Luis Enrique Herranz

What are the most outstanding advances in nuclear safety from the past few years?

It would be pretentious of me to try to explain the advances in nuclear safety in general terms, since they have been made not only in the field of electric power production but also in other fields. Therefore, I will focus on the aspect that is closest to my research work: safety at nuclear power plants, and facilities for the dry cask storage of spent nuclear fuel.

When speaking of recent advances in nuclear safety, it is impossible not to mention the Fukushima-Daiichi accident. Given the recent 10-year anniversary of this event, we shall use it as a temporary reference.

As a consequence of the exhaustive revision of the safety of nuclear power plants, especially regarding natural disasters, it is safe to say that nowadays the safety of nuclear power plants has been optimized even beyond the excellent levels it had before Fukushima. Many improvements have been introduced: a re-evaluation of the potential effects of earthquakes and floods at each site; additional means to reinforce the maintenance of safety functions in the event of large natural disasters; the introduction of new equipments and components to better manage any events that could potentially damage the reactor's core and, if necessary, mitigate the consequences; and, finally, the revision and reinforcement of the established emergency plans.

Some concrete aspects close to my area of work, for example: strategies to prevent and mitigate severe accidents have been strenghtened via mobile power supply equipment; installation of catalytic hydrogen and carbon monoxide recombiners in contention, or filtered contention venting systems.

16 out of the 33 countries with operating nuclear power plants are granting authorizations for the operation of their reactors beyond 40 years. What are the requirements?

At the end of this century's past decade there were at least five commercial reactors that had reached 50 years since the start of their operations. There is an enormous interest in the long-term operation of nuclear power plants. Of course, in order to get a long-term operating license, all plant structures, systems and components must be reviewed in-depth and documented from a safety standpoint. If necessary, the same report can also include material, component and system replacement, repair and/or wear mitigation proposals.

Six nuclear stations have been authorized in the U.S. to operate for 80 years. Do you think we will see something similar in other countries?

The U.S. has been the leader in nuclear technology throughout history in many aspects. Right now, 90 percent of American nuclear power plants have had their licenses renewed for up to 60 years of operation, and other countries are following in their footsteps. In the case of service life extension to 80 years, it is likely that the U.S. will also lead the way since some American plants have already been authorized to operate for 80 years, and 20+ percent of American plants are planning to apply or have already applied for the extension of their operating licenses.

It is a bit far-fetched to assume that other countries will follow suit, but it has certainly created a path that others could follow.

There are currently 51 nuclear reactors under construction around the world. Which are the organizations and safeguards through which the process for authorizing the commissioning of a reactor and the operation of a reactor must go through?

Most countries with developing nuclear projects belong to the “nuclear community” you mentioned earlier, such as China, the U.S., Russia, France, India, South Korea, Finland... these countries have laws and a system of preliminary safeguards currently in force. However, many other countries are viewing nuclear power as a potential option for meeting their energy needs. These includePoland, Lithuania, Ireland, Egypt and Morocco, up to a total of 30 countries. Apart from them, there is a small group of countries like Pakistan, Turkey and Bangladesh that have specific building plans underway.

In these latter cases, the International Atomic Energy Agency (IAEA) undoubtedly plays a key role in structuring the national regulatory bodies, with which it extensively works via its safety standards and the establishment of nuclear safety and safety culture training programs.

After the Chernobyl and Fukushima accidents, what progress has been made in nuclear safety, and what mistakes will it be impossible to make again?

The nuclear industry has shown an amazing capacity to learn from the very few accidents that have occurred at nuclear power plants (TMI-2, Chernobyl and Fukushima-Daiichi). A good example of this is the “Knowledge Management Digest” document that lists the lessons learned from the investigation into the accident in Unit 2 of Three Mile Island NPP that was conducted for over 25 years.

On the other hand, Chernobyl raised many flags for the nuclear community, most of which have been addressed in the documents that both the OECD’s Nuclear Energy Agency (NEA) and the IAEA have released. There is not enough room here to list all the progress made as a result of that accident. Nevertheless, beyond the design modifications that were made on the RBMK reactors that were still running at the time, or the international collaboration project for the construction of the sarcophagus around Unit 4 of Chernobyl NPP, the accident at this Ukrainian station resulted in the explicit acknowledgment that nuclear safety had to be optimized via open collaboration among plant operators. The creation of the World Association of Nuclear Operators (WANO) is, in my opinion, the best consequence of the Chernobyl accident.

Lastly, regarding Fukushima, many specific aspects have been optimized since that accident. From the structure of the reactor regulating system and the need for it to be independent to the optimization of all safety-related systems, components and methodologies. Although the Fukushima-Daiichi scenario is still being explored, it has already led to huge progress being made in terms of accident management support instrumentation, plant decommissioning robotics and understanding severe accidents in BWRs.

How do you think we can improve trust and knowledge of nuclear energy?

Without wanting to go into topics such as the education of our children and young people—and even of their teachers—or using media and social networks, let me point out three things:

The first one is general in nature and is not necessarily connected to nuclear energy (although it is): Let’s help society to understand that we live in a world where zero risk is unattainable. Once we accept this, we can begin to educate people in accepting and weighing risks. But making people who are unaware that they face many risks on a daily basis believe that “absolute certainty does not exist” is difficult for several reasons: because some risks might fall into the “trivial” category, or just because the advantages of accepting a risk simply outweigh the drawbacks.

The second idea consists of feeding society objective, specific, accessible and verifiable data. Sometimes we have tried—myself included—to speak from the “nuclear pulpit,” with our solid ideas based on our technical and knowledgeable “digestion” of a “complex technology.” Let’s allow the public to “walk down that road,” let’s give them the tools to do so—but let’s allow them to make up their mind about nuclear power (for or against it) instead of telling them to “take our word for it."

Finally, the third aspect has to do with communication itself. In the case of controversial technologies such as nuclear power, it is just not true that “bad communication is better than not saying anything at all.” Special attention needs to be paid to the facts and data to be reported. We cannot just let the speed at which information is demanded today compromise its truthfulness, nor can we embrace academic rigor and precision as essential principles that we cannot renounce. Sometimes, speaking in orders of magnitude instead of exact, hard-to-comprehend figures makes it easier to get across messages that are easier to understand. On the other hand, sometimes messages that are fundamentally correct but are released incorrectly can do more harm than good.

In an interview, you called for depoliticizing nuclear power and do away with all ideological blinders. You also said that the energy structure of a country should be a technological subject rather than a political one. Tell us more about this!

I would love to delve deeper into this subject. Unfortunately, I’ve been thinking for a while now that the true goal of the people who make decisions in the name of a country is to get their hands on as many aspects of our lives as possible. So, if you’ll excuse me, I’m not going to talk any more about this specific matter, which I’m still firmly convinced of. On the contrary, let me be more general by saying that if we had the good habit of letting the people who are masters in their field discuss matters and make decisions with an open mind, thinking of what is good for society in the short, medium and long terms, people would in turn accept the results and thank them for the efforts they made to reach common ground, even if it differs from their own opinions. Should we move up to an already hard-to-imagine higher sphere and consider the possibility that our leaders are capable of accepting that same result and efficiently implementing it, we would sadly be entering the land of fiction.

You teach courses and master's degrees and give talks that revolve around nuclear safety. What concerns and interests do you find in those directing their professional career toward the nuclear field?

First of all, I must admit that there is a great difference between the people of my generation and the current generation of young students. The most positive thing that I see in them is their enthusiasm and appreciation for the technical aspects of a technology as amazing as nuclear. As a less positive trait, I perceive a dangerous tendency to “do” instead of “know”, to “calculate” without having a very deep understanding of the subject matter. It is very likely that this second aspect comes from the easiness that new technologies are putting within our reach, allowing us to make one hundred calculations in less time than it takes us to really understand the terms of the equations which the algorithm in question solves. Perhaps things are moving too fast and we should instead be trying to strike a new balance between our knowledge and our ability to do things.

What advice do you give your students?

The first piece of advice is for them to always acquire their judgment based on knowledge, instead of letting emotion or external indoctrination influence them. The second is to enjoy the incredible journey of learning and feel the need to keep learning without being afraid to look back and realize that some thing may not be as they thought it was in the past.

As for nuclear energy, since I lecture about it and enjoy it so much, I hope my passion comes across as unspoken advice. If I had to express it, it would sound somewhat like this: Learn passionately, do things based on what you have learned and keep your level of excitement always high.

A change of subject: How has working at CIEMAT changed in these pandemic times?

The changes have been huge for everyone, not only for us at CIEMAT. As far as I’m concerned, ever since the hard lockdown was lifted, CIEMAT has made sure to provide a safe work environment at all times by establishing protocols and taking measures based on the rules imposed by the competent health authorities.

In my particular case, the pandemic has led to a disproportionate proliferation of meetings. All the professional environments where I work have done their utmost to make remote connections as efficient as possible. My experience, however, has not been good. Given that meetings are one of the best tools we have at our disposal under these conditions, I find their effectiveness questionable, particularly when a lot of people are involved. Keep in mind that, beyond the aseptic reporting of results or discussing all sorts of issues, before the pandemic meetings where one of the most efficient networking tools.

Instead, the high number of meetings, the ease of remote working and the need to do actual work have led to almost endless working days. In sum, I miss the pre-Covid times. Unfortunately, the losses some of us have experienced these past few months will keep us from not longing for the past. Having said that, I do hope that, once things get back to normal (or close to normal, as the case may be), we will learn to make the most out of the most positive things we have experienced during these hard times and incorporate them to improve everyone’s working conditions.

What are the biggest achievements of your research unit and the biggest challenges you had to face as its leader?

It’s hard for me to pick a handful of achievements to highlight. It might be more meaningful to picture the path of a unit that was created in the mid-eighties and has managed to adapt over time. Right now, it is involved in quite a few international projects—and ocassionally even leads them—and is a member of the working groups of the international institutions most closely associated with its areas of interest: severe accidents in present and future reactors and the behavior of nuclear fuel in the reactor and in dry storage.

If I had to choose a couple of noteworthy technical milestones in the life of CIEMAT’s nuclear safety research unit—focusing mainly on the two decades I spent heading it, they would be the interpretation of the Fukushima accident in close collaboration with the Spanish Nuclear Safety Council (CSN) and the in-house training we underwent to be able to study the behavior of spent nuclear fuel in dry storage (a research mainly sponsored by ENRESA). The challenges we faced in both cases were the use of in-house developed and external methodologies; some of which we lead internationally.

However, from a strategic point of view and beyond the aforementioned participation in specific international forums, one of the biggest challenges/achievements of  these past two decades has been the useful research we conducted on behalf of the Spanish regulator (CSN), the company in charge of nuclear waste management in Spain (ENRESA), and some nuclear power plant owners. I strongly believe that, in the case of nuclear safety research, any investment a country like Spain makes should ultimately go to the main actors of its nuclear reality. Thus, we keep working to put our capabilities at the disposal of the aforementioned organizations and companies as well as others we might also work with in the future.

Regarding the difficulties I’ve encountered as the person responsible for our research, I must say that, far from being technical or scientific, they are bureaucratic in nature all the paperwork that burdens our daily work in many different ways. I understand the need to orchestrate administrative actions, but I'm against the crushing bureaucracy that sometimes strangles researchers.