German chain reaction

24 July 2007

Incidents on 28 June at Brunsbüttel and Krümmel, both situated in the German federal state of Schleswig-Holstein, have led to dismissals and resignations of staff and board members of the reactor operating company Vattenfall Europe AG. The managers and the company have come under intense criticism from both pro- and antinuclear politicians, more for the way in which they handled the public information campaign following the incidents rather than for the actual incidents. Even German chancellor Angela Merkel said she had no compassion for Vattenfall because of their information policy.

As a result, Bruno Thomauske, managing director of the Vattenfall daughter company Vattenfall Europe Nuclear Energy GmbH (VENE), was removed from his position; next, the Vattenfall communications director Johannes

Altmeppen resigned, and finally Klaus Rauscher, chairman of Vattenfall Europe – clearly under pressure from Vattenfall chairman Lars Josefsson – declared his resignation during a supervisory board meeting on 18 July.

Vattenfall Europe AG is now headed by Hans-Jürgen Cramer and Thomauske’s position is being looked after by Reinhardt Hassa, a long-time member of the Vattenfall board with responsibility for power generation.

One of the key players has been Gitta Trauernicht, the Schleswig-Holstein minister for social affairs and member of the Social Democrat Party (SPD), one of the coalition partners (with the Christian Democrats, the CDU) of the Schleswig-Holstein state government. Immediately after the incidents, Trauernicht, who is responsible for licensing and supervision of nuclear power plants in Schleswig-Holstein, strongly criticised the Vattenfall management for not correctly informing the supervising authority. However, Trauernicht has not been able to maintain her accusations since all written information given by Vattenfall to the ministry can be found on the Internet. In turn Trauernicht has faced criticism for deliberately misleading the public because of her antinuclear attitude.

Not surprisingly however, other antinuclear politicians – in particular, the federal minister for the environment, nature protection and reactor safety, Sigmar Gabriel (SPD) – have used the incidents along with the resulting information campaign to once again call for accelerated shutdown of the nuclear industry, or at least the ‘transferral’ of the remaining electricity production from older nuclear power plants to newer ones. In this context it is, however, noteworthy that Krümmel, which was started up in 1984, is in fact one of the newer plants.

Gabriel has invited representatives of the four large German utilities that operate nuclear power plants to come to a conference at the end of August to discuss the early closure of older plants. Although it seems the companies are prepared to come to such a meeting, they are not likely to accept the proposals of the minister as they maintain that safety standards of old and new plants all meet the requirements of German nuclear law.

Chain of events, part I: Brunsbüttel

At 1302 on 28 June a short circuit occurred during maintenance work at Brunsbüttel. At the time, some devices at the high voltage switching facility of E.ON close to the Brunsbüttel plant were being exchanged so that the general outside grid failed for a short time. As would be expected in such a case, Brunsbüttel was disconnected from the grid and manually shut down. Immediately measures were taken to restart the plant and a detailed inspection was performed during which a slow fire was detected in the turbine building as well as some cracks in pipe coverings. All this led to electricity supply interruptions in the Hamburg area between 1302 and 1315 and again between 1500 and 1515 with stoppage of about 800 traffic lights and all underground trains. After the repair work, the startup of the plant began on 30 June. Operating staff had checked that there were no objections to the startup procedure and, during the afternoon of 1 July, the plant was reconnected to the general grid.

“”

There was never any danger that the fire might spread to the reactor building or other parts of the station

During the startup procedure there were two unintentional interruptions of the reactor primary water purification system, probably by some wrong manipulations of the staff. Though no radioactivity was released to the outside and no staff member was injured these were notifiable events which, however, were reported to the licence authority only on 6 July and to the public by a press release on 8 July. VENE regarded the event as being of the category ‘normal’, which requires reporting within five days of the incident. Following accusations of taking too long to report the incidents, the company has decided to publish such information on its website in future.

Only one day later a deviating temperature value at a condenser vessel within the safety containment revealed the possibility of radiolytic hydrogen formation which later on was, however, found not to be the case. During that inspection the reactor power had been decreased to about 10%. Also, as in other German nuclear power plants, inadequate dowels were found at various places in the plant. Therefore, it was decided on 18 July to disconnect the plant from the general grid and on 22 July the reactor was completely shut down until all irregularities were resolved.

Chain of events, part II: Krümmel

Also on 28 June, only two hours later at 1502, one of the 740MVA transformers – which transform the generator voltage of 27kV to 380kV – at the Krümmel nuclear power plant (which was operating at full power at the time) started burning with extensive smoke production. The short circuit in the transformer had resulted in an arc which ignited the 70t of transformer oil. The plant fire protection staff arrived at the transformer building at 1507 and the local fire brigade arrived at 1515. Within minutes, both teams were able to keep the fire under control within the transformer building and there was never any danger that the fire might spread to the reactor building or other parts of the station. During the night the remaining extinguishing work was handed over to the plant’s fire protection force. Due to the still very high temperatures it was, however, not possible to inspect the transformer building before 2 July when, as is usual in cases of unexplained fires, at first criminal investigators entered the transformer building and afterwards technical experts inspected the facility on behalf of the supervising authority. All these details were correctly given to the media by VENE and in several public statements by Thomauske.

As a consequence of the interruption of the grid and the resulting fire, the staff decided to shut down the reactor immediately by hand which, in hindsight would not have been really necessary. Also, inexplicably, data about the lapse of time of this procedure was lost. Combustion gases gradually penetrated into the control room through the ventilation system and at about 1540 one of about 25 staff members temporarily decided to use a breathing mask. Also the failure of the internal power supply due to the fire caused the staff to perform a rapid reduction in the pressure, leading to a decrease of the water level within the reactor pressure vessel. The final explanation of the incident and the repair of the transformer will require at least five to six weeks before the plant can be connected to the grid again, and then only at 50% of full power due to missing one transformer. Though the reason for the incident cannot yet be explained there is a possibility that the shutdown of Brunsbüttel could have led to a rapid voltage change which led to a short circuit with the electric spark which ignited the oil coolant of the transformer. The information to the supervisory ministry was first given by Vattenfall on the evening of 28 June and then continuously.

In addition, the public was informed by a press release issued by VENE immediately during the afternoon of 28 June. It was stated that both nuclear power plants, Brunsbüttel and Krümmel, had been closed down in the afternoon by hand, Brunsbüttel because of an earlier grid failure and Krümmel because of a fire in a grid transformer outside the reactor building. In both cases the plants are in a stable condition and no radioactivity was released.

By the evening, the media had already distributed the news. On 29 June, a more detailed report was released with information about the situation at Brunsbüttel. Concerning Krümmel, detailed information could at first only be given on 3 July after expert opinion was available from the supervising associations and showed that there was never any danger to the public.

On 6 July, Thomauske personally informed Trauernicht and also delivered a written report about all processes during the Krümmel incident, which included details of the ‘irregularities’: the opening of the power switch of the second transformer; the disconnection of one reactor feedwater pump; the opening of pressure relief valves; the penetration of combustion gases into the reactor control room; and the loss of operational data during the incident. In order to write and verify this report, the shift personnel had been questioned but the names of the persons actually in charge during the incident and the shutdown procedure were not released to the authority because the Vattenfall management wanted to protect their privacy. This decision later on led on 13 July to the dramatic action of the state prosecutor to send criminal inspectors to the power plant to talk to the responsible shift personnel and to inquire whether they had been negligently injured during the intake of combustion gases – all of which was denied by the staff members.

As a result of the discovery last September of incorrect installation of dowels at the Biblis plant, Krümmel was also inspected and on 9 July, in various areas of the plant similar deficiencies were found, notably in a building with two emergency diesels where special seismic specifications apply. After this discovery, Vattenfall Europe chairman Klaus Rauscher announced on 10 July that Krümmel would definitely not be restarted before clarification of all unresolved problems and after the annual revision arranged for August. One day later a small 2mm diameter leak was detected by the staff at a ventilation pipe of the low pressure preheater, again a notifiable event, though of category ‘normal’.


There was never any danger that the fire might spread to the reactor building or other parts of the station Quote1 Kruemmel, 28 June 2007 Kruemmel Author Info:

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