Table of contents:
- Reactor radionuclides over Helsinki and Stockholm
- Versions: NPP, icebreakers, submarines
- NPP nominal emissions
- Where does the wind blow from?
- Need more information
This week, information was received that the IAEA is discussing, Rosatom comments - information that radionucleides of reactor origin have been found in the air of Scandinavia. What happened, where did they come from, how dangerous is it?
Radionuclides of reactor origin found over Scandinavia
“Very low levels of radioactive iodine (I-131) were recorded at our measuring stations in Svanhovd and at Svanhovd og Viksjøfjell in Finnmark in week 23 (June 2-8),” reports DSA, the Norwegian Directorate for Radiation and Nuclear security. These two measuring stations are located in the north of the country near Kirkenes, near the border with Russia. In addition, an increase in the concentration of radioactive iodine was also noted in Svalbard by the observation station of the Comprehensive Nuclear-Test-Ban Treaty Organization.
"The concentrations detected do not pose a hazard to [human] health or the environment," the DSA says. In an interview with the Norwegian Barents Observer, pedo Møller, DSA spokesman in Svanhovd, reported that the concentration of I-131 was 0, 9 and 1.3 microbecquerel per cubic meter (μBq / m3) at Svanhovd and Viksøfjell, respectively. … These are really very small values.
In accordance with the radiation safety standards in force in Russia (NRB 99/2009), the permissible average annual volumetric activity in the air of individual radionuclides for personnel has been established. For I-131, it is (depending on the chemical form) from 530 to 1100 Bq / m3. The same normative document establishes for the population the permissible volumetric average annual volumetric activity in the inhaled air. For I-131, it is 7.3 Bq / m3.
Thus, the concentration of radioactive iodine in the air over northern Norway is about 1 billion times lower than permissible, for example, in a nuclear power plant, and about 8 million times less than the permissible volumetric activity in the air for the population.
Reactor radionuclides over Helsinki and Stockholm
The Finnish Radiation and Nuclear Safety Authority (STUK) reports that "a small amount of radioactive isotopes of cobalt, ruthenium and cesium (Co-60, Ru-103, Cs-134 and Cs-137) were found in the air over Helsinki on June 16-17." …
“The amount of radioactive material was very small and the radioactivity has no impact on the environment or human health,” says STUK. According to preliminary data, when analyzing a sample obtained by pumping 1257 cubic meters of Helsinki air through a filter, on June 16-17, the concentrations of radioactive isotopes in the air were as follows: Co-60 - 7, 6 μBq / m3, Ru-103 - 5, 1, Cs-134 - 22.0 μBq / m3, Cs-137 - 16.9 μBq / m3.
Annual permissible emissions of radioactive gases and aerosols of nuclear power plants into the environment
The permissible average annual volumetric activity in the air for the population according to NRB 99/2009 is 11 Bq / m3 for Co-60, 46 Bq / m3 for Ru-103, 19 and 27 Bq / m3 for Cs-134 and Cs -137 respectively. This means that the concentration of radionuclides in the air over Helsinki was 1.5-9 million times less than permissible.
The Swedish Radiation and Nuclear Safety Authority, with reference to the Radiation Safety Authority of the Swedish Defense Research Institute (FOI), also reports on the discovery of the same radioactive isotopes in the air over Sweden on week 24, that is, from June 8 to 14.
Estonia also reported about the detection of isotopes of cesium, cobalt and ruthenium in the air "in very small quantities". Estonian Foreign Minister Urmas Reinsalu said that the increase in the level of radioactivity recorded in Northern Europe is certainly anthropogenic and its source must be determined.
Lassina Zerbo, Executive Secretary of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), announced that the radionuclide measuring station RN63 station located in Stockholm detected three isotopes Cs-134, Cs-137 and Ru on 22 and 23 June 2020 -103, "associated with nuclear fission, in concentrations higher than usual, but not hazardous to human health."
He also attached a map on which he marked a rather large region where a possible source of these isotopes may be located. He stressed that the appearance of these radionuclides in the air is most likely not associated with nuclear weapons tests. “We can determine the likely location of the source [of the emissions], but the precise determination of the origin [of the isotopes] is not within the mandate of the CTBTO,” commented Lassina Zerbo.
Area of possible location of the source of radionuclides according to Lassina Zerbo, Executive Secretary of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO)
So, the situation is as follows. On June 2-8, a short-lived radioactive isotope of iodine (I-131) was detected in northern Norway, both near Kirkenes and about 800 km away - on Svalbard. About a week later, a set of other radionuclides (Co-60, Ru-103, Cs-134 and Cs-137) was discovered about 1,100 km south of Kirkenes - on June 16-17 in Helsinki, and on June 8-14 and 22-23 in Stockholm …
More research is required, primarily analysis of air currents at different altitudes, in order to understand whether the detection of iodine in the north of Scandinavia and other reactor isotopes in the south. It is clear that another leak of radionuclides has occurred, and the radiation monitoring authorities of several countries were able to detect them. And, although over Scandinavia the concentrations of radioactive isotopes are small, but at the point where they entered the atmosphere from one of the nuclear installations, the concentrations of hazardous substances could be very significant.
Versions: NPP, icebreakers, submarines
The radionuclides found in the air over Scandinavia are of reactor origin, they are fragments of fission of uranium or plutonium nuclei, and Co-60 is the product of activation of the materials of the reactor structure. These radionuclides are contained in the first radioactive loop of almost any reactor, as well as in spent nuclear fuel (SNF), that is, in fuel elements irradiated in a reactor. Accordingly, the source of the release of such a set of radionuclides can be an accident at an operating or recently shutdown reactor (power, transport, research), leaks from SNF storage facilities near-reactor, or accidents during operations with recently removed SNF from the reactor.
Some of the identified radionuclides have a rather long half-life. For Cs-137 it is about 30 years, for Co-60 it is about 5.27 years, for Cs-134 it is about two years. Ru-103 has a half-life of about 39 days, while I-131 has just over 8 days. It is the presence of relatively short-lived isotopes that testifies to the fact that the leak occurred either at an operating reactor or during operations with "fresh" spent nuclear fuel. Usually, the spent nuclear fuel from a nuclear power plant is kept for several years in near-reactor or near-station cooling pools for several years before transportation; during this time, short-lived radionuclides decay, and new ones are not formed. Therefore, an accident during SNF transportation can hardly be the cause of such a release.
The absence of one of the significant reactor isotopes Sr-90 can be explained by the difficulty of detecting it in low concentrations. Most likely, this isotope, as well as Ru-106 and a mixture of inert radioactive gases were also present in the composition of the release, but were not detected.
Thus, the source of the release of radionuclides is most likely the operating reactor of a nuclear power plant, nuclear submarine or icebreaker. Also, the release could have occurred during an accident with the spent nuclear fuel of these reactors.
Nuclear icebreakers belonging to Rosatom JSC Atomfort, as well as nuclear submarines of the Northern Fleet of the Russian Navy, are based on the Kola Peninsula. The formation of artificial radionuclides also occurs on ship reactors; in case of accidents or unsuccessful actions with spent nuclear fuel, leaks are also possible. The power of ship reactors is much less than that of reactors at nuclear power plants, but they are also nuclear and radiation hazardous facilities. But in the case of a significant amount of release, its source is probably the more powerful reactors of nuclear power plants.
“First of all, the Kola NPP (with four outdated VVER-440 reactors), as well as the bases of nuclear icebreakers of nuclear submarines of the Northern Fleet, located on the coast of the Barents Sea, falls under suspicion. Leakage of reactor isotopes could also have occurred at three operating reactors of the Chernobyl type RBMK-1000 at the Leningrad NPP or at one of the new VVER-1200 reactors,”says Greenpeace Russia.
NPP nominal emissions
But the aforementioned reactor radionuclides get into the air not only in case of accidents, but also during normal operation of nuclear reactors. For Russian NPPs, the Sanitary Rules for the Design and Operation of Nuclear Power Plants (SP AS-03) establish "annual permissible emissions of radioactive gases and aerosols from nuclear power plants [nuclear power plants] into the environment", as well as standards for control emissions of radioactive gases and aerosols of nuclear power plants into the atmosphere per day and in a month. So officially, each nuclear power plant in the country is allowed to emit 18-93 gigabecquerel (GBq) I-131, 2, 5-7, 4 GBq Co-60, 0, 9-1, 4 GBq Cs-134 and 2, 0-4.0 GBq Cs-137. The question of whether these "permitted" gas-aerosol and other emissions from nuclear power plants are dangerous is considered in a separate article.
As a rule, Russian NPPs emit into the atmosphere no more than 10% of the permitted amount of radionuclides. If these emissions do not occur simultaneously, but are extended in time throughout the year, then they cannot lead to the values of radionuclide concentrations observed over Scandinavia.
Rosenergoatom rejects suspicions
The operating organization of Russian NPPs, which is part of the State Atomic Energy Corporation Rosatom, JSC Concern Rosenergoatom, promptly responded to the situation. On the website of the Concern there is no information on this topic, but the RIA Novosti agency on the evening of Friday, June 26, published a message under the heading Rosenergoatom denied reports of an emergency at a nuclear power plant in northwestern Russia. It was not possible to find such messages from JSC Atomflot and from the Russian Navy.
“There were no deviations from the conditions of safe operation at nuclear power plants in north-west Russia in June, the radiation situation corresponded to normal values,” RIA Novosti quotes an official, but who wished to remain anonymous, a representative of Rosenergoatom Concern JSC. - No incidents were recorded at the Leningrad and Kola NPPs. Both stations are operating normally, there are no comments on the operation of the equipment. Since the beginning of June, there have been no deviations in the operation of the reactor equipment of these NPPs, which are taken into account in the regulatory body (Rostekhnadzor), including no damage to the reactor equipment, the primary circuit, fuel channels, fuel assemblies (both fresh and spent), and the like. The total emissions of the Leningrad NPP and the Kola NPP for all standardized isotopes for the specified period did not exceed the control values. There are no incidents associated with the release of radionuclides beyond the established barriers. The radiation situation at the industrial sites of both NPPs, as well as in the areas where they are located - both in June and now - unchanged, at a level corresponding to the normal operation of power units, not exceeding natural background values."
A representative of Rosenergoatom Concern JSC said that the third power unit of the Leningrad NPP has been under scheduled maintenance since May 15, 2020, and that power units No. 3 and 4 of the Kola NPP are under scheduled medium repair from May 16 and June 11, respectively.
It is important to note that it is during planned shutdowns at power units with VVER-type reactors that the nuclear fuel is partially replaced - the first cooling loop is loosened, the reactor vessel cover is removed, and the spent nuclear fuel is unloaded and loaded with fresh nuclear fuel. In this case, the radionuclides accumulated in the water of the primary circuit can enter the environment, and in the case of the presence of leaky or damaged fuel elements, the emissions can be very significant.
At the RBMK-1000 reactors, namely, such a reactor is installed at the third power unit of the Leningrad NPP, the reloading of nuclear fuel is carried out in a different way, without shutting down the reactor. What caused and what is the scheduled preventive maintenance of the third power unit is not reported.
Where does the wind blow from?
The reaction of the representative of Rosenergoatom Concern JSC aroused the suspicion that the release of radionuclides occurred at one of the Russian NPPs.
"It was reported that, according to the calculations of the National Institute for Health and the Environment (RIVM) of the Netherlands, these isotopes allegedly came from Russia, and that the cause of the incident may be a depressurization of a fuel cell in the reactor of a nuclear power plant," writes the RIA Novosti news agency …
Indeed, the Dutch RIVM Institute analyzed data from Scandinavia and performed calculations to determine the possible source of origin of the detected radionuclides.
“Radionuclides are artificial, that is, they are created by man. The composition of the nuclides can indicate damage to a fuel cell in a nuclear power plant. RIVM made calculations to find out the origin of the detected radionuclides. These calculations show that radionuclides come from western Russia. The specific location of the source cannot be identified due to the limited number of measurements,”the Institute's website says, but no more specific information is provided.
"Radionuclides come from Western Russia", - a message from the Netherlands Institute RIVM dated June 26, 2020
Later, the RIA Novosti agency tried to refute this message, citing problems with the translation. But the RIVM Institute confirmed that, in their opinion, the radionuclides entered Scandinavia "from Western Russia," which does not mean that their source is located in Russia.
The map, which was attached to his message by the Executive Secretary of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) Lassina Zerbo, indicates a rather large area as a likely area where an emission source may be located, which includes the southern third of Sweden, the southern half of Finland, Estonia, Latvia, as well as the north-west of Russia - from the White Sea to St. Petersburg. Lassina Zerbo clarifies that radionuclides released in the previous 72 hours could have gotten from this area to the Stockholm area. This area does not include the Russian Kola nuclear power plant, but includes the Leningrad and Kalinin nuclear power plants, as well as the Finnish nuclear power plant Loviisa, and the Swedish nuclear power plants Oskarshamn, Forsmark and Ringhals.
Need more information
At present, it is impossible to say from which reactor the radionuclides detected in the atmosphere over Scandinavia were leaked. In the near future, new measurement data, calculations, estimates may appear. In order to understand the situation, information transparency and information exchange are required.
“We are now exchanging data in the framework of the established cooperation between the Nordic countries,” said Bredo Möller from the emergency preparedness department of the Norwegian DSA.Greenpeace called for prompt international cooperation, including with Russia.
The International Atomic Energy Agency (IAEA) announced that it is aware of the detection of radionuclides in the air and is requesting information from member countries. As usual in such cases, the Agency asked its partners for information, whether these radioisotopes were found in other countries, and about events that may be associated with the release into the atmosphere, according to the official statement of the IAEA.