Talk:Swedish nuclear reactors shut down over safety concerns

number of reactors

I think its written little unclear. I suggest a small rewrite in first part. Like it is written on first page in the synopsis. Its quite dramatic that half of swedens nukelearreactors is closed down. [1] is a good source. Forsmark reactor 2 is very similar to the failed reactor 1. Even if it is closed for maintenance it suffer from same problems. It wont start until it is solved. Together with Oskarshamn reactors 1 and 2 it make 4 reactors not allowed to start by safety concerns. international 20:46, 5 August 2006 (UTC)

[2] is a autotranslation of [3], a statment from the Nuklearcompany. international 21:01, 5 August 2006 (UTC)

POV edit

I removed the statement that information about the incident was withheld from the public for two days since it simply is not true. Several newspapers reported about the incident the same day.

I also replaced the year 2010 with 'in the next few decades'. That may seem a bit vague, but the year 2010 has not been discussed for a long time. The Green Party wants to shut one reactor down in the next four years, not all of them.

I also added some more information about Lars-Olov Höglund, since the article contained very little information about him. He is known as an outspoken nuclear critic and involved in at least two litigations according to the article in Dagens Nyheter and is not a fair and unbiased source. No one else but him seems to share his view that the reactor was close to meltdown. 130.240.96.138 19:18, 6 August 2006 (UTC)

Could you please add a newspaper source that reported the incident prior to July 27th? I could not find one. Also I cannot read the Swedish source you added, can you translate for us, by whom Mr. Höglund's views have been questioned? --Zeitlupe 00:05, 7 August 2006 (UTC)

Reports of the reactor being stopped appeared the same day (such as [4]). News of trouble with the safety systems did however not appear in articles until July 27th (such as [5]). That news about the incident was withheld from the public for two days sounds like everybody thought the power plant was operating normally between July 25th and 27th.

The swedish source I added is from Dagens Nyheter[6] (I tried to find and equivalent English source, but there was none). Yes I can translate it, perhaps this afternoon, I just need to remember to do it. Perhaps there is another Swede around?130.240.96.138 12:04, 7 August 2006 (UTC)

Thanks for the update on the newspaper reports. As for the questioning of Mr. Höglund's statement, I am mainly interested if it was by the SKI (which was already mentioned in the article), by the operating crew of the plant or only an opinion of the author of the article. --Zeitlupe 15:32, 7 August 2006 (UTC)

COOLING SYSTEM DID NOT FAIL

Hi. This is just to correct this great mistake that the cooling system failed. That’s simply wrong because there is an official report that stresses the opposite. It can be found on IAEA website specialised for nuclear incidents. The link is provided here: [[7]]. I urge you to correct this mistake as it leads to knock-on effect on other wiki articles. Log on as a guest and than go to events. For your convinience I provide full report here

Opening of a disconnector in the 400 kV switchyard to which the unit is connected caused an arc and a short. As the voltage on the generator bus bars dropped to about 30% of nominal voltage the unit was disconnected from the grid. The excitation of the generator caused an increase in the voltage level on the generator busbars of about 120%. This overvoltage caused two out of four DC/AC inverters to fail. The failure of the DC/AC inverters implicated that two out of four emergency dieselgenerators did not start as expected, about 30 seconds later in the sequence when house load mode of operation on both turbogenerators was lost. The switchover to off site auxiliary power was successful. but the automatic start of the uninterrupted power supply and the start of two dieselgenerators failed. The two dieselgenerators were started manually after around 20 minutes and all electrical supplies was thereby operational. The scram (shutdown) of the reactor was successful, all control rods were inserted as expected. The emergency core cooling system in two out of four trains was more than sufficient as there were no LOCA. The control room staff was not able to supervise the plant properly as many indications and readings were lost due to the loss of power in two trains. As there was no LOCA or any other safety problems in the reactor and the core cooling capability was more than adequate is the event categorized under as a level 1 event on the INES scale. An increase to level 2 is justified by the common cause failure, two out of four, in the emergency power supply system. To remedy the problem the DC/AC inverters will be modified before the unit is allowed to power up again.--217.211.143.21 10:25, 14 August 2006 (UTC)

217.211.143.21 10:25, 14 August 2006 (UTC)217.211.143.21 10:25, 14 August 2006 (UTC)

my understanding is that power supply to the cooling system was lost, albeit for a short time. is this right? does LOCA refer to "Loss of Cooling <something>"? Doldrums 10:41, 14 August 2006 (UTC)

Hello. Thank you very much for your fast replay and my apologies for changing of the article. I didn’t realize it’s not allowed at first. There was no loose of power at the cooling system and this is why.

This is what happened at Forsmark and would happen in any other plant. Following a power surge that came due to the mistake of crew servicing nearby power cable (I would stress this is separate from power plant and it is not under Power plant jurisdiction) central computer at the plant decided to shut down reactor 1. This also automatically triggered auxiliary power system to start since power plant has lost its main energy source i.e. reactor. In this event there are 3 systems to choose from. Diesel generators, Gas turbines and electricity grid in which case power plant becomes user of electricity. The primary choice is always Diesel so computer automatically started four diesel generators. Due to power surge DC/AC converters on two units were damaged so they failed to start automatically and had to be started manually instead. This however didn’t jeopardize cooling because it is the most important system at the plant. So power went there immediately and two generators (trains) did suffice for them more than enough but some other systems for monitoring failed and had to be supervised manually during those 20 minutes. In case of the complete loose of cooling this would certainly not be number 2 incident which is considered relatively mild

LOCA is acronym from Loose of coolant accident. It refers on event in which cooling liquid (water) is lost due to pipe rupture or some other causes (like valve failure at Three Mile Island). If this happened more water would have to bee pumped in through emergency channels, but this was not the case. In that case gas generators would have been scrambled however chances of these two accidents combining are miserably small.

--217.211.143.21 11:49, 14 August 2006 (UTC)

Correction statement

will this statement of correction cover the error? Doldrums 12:04, 14 August 2006 (UTC)

This article reports that the Forsmark Nuclear Power Plant reactor cooling systems failed. This is incorrect. Two of the four emergency diesel generators supplying power to the plant failed to start as expected, during a reactor shut down. The emergency cooling system, which functioned normally was sufficient to meet the reactor's needs.

Sure. That's perfect. Thanks

--217.211.143.21 12:18, 14 August 2006 (UTC)

Apology

I added an incorrect statement to this article, one that was unsupported by sources. I ought to have been more careful in sticking to what the sources said, and not have attempted to extrapolate from them. I apologise for my actions and will do my best to edit with care in the future. Doldrums 12:31, 14 August 2006 (UTC)