Nuclear Physicist Explains - What are SMRs? Small Modular Reactors 

Thank you for the video. I was wondering if you could make a video about Fusion Reactors, how they work, what are the difficulties with them and wether you think they are the future of Nuclear Energy. Thanks again!

@Elina Charatsidou Being that we see factory built "modular" things, what about recalls? How will the quality control work on this assembly line?

Burying them underground only gives them that much more opportunity to leak into the biota. The safety fail safe systems are not failsafe as the Nuscale design left the moderator in the condenser. You only ever show the small benefits in a 9 minute video but I never see one single negative thing about any of all this Elina. Why don't you tell them both sides of the coin Elina?

Not sure there's enough demand for energy to mass-produce reactors--but that also depends on your definition of "mass produce". For most automobiles, 10,000 cars of one model per year is a small number to produce. Pens are produced by the millions. Same for plastic bottles and hundreds of other consumer items. For railroad locomotives and aircraft, 500 units of one type made per year, such as an SD40-2 or a Boeing 737, qualifies it as being "mass produced". These sound like disposable reactors, build them, plant them where they need to be, and 25 years later, bring the replacement out, swap them, and take the old one off to be buried. Come to think of it, they sound more like large battery packs that make energy from nuclear power, and perhaps they should be designed to be just that. Ideally, they'd be made so they could easily be transported by heavy-duty railcars or even heavy-haul trucks with ease. This means your "dream" maximum design weight is about 20,000 kg, your ideal maximum design weight would be 40,000 kg, and you definitely would want to get the maximum design weight below 60,000 kg. Dimension-wise, your "dream" maximum shipping dimensions for are 3 m wide, 3 m tall, and 16 m long. If you're somehow able to pull this off, most trains and large lorries (called tractor-trailers in the US and Canada) across the globe will be able to safely move them along the major rail and road routes of the world without exceeding the loading gauge of those roads. I don't think that will be practical or safe, since reactors have various requirements, such as shielding, but that would be your dream goal. Here, your ideal shipping dimensions will be 5 m wide, 5 m tall, and 25 m long, this will still allow quite a bit of flexibility in transport, especially if you can keep the weight down. Likely more realistic are shipping dimensions of 8 m wide, 8 m tall, and 40 m long, and this is as likely large as they can be to make inland transportation as an intact, preassembled unit more than a pipe dream--this is probably achievable as many nuclear submarines have a 10 m by 10 m cross section. Note that they can be shipped on their side if designed for that, then turned upright with cranes at the final location. You'll also want to take care to have a minimum number of external protrusions that might snag on things during transport. Burying them in pools might make them relatively safe from most natural disasters, but earthquakes and landslides would still be problems. I think there will be huge problems with making certain they are sited safely so there aren't any repeats of Fukushima. Care must also be taken that the pools don't get drained by sinkhole formation, quakes, or other events, or some provision must be made that it won't be a safety issue should some weird catastrophe drain the pool it is mounted in. Overall, this is a concept whose time is overdue, provided those issues can be addressed.

Thank you! 2 things... The physical amount of material in the core, which being smaller is perhaps not quite as "big" of a worry in terms of containment in the event of a catastrophic accident. Part of what made chernobyl so bad was the enormous size of the reactor and sheer volume of fuel. Also SMRs can be placed closer to heavy industry etc so you don't need a sprawling grid distributing power across the entire country!

Nuscales failsafe left the failsafe in the condenser and wasn't failsafe like Nuscale advertised it. You people don't really think they are failsafe do you?

@@paulmobleyscience 😂

Curious question: Can this be weaponized at all? My only concern is that nuclear technology would be very dangerous in the wrong hands. Would this be an exception? What if some nefarious organization gets a hold of these and somehow builds a nuclear warhead out of this?

​@paulcataluna9796 You can build a military nuclear facility without having any civil nuclear power plants because there are different means to produce enough material for a nuclear bomb. North Korea doesn't have a civil power plant but it has nuclear weapons. Having a wealthy society keeps countries from starting wars and having hostile regimes and dictatorships. We could end povert, hunger and the global warming with cheap smr, the heat of the smr can be used for desalination, high-temperature electrolysis or process heat for the industry, and with CO2 capture nuclear can run CO2-negative because it's the only source of energy producing less than 5 gramms CO2 per kilowatthour, so it can remove more CO2 than it produces. Sorry for my bad English, I hope the message got through it nevertheless.

@@paulmobleyscience The molten salt reactors are failsafe by physics. Even if blown up by a bomb the molten salt will just solidify and encapsulate the radioactive materials.

Highly depends on the availability/price and capacity of renewables like solar/wind and possibly hydrogen fuel.

@@St3v3NWL Nope, renewables with storage are more expensive than even old school nuclear.

@@danadurnfordkevinblanchdebunk Right now, maybe. Who knows what will happen in the next decade.

@@St3v3NWL It's already very clear where we are headed in the next decade by looking at Germany and California, two regions which are committing themselves to renewables. Without nuclear we are going to have exorbitant electricity rates, energy rationing, and massive rolling blackouts.

@Elina Charatsidou Why won't this next response post on youtube? Would their third party company they hired for fact checking know any of this? Hello sir, as a nuclear engineer could I ask your opinion on the difference between naturally occurring H3 Tritum thats extremely rare on Earth and only found in trace amounts in the atmosphere and H3O Tritiated water from H2O neutron capturing from our global water cooled nuclear reactor fleet at tens of thousands of TBq every site every year that is taken up in plantlife where it either replaces hydrogen in the plant or binds directly to the Carbon in the plant to form Organically Bound Tritium which bonds for a longer period than that of Naturally occuring H3 tritium from the sun at a biological Half-life of 12-30 days inside our bodies that causes double DNA strandbreaks, Micronucleus formations, cell necrosis or aptosis, chromosal aberrations and various other phenomena thus negatively affecting human health? Do you think the standards must be reset now knowing this newer research?

what's the status of this?

Can't wait for the inevitable 30% smaller nuclear disasters. What? That's alright, isn't it?

add Paper Industry.

Hi Phil, I've read a lot over the years regarding MSRs, one of its abilities is to work in area's away from large amounts of cooling water this is due to the high working temperature, fan forced cooling would be more than adequate, at 75 I'm hoping I'm still around to see them in action.

That's sad and a little bit pathetic. A decade of sunk cost and man-hours yields no results. I don't fault them, I fault 'political weather.'

@HuntingTarg Incorrect, it was always a scam. Let's not forget the moderator was left in the condenser and the fail safe didn't work...or did we forget?

@@HuntingTarg Do you have ANY basis for blaming it on political weather??? NuScale was given $2 billion in taxpayer money for the project, $400 million for the NRC review and help with the design and free government land on which to build. Do you want the taxpayer to pay everything and just turn it over to the investor firm when complete?

And that is it. It's not about the technology. It's about the money they can make. Incentives drive every successful technology. An nuclear was never a good idea. Just a marketable idea. An now we have things like Fukushima.

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Biggest drawback is there is not and never has been economies of small scale. New nuclear is already the most expensive method to produce power and downsizing will only make it even less cost effective

Glad you liked it!☢️👩🏽‍🔬

The only SMR propotype currently being built in America is located in Argentina, the CAREM (Central Argentina de Elementos Modulares)

Really? My understanding is that there is only an MOU in place. No registered design, no committed finance. Odd that Canada isn't backing it's very own CANDU, favouring a fundamentally less efficient SMR concept. Very strange.

@@aaroncosier735 well, we are refurbishing the CANDU reactors at the Pickering power station to get another 30 years out of them, and we already did the ones at Point Elgin. I think the relative simplicity of installing SMRs makes them an attractive option for the powers that be. There is a big EV transition under way in Ontario, so they need more power relatively quickly in order to supply projected power requirements.

@@WhatWeDoChannel Refurbishing is not quite the same as new build. I agree that doing so gets a little more back out of sunk costs. The *claimed* simplicity of SMRs is so far just advertising. Small reactors are not attractive: they are less efficient and projected to cost twice as much per unit of energy produced. The only selling point is the perceived modularity, which is still a pipe dream. None of the existing SMR concepts has gotten past the drawing board. They will require demonstrators to confirm the basic concepts, and those will not be "modular". Then further rounds to get to a hand-built prototype of the future modular design, then a factory to make them. Don't expect to see SMRs for many years. EVs may increase demand, yes, but they also have a huge storage capacity. They will enable the use and storage of more variable renewables. Rather than increase demand for nuclear, I think EV storage will increase the usability for renewables, which are available *now* rather than SMRs which could yet be decades away.

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That's more of a grid design issue than a reactor system design one, but essentially yes - it would just take a mini-substation with a set of high-power switching inverters. What I want to know is why would you want a yuge solar farm along with an SMR; integrating solar into housing, commercial, and parking structures is fine. SMRs should mean that taking up acres of land with solar should be unnecessary.

Agreed

I think they can be 'saf - _er_ ' than the legacy gen 2 and 3 reactors atill in ooerstion around the world - which is still saying something from the perspective of operating hours per injury. A steam explosion inside a secondary containment vessel isn't cause for alarm - certainly not hazmat and national security personnel. California's MTBE scandal caused A LOT more damage to public health and the environment. Inherent stability design can - and in my unqualified opinion ought to - take such considerations into account and have power limits like you mentioned fixed into its design parameters. Most people don't really want guarantees, they want (principled) confidence.

It's a design feature called _inherent stability;_ basically enough has been learned from both operational data and computer simulations that operating conditions can be anticipated and planned for during the design phase. I still find it astounding.

Until it fails to work!

I do think 25 is overly optimistic. The understanding I had from Real Engineering was 10-15 years before refueling

Coming up in the future! Thanks for the suggestion and support ☢️👩🏽‍🔬

@@YourFriendlyNuclearPhysicist Great! Make sure to please at least mention the Tellurium embrittlement issue for a split second for molten salts or Hallam Nuclear site in Nebraska with lead Bismuth. Thank you Elina

That is precisely what is being done right now in wyoming.

One of the limitations on designs being fabricated and assembled in a factory is transportation. You can't just plan a roadtrip for an assembly massing over 100 tons and 15-20 meters in length. Also, most nuclear countries have strict regulations on how much fissile material can be shipped in one load, how much can arrive at a given destination at once or in a timeframe, and how much can remain undispositioned on site in a specified timeframe. So the limitations on the physical size of SMRs aren't just due to engineering, but also logistics and process control.

Fluid dynamics. Large pipes are more efficient. SMR reactors are being sold as Silicon valley style glossy brochured paper investment schemes, based on flawed (manipulated) simulations. Most of the site costs with a fraction of the total output. Efficiency of scale, large reactors aren't just by chance. We have had small reactors for decades SL1 was an early example....

@@camresearch5120 SL-1 was a real problem.

Thank you so much for the support and I’m glad you enjoyed the video 👩🏽‍🔬☢️

I think some of the SMR proposals have included thorium. Thorium is just a fuel that's harder to burn. Making the engine smaller doesn't better the possibility of using that fuel. You just have to mix it with high level nuclear waste which is in my opinion killing two birds with one stone.

@@MrBrew4321 Thanks. I'll have to try and find more information on that.

Economics depends on a lot more than just the reactor type. The number built, their power output, lifetime, future interest rates and energy prices are all factors and some of these are not known in advance.

In computing and politics as well as energy...😊

​@@HuntingTarg another politics joke... 🤨

Tell that to Texas. Who will be on the National grid after their incompetence lead to deaths.

You can learn about Gamma radiation from cosmology as well as from nuclear physics. Gamma radiation is high-energy, highly penetrating photon radiation that can only be reduced by dense materials that have atomic nuclei close together: Lead, Iron, and Tungsten tend to work well for this, and contribute to a reactor vessel's weight. The 'H-bomb' is a variant of nuclear weapon that produces very little fallout, because it uses a 2-stage fission-> fusion process. Modern "Thermonuclear" weapons use a 3-stage fission->fusion->fission process which increases yield many times, but also creates more radioactive byproducts, aka fallout.

Thanks great suggestions ☢️👩🏽‍🔬

Those are the assumptions. It might not work out that way. At least one proposal is that the reactors be single-use, and the depleted reactor becomes a sort of decay storage enclosure. Not sure how that works out in the event of faults or gross failure. Not sure how confident we can be that an already corroded reactor vessel is somehow a good or dependable containment, either onsite or in transport. How long will it last? What is the deadline for repackaging?

Absolutely, just like you can keep a car running for 100 years. But parts become scarce after just a few years and just like a car, the cost to maintain makes anything more than 25 years no longer cost effective.

Thanks great suggestion !☢️👩🏽‍🔬

When you look at nice glossy advertisement material for an SMR, with nice CGI plant site views, always ask, where is the 100m high stack, where goes the nuclear ventilation of the controlled area, where go the radioactive gases of the coolant purification, where is the cooling tower for the waste heat, where is the tritium discharged? ... And then ask, would the electricity not be cheaper when i build the SMR larger? Then i still need only one plant crew, only one building, only one turbine ...

@@NuclearSavety First the first part, yes exactly! For the latter part, no! Why shouldn't it be possible to use more SMRs in one plant? You are more flexible, it's still easier to manufacture and so on.

@@Deinorius 2 SMR need 2 containments. One twice-as-large SMR needs one containment which costs 30% more .... economy of scale ... And 2 SMR have twice as many valves, twice as many pipes, twice as many valves, basically twice as many points of failure, twice as much maintainence efforts ...

Smr can be located closer to cities or factories that uses most of our electricity, so I thought that pays off for loosing energy from bigger plants due to distance or?! Is it that expensive to have extra control room? Is it not possible to have remote control rooms for multiple smr? I thought it's much faster and cheaper to build an smr than a regular nuclear plant?! Is it not true? More pipes more valves more issues but if one fails an other one can replace it. Meanwhile if something fails in a big powerplant than it's all goes to hell or?!

Very little.

Die US-Firma NuScale hat Aufgeben beim SMR und das Projekt eingestellt, 11-2023. Wieder mal dumm gelaufen für die Atomkraftwerke. Der SMR war ohnehin nur Schwachsinn im Quadrat.

There was a lot of fear and panic created by media over three incidents in nuclear energy history; Three Mile Island, USA Chernobyl, USSR Fukishima, Japan Even though other failures like the Windscale fire were more serious, these three events were lodged in oublic consciousness as evidence that nuclear energy is _inherently_ dangerous and almost any other alternative is preferable. There is an old Hollywood movie that came out months before Three Mile Island, called The China Syndrome, which dramatizes the fearful sensationalism media now tends to tack on to nuclear energy.

The only stupid question is the one that isn't asked. Changing existing nuclear control rooms would require a lot of analysis. Since the inception of nuclear power there has been a lot of rules applied to their control. Wiring must be carefully separated. Nuke plant have separate safety trains that must be largely redundant. They usually have all the wiring pass through a cable spreading room. These are often rather full already. There are fire requirements for all wiring. (Appendix R). Everything must be seismically analyzed for earthquakes. My gut feel is that it would be easier to have a separate "greenfield" structure rather than trying to tie it in with a decades old plant ("brownfield.) Operators in the existing control room (Senior Reactor Operators) require a lot of training. If these operators were also expected to handle a new totally different system, it could be asking much. Critical parts of nuclear plants are statistically analyzed for failures. (Probabalistic Risk Assessment). Will the use of the existing control room introduce new failure modes or increase the risk of existing failure modes? Big analysis there. There is also the matter of when. These places can make a million dollars a day. Are they to be shut down while the new equipment is tied into the control room? Tying new equipment to an existing plant can mean all sorts of local plant equipment that may need to be taken down while the new installation takes place. In addition, the existing equipment may need modifications to allow the installation of the new equipment. These places can be rather full so existing piping and cables may (will) need rerouting. All affected equipment must then be tested. Everything has to be documented to ensure the health and safety of the public. The NRC will have it no other way. All that documentation is extremely expensive. This is my viewpoint from nearly 20 years ago when I worked at a nuke. It's probably even more complex now as the security concerns have grown greatly after 9/11/2001.

​@@daniellarson3068 The only proper way would be to convert an entire plant during a refuel/retrofit. That's a hard sell when many countries are being pressured to simply decommission in the face of 'the green new deal.' Individual installations in remotely located and remotely monitored situations seems more viable to me.

@@HuntingTargYes - Gutting and rewiring control room would take a great quantity of time. Building new would most likely be more cost effective. The problems I discussed above and many others would be simplified.

It requires either enriched U-235, which is expensive and dangerous, or it requires additional alternative fuels which reduce the fast neutron flux and so make the reactor less efficient. It is also possible (generally speaking, IDK how feasible it is for SMRs) to design a hybrid fast-thermal design where Pu-239 (I think this is right) absorbs thermal neutrons as the reactor goes through its fuel cycle and so has secondary reactivity.

With the current reactors that we use this fuel implanted (UO2) when taken out of the reactor will need approx 100.000y to reach background radiation levels

@@YourFriendlyNuclearPhysicist As I understand there is high level waste and low level waste. Is all the spent fuel from inside the reactor high level waste? And how does Thorium decay? I am Norwegian and here the talk about nuclear, specially Thorium breeder reactors, is getting more attention.

There is a graph in this video. ru-vid.com/video/%D0%B2%D0%B8%D0%B4%D0%B5%D0%BE-KnxksKmJa6U.html

She's pretty and why it's mostly men here and you all are hitting on her, stop it

​@@paulmobleyscience sarcasm not your strong point ? take a joke

@@shutup2751 Actually sarcasm is my second language and very fluent in it. Tell me then why the Inverse square law, Talbots law, Lamberts Cosine law and the calculus and trigonometric calculations used in the Bulletin of the Bureau of Standards volume 3 does not apply to extended sources of radiation here on the surface of this planet and explain why that matters in the real world please and thank you sir.

@@paulmobleyscience i am not reading all that mumbo jumbo

@@shutup2751 Wait I thought you knew the language of sarcasm.....You do understand even the pretty Elina can't even answer this and I know that you can't either before I asked it so you must speak a different dialect...my apologies

No; there is something called a buckling ratio, which relates the outer surface area of the reactor volume to the spatial volume of neutron flux within the reactor. When the reactor size gets smaller, the buckling ratio increases, and because of design physics makes it harder for a single unit to sustain power output. Besides other problems like power-to-weight ratio, reactor vessels can't be both small and light enough while generating enough electricity to power things like planes or cars. Or as Issac Arthur put it in his video on fission and fusion energy, "But no really, the Thorium-powered car is so much 🐃💩."

@Ex Lagadema Yes which means they are actually Gen 2 reactors and nothing new. The TRISO pebble fuel surrounded by multiple layers of Carbon with 2 different types to the Thorium decay chain where its U233 for the fissle fuel and not Th232. Or MSR tech with the Tellurium Segregation of the Hasteloy-N issue which makes them much more expensive to the IMSR replaceable core every 4-7 years for the graphite expansion/contraction issue. These designs, fuels and coolants are nothing new and only the attempt of the industry to keep from slipping past 9% globally for our energy needs. They are putting lipstick on a pig and trying to pass it off as the next new hot thing. If you need more I have it all backed up.

Not really, submarine reactors usually use high enrichment uranium. They cannot be used in civilian facilities because of nuclear nonproliferation restrictions. The exception is the Russian reactors for their nuclear-powered icebreakers, which run on "energy-grade" enriched uranium. They use them for their mini-nuclear power plants. One is already in service, four more are under construction.

​@@midnike8783 That's interesting, if they are really building more nuclear icebreakers; the two the USSR built for clearing the port of Arkhangelsk and the White Sea were decommissioned years ago. 'Bout time.

@paulmobleyscience is pooh-poohing good tech all over this channel. The real answer is, yes and no. Yes in that military naval propulsion reactor designs are made to be reproducible so that the same vessel design has the same reactor design throughout the class. No in that they are not fabricated completely in a factory and then shipped somewhere; in naval construction the reactor vessel is first installed, then fueled when the fuel elements are put in place. National security laws & policies dictate that the fuel be handled separately. Propulsion reactors also must vary power output on demand and so do not have inherent stability in their design.

Till one gets nuked or merely taken out by a cruise-missile?

@@grahambennett8151The biggest threat in that scenario is loss of utility power. That is all.

The naval reactors that have been used for decades are SMRs. Although, naval reactors have some problems that aren’t suitable for civilian ship. Yes, a SMR would be good for a steel mill. People even want to directly use the heat to do things like desalinate seawater.

The Russians use such reactors in their nuclear icebreakers and mini-nuclear power plants.

​@@kokofan50military propulsion reactors aren't exactly SMRs; they don't use all the same design principles. They're designed for high, actively controllable output, and consequently don't have inherent stability, and are made with startup/shutdown procedures so they don't need to be monitored when the ship is not deployed or ready for duty.

1) you’re right, but the other benefit more than make up for minor loses in efficiency. 2) it depends on the type of reactor. Molten salt reactors drain the fuel salt into a drain tank that disperses the heat, so the salt solidifies stopping the reaction. The helium in helium cooled reactors have such a high heat capacity that they’ll stay cool until the pile has cooled. The NuScale design uses a water bath to act as a heat sink. There’s a Rolls Royce design that uses the containment vessel as a heat sink. Also, smaller reactors are able to disperse heat better. That’s why they’re less efficient

@@kokofan50 Re 2: 🤦‍♂️ I forgot about the square cube law. Oops. Anyway, thank you for the explanation!

Thermally, compensations may be made. However, the surface-area to volume ratio also impacts the neutron economy: how many neutrons leave the system as opposed to hitting fissile nuclei. Small reactors lose more neutrons, so sustaining a reaction requires that the source of neutrons (fissile material) be used up at a higher rate. Overall this results in less efficient fuel use and more waste per unit of energy generated. Some say this is not the limiting factor, but it doesn't help. Virtually no spent fuel waste has been disposed, so we have no idea how much this adds to the overall costs. Some estimates run very high, so halving efficiency (doubling waste costs) could be a serious matter. Some proponents think not. we will have to see. We will not know for sure until we see major nuclear nations actually dispose of a substantial fraction of spent fuel. Till then it's just hopeful guesses.

No, they are highly enriched PWRs, HWRs, or molten salt designs. They are not designed the same way SMRs are, because they need high-range, on-demand variable power output.

Most SMRs have either online fueling or a set amount of fuel for their intended life span. It’s going to take the laws of physics to fail for passive systems to fail.

@@kokofan50 wait online fueling? How does that work? And they have a lifespan, like after 25 years they will be gone?

@@minhduongnguyen3671 All molten salt reactors remove the salt from the core and pump it in a heat exchanger. Some also want to remove various isotopes to sell for radiation therapy for cancer, to fuel RTGs, and other stuff. After the processing they just a bit of uranium salt to make for the difference.

In some countries (the US I know for sure) there are regulations about having 'eyes-on' security personnel at all times. It adds to cost, but national security concerns of late have shot up regarding domestic threats, and right now energy prices will support the increased cost, even if it is just remote monitoring.

Here it is! Hope you enjoyed it!☢️👩🏽‍🔬

If the water drains away the reactor will shut down. Water is a moderator - slows down fast moving free neutrons to increase the chances for capture or fission of other U236 nuclei. It's a self sustaining failsafe arrangement.

SMRs and RTGs are fundamentally different. Look at NASA's MMRTG (Multi-Mission RadioThermoelectric Generator). It generates electricity by capturing the heat of isotope decay, not through neutron-induced fission, so it's not a reactor in that sense, it's more like a radioactive decay battery. NERVA, which was actually tested in a concept prototype, never flew, but was an actual reactor that used reaction heat to superheat thrust mass. The power supply for the Voyager, Mariner, Viking, Galileo, and Cassini space probes, among others, were RTGs because they can generate power constantly without regard for environmental factors such as sunlight intensity, external temperature, or craft orientation.

Transport and reprocessing would need to be *timely*. No letting spent fuel (or reactor modules) just sit around for thirty years. The reactor site would need to close and ship a hot reactor *knowing* that a slot would be open at the other end. They cannot turn on a new one until they *know* a guaranteed slot is available some years in the future. This would require the existing nuclear industry to experience a very severe culture change.

It means not expanding the people who have nuclear weapons

More but I'm the case of fast reactors that waste has a far lower level of transuranics. "what about the waste" isn't a huge technical challenge so much as an anti-nuclear talking point.

it may be possible to build a bomb out of material that goes as low as 20% enrichment. This was part of the original regulatory cutoffs. Of course, modern electronics can control an implosion device much more consistently than forty years ago. Not a *good* bomb, but enough to be concerning.

Thanks that’s a great suggestion ☢️👩🏽‍🔬

CANDU is a great proven design but no SMR

Petrol fuel tanks need to be inspected periodically, and go through more physical stress from loading & draining than a sealed vessel whose mass barely changes. Unanticipated failure modes are greatly reduced through computer modelling, and a secondary containment vessel + inherent stability design means that a release of radioisotopes into the environment is a very improbable scenario.