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Nuclear Power’s Role in Responding to Climate Change Stampa E-mail
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by Andrew C. Kadak1, Richard A. Meserve2, Neil E. Todreas3 and Richard Wilson4



1)Former President of the American Nuclear Society and Member of the US Nuclear Waste Technology Review Board
2) President of the Carnegie Institution for Science and a former Chairman of the US Nuclear Regulatory Commission
3) Korea Electric Power Company Professor (emeritus) and a former Chairman of the MIT Department of Nuclear Science and Engineering
4) Mallinckrodt Research Professor of Physics (emeritus) and a former Chairman of the Harvard University Department of Physics



             
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Lo scorso 17 novembre, quattro scienziati riconosciuti in ambito internazionale come grandi esperti di cambiamenti climatici - Ken Caldeira (Carnegie Institution), Kerry Emanuel (MIT), James Hansen (Columbia University), Tom Wigley (University of Adelaide e National Center for Atmospheric Research) - hanno firmato un appello congiunto al mondo dell’ambientalismo, affinché l’energia nucleare venisse riconosciuta come una delle soluzioni nel contrasto al climate change.
Questa lettera aperta è stata sottoscritta e appoggiata nelle settimane successive da numerosi altri rappresentanti del mondo scientifico e della ricerca.
In particolare, lo scorso 22 gennaio quattro eminenti personalità in ambito nucleare hanno voluto dare il
loro apporto a questa iniziativa. Si tratta di Andrew C. Kadak (former president della American Nuclear Society e membro del US Nuclear Waste Technology Review Board), Richard A. Meserve (presidente della Carnegie Institution for Science e former chairman della US Nuclear Regulatory Commission), Neil E. Todreas (professore emerito Korea Electric Power Company e former chairman del Massachusetts Institute of Technolòogt - dipartimento delle Scienze e dell’ingegneria nucleare), Richard Wilson (professore emerito Mallinckrodt Research e former chairman dell’Università di Harvard - Dipartimento di Fisica).
Nuova Energia pubblica il testo integrale in lingua inglese del loro intervento.
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Although electric generation from solar and wind can play a role in meeting future energy needs, their intermittency means they are not scalable to the level needed to meet the world’s energy needs without significant gains in storage technology. However, as we elaborate below, nuclear power can deliver electric power in a sufficiently safe, economical and secure manner to supplement supply from other carbon-free sources.



Safety
Today there are 100 nuclear power plants operating in the United States supplying close to 20 per cent of the electricity needs. Worldwide 432 reactors provide electricity to 32 nations. Sixteen nations receive over 25 per cent of their electric energy needs from nuclear power safely and reliably without CO2 emissions that threaten the planet. In total, the nuclear industry has accumulated over 14,500 cumulative years of civil reactor operational experience since the first commercial nuclear plants were built over 60 years ago.
There have been three serious accidents that challenged the safety record of nuclear power: the Three Mile Island (TMI) accident in 1979, the Chernobyl accident in 1986, and the tsunamiinduce Fukushima accident in 2011. The presidential commission (the Kemeny commission) appointed to investigate the TMI accident reported that the major effect on heath, fortunately short lived, was the stress on people both evacuated and not evacuated. In all these accidents there were no immediate public fatalities and only at Chernobyl were there workforce fatalities (28) arising from radiation exposure. The increased incidence of thyroid cancer arising from the Chernobyl accident had two major causes: the silencing of those advising children not to drink milk and the authorities’ failure to restrict distribution of dairy products immediately after the accident.


Additional health effects, if any, from all these accidents to either workers or the affected public are predicted to be a nondetectable increment (3-4 per cent) above the normal background level of cancer mortality in the general population. These small effects should be compared with the significant number of deaths from other energy generating technologies, such as natural gas accidents or health impacts caused by air pollution from coal plants.
The operating and safety record of US operating plants has improved steadily since 1979. Today the plants typically perform near 90 per cent of their maximum potential. No serious incidents have occurred in the US since that at Three Mile Island, due largely to applying the lessons learned from that accident. The plants are continually upgraded to meet the ever more stringent safety standards and expectations of the nuclear industry. As a result of the terrorist attack on the US on September 11, 2001, the nuclear industry modified the plants to handle terrorist attacks of all types, including aircraft impact. These modifications have made the nuclear plants capable of providing electricity and cooling water to important systems at the plant, regardless of the availability of traditional sources of power and cooling water. This record of improvement continues today with additional capabilities being installed to deal with extreme natural disasters such as the one experienced at Fukushima.


The nuclear industry is one of the most highly regulated industries in the world. In the United States, the Nuclear Regulatory Commission has at least two resident inspectors at each power reactor overseeing operations and maintenance. NRC staff monitors the performance of the plants and provide the results in reports available to all at the NRC website (www.nrc.gov). This oversight should provide the public with further assurance of the safety of US operating plants.



Cost
A nuclear power plant is a long-term investment which can last from 40 to 60 years (the license granted by the Nuclear Regulatory Commission). It is widely recognized that nuclear plants are more costly to build than natural gas and coal plants. However, because of the relative insensitivity of the fuel cost to the price of electricity, the cost of power from nuclear plants is more predictable over the long term than that of fossil fuels. This is the real advantage of nuclear energy - namely, a predictable and nonvolatile cost of electricity for consumers.
The average production cost of electricity from existing nuclear plants (excluding the capital cost, which is paid off at this point for most reactors) is 2.4 cents/kWhr in 2012. On average, this is less than the production cost of electricity from natural gas or coal. Of course, some plants have costs above the average and operate in regions with extraordinarily low gas prices.


Recently two nuclear plants have shutdown as a result. The low price of natural gas may force other less competitive plants to shutdown based on local market conditions. But overall, most of the fleet remains competitive even in a period of remarkably low gas prices.
The anticipated capital cost of new advanced nuclear plants such as the US-developed AP 1000 pressurized water reactor is about 7 Billion dollars. Four such plants are currently under construction in Georgia and South Carolina, which are due to start up in 2017-2020. Despite this high capital cost, the long-term cost of power is estimated to be 8.4 cents/kWhr, which is competitive with natural gas prices of 9.5 dollars/MMBtu. Although this break-even cost may be higher than the current price of natural gas, the stability in the cost of nuclear electricity provides an important hedge against future price increases in natural gas, as well as protection from supply interruptions. And, of course, the cost of electricity from natural gas plants does not include any recognition of the carbon emissions that they produce.


The cost of natural gas is very volatile. In 2009 before the shale gas findings it was about 13 dollars/MMBtu and gas in Europe today costs about three times the US price of about 4 dollars/ MMBtu. If the US becomes a major gas exporter, the price of gas in the US will rise toward the world price, with the attendant rise in cost of gas generated power. An important feature of nuclear power is that it will weather the price vulnerability of fossil fuel plants and is considerably cheaper than highly subsidized wind and solar power projects, which must overcome the vagaries of wind and the daily unavailability of sunlight to make a major contribution to electrical supply.

             
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Soluzioni percorribili con l’atomo
di Giuseppe Forasassi | professore emerito Università di Pisa, presidente CIRTEN (Consorzio Interuniversitario per la Ricerca Tecnologica Nucleare)

A livello scientifico internazionale
è largamente riconosciuto che l’energia da fonte nucleare può essere una soluzione utile
e percorribile per ridurre l’impatto ambientale dei gas serra e in particolare della CO2 prodotti nell’impiego di
fonti fossili per la produzione
di energia elettrica.
Questo parere è autorevolmente condiviso dagli autori (A. Kadak, R. Meserve, N. Todreas, R. Wilson) della memoria oggetto del presente commento. I punti principali su cui sono indirizzati l’opposizione e le critiche relative all’impiego dell’energia nucleare da fissione sono in pratica i seguenti: impatto ambientale, rischi e sicurezza degli impianti nucleari, costo dell’energia elettrica prodotta, problemi connessi con le scorie e la disattivazione degli impianti, proliferazione.
Queste tematiche sono e sono state da tempo oggetto di dibatto ed hanno avuto risposte di vario tipo, con diverso livello di accettazione a seconda della competenza scientifica e (a parere dello scrivente) della obiettività degli interlocutori. In estrema sintesi l’impatto ambientale degli impianti nucleari in normale funzionamento è minimo per la scarsa quantità e la facile controllabilità degli effluenti.
Per quanto riguarda la sicurezza, anche semplicemente da un punto di vista statistico, con oltre 430 reattori nucleari in funzione in 32 nazioni e oltre 14.000 anni per reattore di esperienza operativa accumulata a livello mondiale, si ricordano (come dicono gli autori citati) solo 3 incidenti maggiori (TMI in USA, Chernobyl in Ucraina, Fukushima in Giappone) con conseguenze dirette, tutto sommato, molto ridotte (non distinguibili rispetto ai valori di base della popolazione) sulla vita e la salute delle persone direttamente coinvolte, in particolare se confrontate con le conseguenze accertate dell’impiego delle fonti energetiche fossili più comuni come il gas naturale e il carbone. Inoltre gli standard di sicurezza, in particolare in vista dei nuovi tipi di impianti nucleari (IV Generazione) sono in continuo miglioramento, sia per l’esperienza acquisita sia per gli sviluppi presenti e attesi della tecnologia anche in termini di maggiore resistenza degli impianti agli attacchi terroristici e agli eventi naturali estremi.
Anche dal punto di vista dei costi del kWh prodotto gli autori osservano, con dati numerici, che il nucleare può essere considerato conveniente sia attualmente che in prospettiva, in particolare tenendo conto della necessità di ridurre la CO2 per i combustibili fossili e delle tecnologie necessarie per garantire la continuità della disponibilità nel caso del ricorso all’impiego di centrali eoliche o solari; l’impiego del nucleare avrà certamente un effetto benefico anche in termini di riduzione dei costi dei combustibili fossili. Questa convenienza economica è confermata anche dai nuovi impianti in costruzione o programmati in USA, Francia, UK, Finlandia, Cina, eccetera. Per quanto riguarda le scorie nucleari, il problema può considerarsi risolto con depositi superficiali per le scorie con vita media più ridotta e con depositi geologici profondi (USA, Svezia, eccetera), specialmente se combinati con altre tecnologie idonee come il ritrattamento dei combustibili nucleari (per esempio, Francia e altri Paesi) già impiegate oggi e ancor più, prevedibilmente, in futuro.
I rischi di proliferazione con costruzione di armi nucleari potranno essere ridotti progressivamente con lo sviluppo di nuove tecnologie che porteranno a combustibili meno utili per qualità e quantità agli impieghi militari e terroristici, nonché con l’impiego di accordi e la diffusione di sistemi e controlli internazionali destinati agli stessi scopi.
Alle considerazioni precedenti si può aggiungere il già citato sviluppo di tipi di reattori avanzati con maggiori caratteristiche di sicurezza intrinseca e passiva, dimensioni più ridotte di quelli attuali e l’impiego di altri tipi di refrigeranti al posto dell’acqua (come l’He, i sali o i metalli fusi Na o Pb), reattori di cui si hanno esempi già realizzati o in fase di sviluppo o costruzione in vari Paesi. Con le crescenti necessità di energia a livello mondiale si può concludere, con gli autori citati, che l’energia nucleare - anche insieme ad altre fonti energetiche - appare essere una risorsa sicura, economica, già disponibile e sostenibile per rispondere in modo efficace alle esigenze suddette.
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Waste Management
Nuclear waste management or disposal is often cited as an objection to building more new nuclear plants. The nuclear waste is classified into two main categories from operating reactors - lowlevel waste and used nuclear fuel, often referred to as high-level waste. At present both are safely and effectively managed. Lowlevel nuclear waste is disposed of at federally and state licensed disposal facilities in monitored land burial sites. The activity of this waste typically lasts less than 300 years due to radioactive decay (a natural process that leads to non-radioactive materials).
The high-level waste in the form of used nuclear fuel is temporarily stored at reactor sites in used fuel storage pools or in dry casks in shielded concrete canisters. Some believe that this used fuel is a resource that could be reprocessed in the future to provide more fuel for reactors, since not all of the energy value is consumed in the initial period of reactor operation. The French policy, as well as that of several other nations, is to reprocess this fuel not only to produce more fuel and but also as a part of a highlevel waste management strategy to make its ultimate disposal much less challenging by reducing its content of very long lived radioactive isotopes.


An early international consensus based on a US National Academy of Sciences report of 1957 is that geological disposal, regardless of waste form (used fuel or reprocessed waste), is the preferred final state for high-level waste. One properly designed repository will be able to handle all the high-level waste for all US operating reactors for their lifetime. The scientific studies for the US Yucca Mountain Repository Project did not change this preference, but its abandonment led to the formation of the Blue Ribbon Commission, which was asked to recommend a path forward for the disposition of used fuel.


The Commission’s recommendation was to proceed with centralized interim storage of spent fuel and a “consensus” process to site a new repository(s), an approach included in current bipartisan waste legislation in the Senate. Several other nations are already proceeding with their geological repositories. The current leaders are Sweden and Finland; both have selected a site and are developing detailed designs for used fuel disposal.
These efforts, while still uncompleted, are well on track to a successful resolution. At the same time, a geological disposal site for transuranic waste arising from defense programs (a form of high-level waste) near Carlsbad, New Mexico, is successfully operating.



Proliferation Risk
Nuclear power does involve proliferation risk because of the possibility that enrichment and spent fuel processing capabilities could be used for development of weapons materials. This threat is currently managed through international treaties and the conduct of inspections programs. The risk may be amenable to future reduction by technological developments; research is ongoing to develop advanced reactors which can drastically limit the enrichment capacity needed for civil nuclear power, as well to develop reprocessing technology that will produce materials that are much less desirable for weapons utilization. Current light water cooled power reactors, which are the type needed for substantial expansion of civilian nuclear power, are not easily modified for production of the plutonium most suitable for weapons.
While a commercial nuclear power program can be used to mask the initial stages of a covert nuclear weapons program, weapons development by all countries including the United States, France, United Kingdom, Russia, China, India, South Africa, Pakistan, North Korea, and Israel, has been done independently of, and usually prior to, a commercial nuclear power program.


Additionally a rogue nation such as North Korea can develop a nuclear weapon without developing nuclear power reactors for electricity production. For these reasons we do not agree that proliferation risk is a compelling basis upon which to oppose the deployment of civil nuclear power plants. The reality that nuclear power is already widespread suggests that continuing efforts are appropriate to strengthen the international regime to control proliferation.



Life Cycle Emissions Analysis
There have been numerous studies conducted about the life cycle impact of various technologies in terms of CO2 emissions. When compared on an equal basis, nuclear energy (including all aspects of mining, construction, operation and decommissioning of power facilities) ranks as one of the lowest overall emitters of CO2.
The figure from the International Panel on Climate Change provides this comparison and shows that nuclear energy is indeed a “green” source of power.



The Future
Today advanced nuclear power stations are being deployed worldwide based on proven light water reactor technology. New light water reactor designs are under development which will provide further enhanced safety and security features. Additionally, there are new innovative reactors being developed. Most are small modular reactors employing not only water coolants, but also helium gas, molten salts, and liquid metals with improved safety performance based on inherent design safety features. (One such design - the high temperature pebble bed helium-cooled gas reactor - is now under construction in China and is designed to produce 200 MWe of power).



Conclusion
The energy needs of the world are large and growing. The one billion people that do not even have access to electricity cannot be denied the ability to improve their quality of life. Nuclear energy provides a scalable, clean source of safe power which, with other clean energy sources, can meet the world’s needs in a sustainable manner. We applaud and support the efforts of the climate scientist authors of the originally cited letter, Drs. Caldeira, Emanuel, Hansen, and Wigley, for bringing the issue of the need for nuclear power to the world environmental community and policy leaders.

 
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