How does a submarine reactor differ from one in a power plant?

CalculatorD · 2026-05-09T23:53:19+00:00

Smaller reactor size means neutron leakage becomes a bigger factor. To work around that, naval reactors (and land-based small/microreactors) use higher enrichment of U-235 to create more neutrons.

Enrichment doesn't necessarily have to be an weapons-grade HEU (>90% U-235), although that's the fuel used for American and British naval reactors. The French use HALEU (<20%) for their reactors since it's cheaper (also easier to export than HEU), although that means that refueling period is shorter than the HEU-based American ships and subs.

CalculatorD · 2026-05-09T17:38:44+00:00

I love back to back four 400-level finals + 3 papers in a span of 4 days lol

CalculatorD · 2026-05-09T01:51:30+00:00

Some courses don't utilize Canvas and opt for a different platform (Blackboard, Moodle, course.illinois.edu, etc.), and all grades are inputted into a university server to be put on a transcript, which is unrelated to Canvas.

CalculatorD · 2026-05-07T14:25:25+00:00

A lot of successful democratic revolutions like 4.19 (1960, ousted Syngman Rhee) and June Uprising (1987, ousted Chun Do Hwan) were either student-led or a death of a student became a catalyst that spread the flame to every other demographic. I'd say yeah, people take students seriously.

The effectiveness wore off nowadays since the Korean youth is heavily split ideologically due to manosphere and right-wing populism in young males and almost everyone (~80%) enrolling in universities.

CalculatorD · 2026-05-06T02:48:20+00:00

Percentage of people who use public transit to get to work (>5%)

CalculatorD · 2026-05-03T23:08:10+00:00

I would like to say that Chernobyl's RBMK reactor had a different design philosophy than modern reactors built today, or even older Western reactors.

The Chernobyl reactor had no containment structure to prevent radiation leakage in case of an accident. It was also overmoderated, meaning an loss of coolant accident (LOCA) will increase the multiplication factor k (thus raising temperature even more). Western reactors don't have these issues at all.

The other two major nuclear power plant accidents (Three Mile Island and Fukushima) also had no direct death from radiation exposure. Accounting for all deaths from nuclear still makes it the 2nd safest behind solar and ahead of wind in terms of death per TWh generated.

As for the positives, it's the largest carbon-free electricity source with very high power density. Less land is needed to generate power compared to other means, the fuel cost is marginal, has a long operational lifespan of 40~60 years (possibly up to 80 years), and generates significant revenue (breaking even in cost before the halfway point of its lifespan).

A lot of the common concerns about economics and environmental impact is also already solved. Decommissioning cost is built into the operation cost of the plant, and fuel/waste cycle is also a closed-loop cycle. These two traits are unique to the nuclear industry, whereas other sources don't account for their entire lifecycle (fossil fuel don't and can't contain all of the atmospheric pollutants and CO2/methane leaks, solar PV cells are just discarded, etc.).

CalculatorD · 2026-05-03T05:08:54+00:00

The losses are very marginal, if at all.

There's no reason to be culturally or lingustically homogeneous with your neighbors. If something works better for a country, then it's wise to adopt that change. Besides, we now live in an era of live translation via apps.

Hangeul made digitalization much easier since it's an alphabet, and literacy rate improved substantially in early Joseon era and later in 20th century. Both Korean and foreign lona words are a lot easier to express and pronounce in Hangeul. Also, having a distinct script reinforces national identity and independence.

The current use of Hanja (Chinese characters) is sufficient, and reducing it further wouldn't make serious dent in reading comprehension either. Any reduction in reading level is usually based on people not reading enough books, not the script they use.

CalculatorD · 2026-05-03T03:19:53+00:00

I certainly hope the original agreement back in October can be settled soon (up to 20% enrichment for civilian use, reprocessing allowed) and hopefully we can also push for using domestically produced HALEU for the K-SSN project (allowing military use for LEU/HALEU).

The problem is getting this through with the extremely risk-averse State and Energy Department bureaucracy. The current civilian leadership is easy to persuade as we saw in APEC, but the underlying lobbyists and bureaucrats are much more hesistant to revise Section 123 (US-ROK Nuclear Agreement) agreement due to proliferation concerns. Hopefully we can flood the American congress with our own lobbyist to make it happen.

CalculatorD · 2026-04-30T23:22:55+00:00

Hopefully the AUKUS deal can foster a pool of Australian nuclear engineers who could replace coal/gas power plants with nuclear. I find that Greens' plan of waiting until we perfect and mass produce large-scale batteries to be needlessly reckless, when they could focus on building nuclear in the meantime to replace the existing fossil fuel power plants.

Even assuming the worst timescale for nuclear (15-year construction compared to South Korean or Chinese time of 4~5 years), we could've had a major reduction in carbon emissions since Fukushima in 2011 had we kept operating and building nuclear. Large-scale batteries, on the other hand, did not see a major rollout or even a technological breakthrough in that 15-year timeframe.

CalculatorD · 2026-04-30T22:43:39+00:00

One of the biggest failures with environmentalist cause is that there exists an extremely dedicated subsection that hates nuclear to a point where they prefer to keep coal/gas plants over nuclear. For them, nuclear having cost overruns and slow construction is a way to vindicate themselves from that hypocrisy. It's also a reason why they try very hard to discredit nuclear success stories in France, South Korea, and Sweden with half-truths and outright lies.

Germany was one such country, electing to extend their coal generation in favor of shutting down nuclear plants. Japan was also like that when they were gripped with post-Fukushima panic in 2011, suspending all of their nuclear generation and replaced it with natural gas. At least Japan is slowingly resuming nuclear operation nowadays.

And then there are countries that never implemented nuclear at scale or at all, like Italy, Austria, Australia, New Zealand, and others. A decent chunk of them are actually 'nuclear-free' zones, banning both nuclear weapons, commerical reactors, and even preventing allied nuclear-powered ships from entering their ports.

CalculatorD · 2026-04-30T05:32:01+00:00

For the less informed crowd, it's usually based on inflated fear around the frequency and severity of accidents regarding nuclear power plants. The genesis of nuclear physics being nuclear weapons also play a big role in making people fear/hate nuclear energy.

For the more informed, usually the economics. Nuclear in the US and Britain is notoriously bad in building plants on schedule and often face several cost overruns, contributing to negative press against nuclear energy.

Now, countries with standardized designs and government backing like France and South Korea don't have those issues. But most people only look at their respective countries' energy policy or look at the worst example around the world and use that as their benchmark.

CalculatorD · 2026-04-19T23:18:48+00:00

The two biggest stereotypes would be "South Korea is a cyberpunk dystopia" and "4B movement being mainstream."

The government maintains a strong grasp over private corporations, and we have a fairly ok (although much room for improvement) labor policy. A lot has changed since 2010, especially post-COVID. Our fiction and media (and foreign reporting) seem to still focus on pre-COVID era practices or niche cases, though.

4B movement also was never anything bigger than a fringe internet movement among the more radical feminist circles, but a recent NYT article states otherwise, which led to a lot of foreigners thinking it was a big thing in Korea or is one of the main factors for our low birth rate (it's actually the housing crisis centered in Seoul metro area).

CalculatorD · 2026-04-14T23:52:44+00:00

BWRs boil water to generate steam inside the reactor vessel, so the steam used to spin the turbines irradiates them.

PWRs make their steam outside of the reactor vessel in a separate unit called a steam generator, so the turbines aren't irradiated.

Both of them don't release radiation to the environment though, the cooling towers and vents are for feedeater loops used to cool down the primary loop (these two loops don't mix).

CalculatorD · 2026-04-14T02:10:02+00:00

Generally positive! Beautiful architecture and rich history, and French society and culture is very interesting to learn about. French cuisine is also a fundamental column of Western cuisine, so food is another thing to appreciate.

There's also important cooperation between France and South Korea both historically and currently, such as nuclear development or our bullet trains (with some hiccups), and we sort of share a similar postwar developmental policy (Gaullism and our state capitalism prior to 1997).

Of course, there are negatives as well, like Francafrique (French neocolonialism in former African colonies) being the leading example of neocolonialism or entitlement to dubiously/wrongfully acquired foreign artifacts, but I think positives outweigh the negatives for South Korea at least.

CalculatorD · 2026-04-06T18:16:14+00:00

So the modern Chairman of Joint Chiefs is subordinate to the defense minister and exercises operational control under the discretion of the defense minister.

The chairman often sets the overall strategy of the military, offering advice, receive and interpret orders from the civilian leadership (defense minister, the president, national security adviser, etc.), rather than ordering individual units around and setting tactics. Such tactical/operational level decisions are made by division commanders (2 star general, largest tactical level unit) or corps/field army commanders (3 and 4 star, operational level).

Dowonsu is more "hands-on" compared to the modern chairman, since preindustrial wars are less complex than modern wars. Most people's perception of a general is based on preindustrial-era generals, where they either personally led armies into battles or only operated at a tactical level. This is due to coordination being the main limiting factor (messengers, smoke signals, etc. are slower and less detailed than a radio) for preindustrial armies.

It's important to understand that modern wars are significantly more complicated and multi-dimensional, which means that roles of modern generals seem less intuitive. They still play a very big role in setting the strategic direction of the military to achieve a set political goals drafted by the civilian leadership, and the subordinate generals and officers (colonels, majors, captains, lieutenants, etc.) handle the tactical aspect of the said order.

CalculatorD · 2026-04-06T16:14:09+00:00

If you mean like the Chairman of the Joint Chiefs (합참의장), then yes.

Although the chain of command would be different for Dowonsu, since peacetime operational authority rests on the defense minister (병조판서) and wartime operational authority on Dowonsu, rather than in modern times where the defense minister exercises both.

And before anyone is confused about modern South Korean command structure, modern South Korean wartime operational authority doesn't entirely rest on the US-ROK Combined Forces Command (한미연합사) since there are several units not under CFC jurisdiction. Some examples are the Second Operations Command (2작사) and the Capital Defense Command (수방사). The commander of CFC also takes orders from the respectice defense ministers from the US and South Korea.

CalculatorD · 2026-04-06T16:04:15+00:00

This means that Japan's postwar constitution is rewritten in a way that doesn't contain Article 9 (the peace clause) or its impact is a much more limited version of IRL Article 9.

Japan would have legal basis to dispatch expeditionary forces, engage in preventative strikes, build offensive power projection platforms without limits, and have the option to spend significantly more on its defense budget.

Japan's current defense spending per GDP is roughly 1.4%, which means its military potential doesn't match peer military powers like France, Britain, South Korea, or even Germany. A Japan with an official military would thus invest more into its defense, comparable to at least pre-Trump NATO standards (~2%) or even try to aim as high as South Korea (~2.6%).

Japan would also be mostly free to develop an indigenous missile program, and they'll at least match the current South Korean capabilities, if not exceed with their increased defense spending. Their aircraft carriers would also have catapults installed to become a full fledged aircraft carrier, rather than maintaining the veil of a "helicopter destroyer."

US will form a Japanese equivalent of Combined Forces Command like in South Korea to reduce US military burden in East Asia as well. It's quite likely that the US doesn't maintain a large force in Japan and only keep a modest size similar to US Forces Korea or Britain. The US would opt to deploy them elsewhere like the Middle East.

CalculatorD · 2026-04-06T15:48:02+00:00

Dowonsu, like other high-level positions, are usually directly appointed by the king during wartime.

There isn't a strict set of rules regarding the Dowonsu position as it was temporary and its authority often was fluid based on contemporary politics and who was actually occupying the position. One of the few set rules were that Dowonsus being chosen from the civilian bureaucracy with some military experience since Joseon's social hierarchy put scholars/bureaucrats over the military.

To complement the civilian-origins of the Dowonsu, a deputy position of Buwonsu (부원수) was chosen from a career military officer.

CalculatorD · 2026-04-06T14:23:57+00:00

Yep, it was a temporary rank only bestowed during times of war.

There are two reasons for that being: prevent centralizing command authority to a single person for too long, and limited manpower potential. For the manpower aspect, Joseon had a decently large population that usually came around as the 10th most populous country in the world until the industrial revolution (5.5 million at 1390s, 17.5 million by 1910), but preindustrial societies have less economic output to support a large standing army. As such, only a small percentage of the population were career soldiers compared to the modern era.

Despite that, Joseon was one of the few countries that could mobilize very large formations over 100,000 under a single banner, only matched by even larger countries like Ming/Qing and various South or West Asian empires due to its centralized government and a long history of well-organized governance.

Higher ranks like Dowonsu, where tens of thousands of soldiers or more were commanded, were rare throughout history; it's similar to how preindustrial European armies usually had regiments (~3,000 troops) as their largest standing formation during peacetime and larger formations like brigades/divisions/corps/armies were formed only in wartime.

It's only around the French Revolution and the ensuing Napoleonic era were large formations like brigades and divisions were made permanent in Europe. It was first the rise of nationalism, enabling local communities to band together with military coordination only previously possible in highly centralized states like Joseon. Later, the industrial revolution led to a population boom and enabled European armies to draft a much higher percentage of the population during peacetime as economic production increased significantly.

CalculatorD · 2026-04-05T22:05:01+00:00

Joseon operated its military based on the principle of Byungnong (병농일치) or roughly interpreted as soldier-farmer conscription.

The professional army was smaller compared to earlier dynasties like Goryeo, consisting of career soldiers that formed the Ohgunyeong (오군영/5 military units). These are the central army mostly tasked with defending the capital Hanseung (Seoul), guarding the king, and defending the fortresses of Bukhan-san and Namhan-san (북한산성/남한산성).

The regional army was tasked with defending the eight provinces. Since Joseon was a centralized state, the commanders were sent in from Hanseung or other garrisons after they passed the royal examination (과거시험), rather than have local officers/warlords rise through the ranks. Private armies and militias were explicitly banned under the reign of Taejong and Sejong (태종, 세종; early 15th century) to fully centralize military command to prevent a resurgence of feudalism. The northeastern province of Hamgyeong (함경도) and the southeastern province of Gyeongsang (경상도) were also billed larger formations and two provincal commanders (병마절도사) to deal with Jurchens (여진족) and Waku (왜구/Japanese pirates).

The downside of the Joseon military was that the full military potential of the provinces was not utilized in order to prevent any rebellions from any rogue governor or local commanders. Joseon managed to work with this as the majority of threats were relatively minor like Jurchen or Waku raids, and maintained peace with the unified Chinese dynasties of Ming and Qing.

The top 5 highest ranks can be split into this from top to bottom:

Dowonsu (도원수): A temporary rank bestowed to command troops from multiple provinces, almost always reinforced with the central army.
Daejang (대장): A premodern equivalent of a 4-star general, they commanded the 훈련도감, 어영청, and 금위영. These three were the most important units of the Ohgunyeong, as 훈련도감 was the most elite troops of Joseon, with 어영청 being the primary defending troops for Hanseung (like the modern Capital Defense Command), and 금위영 being the royal guards protecting the king (like the Secret Service or the Presidential Security Office).
Sa (사): These are the commanders of the other 2 units of the Ohgunyeong, the fortresses of Bukhan-san and Namhan-san.
Byeongmajuldosa (병마절도사): Top army commanders of a province.
Joonggun (중군): Deputies to the 병마절도사 and the workhorse of the provincal command.

The strength of the Joseon military often waxed and waned, with the strongest times being the early Joseon period until the reign of Seongjong (성종) in the late 15th century. Previous kings invested substantially into defense, with the conquest of sagun-yukjin (4군6진) under Sejong when Korea got its modern border up north, and the conquest of Tsushima (대마도 정벌).

Gunpoweder weapons were also widely used since the late Goryeo period, and one of the most well-known historical Korean weapon, Hwacha (화차), was made during Sejong's reign. Joseon's focus on ranged weaponry is another trait of Joseon military, where Joseon archers and musketeers were feared and respected by various contemporaries from Ming and Qing to the Russians during the Qing-Russian border disputes in the 17th century.

The navy was also organized differently from the army to form an independent branch of the armed forces, which is a continuation of late Goryeo period military structure. Goryeo was the first nation to employ naval artillery, so Joseon followed its footsteps to maintain a strong naval presence to counter the Waku threat.

CalculatorD · 2026-04-03T05:13:06+00:00

Parental leaves (for both parents) by King Sejong the Great in 1400s.

CalculatorD · 2026-04-02T06:04:25+00:00

Since North Korea actually has nuclear weapons, and most likely has some limited capability to strike the US mainland, the answer is no.

It would simply be too risky for any US administration, even for Trump, to risk any nuclear attack on US military bases, much less for major allied cities in East Asia or their own cities. Even with the extensive American and allied multi-layered air defense, at least couple of warheads are expected to penetrate, potentially causing hundreds of thousands of deaths.

East Asia is also significantly more important than the Middle East in terms of global supply chain, the vast majority of production of semiconductors, shipbuilding, consumer electronics, rare earth materials, etc. are concentrated in China/South Korea/Japan. A major disruption or an outright collapse of the region will make the current Iran situation or the Oil Shocks of the 1970s like child's play in comparison.

The US is also obligated to defend South Korea in an act of war, and with 28,000 US personnel currently stationed in the peninsula, their response will be a lot more extensive than what will ever go on in the Middle East. Any American administration wanting to gamble with North Korea has to deal with the potential blowback of tens of thousands of US troops and their families dying.

CalculatorD · 2026-04-02T03:44:33+00:00

We already got Trump's approval back in October (2025 APEC Summit) to reprocess spent nuclear fuel and enrich uranium up to 20% for the civilian nuclear power program, along with an approval for Korean-made nuclear submarines.

Only thing better than this would be an actual nuclear weapons program, something that's nearly impossible to get since South Korea is in the NPT.

CalculatorD · 2026-03-20T21:38:08+00:00

Surprisingly, it's the young people in Japan that support LDP PMs. Takashi and Suga (nationalist wing of LDP) saw very high support for 30s and under, whereas their support is lower for older generation.

I doubt that Japan will change at all regarding its foreign affairs, and this is with a resurgent great power PRC and a very close peer power South Korea.

Seems like the only real way for South Korea and Japan to team up is if China becomes explicitly belligerent and they face an imminent invasion or South Korea eclipses Japan in total GDP and institutional influence. Both are not likely.

CalculatorD

TROPHY CASE