Reprocessing: The Cons

The reprocessing of spent nuclear fuel is a highly complex operation. Over and abovethe intricacies involved in any large chemical plant, reprocessing is also complicated by the highlyradioactive nature of the process materials. As one would expect in such involved operations, reprocessingplants and their associated infrastructure have experienced numerous accidents around the world. The accident(or incident, as the nuclear establishment likes to refer to such events) at the KalpakkamReprocessing Plant on January 21, 2003, which was described by the director of the Bhabha Atomic ResearchCentre as "the worst accident in radiation exposure in the history of nuclear India", is the latest amongthese. It underscores the likelihood of future, and potentially more severe, accidents with significant risksto occupational and public health and the environment. It also adds to the economic arguments againstreprocessing.

Reprocessing is done in order to recover plutonium and uranium from the spent fuel thathas been irradiated in nuclear reactors. Due to the high levels of radioactivity in it, spent fuel generateslarge amounts of heat. So it is first stored in water filled pools for cooling. After cooling, the fuel rodsare chopped up and dissolved in acid. Different chemicals are then added to separate out different elements,which are then converted to different chemical forms for ease of storage. For civilian applications, plutoniumand uranium are converted to solid oxides.

All of these different processes produce large amounts of chemical and radioactivewastes, which have to be managed carefully. Waste is usually classified into low, medium and high level wastedepending on the radioactivity level or concentration. Low level waste is either released into the environmentor mixed into a bitumen (asphalt) matrix. Medium and high level wastes are concentrated and stored in steeltanks. At Kalpakkam, these tanks are placed in underground vaults in the so-called Waste Tank Farm. On January21 three employees who entered that region were exposed to extraordinarily high radiation doses. The cause issaid to be the failure of a valve that led to high level waste entering a tank designed to hold low levelwaste.

There are several aspects of the January 21 event that are worth noticing. The first isthat despite quality control measures a valve failed. That such failures occur, and with reasonably frequency,is not something that nuclear authorities acknowledge often. In facilities like reprocessing plants withcomplex interactions between sub-systems, such relatively small failures could lead rapidly to a majoraccident. The 1979 accident at the Three Mile Island nuclear reactor in the United States was triggered inpart by the failure of a relief valve to close. Fortunately that did not occur in this case.

Second is that there were no monitoring mechanisms for radioactivity levels. Thisrepresents a shocking failure of the authorities at both the design level and at implementation. The failurealso raises the disturbing possibility that the radioactivity of the waste products that are routinelyreleased into the environment (the atmosphere and the sea) is not monitored and that these releases may, onoccasion, carry higher levels of radioactivity than planned causing increased radiation exposure to thepublic.

Third and finally, the BARC employees association claims that they had made numerousattempts to have safety features installed and appropriate procedures followed, but on every occasion theauthorities had cited "emergency" conditions as a reason for not acting accordingly. Severalaccidents in a variety of arenas have been caused by such disregard by the authorities. A classic example isthe 1986 Challenger space shuttle explosion. Engineers working for NASA had repeatedly warned against a launchthat day because of unusually low temperatures but higher authorities discounted these warnings out of concernthat further delays could seriously damage the credibility of the shuttle program.

Given the complicated nature of the reprocessing plant and the many associatedfacilities involved, there is a wide spectrum of credible accidents. Broadly speaking one can classify themore serious accidents into fires, explosions and criticality accidents.

Fires: There are a number of inflammable materials in a reprocessing plant, in particular organic solvents andzircaloy (the zirconium-based alloy used to clad the radioactive fuel elements in reactors). Some of thematerials used for packaging radioactive waste are also inflammable. Any of these could catch fire,potentially leading to the release of radioactivity. One instance was the 1997 fire at the Tokai reprocessingplant in Japan. The fire started in the section where low level wastes from reprocessing were fixed in asphalt(bitumen). After ten hours of burning, the fire triggered an explosion. Thirty-seven workers received varyingradiation doses, mostly from internal exposure to radioactive cesium. Radioactivity levels increasedmeasurably up to tens of kilometers from the site of the accident.

Explosions: Some of the chemical reactions that take place during reprocessing produce explosive mixtures. The highradiation levels also cause the disintegration of chemicals that can sometimes produce hydrogen, which isagain explosive. The last major explosion occurred at Russia’s Tomsk reprocessing plant in April 1993 whenreactions between the nitric acid and organic solvents produced large volumes of a gaseous mixture thateventually exploded. Radioactive fallout from the explosion spread widely and was detected even as far away asAlaska.

Explosions could also occur in tanks that store high level radioactive waste fromreprocessing. Due to the heat produced by radioactive decays, such tanks have to be constantly cooled and lossof cooling could cause drying out and creation of an explosive residue. One prominent example occurred inSeptember 1957 at the Mayak facility in the Soviet Union when a tank containing high level waste underwent alarge explosion (estimated to be between 25 and 100 tons of TNT equivalent) and ejected 70-80 tons of highlyradioactive waste with a total radioactivity of 20 million curies into the atmosphere. Radioactive falloutsettled along a 400 km long swath of land, covering an area of over 20,000 square kilometers, much of whichstill remains uninhabitable. The collective radiation dose to the resident population before it waspermanently evacuated was nearly 6000 person-Sv. This collective dose would be expected eventually to resultin about 300 cancer deaths according to standard estimates of mortality from radiation induced cancer.

Criticality: Also serious are criticality accidents where fissile materials like enriched uranium and plutonium are allowedto reach a concentration where an uncontrolled chain reaction like that in a nuclear bomb results (but withmuch less energy produced). The letter from the BARC Employees Association warns the authorities of thepotential for such accidents at Kalpakkam. Their warning is not without basis; there have been over twentycriticality accidents at nuclear facilities around the world. An example is the accident that occurred in 1999at the Tokaimura fuel fabrication facility in Japan. The accident occurred because workers put fuel enrichedto 16 per cent uranium-235 in a container meant to hold fuel for light water reactors, which is usually onlyenriched to 3-5 per cent. This set off a chain reaction, resulting in elevated radiation exposures to severalhundred workers and members of the public, including three workers who received large exposures, one of whomsubsequently died from acute radiation sickness following a radiation dose of about 16 Sv (1600 rads). Similarevents have occurred in reprocessing plants, for example at the Idaho Chemical Processing Plant, USA in 1959.

These safety issues must be balanced with the two primary justifications offered forreprocessing. The first justification offered is that it produces plutonium that could be used to buildnuclear weapons. The reasons for not acquiring nuclear weapons are sufficiently well known and have beenelaborated elsewhere (see for example Prisoners of the Nuclear Dream, edited by M. V. Ramana and C.Rammanohar Reddy, Orient Longman, 2003). In any case the Kalpakkam reprocessing plant is ostensibly operatedfor civilian purposes.

The second justification offered by the Department of Atomic Energy is thatIndia’s uranium resources are limited and that reprocessing is needed to supply startup plutonium forbreeder reactors that may be used to convert India’s large resources of thorium into chain-reactinguranium-233. But the saga of breeder reactors around the world has been oneof tall promises and poor performance. The French Superphenix reactor, for example, cost more than twice asmuch as an ordinary reactor of similar capacity and operated at an average of about 6.6% of its ratedcapacity. Fast breeder reactors also have serious safety risks. They generate a large amount of heat ina very small volume and use molten metals, such as liquid sodium, to remove the heat. Since sodium is opaqueand burns on contact with air or water, sodium leaks are dangerous. Further, designing reactors and theirmaintenance to take these properties into account has made them costly to build and maintain.

Breeder reactors are also uneconomical because of the high cost of plutonium that isused as fuel in such reactors. The high cost of plutonium, in turn, is because of the high cost ofreprocessing. The total lifecycle cost of the Rokkashomura reprocessing plant being constructed in Japan, forexample, is projected by the Japanese utilities at about $130 billion. Theyare asking for a government bailout. The Japanese reprocessing plant is expected to recover on the order of130 tons of plutonium during its useful life. On that basis, the cost of extracting a gram of plutonium withthis plant will be about $1000. For comparison, the world marketprice of U-235 in natural uranium is today about $4 a gram. The cost of fabricated uranium fuel used in theheavy water reactors at Kalpakkam is about Rs. 16.50 a gram.

To summarize, reprocessing has very substantial risks and costs, while possessing few,if any, benefits. All this adds up to a strong case against thecontinued pursuit of reprocessing.

M V Ramana is a physicist and research staff member at Princeton University’sProgram on Science and Global Security (on leave from the Centre forInterdisciplinary Studies in Environment and Development, Bangalore) and co-editor of Prisoners of theNuclear Dream (Orient Longman, 2003).