International Network of Engineers and Scientists Against Proliferation

A German Plutonium Balance for the Past 30 Years

Martin B. Kalinowski, Wolfgang Liebert, Silke Aumann¹

Up to now, there has not been a clear picture of the German plutonium stockpiles but merely singularly appearing summaries of certain activities and of the amounts originating thereof. The most comprehensive worldwide plutonium balance was presented in the spring of 1997.² It is especially in the German case not detailed enough and presents figures as of 1996 .

Nine plutonium-producing and employing countries presented common guidelines for the handling of plutonium at the end of 1997. The German federal government agreed in the framework of these talks with the other involved countries to annually publish the inventories of civilian plutonium. As welcome as this step towards the establishment of transparency may principally be, the chosen format for these yearly balance reports is unsatisfying. It only contains very few strongly aggregated data which do not allow for attribution to facilities or owners which only have to be precise over and above 100 kg.

The relevant data for Germany on reprocessing within the country and abroad, import and export of plutonium, processing into MOX and use of MOX as well as accounts of current plutonium inventories were collected by the authors of this paper in a study which relies on published material as well as own research and calculations.³ This contribution contains a summary of the results.

In a time in which Germany has discontinued the reprocessing of spent fuel as well as the production of MOX within the country, it should be at least possible to compile a concluding plutonium balance report for these sectors. A detailed survey and review of the plutonium fluxes in Germany is necessary to account for the globally discussed proliferation risk (The danger of proliferation and development of nuclear weapons.) In doing so it has to be taken into account that so-called reactor-plutonium which is obtained from power-reactors with common burn-up also enables the production of nuclear weapons. While it is true that all German plutonium is under nuclear safeguards from the IAEA (International Atomic Energy Agency) in Vienna and EURATOM in Luxembourg, an unauthorized theft can in the best case only be detected. It could generally not be prevented.

It would be beneficial to the international debate if it could be publicly proven that Germany stays above any suspicion: Exact information should be available on the whereabouts of plutonium stockpiles - especially regarding those which are relevant for weapons. In contrast to this, the first official US plutonium balance which was presented in February of 1996 cannot satisfy since it had to acknowledge inventory discrepancies (Material unaccounted for - MUF) of 2.8 t Pu, i.e. 2.5% of the total production. Only a thorough picture of the plutonium fluxes offers the basis for the development of a strategy for the long-term handling of this material.

Summary of reprocessing

Until the end of 1997, 5,437 t HM (heavy metal) in spent fuel elements were relocated from German power reactors, excluding Eastern Germany. Out of that, 5,365 t HM (98.7%) were taken to reprocessing facilities and 70 t HM (1,3%) were brought to a central interim storage facility (Away from reactor storage facilities.) Further 2,835 t HM were stored in the fuel element storage tanks of German nuclear power reactors at the end of 1997. 4,757 t HM were transported to the French COGEMA, which is more than 83% of the total amount of the material which went to reprocessing plants. This illustrates the relevance of the German-French cooperation (see fig. 1.) 187 t HM (3.5%) were delivered to the German reprocessing facility (Wiederaufbereitungsanlage Karlsruhe - WAK), 651 t HM (12.1%) went to the British BNFL. The remaining 70 t HM (1.3%) were delivered to smaller facilities, like the Eurochemic plant in Mol, Belgium.

Figure 1 shows how much of the amount of heavy metal delivered by Germany has been reprocessed until the end of 1997 (total amount: 3,664 t HM.) A combination with figure 2 makes clear that to the end of 1997, 60% of the old contracts for reprocessing in France and the United Kingdom were fulfilled (total amount: 5,641 t HM.) An additional occurence of about 36-45 t of separated plutonium would have to be expected upon complete fulfilment of all contracts. 30 to 35 t Pu (including Belgium and Germany) have already been separated by the reprocessing of spent fuel for German customers.

According to current planning data, the largest share of reprocessing for German customers will in the future still take place in France, yet the British contribution is supposed to increase substantially (see fig. 2.)

Figure 1: Amounts of reprocessed fuel elements in Germany or for German Customers (as of end 1997).

Figure 2: Amounts of fuel elements, for which reprocessing contracts for German operators existed or have been fulfilled (as of mid-1998).

Reprocessing in Germany

The German reprocessing facility (WAK) was run as a pilot project between 1971 and 1991. According to the information given by the WAK, 1,189 kg plutonium were separated in 32 separation campaigns from 204 t HM, of which 17 t HM came from research reactors (see fig. 3.) Statements on the isotopic composition for all 32 campaigns could be made on the basis of more detailed information, such as fuel type and burn-up. Nine reprocessing campaigns of fuel from the MZFR - (Mehrzweck-forschungsreaktor) would be of special interest regarding the proliferation relevance. There were altogether seven campaigns with a fuel burn-up below 10,000 MWd/t, which would allow to expect a high content of Pu-239 in the separated plutonium. The interesting amount of plutonium lies well above 250 kg ^__ a theoretically sufficient amount for at least 40 nuclear weapons.

A small facility called MILLI was once run in the Karlsruhe center for nuclear research which was able to reprocess fuel elements from fast breeder reactors. Significant amounts of especially weapon relevant plutonium could have been separated here as well.

Figure 3: Cumulative Separation of Plutonium in the Karlsruhe reprocessing facility

Reprocessing in France

The overall contract volume with COGEMA currently amounts to 6400 t ated HM of spent fuel. 4,757 t HM of spent fuel elements went from Germany to France until the end of 1997 with an overall plutonium content of 37 - 44 t HM. Until March 31st, 1998, the reprocessing contracts with UP2 (Usine de Plutonium) were fulfilled to a total amount of 1,645 t HM. The German contractors for this are known. The contracts with the UP3 facility which became operational in 1989 are fulfilled to about two-thirds (until March 31st, 1998: 1,909 t HM.) Overall 3,552 t HM German spent fuel were reprocessed in France. In a rough estimate, 27 to 34 t of plutonium were separated there. Since 19 t of separated plutonium were re-imported to Germany until 1998, 17 to 24 t of separated plutonium should still be stocked in France. This amount could only be assessed with greater accuracy if it were known which fuel elements were reprocessed and which fuel composition and burn-up profiles they had. The separation efficiency also plays a role in the assessment of the separated plutonium amounts.

In the French reprocessing practice, in which civic and military facilities are not strictly separated, plutonium of different origin can be mixed or even the deliberate exchange of plutonium of a certain origin or destination for another plutonium charge can take place. The concern is well founded, that plutonium from German reactors could have found its way into the French nuclear weapons program.

The research reactor cores KNK I and II of the Karlsruhe center for nuclear research were reprocessed in the French nuclear center of Marcoule in the years 1976 and 1993/94. There is no clarity on the amount of about 100 kg of plutonium separated during the second campaign regarding its isotope composition and its whereabouts. The whereabouts of the plutonium which was separated during the reprocessing of fuel elments of the KKN (Niederaichbach) are also unknown to the authors. This material is of special proliferation relevance since the reactor only achieved 18 days of full operation and the amount of Pu-239 should therefore be unusually high.

Reprocessing in Great Britain

German nuclear power reactor managers have made reprocessing contracts with the British Nuclear Fuel plc (BNFL) over 2,250 t HM of spent fuel. Two new contracts over a total of 545 t HM were cancelled by the German energy utilities HEW and RWE in 1994 and for some time it looked like more cancellations were coming up.

From 1969 to 1973, only 12 t of German spent fuel were reprocessed in Sellafield with the facility B204. The separated amount of plutonium should be about 100 kg.

Until the end of 1997, the compared with France small amount of a little more than 650 t HM were transferred from Germany to the BNFL. The plutonium content can be estimated at about 5-6 t. The new reprocessing plant for light water reactor fuel, THORP, only became operational in Sellafield in March of 1994. It can therefore be expected that only a part of the German fuel has been reprocessed up to now. Until the end of 1997 this was the case for 56 t with a plutonium separation of about 0.5 t.

Between 1969 and 1982, a total of 351 kg non-irradiated plutonium was imported from England. This is more than what was separated by German clients in England at the beginning of the 70s. There were no more plutonium deliveries until 1995. It remains unsettled how much plutonium which was separated for German power plant operators has been brought back since 1994 to Germany. Probably nothing.

Reprocessing in Belgium

More than 28 t HM from two German power reactors as well as from various research reactors were reprocessed in the reprocessing plant Eurochemic in Mol, Belgium, which was able to reprocess spent fuel from 1966 to 1974. About 110-150 kg of plutonium have been separated. Germany has imported non-irradiated plutonium from Belgium in larger amounts and in the form of MOX.

Imports and exports

Data from the German Federal Export Office (Bundesausfuhramt BAFA) is available on the exported and imported amounts of plutonium in the time between 1968 and 1994 (see figs. 4 and 5.) The import of altogether 10.65 t of non-irradi ish plutonium consists in large part of the return of plutonium which was separated in foreign reprocessing plants. The export of 2.57 t finds its explanation in the production of mixed oxide fuel elements for foreign customers in the Siemens facility (formerly Alkem.) In addition to that, 2,186 kg of irradiated plutonium were exported. The first half ton consisted of the transfer of more than 100 MOX fuel elements of the VAK facility (total mass 6.4 t HM) for direct final storage in Sweden.

The Federal Office of Statistics in Wiesbaden has since 1981 compiled an export and import balance sorted by sending and receiving states and based on customs declarations. A convincing comparison of the two statistics is not easily possible, partly because the statistical office considered the given amounts of all fissile isotopes, not only those for plutonium. However, special differences between the balances can still be discovered.

A series of inconcistencies can be traced back to the fact, that plutonium appears in the trade balance for which no export or import license had been issued by the export authority (BAFA). One example involves the export of 2 kg of fissile plutonium to Pakistan in the year of 1993 appearing in the export statistics of the statistical office. The BAFA denies knowledge of such a large transfer and speaks of a mistake in the statistics of the Wiesbaden office. It asserts that the amount of the real transfer of plutonium was six orders of magnitude smaller.

Figure 4: Import of non-irradiated plutonium sorted by countries of origin

Figure 5: Production of LWR- and FBR-MOX fuel ements in Germany

MOX production in Germany

The processing of plutonium to mixed oxide (MOX) fuel began in Germany in June of 1965 with the production of fuel pellets for SNEAK (Schnelle Nullenergie Anordnung Karlsruhe.) The company responsible for the project, Alkem GmbH, moved in the early 70s from the nuclear research center in Karlsruhe to Hanau. Alkem was taken over in 1988 by the company Siemens AG.

For SNEAK, 600 kg of plutonium were processed which in largest part were made available by the USA. This material has probably been completely processed in Karlsruhe before 1972. The literature for the number of fuel elements produced in Hanau only yields a histogram representation of the yearly processed amounts of heavy metal, where the FBR-fuel is presented in LWR equivalents. The histogram presented in figure 6 of the same values shows the actual heavy metal content.

In the years 1972 to 1992, the company Alkem, later called Siemens fuel element plant Hanau, processed a total of 8,553 kg of plutonium into 164 tons of heavy metal. The old facility was then shut down. The almost completed new facility never became operational. 77% of the plutonium has been processed for LWR fuel elements. Foreign customers had a share of 13% on that. The company Siemens still acts as contractor of MOX fuel elements for German power supply companies by outsorcing orders to other European production facilities.

MOX employment in Germany

Only 12 German nuclear power stations had a license for MOX fuel elements in 1994, of which 5 had not made use by that time. Other nuclear power stations had requested a license. The Gundremmingen power station has since also employed MOX in its blocks B and C in the meantime. The content of fissile plutonium in the first seven MOX employing power stations is typically limited to less than 3.5% and only a quarter or a third of the core is allowed to be run with MOX elements. One single reactor (Isar 2) has an authorisation for 50% MOX in its core.

How much plutonium in MOX was employed in which reactor has not been comprehensively published to the present day. However, the amount of heavy metal in MOX which was employed in German reactors until the end of 1997 has been published in detail. They were 37.5 t HM for 1997 alone and altogether 238.3 t HM until the end of 1997. The therein contained mass of non-irradiated plutonium is not explicitly published. Since less than 3.5% plutonium content can be assumed on the average, a maximum of 8.3 t of Pu could have been employed in LWR-MOX. According to Siemens, about 5.7 tons of plutonium were reused in the production of MOX elements for German light water reactors and 0.85 tons for foreign reactors. Further MOX fuel elements for German customers were produced in Cardarache in France and in Mol in Belgium.

About 1.3 t of plutonium were employed for LWR-MOX in the year 1997. The consumption of the other already separated amounts of plutonium (18-25 t) would therefore take 14-20 years at a constant rate.

Current inventories

Table 1 summarizes the current German plutonium inventories. Almost 80-100 tons of plutonium are currently under German responsibility. The largest part, some 60 to 73 tons, of this fissile material originating from German reactors is still enclosed in spent fuel elements. About half of this (36-43 t) can still be found in the storage pools of the nuclear power plants, while 9 to 11 t are in France and 5 to 6 t are in England ready to be separated from fuel elements.

About 20 to 27 tons of plutonium were present in separated form at the end of 1997. The largest part of it (about 17-24 t) still is in France. If all reprocessing contracts were fulfilled, about 45 t of plutonium would be added to that.

Most of the non-irradiated plutonium which is stocked within the German borders lies in the so-called plutonium bunker in Hanau. A part of the room is at the disposition of Siemens which had a handling license for 460 kg of plutonium. Stockpiles beyond that were handed by Siemens to the Federal Office for Radiation Protection for federal storage. This amount is stored in the part of the bunker which is called federal storage space. The operator company SBK for the fast breeder in Kalkar SNR 300 has usage rights for plutonium which is stored in Hanau.

Because of the secrecy policy, no detailed information was given on the Hanau plutonium inventory in the past. The standard reply for according questions to the federal government was that more than 2 tons of plutonium were stored in Hanau.

In the request for the phase-out and shut-down program for the Siemens MOX fuel element facility more detailed data were made publicly available in the beginning of 1996. According to it, a total of 2,268 tons of plutonium were then still in the Hanau bunker. The largest part of it consisted of 123 fuel elements which were produced in Hanau for the SNR 300. They contain 1.093 tons of plutonium. A good half-ton of plutonium (554 kg) is stored as MOX fuel (i.e. oxidated and mixed with uranium-oxide) and almost a half-ton (455 kg) is stored as plutonium-oxide powder. Of the latter, 140 kg were already delivered back to the COGEMA reprocessing plant. 105 kg plutonium lie in complete fuel rods and 70 kg are in a nitrate solution which was deliverd from the WAK in Karlsruhe and was not allowed to be processed any more. The plutonium in this solution has to be precipitated since it cannot in the long term be safely stored in this form and requires maintenance. Especially sensitive under the perspective of proliferation are the 277 kg of plutonium which were separated from Magnox fuel elements, because the burning in Magnox reactors typically reaches only about 3000 MWd/t and therefore the Pu-239 content can be very high. It is unkown to the authors whether this plutonium still is stored in Hanau or whether it has completely been transported back abroad. It is also unknown to the authors, whether further plutonium with a high Pu-239 content is stored in Hanau (e.g. from MZFR, KKN and HDR.)

15 kg of plutonium are still stored in two containers with 70 cubic meters of liquid HLW-waste in the former Karlsruhe reprocessing plant WAK. Plutonium stored there earlier has been completely transported away according to the WAK management.

Table 1: Inventory of German Plutonium (as of: 1998)

Conclusions for the handling of separated plutonium

Gaps and inconsistencies arise from this attempt to compile a comprehensive plutonium balance.⁴ These could only be closed and clarified by the operators or official authorities which (should) have first-hand data. It becomes evident, after all, that amounts of plutonium are concerned here which in their quantity and quality are so proliferation relevant that a special responsibility arises from it for Germany. A complete clarification of the relevant stockpiles can make the proliferation relevance more evident and can lead to a sensible handling strategy for it.

A proliferation problem arises from the surplus of separated plutonium. As long as the plutonium stored abroad is not brought back to Germany, no direct German access will be possible. There are speculations on the use of German plutonium in the French nuclear weapons program. In addition to that there is the risk of unauthorized subnational groups which would try to gain ownership on weapons material. 2.1 tons of non-irradiated plutonium are still stored in Germany which represents a proliferation concern even while standing under safeguards.

The re-employment of surplus plutonium in MOX fuel elements in light water reactors is not able to reduce the surplus which grows faster by reprocessing than it can be reduced. About 20 t of separated plutonium are stored in France alone, altogether about 20-27 t of plutonium, while the yearly employment of MOX in German reactors currently amounts to only 1.3 t. Opposing this is a yearly discharge of about 600 t HM from all German reactors with a plutonium content of about 5-6 t of plutonium. Even with a theoretically feasible doubling of MOX usage in LWRs would the plutonium consumption rate only match the separation rate in the long term if drastically less fuel elements were reprocessed every year. The reduction of stockpiles is impossible under the current circumstances. A progression of the current trends would imply that the plutonium surplus heap would grow further.

Alternatives to LWR-MOX for plutonium use do not exist. The return in breeders has become obsolete in Germany since the end of the Kalkar project. The acquisition of plutonium by foreign customers is also not unproblematic. There are plans to sell the largest part of plutonium in fuel elements which was intended for the Kalkar fast breeder to the US-American company Advanced Nuclear Medical Services (ANMS). The serious danger exists that ANMS would use this plutonium to produce tritium for American nuclear weapons.

Since the 1994 article law for the modification of the German nuclear energy act, the direct disposal of spent fuel elements is officially recognized as a proof of taking care of spent fuel. In spite of that, the German energy supply companies have declared in the spring of 1997 that they will in the future bring 60% of the spent fuel abroad for reprocessing and that only 40% are designated for direct final disposal.

It has always been indicated that the separation of plutonium is not reasonable even from the radioecological standpoint and for technical reasons of safety. Many nuclear power station operators also increasingly recognize that the usage of plutonium has revealed itself to be uneconomical for them. After the election of the new red-green government in Germany it is expected that the reprocessing of spent fuel from Germany will soon be discontinued.

The surplus of separated plutonium raises the question of how this material can reasonably be processed and safely long-term stored. It should be investigated, whether alternatively to the utilisation as fuel in nuclear reactors this material can be conditioned to radioactive waste for final disposal. Various feasible options are being internationally discussed, e.g. the immobilisation in conjunction with liquid highly radioactive waste or storage rods in bundles mixed with spent fuel rods. But since none of the presented suggestions for the disposal of plutonium are completely unproblematic and since the plutonium itself remains existing, technical ideas for the far reaching elimination of plutonium should also be evaluated.

In March of 1995, the mandate to negotiate a ban on the production of fissile materials for nuclear weapons was agreed upon at the Geneva disarmament conference. Only in August of 1998 was an ad-hoc committee established for these negotiations on the grounds of the 1995 mandate. The mandate will possibly be handled flexibly and extended to further areas. Various states and non-governmental organisations had proposed to involve the civilian nuclear weapons usable materials and past production into the negotiations. This would underline the importance of a possibly complete plutonium balancing and a sensible handling of existing stockpiles.

References

1. Interdisciplinary Research Group in Science, Technology and Security (IANUS) of the Darmstadt University of Technology.

2. D. Albright, F. Berkhout, W. Walker, Plutonium and Highly Enriched Uranium 1996, World Inventories, Capabilities and Policies, New York: Oxford University Press, 1997.

3. This article is a summary of a much more detailed study of the authors. This study will be published by the Vereinigung Deutscher Wissenschaftler (VDW, German Federation of Scientists), Schopenhauerstr. 26, D-14129 Berlin, Germany (fax +49-30-8030/8888). We gratefully acknowledge support by the VDW and Greenpeace Germany.

4. The comprehensive study deals in much more detail with the identified inconsistencies.

Martin Kalinowski and Wolfgang Liebert are senior researchers at IANUS, Silke Aumann worked as assistant to the project. Address: see Impressum