FRANCESCO CALOGERO

FRANCESCO CALOGERO

Professor of Theoretical Physics,University of Rome "La Sapienza", Rome, Italy

Proposed contribution:

Nuclear terrorism:the risk of Highly Enriched Uranium (HEU)

ISODARCO WinterCourse: Andalo, 13.02.03

See the PugwashIssue Brief authored by Jeff Boutwell, Francesco Calogero and Jack Harrison the website of the Pugwash Conferences on Science and World Affairs
www.pugwash.org

[Note however thatthe following presentation is much closer to the presentation given byF. Calogero at the 2002 Amaldi Conference than to the text of the PugwashIssue Brief referred to above]

1. Given a sufficientquantity of Highly Enriched Uranium (HEU), it is quite easy to manufacturea nuclear explosive device.

2. HEU is the onlymaterial that allows the easy manufacture of a nuclear explosive device.

5. The effects ofsuch a nuclear explosion are likely to exceed by far any previous terroristaction.

6. There are individualsand groups who would perpetrate such a terrorist act if they could.

7. The main -- infact, perhaps the only effective -- defense against this danger is to preventthe would-be perpetrators from acquiring a sufficient quantity of HEU.

9. The onlyfully reliable route to eliminate this danger is to eliminate altogetherHEU. This is possible in the long run, compatibly with the maintenanceof civilian nuclear energy.

12. If the pointsmade above are correct, and we do not manage to convey them with adequateimpact to the uninformed public, and especially to -- also uninformed --decision-makers, we carry a responsibility for which we shall be held accountablein the aftermath of a catastrophe which might happen soon.

1. Given a sufficientquantity of Highly Enriched Uranium (HEU), it is quite easy to manufacturea nuclear explosive device.
HEU is Uraniumin which the concentration of the isotope U-235 has been brought to, say,90% or more. By contrast, the concentration of U-235 is 0.7% in NaturalUranium (NU), and it is 3-4% in the Low Enriched Uranium (LEU) used asfuel in most nuclear reactors for the production of electricity.
For the purposesof this analysis it can be assumed that "a sufficient quantity" consistsof 100 Kg (one hundred kilograms) of HEU, although less would actuallysuffice.
By "quite easy"we mean that this could be achieved clandestinely by a small commando.Inclusion of someone with previous expertise in the nuclear field wouldbe useful, but is not essential: indeed my hunch is that even a singleintelligent individual skilled as a mechanical bricoleur and without anyprevious knowledge of nuclear physics could acquire easily, in a matterof weeks, all the needed information and capabilities from easily availableopen sources, as well as all other needed materials besides HEU, to manufacturea nuclear explosive device having the characteristic outlined below.

2. HEU is the onlymaterial that allows the easy manufacture of a nuclear explosive device.
"Most peopleseem unaware that if separated U-235 is at hand it's a trivial job to setoff a nuclear explosion, whereas if only plutonium is available, makingit explode is the most difficult technical job I know". Luis W. Alvarez,key physicist in the Manhattan project, and subsequently Nobel laureatein physics, in his memoirs written in 1987, one year before his death (Adventuresof a physicist, Basic Books, New York, p. 125).
A nuclearexplosive device based on Plutonium requires, to be set off, fast assemblyof a supercritical mass by implosion. This is a much more demanding taskthan can be realized by a terrorist commando in a garage or apartment (seebelow), although it is not beyond the means of most States -- but it requiresthen a lot of previous experimentation, although not necessarily involvingnuclear explosions, and even after such experimentation it remains quitedifficult to realize (it also requires very sophisticated conventionalexplosives and electronics).
The radiationhazards associated with the handling of Plutonium are moreover much largerthan those associated with the handling of HEU. And there is now much moreHEU around than Plutonium (roughly ten times more). But while these aretwo additional arguments to identify HEU rather than Plutonium as the materialof choice for a nuclear explosive device manufactured by terrorists, themain argument to focus primarily on HEU as the source of risk is the onegiven above, that casts much doubt on the possibility that terrorists beat all able to manufacture a nuclear explosive device based on Plutonium,while it emphasizes on the contrary the ease to manufacture such a devicebased on HEU.
There donot exist at present any other materials besides HEU and Plutonium suitableto manufacture nuclear explosives.

3. A primitive nuclearexplosive device based on HEU would not be transportable, and its explosiveyield would be unpredictable, but it is quite likely that it would exceedthat of all previous terrorist explosions, and there is a significant probabilitythat it would be analogous to that of the Hiroshima bomb.
The manufactureof a transportable reliable weapon is a much more demanding task than theconstruction of a bulky non transportable device. The explosive yield ofsuch a device would be difficult to predict in advance with any precision,but it is unlikely that it would be less than the equivalent of severaltons of high conventional explosive (say, TNT -- in the largest terroristact so far, the Oklahoma explosion, no more than three tons of explosivewere employed), and it is quite possible that it would be thousands oftimes larger (the yield of the Hiroshima bomb -- the first HEU-bomb, explodedon August 6, 1945 without having ever been tested -- was equivalent toover ten thousand tons of conventional explosive (say, TNT), this energyrelease being produced by the nuclear fission of about one kilogram U-235).

4. The most likelyscenario of a terrorist act involving a nuclear explosive device is thata sufficient quantity of HEU be smuggled into a rented apartment or garagedowntown in one or more cities and that the device(s) be manufactured clandestinelythere and then set off by remote control or via a timer allowing ampletime for getaway.
SmugglingHEU is no more difficult than smuggling, say, any forbidden drug like cocaineor the material to produce it. HEU can be hand-carried without any radiationrisk, and 100 Kg of HEU could be parceled in, say, five one-liter cartonssimilar to those used for milk. Manufacturing a non transportable deviceis much easier than making a transportable bomb.

5. The effects ofsuch a nuclear explosion are likely to exceed by far any previous terroristaction.
A Hiroshima-typeexplosion downtown in a large densely-populated city is likely to causeseveral hundred thousand, possibly millions, of casualties, and propertydamages that, to the extent they could be estimated (many inestimable masterpieceswould also be lost), would amount to trillions of dollars.

6. There are individualsand groups who would perpetrate such a terrorist act if they could.
After September11 this is hardly in doubt.
The widespreadview of nuclear weapons as the ultimate "absolute weapon" is moreover likelyto prove particularly attractive to individuals and groups bent on perpetratingterrorism, inducing them to make major efforts to acquire the capabilityto set off one or more nuclear explosions.
And it isalso clear that such individuals and groups exist who muster quite substantialfinancial resources.

7. The main -- infact, perhaps the only effective -- defense against this danger is to preventthe would-be perpetrators from acquiring a sufficient quantity of HEU.
The transformationof Natural Uranium, or even of LEU, into HEU is certainly beyond the meansof any terrorist group, or for that matter of most States. (Saddam Hussein's Iraq spent billions of dollars in a clandestine program which only managedto produce gram quantities of HEU; however Pakistan has certainly managedto produced a few hundred kilograms HEU, which is the main raw materialfor their nuclear arsenal). Hence the only way for a terrorist group toovercome the technological barrier that prevents them from achieving anuclear explosion is to acquire (a sufficient quantity of) HEU. This canonly be done illegally, since HEU is not available for sale, and it isonly possessed legally by (few) States.

8. Adequate resourcesshould be allocated to strengthen the physical security, especially againsttheft or clandestine diversion, of HEU. But there is no guarantee thatthis line of defense will be adequate.
In the formerSoviet Union -- mainly in Russia -- there are now more than one thousandtons -- one million kilograms -- of HEU, namely enough to manufacture easilyover ten thousand nuclear explosive devices. It is known that not all thismaterial is adequately guarded. Over the last few years substantial funds(almost half a billion dollars per year) have been allocated by the USAto help Russia to upgrade the accounting and the physical security of thisand other (Plutonium) fissile materials, as well as to prevent the leakageof nuclear-weapon expertise out of Russia, and, although more than halfthese funds were initially funneled to the USA nuclear-weapon labs ratherthan to Russia, these initiatives have certainly resulted in a significantimprovement of the situation. Other affluent countries (Europe, Japan)have also contributed, but only to a marginal extent. It is however widelyrecognized that much more remains to be done, and also that the efficacyof any protective system, however technologically advanced, rests ultimatelyon the competence, dedication and reliability (including resilience againstcorruption) of the staff who must make it work, including those at thevery end of the hierarchical ladder. Unfortunately concerns in this respectare well justified in a social environment where salaries at the end ofthe relevant hierarchical ladder are very low (say, of the order of onehundred dollars per month) and sometimes were not paid at all.
The othercountry that possesses substantial stocks of redundant HEU is the USA (severalhundred tons). The physical security of this material is presumably betterguaranteed, although concerns remain about theft/diversion by an insider,who might be motivated by greed or be a supporter of terrorism (it is clearafter Oklahoma and after the so-called unabomber that such individualsdo exist in the USA and may behave quite cleverly even if they are crazy).
These enormousstocks of HEU are by-products of the spiraling out of the nuclear armsrace during the Cold War, that yielded inflated nuclear-weapon establishments-- oversized by any reasonable measure (at least in hindsight -- althoughsome pointed this out at the proper time, but were not listened to).
The quantitiesof HEU that exist in other countries (France, China, United Kingdom, Israel,Pakistan, India, South Africa,…) are smaller or much smaller, and presumablythey are much better guarded because, especially in the case of countriesthat posses little quantities of military HEU, this material has such ahigh strategic value to mandate a high degree of protection.
StealingHEU is particularly easy when it is stored in the oxide form, in whichcase its physical state as a powder makes it less susceptible to preciseaccounting.
Of courseresources should also be allocated to intelligence networks and operationsaimed at preventing stolen HEU from getting into the hands of would-beterrorists, or, if this happens, at allowing a preventive interventionbefore the terrorists use that HEU to manufacture a nuclear explosive device-- but no such initiative can guarantee with any certainty the preventionof a catastrophic outcome.

9. The onlyreliable route to eliminate this danger is to eliminate altogether HEU.This is possible in the long run, compatibly with the maintenance of civiliannuclear energy.
It is unlikelythat our civilization can avoid catastrophic disasters for the indefinitefuture, if large quantities of HEU continue to be available. The only long-rangesolution to this problem is the total elimination of HEU. It is importantto realize that this is compatible with a continued reliance on civiliannuclear energy, which could be entirely based on Natural Uranium and LEU(and possibly Plutonium) as nuclear fuels. Already now the only uses ofHEU other than as nuclear-weapon material is as fuel for a few small researchreactors (which are in the process of being phased out worldwide, withfew exceptions) and for (most of) the nuclear reactors used for naval propulsion,especially for submarines (and, at least in some countries, the processto phase out also this use is already in progress, for instance in Franceit is planned that the new naval reactors shall be fueled by LEU ratherthan HEU). And almost everywhere, including in all the main nuclear countries(USA, Russia, UK, France, China), the production of HEU has now stopped-- although there is no international Treaty sanctioning these unilateraldecisions (it would of course be wise to pursue such a Treaty).
It is remarkablethat much more attention has been devoted to the issue of reconciling thesurvival of our civilization with the threat entailed by Plutonium, thanto the similar problem with respect to HEU. The main reason is becausethe first problem (Plutonium) is much more complicated to deal with thanthe second (HEU: see above and below). This seems an example of a well-knownsocietal paradox: sometimes the fact that a problem is relatively easierto address results in its neglect rather than in its solution getting priority.

10. In the immediatefuture -- which is our main concern -- every effort should be made to eliminateas quickly as possible as much HEU as possible, in particular the HEU thephysical security of which is a matter of more justified concern. Thereare no technological barriers preventing major quick progress in this direction,which is instead mainly impeded by commercial considerations.
The eliminationof HEU is technologically easy and quite straightforward: de-enrich theHEU by mixing it with Natural Uranium (or possibly even with Depleted Uranium(DU) -- namely Uranium which contains less U-235 than NU -- a materialof which there exist large stocks left over as tails from the enrichmentprocess that produced the large existing stocks of HEU and LEU). This couldbe done very quickly and inexpensively in a number of ways: in the gaseousstate using uranium exafluoride, in the metallic state by melting, in theoxide state by mixing powders. The entire stocks of HEU could be eliminatedin this manner quickly (within very few years), and the actual costs involvedin this process (not including any compensation for the costs originallyinvolved in the production of HEU) would be marginal (less than, say, onehundred million dollars for all the HEU now in existence). In all casesthe end product is guaranteed not to be usable for manufacturing nuclearexplosive devices as soon as it is de-enriched to, say, less than 20% U-235content; and it can as well be guaranteed that re-enrichment of the resultingmaterial to HEU would be exceedingly difficult, certainly beyond the meansof any terrorist group and indeed of most States.
There isanother motivation to proceed in this direction -- in addition to thatof eliminating a material, HEU, the availability of which puts at riskthe very survival of our civilization. The process of de-enrichment maybe conducted so as to yield as its end product LEU, which is a commerciallyvaluable material inasmuch as it can be used as fuel in most of the nuclearreactors used by utilities worldwide to produce electricity. Hence theLEU obtained in this manner easily and at low cost from the large stocksof available HEU could be sold to the utilities that produce nuclear electricity,and the resulting income would allow to compensate not only for the costof de-enriching the HEU to LEU, but as well -- at least in part -- forthe expenses originally incurred to produce the HEU (enriching Uraniumis of course a much more expensive job than de-enriching it, partly becauseof the enormous energy consumption required, due to the fact of workingagainst the second principle of thermodynamics: it is estimated that atsome point the energy consumption of the Uranium enrichment plants at OakRidge in Tennessee exceeded that of France!).
But unfortunatelythis fact -- the possibility to get an income from selling to electricalutilities the LEU obtained by de-enriching HEU -- which should havefostered the process of elimination of HEU -- turned instead out to blockquick progress in this direction, because it brought into the picture commercialconsiderations which entailed enormous complications and became the dominantelement in determining the scope and the pace of this process, with theprofit element, and the associated concern to avoid a decrease of the worldmarket price of LEU, taking first seat with respect to the security motivationsto eliminate as much HEU as possible as quickly as feasible.
It so happenedthat the implementation of the important agreement reached among the USAand Russia at the beginning of the 90' to de-enrich to LEU five hundredtons (half million kilograms) of Russian HEU was staggered over twentyyears (what a sense of urgency!). To make matters worse the agreement wassold by the US Administration to a reluctant US Congress with the promisethat it would be effected "at no cost to the American tax-payer", and itsimplementation was assigned to an American institution, the United StatesEnrichment Corporation (USEC), that had no interest to begin with to importRussian LEU (the natural competitor to its own activity) and which wasmoreover, at the same time, transformed, from being fully owned by theFederal USA government, into a private company, that obviously was notwilling to lose money in the interest of U. S. and world security. Theidea of this "HEU deal" was that Russia (that is, Minatom, the institutionin Russia that is in charge of all nuclear matters) would de-enrich HEUto LEU (with the properties of this material specified to fit commercialstandards of enrichment and purity), sell it to USEC, who would then re-sellthe LEU to electrical utilities and thereby recoup the money paid to Minatom(and also make some profit). The order of magnitude of the funds to betransferred to Minatom for the entire HEU deal was 12 B$ (twelve billiondollars). USEC assigned to this operation the public-relation name "megatonsto megawatts" and made much publicity about the fact that it entailed thetransformation of something very dangerous (the basic material to manufacturenuclear bombs) into something useful (electricity), but in fact -- in thecontext of a world decline of investments in nuclear energy and thereforeof a world glut of Uranium hence a decrease of the market price of LEU-- USEC has been far from enthusiastic about implementing the HEU deal,which more than once was on the verge of foundering because of disagreementsabout its financial details so that it had to be rescued by interventionsof the U. S. Administration, and in any case was realized even more slowlythan originally envisaged (so far, after almost a decade, less than 150 tons of Russian HEU have been eliminated). At the moment the deal has beenrescued once more and is proceeding at the rate of 30 tons of HEUeliminated per year. And USEC -- in contrast to Minatom -- does not seeminterested in extending the deal to include additional quantities of RussianHEU.

11. Procedures whichwould by-pass these commercial difficulties have been suggested, but theirimplementation has been so far stifled by lack of interest and by the unwillingnessof (affluent) States to allocate the financial resources needed in theshort run, altogether not exceeding B$ 10 (ten billion dollars).
In the aftermathof September 11, and in the light of the above considerations, it is naturalto suggest not only that the implementation of the USA-Russia HEU dealdescribed above be guaranteed and accelerated (by-passing altogether USECif need be), but also that serious consideration be given to supplementaryinitiatives aimed at bringing about the elimination of as much HEU as possibleas quickly as possible. It is quite obvious what to recommend in this respect.
From a technologicalpoint of view the immediate goal should be to de-enrich to less than 20%U-235 content as much HEU as possible as quickly as possible, so as tomake it unfit as material for nuclear explosions. Such a de-enrichmentcould be realized much more quickly and rather more cheaply than that aimedat producing commercially viable LEU. Additional de-enrichment which fitsthe precise specification on U-235 content and overall purity requiredto make it commercially viable as LEU could be postponed to the moment-- possibly decades later -- when this material shall find a buyer -- whowill then specify the precise characteristics of the required LEU.
Affluentcountries like the USA, the UK, France, should proceed in this directionforthwith, eliminating to begin with, as quickly as possible, all the HEUthat is recognized as now redundant. This entails of course forsaking some-- albeit, for reasons we will not go into here, only a quite minor fraction-- of the separative work, hence of the expenses, originally made to producethis HEU.
Countriesthat are now facing economic difficulties, like Russia, should also proceedin the same direction, but are unlikely to do so unless they get some immediatefinancial inducement, in the guise of compensation for the separative workthat is thereby forsaken. A reasonable form of such financial inducementwould be in the guise of a loan without interest, to be paid back if andwhen the material produced from the de-enrichment of the HEU gets eventuallysold as LEU. The financial inducement should be sufficiently substantialto motivate Russia to take very good care and retrieve all its HEU andto de-enrich as much of it as possible as quickly as possible. The amountof such a financial inducement shall of course be subject to negotiationand mutual agreement; an indicative figure could be $ 10 (ten dollars)for every gram of HEU eliminated, entailing a total cost of $B 10 (tenbillion dollars) for the elimination of 1,000 (one thousands) tons of HEU,taking thereby care of essentially all the Russian HEU that constitutesa potential risk. There is little doubt that Minatom and Russia would bequite willing to enter such an agreement and to implement it speedily,even if it would entail -- as it certainly should -- some accompanyingmeasures of transparency, to guarantee that no additional HEU is beingproduced in the meantime, to measure the amount of HEU that is being eliminated,and to safeguard (possibly via the International Atomic Energy Agency)the material produced so that, if and when it is eventually transformedinto LEU and sold, the loan be paid back. It is conceivable that Russiamight eventually earn twice as much money from the sale of LEU than the$ 10 (ten dollars) for every gram of HEU eliminated, indicated above asa possible no-interest loan for de-enriching HEU, though such estimatesare quite conjectural given the uncertainty about future market pricesof LEU. Analogous terms should be offered to other States -- in particular,to all the New Independent States resulted from the disintegration of theSoviet Union -- where there also are (minor) quantities of HEU. The fundsneeded to finance this operation should come from all the affluent countriesof the world who have a stake in the prevention of nuclear terrorism --presumably primarily from the United States, but as well from Europe, Japan,Canada, the OPEC countries, possibly even from some private donors… --although the urgency to start this process should take precedence overattempts to forge immediately a large coalition in order to share the costs.Of course the overriding motivation for undertaking this project and allocatingto its speedy realization the required financial resources -- which aresubstantial but not outlandish -- should be the security of each country,and of the world as a whole, in the face of the tremendous threat of nuclearterrorism (not the prospect of making money by eventually selling LEU toelectrical utilities).
It is alsoconceivable that, in the context of the negotiation of such a deal, someconditions might be agreed on the way the funds will be utilized by thecountries receiving them: for instance it would be desirable that thosereceived by Russia be used, at least in part, to fund agreed measures ofnuclear disarmament and/or the elimination of the enormous stocks of chemicalweapons which Russia agreed to dispose of under the Chemical Weapon Convention,a commitment it seems however difficult for Russia to meet because of itscost. However all such conditions should take the back seat with respectto the main goal, to eliminate as much HEU as quickly as possible; indeed,even if (parts of) the funds transferred under such an agreement to somecountry were to end up in private bank accounts in exotic places, the mainpurpose of this operation would have been successfully achieved: indeedthose situations where something like this is more likely to happen areprecisely those more in need of an intervention the end result of whichis the elimination of any temptation to make money by selling HEU clandestinely.In this respect the funds allocated to the elimination of HEU are moreeffective in definitely solving a problem than those allocated to upgradingits physical security, that require a continued additional commitment tomake sure the protective barriers raised do continue to operate throughtime.
An interestingvariation of the financial scheme outlined above has also been variouslysuggested (in Italy, by the Landau Network - Centro Volta, under the alluringtitle "Swap of debt for security"), in which some affluent countries, ratherthan providing cash, put on the table their credits, offering to transformthem from interest-paying debts to non-interest-paying loans. For instanceRussia -- out of a total debt of over $B 71 (seventy-one billion US dollars)inherited from the past -- owes Germany over $B 26 (twenty-six billionUS dollars) and Italy over $B 6 (six billion US dollars), and pays yearlysubstantial sums as interests (although the capacity hence willingnessto do so is dwindling).
But unfortunatelyso far neither sufficient interest in, nor indeed any awareness of, thisproblematique seemed to emerge among the leadership of the main Stateswho should be at the forefront of the attempts to eliminate the tremendousrisk of nuclear terrorism -- including in particular the United Statesand Europe. Some possible progress in the right direction might emergefrom the very recent G8 decision (dubbed 10+10/10) to allocate 10+10B$ (10 by the USA, 10 by all the other affluent countries) over the next10 years to the general problematique of preventing the proliferation andterroristic uses of Weapons of Mass Destruction: but the implementationof this program does not seem to be very effectively pursued (althoughit might still be too early to pass judgement).