(369.3619) WISE Amsterdam - The Sosnovy Bor-3 Light Water Graphite Reactor (LWGR) suffered an accident in at least one of it's fuel channels as a result of the on line fuelling processes. Apparently one of the pressure seals failed due to a loss of pressure. Greenpeace said that early the same morning it had received reports that there had been a release of gas and 3,000 curies of radiation.
Later, however, the Public Relations Department of Russian Minatom denied this, saying only that there had been releases exceeding the "sanitary rules and regulations" for this type of reactor. [In other words, they were saying there were no releases above the levels permitted under International Atomic Energy Agency (IAEA) regulations.] Minatom said the released gas contained inert radioactive gases, iodine-131 and various short-lived isotopes. Minatom's chief operating engineer, S.P. Krylov, informed the IAEA that the release of Inert radioactive gases had only reached a level of 319 curies/day (the maximum permissible release, according to the IAEA, is 500 curies/day). Minatom reported the environmental releases were through the aerosol filters of the plant and that the reactor had been stopped and was cooling down.
When Minatom (the Russian Federation's Nuclear Power Plant Operating Directorate) originally reported the accident to the IAEA, it rated it at level 3 on the IAEA's International Nuclear Event Scale (INES). The INES rates incident-accidents on a scale of 1 to 7, with 7 being the most severe. Level 3 is defined by the IAEA as a serious "incident", not an accident. This means that there have been external radioactive releases above authorized limits, but, again according to the IAEA, public health has not been endangered. (The Chernobyl accident was rated a 7 by the IAEA.)
At that time there were also reports that the reactor had itself suffered from high levels of on site radiation and had been contaminated. This could have been consistent with the level 3 rating. However, in a report sent to IAEA later that afternoon, Russian authorities had downgraded the accident to level 2, meaning that the release on-site was not significant. The IAEA says the data they were given in the report for airborne activity on-site and off-site is consistent with the this second rating. But the IAEA went on to say, "there is an indication of a somewhat higher than authorized release of iodine from the stack. The final determination of the level will be made after a more detailed evaluation." [At that time the IAEA had not independently rated this accident.]
At 2:00 PM GMT, monitoring stations in Finland, Sweden and the UK were not picking up unusual levels of radiation. By 3:00 PM GMT, however, there was a report that monitoring stations in Finland had begun picking up slightly higher than normal readings. A spokesperson for the Finnish Center for Radiation and Nuclear Safety in Helskinki said, "The increases are minute and are only detectable very high up in the air." This report is inconsistant with Russia's Minatom attempt to down-grade the accident. Even in the official press release from Minatom, the figures for the radioactive release of Iodine-131 are listed as "less than 0.2 curies/day" when the maximum permissible release is 0.05 curies/day.
According to ÖKO-Institut in Darmstadt, information they received directly from Lovisa in southern Finland says that on 24 March the level of iodine-131 there was 4.7 millibecquerel per cubic meter. This is 1,000 times higher than before the Sosnovy Bor accident. The institute also reports that this level of contamination indicates probable partial damage to the core, and fuel rods are likely to have been damaged.
A news agency in St. Petersburg itself reported increased radiation near the city, and there was a report from Sweden that the plant was not cooling and that there is panic in St. Petersburg.
If the initial reports from Greenpeace International of 3,000 curies released are correct, this would make the "incident" the third worst accident (where the results had been monitored). Chernobyl released 7 million curies in 1986, Windscale in the UK released 20,000 curies in 1957, and an early accident at the Hanford plutonium processing plant in the US released 205 curies. These accidents previously held the first, second and third positions for known releases of radiation into the atmosphere. The Three Mile Island accident, which marked the end of new nuclear power construction in the US, released 17 curies.
Analysis
Though the information is not complete and in some cases contradictory, a likely preliminary
analysis can be drawn.
Unlike most western reactors, RBMK's have many fuel bundles. For these gases to have been released, some error in their handling must have occurred, possibly from a fuel element being broken or partially melted. Minatom has reported that only one channel was damaged. These reactors were designed to contain two or three melting fuel elements. However, there are serious design problems and deviations from its own specifications.
N.F. Lukonen, former minister for Atomic Energy in the USSR, was part of a specialist group which published a report in May of 1988 reviewing this reactor design. This document indicated that there were 30 serious deviations from the safety requirements in the design and that it was technically impossible to correct nine of these faults. Initially, after the Chernobyl accident, that disaster was blamed on operator errors. It is now admitted even by the IAEA that the fault was not in the operators, but in plant design. (See "In brief")
Background:
The Swedish Nuclear Power Inspectorate (SKI) reviewed all four of the Sosnovy Bor plants and asked
for units 1 and 2 of the Sosnovy Bor complex to be closed down because they were unsafe. However,
the Unit 3 plant, which suffered today's accident, has been recently retrofitted and was considered
one of the safer plants of this design.
The plant itself is the same RBMK design as Chernobyl 4 which suffered a partial meltdown in 1986. [For a description of this type of plant, see the WISE Chernobyl Special Edition, Vol.349/350, 5 Apr. 1991.] There are 11 operating RBMK plants of this design in the CIS (plus the Baltic states).
[Though there has been much talk about the EC fund of 53 million Ecu for retrofitting old reactors in the CIS, Nucleonics Week reports that Russian and Ukranian officials are "fed up" with trying to tap these funds, because they realize that all of the money will be going to EC companies and not their institutions. Although the funds have been available for over six months, former "Soviet authorities and the EC Commission have not yet been able to establish appropriate contact".]
Sources:
- Greenpeace UK, phone call and press release
- Herman Damveld (NL)
- IAEA phone call and Press Release Nos.284 and 366, 24 Mar. 1992
- FMKK (Sweden)
- Media Transcription Service (UK) ref no. 1704, International Herald Tribune (US), 25 Mar., p.1
- Nucleonics Week (US), 20 Feb. 1992, p.11
- Öko Institut, phone call and E-mail.
Contacts:
- Paxus Calta, WISE-Amsterdam, tel: +31-20-639-2681
- Anthony Froggatt, Greenpeace UK, tel: +44-71-226-3151
- Mr. Meyer, IAEA, Wagramerstrasse 5, PO Box 100, A-1400 Vienna, Austria, tel: +43-1-2360; fax: +43-1 234564
- Media Transcription Service, 49 Grape Lane, Croston, Lancashire, England PR5 7HB, +44-772-601519
- David Stott, E-mail gn:mts
- ÖKO-Institut, Bunsenstr. 14, D-6100 Darmstadt, Germany 49-6151-8191-20.
 |
 |
 |
 |
 |
|
 |
 |
 |