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Booming as a Driving Force to Trade (Reactors?). Professor Georgy Toshinsky: talk on boomed reactors.

AtomInfo.Ru, PUBLISHED July 10, 2011

Professor Georgy Il'ich Toshinsky, PhD, Principal Manager of SVBR Project, Director Advisor of Institute for Innovative Technologies of SSC RF-IPPE is answering the questions for AtomInfo.Ru e publishing.


Georgy Toshinsky

End of traveling wave?

Professor Toshinsky, currently small power reactors are much spoken about. For example, in the USA a great number of such projects are underway. Most of the designs are light water reactors; but there are some projects, which will be interesting for designers of fast reactors, such as traveling wave reactors, "Hyperion", 4S, and some others.

Indeed, these are very interesting innovative projects, which development is at different design stages. They possess the following common feature: their development was preceded by a vigorous advertising campaign in mass media, which produced an impression that the real aims had been almost obtained or would be easily achieved.

Now it is too early to draw a conclusion for many of the projects that you named due to lack of the technical information. I'll try to assess them on the basis of the currently known data.

Let us start talking on traveling wave reactor, i.e. TWR. The first question: is it true the TWR Project that was so much spoken about in mass media does not exist any more?

Not quite so. The authors of the concept, which was difficult to be realized in practice, turned to a clearer concept of a standing wave reactor (TP-1) that in principle allows finding the solution to the tasks stated for TWRs. Let us consider the details of these concepts.

First of all, the concept of traveling wave reactors is very interesting. The US scientists agree that USSR scientists S.M. Feinberg and E.P. Kunegin were the ideologists of the concept. In 1958 they proposed a reactor that could operate in a mode of depleted uranium make-up. The reactor should be initially fueled by enriched uranium, then inside the reactor uranium-238 could be reprocessed in plutonium.

These are "breed-and-burn" reactors.

Yes, the common name of those reactors is "breed-and-burn" reactors. Physics of such reactors is clear. For fast reactors a breeding ratio (a ratio of converting uranium-238 in plutonium) is very high. Of course, the core must be designed in a way that critical concentration of plutonium is equal or less than equilibrium concentration.

To move further, please tell us about CANDLE - a burnup strategy proposed by Hiroshi Sekimoto, the basis of TWRs.

This is a Japanese variant of "breed-and-burn" reactor that was proposed in Tokyo Institute of Technology by a research group headed by Hiroshi Sekimoto. In this variant there is a cylindrical core with a starting load of enriched uranium or uranium-plutonium fuel. A uranium 238 screen abuts on one end of the core. Plutonium is step-by-step built up in the screen, the core is moving towards the screen and a subcritical area with burned fuel is left behind the core.

A Japanese name of that burnup strategy is CANDLE (Constant Axial shape of Neutron flux, nuclide densities and power shape During Life of Energy production). However, a conception of the ignited cigarette is clearer for understanding. Ash (spent fuel) is on one end of the cigarette, further there is a small burning region (chain reaction zone), and then there is tobacco (uranium 238 that will be involved in the process of generating energy).

Has anyone validated experimentally an opportunity to construct a traveling wave reactor or reactor based on Sekimoto CANDLE?

No, it has not been validated experimentally anywhere and by anyone.

In other words, do we have only calculation codes?

Yes, we do. However, today codes have been developed well and I think we should trust the codes. The major difficulties are not in physics.

Well, but what should we do with drifts per atom?

For that reason I also said the major difficulties were not in physics. For "traveling wave" to travel, very deep fuel burnups are necessary. Dense fuel must be used. Oxide fuel is not right for this purpose. At least, nitride fuel could be used, but metal fuel would be better. "Close" lattice of fuel elements is also required.

However, currently nitride fuel is on a stage of research but not research and development.

Certainly. It was made in pilot production, reactor BR-10 operated with two cores, but uranium fuel was used and burnups were much less then it was required.

I said earlier that for "traveling wave" to travel, very deep fuel burnup is necessary. On average, 20 % burnup on heavy atoms is minimum that is required. But 40 % burnup would be better for traveling wave is, as it has been told for TWR.

20 % burnup is not too much.

Not so. It is very much. Now mean burnup in fast reactors with uranium oxide fuel is ~6 %, maximal burnup is 11 %. In other words, mean burnup in TWR must be increased three times and it would be better to increase it six times.

20 % burnup was obtained in BOR-60.

Even over 20 %, but MOX vibro-fuel was used. However, vibro-fuel is less dense. Don't forget that it is vibro-dense oxide fuel and its density is not sufficient to meet the TWR purposes.

Now I'll tell on drifts per atom, which you asked about. In TWR a damaging dose for a fuel element's cladding material is 400-500 drifts per atom (dpa). Let's compare. The design parameters of BN-800 were asserted to be 93 dpa. It is enormous difference. There was an article in AtomInfo.Ru e publishing, devoted to the researches in VNIINM A.A. Bochvar All-Russia Research Institute of Inorganic Materials. They told about the task to obtain 133-164 dpa (not more) by the year 2020.

Conclusion. Today and even in the nearest future the required extra-deep burnups and extra-deep drifts don't allow considering the TWR concept as a real one. First, its realization must be verified by multi-year tests, then long irradiation experiments and researches must be performed and so force.

About other problems of traveling wave. The core height must be elongated (including a uranium-238 screen). However, the elongated core cannot be constructed because hydraulic resistance is growing sharply as fuel elements must not be in a "loose" lattice. Else, high conversion ratio cannot be provided. In other words, an intrinsic contradiction is peculiar to the conception.

Having analyzed all nuances, the TWR initiators proposed a variant of fuel elements re-cladding. What is it? There is a long fuel element, with enriched fuel in a bottom part in the beginning of the lifetime; in the end of the lifetime the top part, where uranium-238 was, will become active. After the reactor has been shut down, fuel is unloaded, expired metal claddings are removed, the upper part of the fuel column, which was a zone of chain reaction, is installed in the bottom of a new cladding, a uranium-238 screen is mounted above. Then re-cladded fuel is loaded in the reactor. So, a mode of depleted uranium makeup is realized in the reactor.

But what is there an essential distinction from SNF reprocessing? From the standpoint of radioactivity, this is contamination too.

The point is not only in contamination. In the re-cladded zone you must maintain a vector of plutonium enrichment as it was before re-cladding. Otherwise, the reactor won't operate. In other words, the idea is brilliant, but it cannot be realized in practice.

What is the final? The experts in "TerraPower" have figured out that a traveling wave reactor cannot be technically realized now. Currently they are developing concept of a standing wave reactor. Therefore, we can say a traveling wave concept has ended.

Standing wave vs. traveling wave concerning "breed-and-burn" reactors.

A standing wave reactor is a standard reactor with heat-transferring sub-assemblies, which in an event of obtaining the allowed burnup values and damaging dose for claddings can be reloaded, rearranged, fresh sub-assemblies with depleted uranium can be added.

You are repeating the words of the content of engineering reports on "breed-and-burn" reactors, which were issued in Russia in the 90s. We know that IPPE and you personally were dealt in that research area.

Yes, it's true. It is the concept that we developed 15 years ago. The American name of the concept is TP-1 or "TerraPower-1". It is a sodium cooled standing wave reactor of 500 MWe.

But it closely resembles a project of reactor SVBR-600.

It's quite true. Many parameters of TP-1 are similar to those of lead-bismuth cooled reactor SVBR-600. Fist that concept was presented in 1994 in Pittsburgh at the Conference on Advanced Reactors Safety (ARS-94).

Reactor TP-1 can be technically realized in contrast to TWR. It is a standard reactor, which will be shutdown for partial refuelings. However, the burnup and drifts problems remain but they are less burning.

Let's suppose, TP-1 is constructed. What will be the benefits? Well, there will be depleted uranium makeup, but the problem of spent nuclear fuel (SNF) will not be solved. What shall we do with spent nuclear fuel of TP-1?

How the experts in "TerraPower" are going to solve the problem? This concept allows to increase sharply (ten times or more) use of energy potential of natural uranium as compared with a current level. So, the spent sub-assemblies of TP-1 are supposed to transport to be finally buried in geological formations. Of course, it won't be possible to use built up plutonium.

It is difficult to imagine that nuclear (and other) community will agree with the fact that the materials with plutonium content of up to 10 % will be buried in geological formations forever. This will be a plutonium underground depository, and it will attract all potential dealers. Moreover, it will be potential radiation hazard as well.

So, I believe that public opinion won't agree with that option. We should not bury the SNF, but we should bury nuclear waste, fission fragments, which have been released in a closed cycle when reprocessing the SNF. All the rest must stay in the cycle. A standard fast reactor operating in a closed nuclear fuel cycle (NFC) can manage it. That's all I wanted to say on an issue of traveling and standing waves.

Unreal deadline for a real unit

The next is Project "Hyperion" which we have told several times. It is the most scandalous project for the recent years (we don't take into account TWRs and Bill Gates).

"Hyperion" as well as TWR is sponsored by private firms. The sponsor of TWR and TP-1 is Bill Gates, the sponsor of "Hyperion" is "Hyperion Power Generation".

The question that is not entirely keeping to the subject. In the USA during the last months two private investors interested in nuclear power confronted with financial difficulties. One of these two firms is accused of financial intrigues and its business is under investigation. Is it right that commercial nuclear power development is supported by private companies? We understand when "Westinghouse" is managing the new projects. However, we cannot agree when such projects are managed by beginners without proper skills.

I cannot be so categorical. The private investor is financially sponsoring development of the project. There is an opportunity for the scientists, designers, engineers to develop innovative designs. That fact is viable. However, safety must be under the state control.

But why "Westinghouse" or "General Electric" does not manage such projects as TWR or "Hyperion"? Why are the unauthorized persons who have money but no skills in nuclear power dealing with such projects?

I cannot answer the questions. You should ask these questions to them. However, we should understand that nuclear power is not profitable for the private business. Long investments without prompt repayment. Only large enterprises with strategic goals can manage such projects. As for the small power projects, the additional issues on their economics appear.

Well, let us speak about "Hyperion".

For the recent two years the concept of "Hyperion" has changed principally. Not long ago it was a futuristic reactor with uranium-hydride fuel, it was supposed to be self-controlled. The reactor released and returned back hydrogen when the temperature changed that affected the spectrum and allowed to maintain the reactor in critical state due to nature laws.

Together with hydrogen radioactive gaseous fission fragments were released from the core and did not return back. In view of the Fukushima accident the idea of hydrogen release is shocking.

Evidently, they have realized it themselves. As currently lead-bismuth has been much spoken about, they have turned to it. Now the "Hyperion" conception looks real. However, the terms of its implementation, which have been announced by the designers, are unreal.

Why? Because there is no fuel for reactor "Hyperion". They are going to use new fuel that is not in production, has not been tested, and is not licensed. How are they going to get a license for operating the reactor with untested fuel?

However, they said they were going to use oxide fuel in case of licensing problems.

In case oxide fuel is used, characteristics required for reactor "Hyperion" will not be obtained. The reactor is small, operating the reactor using oxide fuel requires heightening the enrichment. At this point, the IAEA requirement concerning 20 % enrichment as maximum, will be violated.

In case enrichment is over 20 %, reactor "Hyperion" cannot be exported. However, it can be used within the USA, as the USA is a nuclear country.

Yes. But for what purpose?

That is, there is no market within the country.

I cannot say it so categorically. We know about an incident with reactor 4S developed by "Toshiba" Corporation. This is a 10 MWe reactor proposed to be constructed in Alaska.

The number of residents in city Galena (Alaska) is about 600. The electricity is very expensive there as fuel is imported. It was an idea to construct a unit with reactor 4S near Galena. However, despite the residents agreed, construction of the unit has not been licensed up to now.

The Galena residents (over 600) were not able to pay the required money for construction of the unit.

"Toshiba" Corporation was willing to pay for construction of the reactor.

Yes, "Toshiba" Corporation was indeed willing. However, today they are going back on their word.

It is reasonable, it's business and "Toshiba" Corporation has calculated all the variants: to give "free of charge" somewhere in order to return back much more. It is evident that the lower the power is, the higher the electricity cost will be and there will be less number of sites where a small-sized power plant will compete with plants using fossil fuel.

Therefore, in the USA it is Alaska.

For example, it is Alaska. Maybe, there are some other regions in the country. That must be analyzed. However, it is clear there must be an export opportunity for small-sized power reactors. Otherwise, the market will be thin. So, the IAEA requirement concerning 20 % enrichment must be observed.

So then, facility "Hyperion" with lead-bismuth coolant is quite realizable.

Yes. As compared with our concept of SVBR-10 (developed by FSUE EDB "Gidropress" and FSUE SSC RF-IPPE), its power is larger and it operates using nitride fuel. Reactors SVBR can also use nitride fuel but they can operate using uranium oxide fuel enriched in less than 20 %. Our task is to design the facilities, which can be constructed tomorrow and which have already passed (or nearly passed) the required scope of research and the necessary scope of research and development.

In contrast to our projects, "Hyperion" designers have to develop nitride fuel. There are no principal constraints for designers and the problem will be solved. The major question is "when?" with due account that it is necessary to perform tests to verify the resource characteristics. Therefore, it is not clear when reactor "Hyperion" is going to be available for the market.

So, I am repeating my words that the "Hyperion" concept is realizable, but the terms of its implementation, which have been announced by the designers, are unreal.

Actually, one more question concerning reactor "Hyperion". Lead-bismuth circulation is realized by natural convection. Yes, it is simpler, there are no pumps. However, efficiency of heat removal is several times lower, economical characteristics of the facility are reduced.

Professor Toshinsky, we would like to ask you a question that we asked the other interviewees. Aren't you afraid to make a reactor without pumps, in which there are no opportunities for compulsory circulation of coolant?

Why should we be afraid? Boiling reactors operate using water natural circulation. Bilibinskaya NPP operates without pumps, there is only feed pump that supplies feeding water from the turbine. And the reactor itself operates using natural circulation. Let us remember our vessel boiling reactor BK-50, western BWRs. By the way, there were pumps at Fukushima reactors, and how did it help?

I think there should not be any phobia. The point is that when we use liquid metal coolant, in which difference in densities for hot and cold coolant is not as much as that for boiling water, we cannot obtain high motive head and efficient removal of heat. Therefore, less power can be obtained from the identical volume at the same metal-intensity. So, the less the power is, the higher the specific capital expenditures are, and the lower the competitiveness is. That's all. Natural circulation is very good and necessary for cooling if there is no electric power.

That is why reactor "Hyperion" cannot achieve 100MWe in contrast to SVBR.

Surely. This is maximum for its dimensions. And in case of constructing a heavy-metal cooled reactor of 100MWe with natural circulation, its metal-intensity and cost will increase many times.

As for the pumps. Abroad it may be some fear to use pumps for lead-bismuth circulation. We have gained such experience at nuclear submarines' reactors. Altogether, about 50 pumps were tested in practice. There were two failures without any serious consequences, but by nowadays all errors have been eliminated.

Should we consolidate?

Again we are speaking about customers of reactor "Hyperion". Advertising campaign for that reactor is more powerful than that for Bill Gates. It is even proposed for the Marianas.

The company that is promoting reactor "Hyperion" has signed over 100 Intention Protocols.

When do you think reactor "Hyperion" will be available for production in quantities?

I think, commercialization of project "Hyperion" is possible to realize not earlier than in 2020, but not in 2013 (as they have announced).

And what about consolidation of Russian and American efforts? Our Project SVBR and their Project "Hyperion". Will it be useful?

Consolidation of efforts is a political issue concerning relations of two countries. It is clear that Americans want to get the maximum information as lead-bismuth experience has been gained mainly in Russia. And what will we get from them? I don't know.

S.V. Kirienko and O.V. Deripaska have signed the documents on conditions of designing and commercialization of SVBR technology. Within the frameworks of a state-private partnership joint venture OJSC "AKME Engineering" is organized. The tasks of the project have been stated, works on the project have been launched, regular financing for the project is assigned. The issue concerning the new participants of the project should be considered by stockholders of OJSC "AKME Engineering".

Anyway, I think the nuclear part must be performed in Russia. Though, it must not be ruled out that certain components should be purchased abroad in case they are cheaper and their quality is better. However, integration must be realized in Russia. Therefore, there is a counter-question: what for do we need consolidation of efforts?

Well, as for project "Hyperion", it is clear that there are ways for collaboration with the USA (business-agreement or purchase of components). And is any collaboration possible on "TerraPower" projects?

I think in case Bill Gates is going to invest money into that technology, Russia must be a collaborator but without any responsibility for realization and final results of the project.

I don't eliminate the fact that in the course of development of TWR (TP-1), the viable theoretical and practical results will be obtained, first of all, those on deep fuel burnup and large damaging doses. These results will be also useful for designers of traditional standard fast reactors.

Bill Gates along with his team is focusing efforts on fuel burnup and damaging doses. And we are interested in material's temperatures. However, won't collaboration with "TerraPower" result in dissipation of domestic specialists' efforts? In case there were hundreds of high qualified domestic specialists, few of them could collaborate with American experts. But it is impossible.

Yes, such risk is real. Though, the correct distribution of efforts is possible. And here is an interesting variant: to develop as an international project our new research reactor MBIR that is supposed to be constructed in Dimitrovgrad. In case we succeed in persuading Bill Gates to take part in Project MBIR, it will be a great benefit for the world nuclear power.

We are looking forward to construction of MBIR. However, we can see that the opportunities, which are supposed to be realized in MBIR, slightly differ from those in BOR-60. Is it real to persuade the foreign partners to collaborate in that project?

Maybe, fast neutron flux density in the first cores of MBIR will slightly differ from those in BOR-60. However, in our country there is wide experience of upgrading research fast reactors. For example, BR-5 was upgraded to BR-10. I believe the opportunities of MBIR will be extended in the course of operation.

Utopian class reactor

We have just remembered reactor 4S. What is your opinion on this facility?

This is a modular reactor, which is peculiar all advantages of that type reactor. What is a weak side of 4S? That reactor facility is irrepairable. It is an integral type reactor with electromagnetic pumps, intermediate sodium-sodium heat-exchangers, cooling heat-exchangers. However, absolute reliability of the equipment is expected. It is supposed that a module with reactor 4S will operate long without replacement and repair of the equipment installed within the reactor monoblock. This is only possible in case of absolute reliability of the reactor equipment.

Is there any access to the equipment?

No, there isn't. It will be very difficult, practically impossible, to access the equipment in the process of reactor operation.

In addition, reactor 4S should be installed underground.

I would say it should be installed half-underground. The company reported that the service lifetime will be 30 years without refueling. From the standpoint of physics it is quite achievable.

That is, Japanese scientists rely on quality of reactor 4S.

Yes. And I think they are mistaken.

Now we won't touch upon the Fukushima accident. However, not long ago their trusting in quality let them down at reactor "Monju".

I believe that technical culture in Japan is very high, but experience is required as well.

We laid open to public the data on failures in their centrifuges, and we have questions to their technological culture.

I see. However, I am speaking about specific reactors with sodium coolant. In 1995 December a fire happened at reactor "Monju". As a result, the program on fast reactors in Japan was stopped for 15 years. Last year the reactor was launched, but it was shutdown almost after launching because a steel column of the refueling equipment unit dropped into the reactor vessel.

And up to now they don't know how to remove it.

That's true. Now about research sodium fast reactor JOYO. It is shutdown as there was an accident too. That is, Japanese scientists faced with technical difficulties.

It should be highlighted that in all countries the process of mastering the sodium technology was hard. In my opinion the operation of BN-600 is a major breakthrough in Russia. And this is an outstanding achievement of Russian scientists, designers, engineers, operational personnel. Of course, there were leaks, problems with steam-generators. However, the technology is operating, currently BN-800 is under construction and development of BN-1200 is underway.

Here, people experience is viable. That experience cannot be described in books. Experience, which is succeeded by generations, designers, operational personnel. In Japan there is no such experience.

How old is Project 4S?

I first heard of Project 4S in 1995. I liked the conception very much as it was a modular one. However, in addition to irrepairability, there is an untraditional new scheme of reactivity control. The reflector moves slowly, the core is long, chain reaction only occurs in a short part with the reflector.

That is, some kind of a candle.

Yes, there are some common features. I think I am not mistaken to say the reflector is moving with a speed of approximately 1 mm per week.

And what will happen in an event of system failure?

I have told already in that system nothing can be replaced on the spot. Mentality of Japanese designers is quite different as they believe that there must be no failures at all. Russian designers don't think so, and I am inclined to trust our domestic specialists.

Our designers insert in the project all possible failures and think what should be done in an event of each failure. The approach of Japanese designers is quite different: their goal is that the design must have no failures at all. Of course, the aim is wonderful, but not real. So, it is an utopian class reactor.

Africa didn't build by itself

The Project of Pebble Bed Modular Reactor (PBMR) was closed last year. It was a small power high-temperature reactor designed under a slogan "Africa builds by itself". Wouldn't you like to draw a conclusion on this program?

It was a very interesting project. The advertising campaign for this project was powerful. They spoke about hundreds of customers all over the world. The full cost of the project was estimated to be ~ 1 billion.

The conception of gas reactors possesses a general shortcoming: it is very difficult to overcome the consequences of the accident of tightness failure in the primary circuit. Under normal pressure gas can remove heat very poorly. It is true even for helium.

Therefore, we need high pressures, about 100 at. In an event of tightness failure, helium will be released from the primary circuit, it will be replaced by air, and there will be no natural circulation. But residual heat must be removed.

For that reason, special fuel is made for such reactors, i.e. microfuel with multi-layer coating in a graphite matrix. Tests have revealed that before accidental temperatures have been obtained, gaseous and volatile fission fragments won't be released from microfuel. However, we have to examine what will happen with a heap of spherical fuel pebbles in an event of loss of circulation. Won't it burn? Nevertheless, graphite is a fuel component, and in an event of tightness failure air will penetrate into the circuit.

To make that fuel heat-resistant, different solutions are used, multi-layer silicon carbide, pyro-graphite and other materials are applied. The solution to a heat-resistant problem is found. At the same time, the task of spent nuclear fuel (SNF) reprocessing is becoming much more complicated, it requires own infrastructure for the fuel cycle and corresponding expenditures for its development and functioning. The alternative is PBMR operation in the open cycle without reprocessing. I doubt whether it could be accepted.

Moreover, in PBMR the spherical fuel pebbles, which diameter equals to that of a tennis ball, must cycle through the core ~ 6 times. Circulation of spherical fuel pebbles is realized with the help of screw conveyers. On unloading, fuel pebbles must be moved to the burn-up assaying equipment. After burn-up has been determined, fuel pebbles must be routed either to the spent fuel tanks or back to the core, depending on the burn-up. However, technological realization of the process is difficult. Regarding to this, a concept of Russian-American Project GT-MHR is much more realizable. In that project the fuel shaped as graphite hexagon units is replaced in the process of partial refuelings.

It is interesting to highlight the following. Project PBMR was promoted by state company ESKOM but it didn't result in success.

I can suppose this project is a result of lobbying. When financers give credence to incompetent people, the result will be always negative.

Government's gift

Currently Belgium System MYRRHA (Multipurpose Hybrid Research Reactor for High-tech Applications) is much spoken about. MYRRHA is a sub-critical lead-bismuth cooled reactor operating in tandem with a proton accelerator. What do you think about it?

I would like to say that as for the announced terms, this project is the most realizable. Maybe, first launch of the system will be this year. MYRRHA is developed by Europeans to solve the problem of minor actinides transmutation.

Of course, we esteem the highlighted problem, but in our opinion it is not a major problem of nuclear power.

Well, it is a vital problem for densely populated countries and areas such as Europe, South Korea and so on. The people in those regions are troubled by long storage of SNF with high radiation potential. And they wish to reduce this potential by transmutation of the series of nuclides including minor actinides.

But why cannot we transmute actinides in a conventional normal BN reactor?

This requires to develop BN reactors and not all countries agree with that. But it is not only reactor BN, as each fast reactor is able to transmute minor actinides into fission fragments.

How did the concept of accelerator-driven transmutation systems originate? It happened right after the Chernobyl disaster, when there was fear of prompt reactor runaway. In case of a sub-critical system, prompt reactor runaway cannot occur. For that reason, the idea of hybrid systems was supported by the certain governments.

There is a "social" aspect, more correctly, political one. Many countries don't want to finance development of the reactors, as they consider the private companies must be dealt with it. At the same time, they finance transmutation systems especially if it is not only a reactor, but it is a system with improved safety, which will assure in future the solution to the problem of long-lived radioactive waste.

What is MYRRHA? It is a sub-critical reactor. From above the accelerator a proton beam is delivered. The whole refueling system must be on the bottom as well as the control system. Technical realization of that is very difficult.

They have implemented a system of "under-melting" optical video camera, ultrasonic visualization. That is, they watch everything that happens in the facility in a megahertz ultrasonic range. This is a great technical achievement.

However, the main question is how it will operate. The additional difficulty is that a proton beam is pulsing, it will cause pulse load for heat release, and fuel does not require cyclic loads.

We have two facilities instead of one. Therefore, we have two sets of problems.

That's true. The cost is doubled, and reliability is reduced. Hamid Ait Abderrahim, Principal Manager of Project MYRRHA, whom I have met with, understands the situation clearly. Finally, in case of severe difficulties, it will be possible to "cut off" the accelerator and there will be a lead-bismuth cooled research reactor with fast neutron spectrum.

In principle, nobody is objecting. If the government is financing perspective scientific and research work of our colleagues and has established a purpose, we are welcoming it. However, is it real to speak about commercialization of MYRRHA?

No, it is not. In no circumstances. MYRRHA is not a commercial project at all. It is an experimental nuclear facility that has been built with the help of government (European) financing. Russian specialists are working there too. It is planned to build a large international centre for data exchange, obtaining the new information and so forth.

Ideal cannot be achieved

Professor Toshinsky, we talked about several reactor projects. The following should be highlighted: in each project different coolant is used, i.e. as for coolant, the opinions are different.

It will never be the same opinion for the coolant. There is no ideal coolant in nature. Each coolant that was used or proposed for usage possesses its own advantages and drawbacks. Option for coolant is a task that depends not only on coolant's parameters, but on coolant's mastering and reactor purposes.

Of course, sodium is the best heat-transferring medium. However, when speaking about nuclear reactor coolant, we should take into account the other coolant properties, which burden the reactor facility. It is coolant's chemical activity of interaction with air and water.

It is worth to say (I have touched upon BN-600 already) that Russian engineers and designers have overcome all these difficulties, reactor is operating normally, but it has resulted in a higher cost of the system.

What can justify the higher cost? For example, it is the fact that sodium allows to provide high power density of the core, and in case breeding ratio is high enough, short doubling time of plutonium can be obtained. And if that requirement is vital, there is no alternative to sodium at all.

But now that requirement is not stated in Russia.

In Russia that requirement is not stated, but in China and India that requirement must be met. In different countries the approach is different. And if Russia does not want to lose leadership, we must think how to meet that requirement.

However, as we accept the fact that we should only breed and replace the spent fuel (the amount of bred fuel equals to that of spent fuel), i.e. BR=1, we should consider other coolants, for example heavy coolants, which make possible the operation in a mode of fuel self-providing. In heavy coolants excess plutonium is not built up, and they are not overburdened with the problems concerning insertion of the intermediate circuit. That's right, so currently in force Federal Target Programme "New Generation Nuclear Power Technologies " provides lead cooled BREST and lead-bismuth cooled SVBR along with BN 1200.

So, we should agree that each coolant possesses its own advantages and drawbacks. We know about water from heat power engineering. Water is cheap, comfortable

but it is corrosion-hazardous.

For any coolant (helium is an exception) there are limits on a temperature range and limits on addition agents. The statement that sodium cannot corrode is not right. It will be right on the assumption that oxygen concentration in sodium is minimal. Increase of oxygen will cause corrosion.

For lead and lead-bismuth we should also normalize the oxygen. For water almost ten quality parameters (pH is the first) should be met. Only helium is chemically inert. Shortcomings of helium are as follows: high pressure, large expenditure of energy for circulation. Therefore, in helium cooled reactors the expenditures for own needs are higher than those in water cooled or liquid-metal cooled reactors.

However, the higher efficiency can be obtained.

Yes, I agree. I am highlighting again that each coolant possesses the own advantages and shortcomings. You should choose reasoning from the reactor purpose and extent of coolant's mastering. The task is difficult, with multiple factors, in which one should take into account not only heat-transferring properties, but all the others as well.

And are there efforts to design ideal coolant? It is said that in IPPE there were attempts to design sodium-lead coolant that coupled the advantages of both coolants but without their shortcomings.

Yes, the reports on such works were considered. However, unfortunately such coolant has not been designed yet. But the attempts are made. If lead is added in sodium, we'll eliminate inflammability and explosion hazard of sodium but other problems will appear. Operating such coolant will be very difficult.

Not all coolants passed testing by time. The organic coolant was used. Low pressure was an advantage. However, the problems of radiation and thermal resistance resulted in difficulties in operating the "ARBUS" facility (deposits, gums, hydrogen, others).

Minsk Project on dissociating gas was developed

Obninsk Project on mercury was developed.

Nobody has ever considered mercury as widely used coolant. It was only used in first small experimental fast reactors, which didn't require heating. Mercury is expensive and toxic.

But it was not activated.

Everything happened there. Mercury captured neutrons, proper neutron balance could never be obtained there.

Large and small SVBR

Surely, when speaking with Principal Manager of Project SVBR we would like to touch upon SVBR-100.

I have already told development of the Project is underway. 50 % of financing is provided by the independent power company controlled by O.V. Deripaska. Financing is realized via state-private joint venture OJSC "AKME Engineering". Launching is scheduled in 2017. The task of the designers (Chief Designer of the Project is Limited Liability Company "EDB Gidropress" and Scientific Supervisor of the Project is SSC RF-IPPE) is to perform by the fixed date the necessary R&D for reliable realization of the Project.

As the scheduled terms have been assigned and financing is limited, the Project is being developed on the basis of the conservative approach. The potential that allows in future heightening the safety level and improving the economic parameters is not realized in the Project. These purposes have to be realized in the next generation of lead-bismuth cooled reactors.

SVBR-100 is a first civilian reactor with lead-bismuth coolant. It is not right to think that SVBR 100 must solve all the problems. The design of the reactor must be maximally simple, reliable and it should be supported by tested technical solutions.

However, this will postpone for a long time the quantity construction of reactors SVBR.

I don't think so. First, the realized experimental-industrial power-unit will possess competitive technical and economical parameters within the facilities with identical capacities. Then, when we are speaking about an advanced lead-bismuth reactor, it does not mean that we bear in mind a new project. The design of the advanced reactor will be almost the same, not much renew will be required. The same pumps will be used, but the equipment will be different.

It is difficult, especially after the Fukushima accident happened, to forecast the power situation in the world in 2017. Is it reasonable to forget about other SVBR variants, such as SVBR-10?

The demands for energy will always exist. When speaking about SVBR-100, 100 MWe is a proper option for power. In that reactor operating on mixed oxide fuel, core breeding ratio equals to 1.

It means that in the closed cycle the reactor will operate in a mode of fuel self-providing without consumption of natural uranium. The fuel cycle will be that used in large nuclear power for BN reactors.

We have been told that 100 MWe corresponds to a city, which population is 100 000, i.e. Obninsk.

Yes, that's true. It is approximately 1 kW for the person.

On the other hand, why shouldn't it be more? Why cannot it be 200 MWe? After all, the economic parameters will be better. The reason is that such module cannot be transported by railway. And dimensions of our module allow its railway transportation. Thus, the number of potential sites increases.

The specialists in "EDB Gidropress" say that we should give up the requirement to railway transportation for the unit.

Yes, but it is for reactors WWER. Their priorities are the economic parameters and high capacities. Our foreign competitors allow 1600 MWe for light water reactors and don't presume their transportation by railway.

They have highways and water routes.

Yes, that's right. In Russia freight is mainly transported by railway, and many our roads do not fit for transportation of such heavy freight. The West can give up the railway transportation. However, in Russia giving up the railway transportation will reduce at once the number of potential sites.

Now about SVBR-10. Yes, that project can be realized in short terms, it requires less scope of R&D than those for SVBR-100. However, the economical parameters of SVBR-10 will be worse than those of SVBR-100. If power reduces 10 times, the specific cost of the plant will increase 2,5-3 times.

On the other hand, it is possible to connect to SVBR-10 medical beams and so forth.

Yes. That's right. However, these are additional applications, which will affect the commercialization slightly.

There is no medical beam in Moscow and in the region. So, construction of SVBR-10 in Obninsk with a beam for medical purposes will be a rescue for many people.

I think it will be better to construct a special facility for that purpose. And it shouldn't be a reactor, but a system on the basis of the accelerator, which does not depend on criticality and nuclear safety. In case such designs are realized, the treatment facility will be almost in each hospital.

Will it be better to test the new types of fuel for SVBR in a small power reactor, i.e. in a lead-bismuth research reactor? Why isn't it possible to use SVBR-100 in commercial purposes and to use SVBR-10 in scientific and research works and R&D?

There is no need in a special reactor for research, as the cost of the research reactor is not much lower than the cost of the experimental-industrial unit with SVBR-100.

There are other ways for testing the fuel. Tests should start in BOR-60, assemblies (not a single one) should be irradiated there. Then the tests should be performed in reactor BN-600.

From the standpoint of radiation resistance of the material and fuel, it doesn't matter what coolant is inside the cladding, sodium or lead-bismuth. Everything will be identical inside. The fast neutrons are viable. And that is the shortest way of realization of the point. We will have one research reactor (MBIR), in which among the others there will be loops with lead and lead-bismuth coolants. I think it will be too much expensive to build the second research reactor.

This question is concerning the intellectual property. The impression is that now small west companies use an interest in small power to make attempts to leave this field for themselves. They want to take out a large number of patents and then use the patent funds for life. Won't it limit nuclear power development in Russia? Won't our competitors take out patents on our ideas?

I would like to say that we watch the situation very closely. The authorized capital of OJSC "AKME Engineering" contains the point on intellectual property, i.e. the point concerning the results earlier obtained at "Rosatom" enterprises including SSC RF-IPPE.

These all will be drawn up as intellectual property with corresponding rights. The purpose is to eliminate obstacles and to impede somebody else to use the results. Indeed, this is a very serious issue.

The suspicion is that behind many West advertising campaigns there is some kind of gamble. To gamble - to take out patents, to attract the investors under the patents, and then whatever will be.

Now to take out a patent, one only needs money. Practicality does not need to be validated. It is important that there is some new idea. In some time it may become clear that expenditures were useless.

Our position is well-defined. In case we are taking out a patent, we must be confident that it will be useful, and there will be taken out patents for all innovations, which will be implemented in the SVBR Project.

And can be there a situation when for a certain technology that is already in use but not patented, a patent is taken out in the West?

No, it cannot. The patent analysis has been realized by OJSC "AKME Engineering". A group of patent engineers was working. They don't find such situations though there were certain attempts to impede our work. For that reason, we are not going to discover the technical information concerning SVBR details prior to the required time. That will be done when necessary.

The time when we were ready to disclose the significant information to the West passed. Now we have Federal Target Programme, all significant innovative technologies are being financed. That is why we are not nervous when we watch booming organized by our West competitors.

It is clear for us that in most cases there is no content behind the advertisements. And we know we won't be late.

Professor Toshinsky, thank you for the interesting interview for AtomInfo.Ru e publishing.

Interview was prepared by Igor BALAKIN and Alexander UVAROV (AtomInfo.Ru).

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