Fissile Materials versus Strategic Materials
A “strategic nuclear material” is any substance that can be used as a nuclear explosive – that is, capable of causing an atomic explosion.
A “fissile nuclear material” – or simply “fissile material” – is any substance that can be used as fuel in a nuclear power reactor.
They are not the same thing. Not at all.
By Gordon Edwards
[Disclaimer: Almost all nuclear power reactors in the world today use a “moderator”. In the following discussion, when the phrase “nuclear power reactor” is used, only such “moderated” nuclear reactors are meant ; they are sometimes called “slow” reactors.]
It is true that most strategic materials are fissile. Materials that are usable to make a nuclear explosive are, in most cases, also usable as fuel for a nuclear power reactor of appropriate design. But that is not always the case; not all strategic materials are fissile. [See plutonium.]
More importantly, not all fissile materials are strategic materials. In fact most of the fissile material in circulation around the world is not nuclear-weapons-usable (i.e. not strategic).
In particular, the fissile material that is used to fuel the existing fleet of nuclear power reactors around the world is NOT strategic nuclear material. If terrorists hijacked a shipment of such fuel, they could not make an atomic bomb with it, even with the fanciest chemical processing laboratory in the world. (Unless the fuel is highly enriched, which is almost never the case, or contains plutonium, which is sometimes the case.)
[Caveat: Some research reactors and a few power reactors have used highly enriched uranium as a fuel; such fuel IS strategic nuclear material. Also, some power reactor fuel is made with plutonium as well as uranium, or instead of uranium; THAT type of fuel has to be regarded as strategic nuclear material, in the sense that a relatively straightforward chemical process can extract nuclear-weapons-usable material.
See http://ccnr.org/plute_sandia.html and http://www.ccnr.org/Findings_plute.html .]
The Fissile Materials Report
Although the following article refers to the “Fissile Materials Report”, published by the “International Panel on Fissile Materials”, this is in fact a misuse of terminology. The Panel is actually concerned only with STRATEGIC nuclear materials – rather than all types of fissile materials – and THAT’S what the report deals with.
There are two types of strategic nuclear materials of concern to the Panel:
(1) Highly Enriched Uranium (HEU);
(2) Any reactor-produced plutonium.
Highly Enriched Uranium (HEU)
Uranium is a naturally-occurring element that can be mined from the Earth. And when uranium is dug out of the Earth, no matter where on the planet this may be, it is found that the concentration of uranium-235 (a rare variety of uranium) is only 0.7 percent. In other words, only 7 atoms out of 1000 are U-235. Almost all of the other atoms are uranium-238,
by far the most abundant variety of uranium found in nature. There are also a few atoms of uranium-234 (U-234) sprinkled in here and there: U-234 is a much more rare variety of uranium than U-235, and it has no practical use.
U-235 is a fissile material, whereas U-238 and U-234, by themselves, are not. However when the non-fissile varieties of uranium are mixed with a sufficient quantity of U-235, the resulting blend is a fissile material, because it can be used as fuel in a properly designed nuclear reactor. Indeed, natural uranium – without any enrichment at all – is used as fuel in CANDU reactors; and “low-enriched uranium” (LEU) – in which the concentration of U-235 is only 3 or 4 percent – is used as fuel in most other commercial power reactors in the world.
But this kind of fissile material – the kind used to fuel most commercial power reactors – cannot be used to make an atomic explosion of any kind. It is not strategic nuclear material.
To make an atomic bomb using naturally-derived uranium as an explosive, the concentration of uranium-235 has to be increased to at least 20 percent or more; when this has been accomplished, the uranium is said to be “highly enriched”. Such uranium is then called HEU = highly enriched uranium. HEU must be guarded with utmost care, because anyone having access to enough HEU can use it to make a powerful atomic explosive device.
[Most uranium-based nuclear weapons use uranium that has been enriched to more than 90 percent U-235; this is called “weapons-grade uranium”. However, HEU that is not weapons-grade can also be used to make a nuclear explosive device of enormous power.]
Reactor-Produced Plutonium
Plutonium is not a naturally-occurring element; it cannot be mined from the Earth because it does not exist in nature to any measurable degree. However, plutonium is created inside all nuclear reactors fuelled with U-235, regardless of the degree of enrichment of the fuel.
Plutonium is created when a U-238 atom (always present to some degree in uranium fuel) absorbs one or more neutrons and undergoes a series of transmutions into various varieties (isotopes) of plutonium: most often ending up as plutonium-239, but sometimes becoming plutonium-240, plutonium-241, or plutonium-242. In addition, some small amount of plutonium-238 is created.
Both plutonium-239 and plutonium-241 are excellent fissile materials, and both are likewise strategic materials. They are both powerful nuclear explosives, and they are both usable as fuel in a nuclear power reactor. In fact, the future of the entire nuclear industry may hinge on the potential use of plutonium as the “nuclear fuel of the future” — because natural uranium supplies are not expected to outlast the world’s oil supplies.
What about the other plutonium isotopes? It is a little-known fact — even among most nuclear engineers – that, while plutonium-240 and plutonium-242 are NOT fissile materials (they cannot be used as fuel in a commercial nuclear power reactor) they are nevertheless both strategic nuclear materials!
Both plutonium-240 and plutonium-242 can be used as a nuclear explosive material, but neither one can be used (by itself) to fuel a nuclear reactor. It’s the moderator inside the nuclear reactor that makes the difference. There is no moderator in an atomic bomb or in any other kind of nuclear weapon. Plutonium-240 and plutonium-242 are both more powerful explosives than weapons-grade uranium is.
Consequently, ANY mixture of plutonium isotopes that is produced from a uranium-fuelled nuclear reactor is classified as strategic nuclear material. Even if the plutonium is blended with other material, such as uranium or thorium for example, it is possible to extract the plutonium using straightforward chemical separation methods, yielding a powerful nuclear explosive material. See http://ccnr.org/plute_sandia.html .
For that reason, the use of MOX fuel (consisting of a plutonium/uranium blend or a plutonium/thorium blend) is infinitely more dangerous than the use of natural of low-enriched uranium fuel. Anyone hijacking a shipment of MOX fuel is just a few steps away from having a usable supply of nuclear explosive mnaterial.
Gordon Edwards.
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Fissile Material Report:
U.S. HEU stockpile at 595 tons
(100-plus tons at Oak Ridge’s
Y-12 HEU Management Facility)
By Frank Munger, “Atomic City Underground” blog, Oct 24, 2013
http://tinyurl.com/l5uw5hm
The International Panel on Fissile Materials this week released its 2013 Global Fissile Material Report. It’s the seventh annual report of its kind.
The current global inventory of highly enriched uranium is estimated to be about 1,380 tons, plus or minus 125, according to the report.
Oak Ridge, of course, is a key player, with the Y-12 nuclear weapons plant hosting the nation’s primary stockpile of highly enriched uranium.
Here’s an excerpt on the U.S. HEU stockpile:
“The total U.S. HEU stockpile is estimated as 595 tons, as of the end of 2012. In 2006, the United States declared that, as 30 September 2004, a total of about 690 tons of HEU remained from the 850 tons of HEU it had produced or acquired since 1945. The stockpile is declining because of the continuing blend-down of 210 tons of HEU declared as excess to military requirements.
“Through the end of 2012, approximately 141 tons had been down-blended.. The HEU down-blending rate has slowed from about 10 tons per year to 3–4 tons per year. Downblending of the remaining U.S. HEU already declared excess is planned to take at least until 2050. According to the U.S. Department of Energy, “a review of surplus HEU material that will be available in the next several years shows a relatively small supply to initiate a new down-blend contract offering.”
“The excess HEU expected to be available for down blending has decreased by about 24 tons. On 29 April 2011, the U.S. National Nuclear Security Administration stated that, “based on historical data, DOE anticipated that up to approximately 32 tons of the [160 tons designated for naval reactor fuel] HEU might be unsuitable for use as naval reactor fuel, and proposed to down-blend rejected material to LEU.” Since the, the Navy has found unsuitable only 8 tons of this 160 tons of excess HEU. Accordingly, the amount of HEU reserved for U.S. naval fuel has increased from 128 tons to 152 tons—and the amount of excess U.S. HEU decreased by the same amount, i.e., by 24 tons.
“Questions were raised about the security of the U.S. HEU stockpile in July 2012, when three anti-nuclear activists penetrated the high security system surrounding the newly built Highly Enriched Uranium Materials Facility (HEUMF) at the Y-12 site in Tennessee, which contains over 100 tons of HEU. All nuclear operations at Y-12 were shut down for some time. An official investigation found that:
” ‘The Y-12 security incident represented multiple system failures on several levels. For example, we identified troubling displays of ineptitude in responding to alarms, failures to maintain critical security equipment, over reliance on compensatory measures, misunderstanding of security protocols, poor communications, and weaknesses in contract and resource management. Contractor governance and Federal oversight failed to identify and correct early indicators of these multiple system breakdowns. When combined, these issues directly contributed to an atmosphere in which the trespassers could gain access to the protected security area directly adjacent to one of the Nation’s most critically important and highly secured weapons-related facilities.’ ”
