Plutonium Program : Stuck with the Past

Together with other European utilities, Swiss electricity utilities signed reprocessing contracts with French and British reprocessing companies, COGEMA and BNFL respectively. The total amount of fuel to be reprocessed is between 1,000 and 1,100 tonnes of heavy metal (see article) which corresponds to about one third of the total quantity of fuel produced during forty years of operation of the five power plants. However, besides increasing doubts over the reprocessing option, it remains to be seen if the Swiss nuclear safety authorities will agree with the operation of the plants over a forty-year lifespan.

With the reprocessing contracts, Switzerland is entitled to a considerable amount of separated plutonium. The only use for this plutonium in Switzerland is to introduce it into mixed oxide fuel (MOX), containing both plutonium and uranium. Since the middle of the 1980s, first one and then another utility started to use MOX fuel. It is highly probable that the plutonium produced through the reprocessing of Swiss spent fuel will not all be used. Therefore the country, as others, is likely to be confronted with a significant plutonium stockpile.

Given the stockpiles of plutonium owned by all the countries which have developed the plutonium industry, it is clear that no country would be willing to take responsability charge for Switzerland's plutonium.

The NOK utility operating the two Beznau reactors has used MOX fuel on an experimental basis as early as 1978. Currently, MOX fuel is used on a commercial basis in the three PWRs operated in Switzerland (two at Beznau and one at Gösgen). The Belgian company Belgonucléaire - with the P0 plant at Dessel/Mol - and the British BNFL - with the MOX demonstration facility MDF at Sellafield - have both produced MOX fuel for the Beznau plant. The MOX fuel supplied to the Gösgen plant was produced by Belgonucléaire.

All shipments from the UK are made by air, a practice based on the argument of an increased level of physical protection. However, this transport mode raises severe safety issues since the casks in which the MOX is transported cannot ensure that criticality is not reached with the MOX fuel in plane crashes. This aspect concerns France particularly since the route is mostly above French territory. The Swiss transport practice is all the more surprising as the nuclear industry never transports MOX produced in France by air. Equally, all shipments from Belgium, also through French territory, are carried out by road.

After a trial period from 1978 to 1980, Unit 1 of the Beznau plant was commercially loaded with MOX fuel in 1988. UnitÊ2 was first loaded with MOX fuel in 1984. For both units, the maximum at-once licensed number of MOX fuel elements is 48 out of the 121, thus a share of 40% MOX fuel in the core. The latest shipment of MOX fuel to the Beznau plant was an air transport of MOX from Sellafield during 1997, when 4 MOX fuel assemblies were loaded. The small number of MOX fuel assemblies (totalling to some 120 since 1978), as compared to the 40 enriched uranium fuel assemblies which were replaced on unit 1 of the Beznau plant, indicates that the Beznau plant is not using as much MOX fuel as it is licensed to. Apart from operating problems at Beznau, one may suppose that the British BNFL is not able to produce MOX fuel quickly enough.

The Gösgen reactor has been using MOX fuel since summer 1997, when 8 MOX fuel assemblies were loaded, out of 40 assemblies which were replaced. This corresponds to 20% of the fuel replaced, while the plant is licensed for 30% MOX.

In total 28 MOX fuel assemblies were supplied to the Gösgen plant already during April and May 1997 from Belgonucléaire. The operator Kernkraftwerk Gösgen-Däniken AG has therefore stored the MOX fuel on-site. Apparently Belgonucléaire was not willing to store this MOX fuel before shipping it to Switzerland according to Gösgenâs refuelling schedule.

Storage of fresh MOX fuel on reactor sites is not authorised in France. MOX fuel is therefore sent to La Hague where it is stored in spent fuel ponds pending shipment to the power plants. However, storage of fresh MOX fuel at the power plants is authorized in Germany.

According to the figures supplied by the Swiss representation to the IAEA in March 1998, "more than 2.2 tonnes of plutonium" in MOX fuel has been used in Swiss reactors.

It is noteworthy that only two utilities are using "some of" the plutonium being reprocessed from the spent fuel from all Swiss utilities. Also, the original plan to reprocess the total spent fuel quantity to be produced by the nuclear power plants is somewhat incoherent. On one hand, using MOX fuel will produce spent MOX fuel which will not be reprocessed; on the other hand, the spent fuel from the last years of operation of the plants would be reprocessed and would produce plutonium which would be impossible to use... in the shut-down plants. Even if Beznau and Gösgen used the MOX licence to the maximum allowed extent (consuming 1 tonne of Plutonium annually), there would result a yearly surplus of another tonne. Swiss authorities clearly should have required a review of the reprocessing contracts following the 1990 moratorium.

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