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Project Heavy Metal

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PART I: History & Heavy Metal I

Takin' A Ride on yo momma


Iverican research for nuclear power plants began in 1950. Two of these projects would be for a shipboard marine reactor. These two pioneering projects would serve as the wurlds first attempt at marine nuclear reactors. Two developments precipitated the expansion of Iverican research of designs for power generation. First, the success of the since-decommissioned atomic weapons programme (1947) and second, the successful test of the first Generation I land-based reactor prototype by the Leon Technical Institute (1954). Tentative steps taken by these programs lent confidence to the Armada Division of the Oficina dei  Teqnologia Militar (OTM) or Office of Military Technology, who completed preliminary research in 1956 and released a whitepaper in 1958. The joint Parliamentary-ExecMin Armed Service Technology Committee (ASTC) reviewed and approved the whitepaper in 1959. A year later, seed-funding was issued to draft and design a Pressurised Water Reactor using alloy cased 5% enriched Uranium-235.  The OTM designated the project and its team "Project Heavy Metal".


Diagram of a Pressurised Water Reactor


The design was to power a direct steam turbine drive with a power output of 20 Megawatts. The drafts went through several phases of review and re-drafting. By 1962, the Armada Design Office asked the Heavy Metal team to create an additional submarine reactor design based on the positively-received initial drafts. After expanding the team and securing more funding from the ASTC, the project team spent two more years designing both concepts. In 1964, Heavy Metal revealed its two design results.

The first design was created as a surface ship reactor with a power output of 15 MW. Designated Heavy Metal I (HM1), it was almost identical to the preliminary draft save for an added turbo-electric transmission. The reactor was a large cylindrical object measuring 9.2 metres in length and 3.6 metres in diameter. It had to be transported via train car and took 94 hours to install onto the test ship. Two reactors were installed on the test ship VRI Ventura, each powering electrical systems and separate shafts. Testing was completed in coastal Providencia, the Narvic Sea, and the North Adlantic Ocean in both calm and stormy conditions. Safety testing for emergency shutdown, meltdown contingencies, and "cold-starting" was also conducted. 



Heavy Metal-1 during land-based testing, Subic Naval Yards, 1964.

The second design was a submarine reactor with a much smaller core and an output of 10 MW. It used fewer fuel rods and had mechanical & pneumatic mechanisms to protract and retract several boron-cadmium control rods. This was a necessary feature to counteract the predicted instability and forces the reactor would experience. It was a given that if the submarine rolled 180 degrees, gravity-reliant control rods would not protract into the core effectively. The design was more compact overall, however, it used a direct steam turbine propulsion due to space constraints. Though this submarine reactor design passed review, only a model was built. The team had intended to create the submarine reactor prototype but was unable to when the Ministry of Defence withdrew funding in November of 1966.


In May of 1966, the Iverican Banking Industry collapsed due to the default of the Nou Stille Bank of Commerce. Government priorities were re-assessed and most speculative projects like Heavy Metal were cut from funding and suspended. A chain of defaults in financial and banking industries forced the government into bail-out situations which caused much of the Ministry of Defence's total budget to be cut. Faced with the prospect of liquidating military assets or cutting development, the MoD chose to implement a moratorium on nearly all active projects in development.


While overall, the project and its first design were successful, there remained issues and concerns. Particularly, instability in the reactor caused by poorly enriched U-235 and an inadequate pressure system caused several supercritical surges during testing. Steam build-up improperly dispersed in the system resulted in a weakness forming in the turbine housing after 1460 hours of uninterrupted testing. Graphite used as part of control rods were also found to have contributed to the instability. For the most part, tests were forced to run the HM1 Reactor with control rods partially inserted. Often, this resulted in subcritical performance. Cold restarts were frequent after prolonged running and after supercritical surges. Long idle periods followed the shutdown as the Xenon neutron poison generated as a byproduct had to be cycled out with the old coolant water. As a result, HM1 only met its endurance test goal of "2190 hours in continuous operation" once during its 12-month testing period. Previously, the HM team projected that HM1 would likely remain stable and active throughout the entire 12-month testing period unless shutdown for other tests.


Before the Heavy Metal Project was suspended indefinitely, the team managed to release a research report detailing the test data, conclusions, extrapolations, and recommendations. Chiefly important were the recommendations to redesign the pressure management system and for future teams to have full oversight on materials procurement. The research levied much of the blame on HM1's performance on the OTM's insistence on enriched uranium not approved by the Leon Technical Institute and on the use of graphite components. 


When the project was suspended, records were sealed and classified. Though the OTM targeted January of 1970 as a tentative date for the resumption of testing, the outbreak of the Second Argic War in 1968 resulted in much of the team being recruited into different programs. The Ministry of Defence prioritised missile technology and nuclear weaponry during the war and shelved the Heavy Metal project indefinitely. The project would not be broached again until the end of the war--when the United States of Prymont purchased Heavy Metal research data and designs for an undisclosed amount. It is widely believed that the research data assisted in the creation of Prymont's much more efficient, stable, and safe Marine-1V surface ship reactor and Marine-1S submarine reactor.


SRBM shot down during the  Second Argic War


Less known, but significant consequences of Heavy Metal's suspension were felt by the Republican Armed Service of Iverica. Particularly, the design of the Republica Class aircraft carrier, the Mavini B-Class light carrier, the Sicario class fleet submarine, and the Domitor Class guided-missile submarine. All four classes had been designed with nuclear propulsion in mind. The Armada Iverica had proactively commissioned the design of these vessels under the presumption of Heavy Metal's success. All 4 designs were drafted at significant expense and were likewise suspended until they were redesigned for diesel-electric power plants. It would be at least a decade before any of the 4 intended-to-be-nuclear ships were built.


Inevitably, the risks involved and the political climate surrounding the project caused the OTM and the ASTC to lose impetus. When the Prymontians made their M-1 series of reactors available for allied purchase in 1980, the ASTC rejected pending proposals to restart the Heavy Metal project and simply approved the purchase of the M-1s instead. It would take 20 years for the politics surrounding the project to change. In this time 2 reactor related incidents are believed to have caused the loss of one submarine and caused severe damage to another. 


By 1991, Project Heavy Metal 2 was approved with some of the original members of the pioneer team leading a research and development program with nearly twice the manpower and funding. This time, the project lead's friendship with the then-newly elected Defence Minister, Ricardo Ibanes, is believed to have contributed to the carte blanche the HM2 team had over materials.



Early Reference Diagrams for "Heavy Metal II", later designated as "Mk. II" 




OOC: OwO Iverica, wuts this then slut? This is my attempt to have a go at nuclear energy development, though focusing on nuclear marine reactors here. I'm going to try maybe 3-4 part RP to establish historical context, challenges, and innovations. Bear in mind this is undertaken because Iverica's tech-level and economy checks out for this kind of project.

I'm thinking Part II will talk about Mk. II and Materials: including enrichment and progress made with the reactor design. Part III or Part IV may include an anecdotal story. The last part will talk about the currently in-development Mk. III HEU reactor with @Gallambria.

There's also an Easter egg. Finding it will earn you one afterlife Lamborghini from yours truly.

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  • 3 weeks later...

PART II: High-Assay, Electric Drives, & Heavy Metal II


With the carte blanche the team had, research for Heavy Metal II was substantially faster. By 1992, the team had drawn up a far more ambitious design for nuclear marine propulsion. It borrowed heavily from the time-proven elements of the Prymontian reactor and drive system but with substantial advancements planned.

First, the fuel rods to be used were planned to be made of a higher percentage of Uranium-235. Second, control rods and their systems were also redesigned and were outlined to be made of much more stable materials. Third, improvements to the mechanical drive system were also made. Though still a purely mechanical system directly connected to the steam turbine, improvements were made to the transmission, cooling, and pumps- all improvements that reduced the system's acoustic profile.


New Fuel

The design passed review. However, there was one issue. Inspection of fuel rods produced domestically yielded a dubious evaluation. HM Team members were not satisfied with the enrichment process and the overall quality of the fuel rods. After 3 months of indecision from the Ministry of Defence, the HM team obtained clearance to reach out to the @Gallambrian Government. Discussion and red tape delayed the team a further 9 months. At last, in 1993, several test rods were obtained. Concurrently, Gallambrian consultants were also brought in to assist with the creation of a new enrichment facility in Léon Province. The aim for the facility was that it was to eventually produce fuel rods ranging from 10%-15% U-235.

At that time, the Gallambrians had also been developing improved processes and more advanced Zippe-type Centrifuges for extracting U-235 from the base U-238. In February of 1993, both governments approved a joint research and development program that would venture into a new process of enriching Uranium. Researchers from both nations eventually pioneered an electrochemical process in which still-irradiated fuel from research reactors and active power plants were treated in a salt chemical bath before using an electrolysis-like process to shed impurities from the enriched Uranium. At that stage, the output is very small amounts of Highly Enriched Uranium which is further processed chemically and then physically through a centrifuge. The HEU is then diluted with lower enriched Uranium and then cast in a high-temperature furnace.

The output was classified as High-Assay Low-Enriched Uranium (HALEU), the percentage was significantly higher than most reactor-grade rods of the time. The decision to venture into higher percentages was attributed to both governments' long-term aims of efficiently producing weapons-grade Uranium. At the time, the short-term goal for the HM team was to simply lengthen service life and increase reactor efficiency. Higher percentages effectively meant reducing the rods in the design. HM2 was designed with only half the scale and fuel rod bundle of HM1 but was projected to have more than 5-times the nominal output of HM1.

The facilities would take 3-years to construct. In the interim, the less-efficient centrifuge enrichment process was used to produce a limited number of test rods. In 1996, the first HALEU rods were tested in a land-based test reactor in Léon.

During the R&D process, the HM team also produced a supplementary research proposal regarding the incorporation of Zirconium extraction into the enrichment process.

The HM team had spent the interim productively. Throughout the year they completed several new control rod sets, a scale reactor model on test submarine SSN(X)-049, and completed the installation of the new drive system on submarine 049. The functional drive system was also tested with a temporary battery and electric turbine. Materials for the HM2 reactor unit, coolant system, pressuriser, and steam generator, had all been procured with most systems already in place when the finished reactor unit arrived in the winter of 1993.



Nuclear Fuel from pellet to bundle


Moderators and Control Rods

The new control rods no longer had any graphite elements. It was discovered that the use of an additional moderator, like graphite, in a Pressurised Water Reactor (PWR) was redundant and caused instability while providing little only marginal efficacy in neutron moderation versus the light-water system already in place. The control rods with graphite elements had only been used as a cost-saving measure- as they had been excess rods used to test a Boiling Water Reactor (BWR) prototype. At that time, the HM team had no access to research on how graphite might have affected the HM1 prototype. 

Furthermore, a Silver-Indium-Cadmium alloy rod design had been chosen in favour of the previously used High-Boron Steel. This was chosen for 2 reasons. First, the alloy rod was projected to have a longer service life compared to the Boron rods. The design had far better corrosion resistance and would more than survive the projected service life of HM2. Second, advances in alloying technology and production efficiency in Iberic metal-working facilities resulted in cost estimates for the alloy design being significantly lower than the enrichment process for Boron rods.

Concerns were raised in 1999 after testing resulting in some Ag-In-Cd control rods failing. Failure occurred at temperatures between 1470 and 1600 Kelvin. Despite the fact that failure only occured at more than 4-times the critical temperature inside a reactor, the Heavy Metal team took no chances and recommended a replacement design. After the test, future rods featured improved zirconium-alloy guide tubes treated and oxidised.


The Alloy Rods after being tested to failure

Other Systems

One of the most noticeable changes was the relative reduction in space taken up by the reactor housing and the cooling system. The reactor was to be significantly smaller measuring approximately 4 metres in length and 2 metres in diameter. 

All cooling pumps had been removed in favour of static heat exchangers to be used in a new Natural Circulation Cooling system. Much of the piping was also improved from the HM1 steam turbine design. A newer 17-7PH tempered and rolled stainless steel was used, resolving previous pressure-resistance issues and increasing corrosion resistance.

Advancements in precision tooling brought about by the growing role of computers and automated machining had greatly reduced the error margin in the sets of test components ordered. This was most noticeable in the reduction of noise from the operation of the mechanical transmission. The greater precision had also reduced the noise created by the entire system of the drive shaft, gearbox, differentials, final drive and variable pitch screw. 

A pumpjet propulsion was also added to increase cruising speeds and manoeuvrability while maintaining a relatively low cavitation during operation. This measure was included alongside a 7-blade variable pitch screw design, vortex diffuser, and shroud.


SSN(X)-049 nicknamed, "Lead Zeppelin", in drydocks.


By late 1993, the first test unit, which used Gallambrian fuel rods, was ready. It was installed on SSN(X)-049 in January of 1994 and was successfully started while 049 was held fast in one of the covered berths of the Subic Naval Yards. After a week-long battery of tests that simulated cold-start, shutdown, scram, and operation at different loads, 049 was allowed a test voyage while surfaced. She cruised approximately 1,235 kilometres to Manille and reached her governed and surfaced top speed of 19 knots. At Manille test data was reviewed and it was determined that HM2 and its drive system were much more stable than HM1. 049 was cleared for further testing. In March, she completed a 6,000 km voyage to the Ultramares and back to Subic. Approximately 5,000 km of the voyage was conducted submerged and flank speeds were also tested for prolonged sprints.

HM2 was tested for a further 25,000 km over the year, in which it spent most of the time active. During testing, HM2 never reached supercritical levels outside of simulations. The design had passed with flying colours. A stark contrast to the issues which hounded HM1.

At the end of testing in 1995, HM2 was rated for a nominal output of 52 MW. She was to use fuel rods of 10% enriched uranium was controlled by 80% silver, 15% indium, and 5% cadmium alloy rods. Graphite had been written out as a moderator in light of the HM1's post-test research report. During testing, HM2 and its drive system took SSN(X)-049 to speeds of 19kn surfaced and 23kn submerged. Run normally, it was estimated that the HM2 could run at 7-10 years before refuelling and overhaul (ROH). In hindsight, engineers suggest that most HM2 equipped subs could have run for longer. For safety reasons, this was never tested. All HM2 subs were required to undergo ROH during their 7th year.

The test submarine was later commissioned and redesignated SSN-049, Prometeo but not before facing extremely stiff opposition. The Heavy Metal team unsuccessfully but vigourously petitioned the Armada to name the ship and its class the "Lead Zeppelin" (which had been the accepted nickname through its entire test life), the "Black Sabbat", or the "Iron Lady".



SSN-049 breaks through ice in the Argic Circle during a test voyage.



Still unsatisfied with the design of the propulsion system the HM2 team petitioned and was cleared to create an improved system just 2 years after HM2 entered production in 1997. The team designed and built a reactor dubbed HM-2E, a reactor with 3-times the nominal output using 15% HALEU.

The design goals were primarily higher output and the incorporation of newer electric drive systems. The HM2's pressuriser, generator, and cooling systems were not changed. Instead, minor changes were made to the reactor and newer fuel rods. These rods were the first batch produced from the recently-completed Léon Nuclear Materials Facility.

The most visible changes were to the drive system. The turbine now powered a turbo-electric system which powered an electric motor. This switch greatly reduced the number of mechanical parts and reduced the total area the system took up in the compartment. This space allowed for the installation of several batteries. These were charged from the spinning turbine and motor shaft and would serve as an auxiliary power unit (APU). 

The overall effects of this modification were startling. The test submarine had a far quieter acoustic profile due to the removal of most mechanical elements in the drive system. The turbo-electric system, combined with the electric APU meant that submarines with this propulsion system could reduce the turbine rate and switch mostly to battery APU, allowing for extremely quiet operation. Additionally, newer submarines using the HM2E, redesignated Mk. II-E could achieve governed speeds in excess of 28 knots submerged.




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Part III - Beyond Diffusion and Centrifugal Enrichment

The Background

While development of centrifugal enrichment technologies continued throughout the early and mid 90's, Gallambrian scientists at the Gallambrian Atomic Energy Commission (GAEC) looked further afield for more economical and higher quality enrichment technology. In a 1994 thesis, Dr. Anthony Hargraves and Dr. Isabella Sabin from GAEC suggested that preferential excitation of ²³⁵UF₆ using a pulsed laser operating at 10.8μm optically amplified to 16μm was more economical and yielded higher results than the more traditional methods of laser-based enrichment.

Testing of the technology began in earnest in the early 2000's by GAEC and its successor agency, the Gallambrian Nuclear Science & Technology Organisation (GNSTO) in order to confirm the theories of Hargraves and Sabin. Small batch tests were ran at pulse rates of 50-60Hz, which showed that at low rates there was considerable inefficiency. While testing continued over the coming decade, tests were ran on a bigger scale, which lead to developing the parameters and setups needed to produce high levels of highly enriched ²³⁵U.

It was found that using the cascading interconnection model, higher enrichment levels were achieved when moving up the cascade. Where, when the batch recycling model was used, it was found the 90% HEU could be developed faster, but drawbacks were discovered. It was discovered with the batch model, that when the feedstock's enrichment factor was at or around 2, 25kg of 90% HEU was acquired in 8 Stages, however this model required 49,382kg of 3.5% uranium feedstock. This equates to to approximately 42kg per kg of 90% HEU.


The Outcome

With Gallambria's growing population, and heavy reliance on a already constrained coal-based system, The Gallambrian Government along with GSIRO and GNSTO, in 2009, approved the development of a commercial refinement program utilising the Hargraves-Sabin Laser Enhanced Isotopic Separation (LEIS). It was projected to be able to generate 2,500 tonnes of 42% HEU per year given their submitted plans and approved designs.

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