Will safety issues close another Japanese nuclear reactor?

[kristopher]

Gov't panel to discuss whether to decommission Genkai No. 1 nuclear reactor


The government's Nuclear and Industrial Safety Agency (NISA) decided on Nov. 29 to set up a subcommittee to discuss whether to review its safety assessments of the No. 1 reactor at the Genkai Nuclear Power Plant in Saga Prefecture in what could be a step toward decommissioning the aging reactor.

NISA, an arm of the Ministry of Economy, Trade and Industry, made the decision after some experts said at its hearing on measures against the aging of nuclear reactors on Nov. 29 that the pressure vessel of the Genkai No. 1 reactor was deteriorating faster than generally assumed and that the reactor should be decommissioned. The No. 1 reactor, the oldest reactor operated by Kyushu Electric Power Co., became operational in 1975.

It has been revealed that a process called "embrittlement" by which the pressure vessel becomes fragile after being exposed to neutrons emitted from the reactor core has progressed much faster than previously thought. Therefore, some experts have pointed out that the vessel, if cooled down quickly, could break down easily.

The No. 1 reactor will go through regular inspections from Dec. 1, but NISA's subcommittee plans to come up with final safety assessments of the reactor by the end of March 2012, and therefore there is a possibility of the reactor remaining shut down at least until then. Moreover, depending on the subcommittee's conclusions, Kyushu Electric's explanation that there is "no safety problem" could be undermined and calls for decommissioning of the reactor would likely emerge stronger...

http://mdn.mainichi.jp/mdnnews/news/20111130p2a00m0na012000c.html


I wonder if this is actually more related to the deception that was involved in in trying to get the plant restarted?
From wiki:
In early 2011, Units 2 and 3 were suspended for routine maintenance. Following the Tohoku earthquake, Kyushu Electric voluntarily sought reapproval with the town of Genkai and Saga prefecture to make sure that there would be no objection to turning the reactors back on. Negotiations extended several months past the normal restart time.<2> Because Units 2 and 3 were not restarted for the summer, Kyushu is expected to have an electricity shortage and only be able to meet 85% of normal summer needs.<3>

After the mayor of Genkai extended his approval, the larger consensus of Saga prefecture was sought. A meeting was organized to inform the people in the district and to get permission to restart the reactors. The meeting was broadcast live on TV and the internet, and viewers were invited to submit their opinions by e-mail or fax. However it became known, that the board of the Kyushu Electric Power Company had specifically instructed employees of the plant to sent emails to this meeting with positive mails for the restart. Later was admitted that not only employees of the utility but the workers of 4 affiliated firms too—more than 1,500 people in total—were involved in this. A big scandal broke out in Japanese media, because the whole meeting appeared to be manipulated.<4[/i>

At the same time as this crisis broke, Prime Minister Naoto Kan unexpectedly requested more stress tests of the reactor. This seemed to imply, despite the earlier assurances of the national government, that the routine maintenance and additional post-earthquake tests had not been sufficient to clear the reactors for restart, and that the mayor of Genkai had therefore approved the restart without complete information about the reactors' safety. As a result, the mayor rescinded his approval.<5> The governor of Saga, who had not yet given his approval, also expressed surprise.<6> Chief Cabinet Secretary Yukio Edano flew to Saga prefecture immediately to apologize to the governor in person.<7> On July 9, Kan also apologized.<8>

On July 12, actor Taro Yamamoto, a Tokyo native who had flown into Saga to protest the potential restart, broke into the offices of Saga prefecture trying to force the governor to come out. He was unsuccessful but proclaimed that he was glad he had come to protest.<9>...

http://en.wikipedia.org/wiki/Genkai_Nuclear_Power_Plant


Here is another instance where the Gov of another prefecture finally admits to similar tactics.
http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=115x318737

[Yo_Mama]

1. Don't take this the wrong way, but

if concern about safety issues WON'T shut down reactors (or require redressing the safety deficit), then we'd all better be investing in escape hatches. The issue of older reactors is present around the world and hasn't, IMO, been fully addressed.

A degenerating reactor vessel is a recipe for disaster. An accident that could be innocuous or cause very small emissions in a vessel with full integrity could prove very dangerous in such a vessel.

At Fukushima Daaichi, they came very close to total disaster:
http://mdn.mainichi.jp/mdnnews/news/20111130p2g00m0dm147000c.html

But remember, the reactor vessels at 1, 2 and 3 were also subjected to very high pressures. The combination of weakened structure and an erosive/corrosive event could be terrifically dangerous - resulting in rupture. There is no need to run such a risk. It's not as if older reactors aren't decommissioned often enough.

We still, btw, do not know quite what happened at reactor 2. From TEPCO documents, it appears that they think the torus ruptured under the floor. I don't suppose we'll find out for some time. You can replace most reactor vessels in entirety, although I do not believe that would be done at this reactor. But you also have the issue of aging in other portions of the structure.

There are other reactors at Genkai NPP:
Reactor 4 is operating and scheduled to go to full power soon. I see no reason to run any additional risk with reactor 1.

Btw, I expect the utility co shareholders to start exercising more caution in Japan. The TEPCO losses have made shareholders far more safety-conscious too.

[kristopher]

2. Take it the wrong way? What does that mean here.

I have no trouble with open and honest discussion.

I posted the Mainichi article this morning. Since then there has been more reporting. The TEPCO scenario referred to below is what is reported in that article.

Institute of Applied Energy: Corium Could Be 2 Meters Deep into Concrete

TEPCO's worst-case scenario (here and here) pales in comparison with the analysis by the Institute of Applied Energy, also presented on November 30 at the workshop held by the Nuclear and Industrial Safety Agency.

From what Yomiuri Shinbun reported (01:01AM JST 12/1/2011):
国の委託を受けて実施したエネルギー総研の解析では、1号機は燃料の85%、2、3号機は70%が格納容器に落下。炉心を取り囲むステンレス製の大型構造物「シュラウド」が損傷したり、格納容器の床のコンクリートも最大2メートル侵食したりしていると指摘した。そのため、コンクリートに支えられた圧力容器が傾いている可能性もあるとした。

The analysis done by the Institute of Applied Energy commissioned by the national government, 85% of fuel dropped to the Containment Vessel in Reactor 1, and 70% of fuel dropped to the Containment Vessels in Reactors 2 and 3. The researchers at the Institute pointed out the possibility of the damage to the stainless-steel shroud that surrounds the fuel core, and of the corium having eaten away the concrete floor of the Containment Vessel up to 2 meters deep. Because of that, they also said it was possible that the RPV got tilted.

http://ex-skf.blogspot.com/2011/11/institute-of-applied-energy-corium.html

The red circle at the bottom is the depth of the TEPCO scenario,. The 2 meter scenarion from Inst. of Applied Energy has the corium contained only after it hit the steel vessel.
See also:
http://ex-skf.blogspot.com/2011/11/now-they-tell-us-series-tepco-admits.html
http://ex-skf.blogspot.com/2011/11/tepco-says-corium-would-stop-at-70.html


About the "escape hatches":
From the OP, "Kyushu Electric's explanation that there is "no safety problem"..."

If they hadn't been caught astroturfing these hearings would probably never have taken place. Due to the expertise required this industry even more than most creates an incestuous relationship between regulated and regulator.

And for an example of what the real "problem" with nuclear is - that's the one that will never be engineered out - definitely see :
http://mdn.mainichi.jp/mdnnews/news/20111130p2g00m0dm029000c.html