Three days after the Fukushima incident Federal Councillor Doris Leuthard announced that all planning permissions for new nuclear power plants have been adjourned1. The National Council and the Council of States agreed to the ban on the construction of new nuclear power plants already in the following autumn session in 2011. However, a plebiscite on this important issue is still missing. The opinions of the political parties differ. One didn’t want a ban on developments of new technologies, and would like to revisit the issue in the context of a new Energy Act. In the Swiss Energy Strategy 2050, updated subsequently to the Fukushima accident, it is intended that nuclear power plants are decommissioned and not replaced “if safe operation is not anymore ensured”. It is anticipated that this will be the case after 50 years. Shut down would happen in Beznau I in 2019; Beznau II and Mühleberg in 2022; Gösgen in 2029 and Leibstadt in 2034. Now, by means of the nuclear phase-out initiative the Swiss people can vote on the issue. The initiative requires to take the existing nuclear power plants out of service after a fixed period of 45 years, so 5 years earlier as (preliminary) assumed in the energy strategy 2050, namely Beznau I one year after the approval of the initiative, Mühleberg, Beznau II, Gösgen and Leibstadt 45 years after its commissioning. The vote is planned on 27 November. The Federal Council rejects the initiative, but issues an indirect counter proposal with reference to its Energy Strategy 2050.
The Federal Council has made a key statement within its comments to the first package of measures in the Energy Strategy 2050 and to the popular initiative “For an orderly phase-out of nuclear energy (nuclear phase-out initiative)”. Nuclear power plants shall not be shut down, as required in the initiative after a fixed operation time, but shall continue to run “as long as they are safe”.
The layman wonders what “safe” means and how the proofing of security is done. Actually a clear decision criterion can be found in the shut-down regulation of the DETEC (Federal Department of the Environment, Transport, Energy and Communications), namely, that a reactor is not sure anymore and must be decommissioned, if among other things, the so-called adjusted brittle fracture reference temperature of the material of the reactor pressure vessel (RPV) reaches the value of 93° C. This value increases with increasing operation time due to embrittlement of reactor pressure vessel under the constant neutron radiation from the reactor inside. With increasing brittleness the risk of spontaneous fractures or cracking of the reactor wall at the start of the reactor (cold) or in the case of an emergency cooling with cold water increases, which can lead to the uncontrolled release of radioactivity. Because the reactor pressure vessel is not interchangeable, the end of operation of the NPP is determined unambiguously and clearly.
Concerning the statement of the Federal Council “as long as operation is safe” and how close the nuclear power plant is to a “precarious” state, there is almost no public discussion, although many people and large areas in Switzerland would be affected in the event of an accident. The evidence of safe operation should be provided in a transparent manner. Swiss environmental organisations request hearings on the subject with public discussion. The few public documents available are not sufficient to be able to assess the arguments of proponents and opponents of nuclear energy.
In order to assess the growing embrittlement of the reactor pressure vessel, specimen made of the same material are hooked into the RPV in front of the wall of the pressure vessel. They are to a higher degree exposed to the radiation, experience and indicate in an accelerated way the embrittlement of the RPV. Roughly every 10 years, some samples are taken out and tested. The tests allow predictions on when the end point of operation as given by the legislator will be achieved. The current method, proven over decades, after which the crucial reference temperature is determined, is seen as conservative, but shows already a close vicinity to the final shut down criterion at the oldest nuclear power plant in the world. Just in this situation it does not increase confidence in the “safety assessments” if you must realise that now a new, less conservative detection method is applied, which again shows a large distance to the end-point condition and allows continued operation for a longer time. Since it doesn’t help that this new method is already applied in other countries based on a “master curve” for typical RPV materials. Other countries switch off their reactors rather after 25 years than 30 years, so that the problems are not virulent there.
This way evidence is limited of the progress of aging of the material and of the results of investigations conducted so far. Within the few published data consistencies in terms of a direct and detailed comparison of old to new measurement methods is not provided. Also it appears that today’s extended operation times of the NPP were not originally planned and one is running out of ordinary test specimen. Now new types of material samples and material data are used, which are not directly related to the original material and thus do not reflect a true picture of the situation in a particular reactor. Only the new “master curve” approach allows such dubious procedure.
As matters stand, in particular with the newly detected foreign material inclusions in the RPV after “safe” operation over decades, Beznau was consequently shut down in March 2015. New tests concerning the strength of the RPV material as well new calculations of the RPV integrity are needed. The power plant operator examines the issue with great efforts to provide evidence of further safe operation. Even a “replica” of part of the RPV was produced newly this year according to the old specification out of the sixties. It is more than doubtful whether exactly the same material properties can be reached as 60 years ago in another foundry with other equipment and with other employees and whether the tests will be meaningful. Not to mention, that the embrittlement due to the long term operation can be only theoretically extrapolated. In those years the nuclear power technology has been in a pioneering phase, many things were still in progress. The manufacturing processes as well as their documentation were in these years far behind current standards in industry. Due to this ambiguities, the SES (Swiss Energy Foundation) requires well-reasoned that second opinions from independent experts must be obtained on the subject. To act hasty under constraints neglecting important engineering principles, to finally get the “right” data for the installed components gives rise to doubts as to the seriousness of all security proofs, carried out so far.
In most countries nuclear power plants are for good reasons shut down on average after 25 or 30 years of operation. In the technical world, the so-called “bathtub curve” is a well-known phenomenon. The failure rate of a technical system is high in a condition as new, also known as teething troubles. It remains low over a longer period of operation. With increasing age of a technical facility the failure rate starts to rise again. This proves also for nuclear power plants, where the risk of a major accident increases with the runtime. You may experience this in a similar way with your private vehicle. Why should in Switzerland an operation time of NPPs of 50 to 60 years aimed at in contrary to all technical experience, an age where there is clear evidence of increasing failure rates? It is a pioneering generation of NPP’s, in which today’s improvements in security are still not incorporated and which cannot be retrofitted to that level. Most nuclear power plants are shut down “for economic reasons” as it is glossed over. Hidden behind such statement is, that significant investments are to be done to continue to operate reasonably safe. But the risk of occurrence of further defects remains high.
The Federal Council replied to the nuclear phase-out initiative with an indirect counter proposal, essentially based on the “Energy Strategy 2050” as revised after the accident in Fukushima 2050. There is a strange discrepancy in the arguments. The initiative of the nuclear phase-out focusses clearly to avoid the increased risk of aging nuclear power plants. – The Federal Councils counter proposal aims as well on a nuclear phase-out, but not in the same clarity. Its plans for the nuclear phase-out are conditional. It wants to leave sufficient time for a wider deployment of renewable energy and the potential use of transitional solutions, for example gas power plants. Also the variety of specified and planned subprogrammes, which are as such correct, take a step forward. Planned efficiency gains when using electric power, also the programmes on buildings aim at saving energy, oil and gas, but are in relation to the main issue dilutive. Among insiders, you can hear even the opinion that the rather hesitant way in the introduction of the new renewable energies in Switzerland could end in a situation where “nuclear energy is further on needed”. It should be noted that Switzerland with regard to the use of energy out of photovoltaics, wind and biomass comes in last in a ranking of European countries. The influence of lobbyists prevents from making progress in using new renewable energy. The risks of nuclear energy, in particular if the technical equipment is old and outdated and can’t even with extensive retrofit measures not be brought on the latest technology level, are not addressed in the proposal of the Federal Council at all.
A clear vote of the people for an upfront specified limitation in operation of the nuclear power plant will avoid unnecessary risks stemming from operating old and outdated nuclear power plants. It will bring a more dynamic introduction of new renewables in Switzerland. This includes that building further Swiss pumped storage plants, some already planned, but suspended, shall continue with priority and the plans shall be followed. Storage facilities, Switzerland is predestined to build them, are a natural complement to the volatile generation of wind and sun, domestic and abroad. Switzerland as a high-tech country should also contribute to the trend-setting technologies “Power to Gas”. A clear endorsement to the planned shut-down dates of nuclear power plants would be a signal to promote the research activities and the construction of demonstration plants in all areas of power generation and storage. •
1 “Tagesgespräch” mit Bundesrätin Doris Leuthard, SREF, 28.8.2015, “Der Atomausstieg war kein Bauchentscheid”
Impressively, comparisons of younger and older generations of nuclear power plants show that “age driven” events happen in older types, which are naturally even longer in operation, 4 to 10 times more often.* The level of knowledge in the design of the first generations of reactors was rather small compared to those built later. Lessons are learned also from accidents. The development of science and technology, as well as the awareness of the risk of nuclear installations was developed over time and meant that more extensive, multiply redundant and independent safety systems have been introduced. But the shortcomings of old reactors cannot be fully overcome through retrofits. An old Citroen 2CV as built in the sixties still doesn’t comply to the current safety level by just installing safety belts and head restraints.
* Studie im Auftrag der Bundestagsfraktion von Bündnis 90/Die Grünen, Wolfgang Renneberg, 22.06.2010
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