Honor among nuclear neighbors

We’ve received a lot of questions about radioactive isotopes that were detected in the atmosphere in late June by monitoring stations in northern Europe. We’ve been gathering information and touching base with knowledgeable experts to help clarify the situation. We will state right off that the levels of radiation that were detected are extremely small, in the microbecquerel per cubic meter (µBq/m3) range, and pose no risk to human health or to the environment. This was not a nuclear weapons test, or a major accident. Nevertheless, this is the third widely detected but undeclared radiation release in the region in almost as many years, and this should concern all of us.

In late 2017 a plume of Ruthenium 106 was detected over much of Europe. Despite Russian denials which continue to this day, researchers have been able to narrow down the possible origin to the trouble-plagued Mayak complex in the southern Urals. In fact, as we reported at the time, Mayak was a leading suspect from the beginning, but it has taken two and a half years for detailed analytical evidence to be assembled and published. Even then, in the absence of timely access to the site and physical evidence following the release in 2017, or the discovery of a definitive technical “signature” that identifies the site, researchers are ethically constrained from stating in absolute terms that Mayak was the source. In August, 2019, a fatal explosion involving a rocket engine test with an “isotope power source” occurred in Nyonoksa, near Severodvinsk in the Arkhangelsk region. This time, because of the number of witnesses and immediate local media coverage, the Russian government quickly admitted that an accident had occurred, but still refuses to provide accurate information about the radiation releases or risks.

This most recent release unfortunately seems to be following these alarming precedents. Our immediate take aways are: 1) We don’t know yet where it came from, and 2) unless the responsible government declares the release, it will probably take years for researchers to analyze the data and identify the source with any degree of certainty. This analysis began immediately and is still in its early stages.

To summarize what we know, during the week of June 8 –14, 2020, a radiation monitoring station in  Visby, Sweden detected higher than normal levels of Cs-134, Cs-137, Co-60, and Ru-103, all of them associated with nuclear fission (as opposed to natural radiation sources). The release was believed to have originated from somewhere on or near the Baltic Sea. The Swedish Radiation Safety Authority announced the detections in a tweet on June 23, and followed up with more detailed data on June 30 (published in English on July 3).  Finnish and Estonian radiation authorities also announced detections made during a similar time period. The former were in air samples collected in Helsinki between June 16 and 17; the latter between June 14 and 21. On June 27, Lassina Zerbo, Executive Secretary of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO), which operates the global IMS network of extremely sensitive radiation and seismic monitors, made an official announcement via Twitter about additional detections made at the CTBTO station in Stockholm on June 22-23. Zerbo included an initial map with his tweet showing the possible source region of the release:

Source: CTBTO

(SEP63 is the Swedish CTBTO monitoring station in Stockholm. Please note that the orange-shaded area of this map shows the estimated area within which the source of the release was likely located. It does not show the extent of the release, a radiation plume, or fallout. We think some people are confused by this, and believe a simple dotted outline would have been better.)

The CTBTO uses extremely sensitive equipment, but while it announces issues of public concern like this one, the data itself is usually not made public, for nuclear security and diplomatic relations reasons. Although Sweden has published basic information about the isotopes detected and their levels, other detailed isotope measurement information would be welcome.

As far as publicly available information goes the data is limited. Based on the available confirmed evidence, however, our best guess at this point is that mishandling of used fuel caused the release. This is no more than an educated guess, however. Since the first flurry of notification and press activity a week or so ago, little new data has been made public. But this quiet does not mean that nothing is happening. Labs throughout the region and elsewhere are certainly now examining weather patterns and other factors that need to be considered while evaluating readings at various monitoring stations in order to ascribe them to the same event. Monitoring stations in the region are now undoubtedly closely scrutinizing air samples taken during the period in question to see if faint radiation traces that might be related were also detected. Confirming the location and timing of the detections, combined with understanding of the wind and other meteorological dynamics during those days, will help determine the likely dispersion of the release. This will help narrow down its possible origin and cause.

Cheryl Rofer, a retired chemist from the Los Alamos National Laboratory active in the open-source non-proliferation community, published a brief but informative initial breakdown several days ago. She observes:

“Iodine-131 was observed at more northerly stations and on different days than the other isotopes. It has a half-life of 8 days and is a fission product, as are the other isotopes except for cobalt. Cobalt is an activation product of the steel containment vessel for a reactor. It seems likely that these observations come from a leaking nuclear reactor, but where?”

On June 27, official Russian sources were reported as denying that there had been problems at either of two Russian nuclear power plants located in or near the CTBTO’s estimated release zone:

“Two nuclear power plants in northwestern Russia – the Leningrad NPP and the Kola NPP – operate normally, with radiation levels being within the norm, a spokesperson for Rosenergoatom Concern (part of the Rosatom state nuclear energy corporation) told TASS.”

Rosenergoatom is quoted further as stating, “There have been no complaints about the equipment’s work,” “Aggregated emissions of all specified isotopes in the above-mentioned period did not exceed the reference numbers,” and radiation levels around the two powers stations “have remained unchanged in June.”

This is, of course, almost identical to the repeated denials made by Rosatom and Russian media sources following the 2017 Ru106 release, which were eventually contradicted by the scientific evidence. In a sense, then, through these recent denials official Russian sources have publicly nominated suspects that warrant closer scientific examination.

Rosenergoatom specified that it checked the Kola NPP, near Murmansk which began operating in 1973, and is at the extreme northeastern edge of the CTBTO’s estimated release zone. It has a history of incidents. It also specified the Leningrad Nuclear Power Plant (Leningradskaya AES), which falls well within the estimated release zone, and has a history of minor accidents. It began commercial operation in 1974. One of the five reactor units onsite was shut down for decommissioning in 2018, and fuel unloading is expected to take until 2023. Once again, we must note that there is no publicly available evidence yet which links the release to either of these facilities, just that official Russian sources themselves have called attention to them.

On June 27, the IAEA issued a brief statement saying it is seeking information from member states:

“The International Atomic Energy Agency (IAEA) is aware of information from the Provisional Technical Secretariat of the Comprehensive Nuclear-Test-Ban Treaty Organization (CTBTO) that its International Monitoring System (IMS) detected elevated levels of three radioisotopes Ru-103, Cs-134 and Cs-137 in the air at an IMS monitoring station in Sweden.

“As per standard practice in such cases, the IAEA has contacted its counterparts requesting information on whether these radioisotopes have been detected in their countries, and if any event may have been associated with this atmospheric release.”

Since the IAEA essentially operates on the “honor system,” it can’t do much more than this. As of the time of writing, almost three weeks have passed since the first detections in Sweden, and no nation has come forward to give notification as stipulated by the IAEA Convention on Early Notification of a Nuclear Accident. The IAEA has followed up with brief statements acknowledging receipt of information from over 40 countries, and its preliminary assessment on July 2 that the releases are “likely related to a nuclear reactor that is either operating or undergoing maintenance.”

“Based on the IAEA’s technical analysis of the mix of artificial radionuclides that were reported to it, the release was likely related to a nuclear reactor, either in operation or in maintenance. The IAEA ruled out that the release was related to the improper handling of a radioactive source. It was also unlikely to be linked to a nuclear fuel processing plant, a spent fuel pool or to the use of radiation in industry or medicine.”

As in 2017, while not yet confirmed, most signs seem to point towards Russia. This is the third similar episode since late 2017 in which the country has flaunted its noncompliance with an important nuclear agreement. This, more than the radiation risk itself, is why this episode is of great concern. The honor system only works if it is upheld.