Request for right of reply, addressed to the CEA
following the publication of a text damaging my reputation
January 23, 2012
March 29, 2012: no response
On November 17, 2011, the CEA placed on its website a text that characterized my writings as intellectual dishonesty. Here is the full text, 4,625 words, thirty thousand characters:
Response to the paper "ITER: Chronicle of an announced failure" by Mr. Jean-Pierre Petit, published on November 12, 2011 in the magazine Nexus, prepared by the Commissariat à l’Énergie Atomique et aux Énergies Alternatives. November 17, 2011.
Introduction
The argumentation developed in Mr. J.P. Petit's article, a member of the French anti-nuclear association "Sortir du nucléaire," aiming to challenge the ITER project by inciting irrational fears, is built on excerpts, taken out of context, from a recent doctoral thesis prepared at the CEA's Institute for Research on Magnetic Confinement Fusion and defended in November 2010 at the doctoral school of the École Polytechnique on the specific issue of disruption phenomena that may occur during the operation of ITER.
A disruption, a well-known phenomenon, is an instability that can develop within a Tokamak plasma. Charged with a large amount of energy, it leads to the breakdown of magnetic confinement and results in a high-intensity electrical discharge towards the vacuum vessel wall, causing the risk of damaging it.
This high-quality thesis is based on 50 years of work by a global scientific community of several thousand professionals around the world, and constitutes the recognized basis of the current scientific debate on the subject.
There is abundant literature on the subject of disruptions, notably in the articles regularly published in the journal "Nuclear Fusion." They constitute the official and public physical basis of the design of ITER.
Observing that Mr. J.P. Petit's article only retains selected excerpts from works that rightly highlight the attention that the scientific community must pay to disruption phenomena, one can only conclude that Mr. J.P. Petit has a manifest intention of political polemics and malice, and certainly not a quality scientific work conducted in a constructive critical spirit, intended to advance the subject.
We are distressed to note the carelessness with which scientific information published in internationally renowned journals, their authors, but also the readers of the article itself, are manipulated for partisan purposes unrelated to research and the advancement of knowledge.
By such behavior
intellectually dishonest
, Mr. J.P. Petit disqualifies himself ipso facto from the debate, whether scientific or societal.
This document aims, on the one hand, to respond to the most grossly inaccurate points of Mr. J.P. Petit's analysis, both scientifically and in terms of the general context of the research, and on the other hand, to provide the reader with the main keys to understanding this same context and the exact role that ITER must play in magnetic fusion research over the coming decades.
Analysis of Mr. J.P. Petit's criticisms.
The main argument of Mr. J.P. Petit is that ITER cannot withstand disruptions, which correspond to a rapid shutdown of the plasma. Let us analyze point by point the criticisms made in the article (the excerpts from the article are in italics).
p.91, "From this reading, one gets the impression that magnetic confinement fusion and Tokamak physics, extremely complex, are not at all mastered by theorists. No modeling of the behavior of the plasma contained in these machines is representative, in the sense that it will remain for a long time impossible to manage, even with the most powerful supercomputers in the world, a problem involving 1020 to 1022 electrically charged particles, all interacting with each other."
These statements are surprising from someone who claims to be an "eminent specialist in plasma physics." There are numerous examples of theories and models that work well with a large number of particles. It turns out that Magnetohydrodynamics (MHD) is a science that allows the dynamics of a plasma or a conducting fluid with a very large number of particles to be described. The computing power currently available even allows for full-scale simulations. Unless Mr. J.P. Petit is questioning the very work of the scientific community to which he belonged more than 20 years ago, he cannot seriously support an assertion that it is impossible to simulate a dynamic system involving a large number of particles.
That said, no one has ever claimed that Tokamaks are and should be designed based on numerical simulations. In practice, the technical specifications of a Tokamak regarding their resistance to disruptions are based on "laws," called "engineering laws," concerning the energies and characteristic times involved in this process. The values chosen for ITER have been validated by experiments conducted on a large number of Tokamaks over more than half a century. Numerical simulations of disruptions have only recently appeared, notably in the thesis of Mr. C. Reux, which Mr. J.P. Petit greatly emphasizes.
In fact, the results are very encouraging, even if their accuracy can still be improved. It is worth emphasizing again that these simulations represent an additional refinement in the understanding of Tokamak plasmas, and not the basis of the design of ITER, which has long been validated by the "engineering laws" mentioned above.
p.91: "All the Tokamaks in the world, including Tore Supra and JET, have become unmanageable, due to extremely varied causes."
This statement is obviously wrong and completely false: Tore Supra and JET have been operating satisfactorily and perfectly safely since 1988 and 1983 respectively, i.e., more than 20 years of operation for Tore Supra and almost 30 years for JET. Disruptions regularly occur in these two machines (as in all others), but they have never led to destruction, nor to a loss of confinement of toxic products, as fantasized in Mr. Petit's scenario. 30 years of incident-free operation is certainly not what one would honestly call an "unmanageable" situation!
p.92: "disruptions... generate forces capable of deforming the wall structures like straw"
The first wall elements and structures of Tokamaks, and in particular of ITER, are obviously designed to withstand the forces generated by disruptions, including the most powerful ones. These elements are arranged in such a way as to minimize the electric currents that circulate through them during a disruption, thus limiting the tensile forces they may experience. Moreover, in case of extreme situations causing superficial damage to these elements,
these elements are designed to be replaceable.
The photograph shown in the article and taken from the thesis (damaged Tore Supra element sou...)