13.06.2018 | Beznau safe in the case of earthquakes

No radiation risk

The Federal Council wants to specify dose limits connected with rare earthquake occurrences in certain ordinances. What sounds technical and mundane has been suddenly turned into a scandal: Allegedly, the Federal Council and authorities would be exposing the population to higher radiation risks. Courts become involved. Are these allegations true? We did some fact-checking in the case of Beznau.

An earthquake that based on probability calculations would only occur every 10 000 years is a severe one. Experts estimate that in such an extreme event some 25 per cent of buildings and infrastructure would be destroyed. What would an earthquake of this magnitude mean for the Beznau nuclear power plant? What regions would be contaminated? How many people would have to be evacuated? And what long-term health effects can be expected?

The Supervisory Authority is investigating whether the legally prescribed radiation dose limits to which the population would be exposed are fulfilled in such a case. The investigation focuses on severe earthquakes and takes a close look at a so-called "isolated incidents". An isolated incident is an event that does not have to do with an earthquake, but coincidently occurs at the same time.

All goals to protect the population fulfilled

What would happen at Beznau in the event of an earthquake that only occurs every 10 000 years? The answer is simple and rational: All goals to protect the population are fulfilled at KKB: Cooling the reactor core, controlling nuclear chain reactions, containing radioactive materials, limiting radioactive exposure - no disaster scenarios.

In such a case, a dose limit of 100 millisieverts (mSv) applies for a person near the nuclear power plant (a distance of 300 metres), working in the area with the highest dose, and who lives and buys food produced in the affected area.

Beznau complies to this limit by a large margin. Hypothetically a person within 300 metres distance would be exposed to a dose of 32?mSv. The town of Döttingen is located somewhat more than 3 kilometres from the plant. The exposure there would be ten times smaller, and much lower than the radiation dose of 5.5 mSv to which we are exposed on the yearly average through natural radiation in Switzerland. Further away, the radiation would hardly be detectable. Here again: no disaster scenarios, no danger for the population.

Like moving to Lucerne

Back to the hypothetical case:  What are the long-term impacts of radiation for a person situated 300 metres away from KKB? All-clear here: The person's life dose would be slightly higher, but completely harmless in terms of health. An accident would have exactly the same impacts if the person were to move out of the region around Beznau (very low natural radiation), for example, to Lucerne (slightly higher natural radiation). Health risks to the population owing to Beznau in the event of an earthquake occurring only every 10 000 years are out of the question.

The Federal Council creates clarity

But what about the allegation that the Federal Council is surreptitiously increasing the dose limit by a one hundredfold? Up to now complainants in the court proceedings argue that according to the Radiation Protection Ordinance a limit of 1 mSv applies in the event of an earthquake occurring only every 10 000 years.

In fact, the Radiation Protection Ordinance does not clearly specify what earthquake category would be attributed to one occurring only every 10 000 years. The hazards assumptions ordinance clarifies this point by specifying the applicable failure category and the dose limit (100 mSv) for this type of earthquake. The ordinance provisions focus specifically on nuclear power plant failures.

In contrast, the Radiation Protection Ordinance regulates overall radiation protection for all possible types of exposure in daily life (medicine, research, industry, etc.). Specific regulations have priority for nuclear power plants. The situation is clear but leaves room for misinterpretations as the example shows. The Federal Council wants to clarify this issue with a revision and simplification of the ordinances: "... the current practice will now be clearly and explicitly reflected on the ordinance level."

The Federal Council wants to achieve this with three measures:

  • Clarity that no failure event spectrum must be considered for earthquakes, but rather two concretely specified incidents (occurring only every 1000 and 10 000 years). In all other countries around the world, nuclear power plants are designed in line with the specifications of the International Atomic Energy Agency (IAEA) and for a maximum of two, discrete earthquake scenarios. The safety cases during operation are the confirmation of the correct plant design and are therefore also only required for two single earthquake cases. The dose limits must be adhered to for these two events (1 or 100 mSv respectively).
  • Decoupling of the failure categories in the Radiation Protection Ordinance.
  • Anchored at the Swiss Nuclear Energy Ordinance level

Years ago, the Federal Council announced its intention to bring explicitly established rules previously stipulated in Federal Nuclear Safety Inspectorate guidelines into the Nuclear Energy Ordinance. In 2012, the independent nuclear safety advisory commission to the Federal Council also pointed out that there was a need for clarification. So, it is out of the question that - as alleged by the complainants - that the ordinances were adapted on short notice owing to legal action.

The dose threshold applies to a person that is directly near the nuclear power plant when the cloud passes overhead, that has been living and working for one year at the location with the highest dose, and eats food coming from the affected area for two days.
Shut down Beznau by hook or by crook?

The facts are clear. The Federal Council does not want to raise dose limits and these would not - worldwide among the strictest - represent an extraordinary problem for human-beings or the environment in the case of an incident. The aim is a different one for the complainants: To reduce the dose limits by one hundredfold and then have Beznau shut down based on the change in dose limits.

After Beznau opponents experienced political failure with the nuclear phase-out initiative in 2016 and after the allegation regarding "1000 holes" was technically refuted by the Supervisory Authority and international experts, this is the new legal trick that is supposed to bring success. It appears to be the only way. After all, CHF 2.5 billion were invested in safety-technical upgrades for Beznau and it fulfils all the national and international requirements at all times.

What ENSI says

At the end of March 2018, the Swiss Federal Nuclear Safety Inspectorate (ENSI) published a statement on the partial revision of the Nuclear Energy Ordinance. ENSI stated:

The revision does not lead to any safety cutbacks for Swiss nuclear power plants. The specifications remain the same. The Federal Council wants to define what has already been the practice - and what was also clearly the intention of the legislation.

Nuclear power plant operators must continue to prove that plants meet a dose limit of 1 millisievert (mSv) in the case of an earthquake occurrence that is statistically only expected every 1000 years. For earthquake occurrences that are statistically only expected every 10 000 years, they must continue to comply with the 100 mSv limit.

The demand by nuclear power plant opponents to restrict the dose limit for an earthquake that only occurs every 10 000 years to 1 mSv is disproportionate in view of the average yearly natural radiation dose of 5.5 mSv.

The Beznau nuclear power is equipped to master a severe earthquake that is statistically only expected every 10 000 years by a large margin.

More information on www.ensi.ch

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