrolitic carbon
• 2400 °F coolant temperature
• Elemental carbon structure
• Run at LANL from 1959-1971
• Spin-off of Project Rover (nuclear rocket)
• Rotating core loader
• Un-clad annular porous carbon extruded fuel elements
• Remote online refueling

• High-pressure uranyl phosphate solution fuel
• Highly-enriched uranium
• Would have made 10-50 MWe compact reactors
• Remote power for military bases
• LAPRE-II started in 1959
• See e.g. LAPRE-II (1960)

• Molten Plutonium-Iron alloy fuel in tantalum tubes
• Developed for fast breeder reactors
• Ran in 1960
• In-situ reprocessing
• See LAMPRE I FINAL DESIGN STATUS REPORT

• Nitrogen-cooled
• Supported the truck-mounted Army reactor
• 1962

• Lifted the ORNL Health Physics Research Reactor
• Went up 1500-foot tower
• 1962
• A small Japanese village was built at the bottom
• Tower provided information on neutron dose from elevated sources on tissue

• Nuclear-powered rocket for space propulsion
• Liquid-hydrogen cooled
• NRX-A2 ran in 1964 for 6 minutes, and then 20 minutes

• Follow-up from the ARE
• Focused on commercial power potential
• Ran at ORNL in 1965
• Formed basis for Molten Salt Reactors
• Developed an entire program plan for MSBR (ORNL-5018)

• Congress was concerned about falling behind UK and USSR in power reactors
• Rickover was put in charge b/c he could get stuff done
• Dev program tried various fuels, settled on UO₂ with zirconium clad
• Nuclear design by Bettis: HEU seed with NU driver
• Fierce opposition b/c LWRs are inefficient with uranium resources
• Had 2 B&W U-tube SGs and 2 Foster Wheeler straight-pipe SGs
• Critical on December 2, 1957, cost $72.5M
• Open design: all details published at Geneva 1958
• Operated reliably
• 10x more expensive than an equivalent fossil plant

Construction of a boiler chamber in the Shippingport PWR (from Library of Congress)

• Major AEC program started in 1955
• Focus on advanced reactors most likely to achieve economic parity with coal
• Government benefits:
  • waive fuel usage fees
  • perform pre-construction R&D
  • subsidize post-construction R&D
• Intended to inspire private investment in nuclear
• Three main rounds
• Round 1: applicant would fully fund, construct, and operate nuclear and turbine island
• Round 2: focusing on rural utilities, applicant built turbine island; AEC built nuclear island and offered option to purchase

• Consortium of New England utilities came together to propose
• AEC selected under round 1 PDRP
• Constructed by same team as Shippingport
• On time, on budget
• Operated beautifully

Film: Operating Experience Yankee Rowe (1964)

• Consortium of 23 utilities came together to propose
• AEC selected under round 1 PDRP
• More expensive than expected
• Many operational challenges
• Core melt and recovery
• Shut down early due to abysmal economic performance
• Generated roughly 13.5 EFPD total

• Small utility in Nebraska
• SGR concept appeared highly likely to be economical (low pressure, high temperature, low enriched fuel)
• Literally shared a turbine with a coal plant
• Leaking moderator cans caused operational outages
• Utility declined to purchase
• Coal plant is still there today
• Cool historical films online

Film: The Hallam Reactor (1964)

• Proposal from Rural Cooperative Power Association with newcomer constructor
• Many arguments with contracting
• Municipal reactor in tiny town
• Natural circulation
• Entire control system replaced (single channel -> multi)
• Reactor vessel reworked
• Plant ran for 4 years, but was leaking primary coolant
• When shut down to find problem, repairs deemed too expensive
• Plant was decommissioned, converted to fossil in 1968
• Building torn down around 2021

Film: Nuclear Energy Goes Rural (1963)

• Municipal reactor in tiny town
• Town initially hyped about it: dubbed itself the Atomic City
• Another promising concept: low pressure, high temperature
• Lots of operational and reliability challenges
• Town declined option to purchase
• Shut down early

• Built near Sioux Falls, SD
• Consortium of investor-owned utilities
• Goal was to get practical experience operating a nuclear plant
• Longest run was 30 minutes
• Ran for about a year, had accident in 1967, decided to abandon
• Now a 327 MWe gas plant runs on the site

• Third-round PDRP reactor, proposed by group of 4 utilities
• First US power reactor with heavy water
• 1.5-2% enriched uranium, 65 MWe
• Produced saturated steam, which was fed into an oil-fired superheater
• Operated from 1963-1967 with 78.14% availability
• Co-located with coal AND hydro plants!
• AEC paid $11.3M, industry paid $32.1M
• Power was uprated, but 3 of 4 test assemblies failed
• See Willoughby 1967 or Nath 1967 (neutronics benchmark anyone?)

Co-located coal, hydro, and nuclear, thought to be unique worldwide.

• Advanced BWR: Increased thermal efficiency
• Allowed use of off-the-shelf turbine
• Increased corrosion and fuel failures
• Costly repairs and modifications
• Technical difficulties led to shut down in 1968
• Digitized film on Youtube

• Unsolicited proposal by Philadelphia Electric Co. and other utilities
• Ran from 1967 - 1974
• First HTGR in USA
• 37.2% thermal efficiency
• 538 °C superheated steam at 10 MPa
• Capacity factor 74%
• Uneconomical to operate alongside GW-scale neighboring BWRs because it was too small
• Major retrofit was required to meet revised safety criteria

• Joint proposal from Consumers Power and GE in 1959
• Fun promotional film ft. Ronald Reagan
• World's first direct cycle, forced circulation, high power density BWR
• Constructed in 29 months for $27M
• Ran beautifully, shut down in 1997
• 9 miles from my mom's house
• Film: Head Start on Tomorrow (1962) ft. Ronald Reagan

• Co-located with coal-fired Genoa Station #3
• Forced-circulation, direct-cycle BWR
• Constructor, Allis-Chalmers, struggled to deliver it due to various problems; was initially 4 years late
• Contracted under 2nd round terms, though far past deadline (1961)
• Expected to give useful technical info about medium-sized BWRs
• Ran until 1987, when it was deemed too small to compete economically and decommissioned

NRC photo

• Southern California Edison-Westinghouse joint proposal
• More than 2x the size of Yankee
• Forced-circulation, direct-cycle BWR
• An extra containment was built around the dome later
• Ran well until 1987, when it was deemed too small to compete economically and decommissioned

San Onofre 1 (DOE photo)

BWR dev pathways (from ORSORT)

The key to Dresden

The inherent characteristics of sodium reactors make the SEAWOLF propulsion plant expensive to build, complex to operate, susceptible to prolonged shutdown as a result of even minor malfunctions, and difficult and time consuming to repair. These facts clearly demonstrate that sodium is less desirable for naval reactors than pressurized water.

Saint-Laurent Nuclear Power Plant (CC-BY-SA Clicgauche)

Gravelines PWRs in France (AREVA image)

Smolensk NPP (CC-BY-SA Originaldatei)

Balakovo (CC-BY-SA Seetenky)

• Atoms for Peace showcase
• Launched in 1962, went to Seattle World's Fair
• The NS Savannah film (1964)
• Traveled 450,000 nautical miles
• Visited 45 foreign and 32 domestic ports
• Visited by 1.4 million people
• Low cargo capacity
• Streamlined design didn't work well with new automated ports
• Deactivated in 1971
• Sitting in Baltimore now, awaiting purchase or scrap

NS Savannah in Seattle, 1962 (MOHAI)

• Twin Be-moderated Pb-Bi cooled reactors
• Launched in 1962 with a crew of 144,
• Leaky seals caused impure primary coolant
• Flow blockage: overheat, power reduction
• Rods pulled anyway, melting fuel
• Liquid fuel entrained in primary loop
• 9 fatalities from ARS
• See Zrodnikov, 2000

The ill-fated K-27

• 5x more power than ML-1, still on a truck (2.2 kWe)
• HEU fast reactor
• Enriched lithium-7 primary coolant
• Enriched potassium-39 reflector coolant
• Sodium secondary coolant
• Three EM pumps
• FT-12 jet engine power conversion
• Control drums
• Weirdly written into 10 CFR 3 Part 725
• Competed with potassium metal turbine systems like SNAP-50/SPUR

The LCRE system, from CNLM-5170

3000 lbs. reactor with a 78,000 lbs. DU/LiH shield

• 500 Watt nuclear fission reactor in space
• Uranium Zirconium Hydride (TRIGA) fuel
• Electromagnetcally pumped NaK
• Rotating control drums
• Thermoelectric power conversion
• Ejected reflector after 43 days of operation
• Still up there!
• There were also 31 USSR RORSATs in space

Print showing SNAP-10A

• Offshore Power Systems JV between Westinghouse and Newport News
• Partially built a nuclear reactor gigafactory in Jacksonville, Fl
• Got manufacturing license from NRC to build 8!
• My writeup with details

The Manufacturing License!

The SER

• Natural safety without backup systems
• More practical to finance (smaller)
• Decarbonize hard-to-decarbonize sectors
• Industry
• Shipping
• World-scale million-year+ sustainability (breeding)
• Waste processing/reduction

But...

• There are lessons to be learned in initial construction and scaling
• New reactor development is hard and slow

A small reactor (ANL)

• Advanced large LWRs
• Modular construction
• Simplified systems
• 72 hours without backup power
• Digital instrumentation and control
• ABWR, AP-600, AP-1000, APR-1400, Hualong 1, VVER
• Small water-cooled reactors
• Modular delivery and/or construction
• Depends on economies of mass production exceeding economies of scale

An AP1000 advanced reactor (Westinghouse)

Pros

• World-scale sustainability
• Waste processing/reduction
• Natural safety
• High thermal efficiency
• Industrial heat

Cons

• Higher fissile concentration
• Chemically reactive coolants
• Extra costs from extra coolant loops
• Plutonium scares people

Fast reactor history (adapted from Walter, Fast Breeder Reactors)

• Plentiful in India and China
• Used in Indian Point initial core
• Works well with fluid-fuel reactors
• China about to turn on a new experimental Thorium Molten Salt Reactor called TMSR-LF1
• Does not completely eliminate proliferation or waste issues

The TMSR-LF1 in China (WNN)

• Much less radioactive waste
• No afterglow heat to cool
• Many highly-funded startups catching headlines
• Extremely challenging physics
• Mostly unknown power conversion
• Often necessitates tritium breeding
• Often a powerful neutron source
• Worth investigating, but lets not rely on it