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Sendai reactor power ramp-up halted due to pump problem

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If the PM is so confident that the nuclear plants are safe, he should move his office there. Those who don't learn from history.... you all know the rest. Just wait until the next accident that is due to either a natural or man made disaster and those in charge will say, "There is no way we could have foreseen this."

4 ( +7 / -3 )

Engineers and regulators have warned that the utility may encounter equipment problems and failures as the Sendai No. 1 reactor has been idled for more than four years.

may encounter is NOT something id like to hear when running a frigging Nuclear Power Plant. Wasnt the IAEA suppose to fully check and OK the reboot, which means, shouldnt the reactor be 100% in tip top shape?

4 ( +6 / -2 )

Bwahahaha! The world's highest safety standards, yet one of the pumps that supplies the cooling system (to stop a meltdown) is not working properly? The JT moderator will not let me use the vocabulary I want to describe this freaking mess! This plant was supposed to be inspected and passed all safety checks. How did they miss one of the main cooling system pumps being full of saltwater! How can anybody believe a single word these twats say?

10 ( +13 / -3 )

........one of the main cooling system pumps...........

"..........in the plant’s secondary cooling system, "

Don't exaggerate.

-1 ( +5 / -6 )

Harry_GattoAug. 21, 2015 - 04:59PM JST ........one of the main cooling system pumps........... "..........in the plant’s secondary cooling system, " Don't exaggerate.

Don't hold your breath.

0 ( +1 / -1 )

Just goes to show how short-sighted this whole drama is. Machinery (power stations, cars, aircraft) are all designed to be operated. Allowing them to lay dormant for years on end is a recipe for disaster. Japan's nuclear industry is effectively damned whatever it does. If it bows to public pressure and pulls the plug (pun intended) the nation's use of fossil fuels will markedly increase and everyone will be upset (because renewables have still not reached the point of being a viable alternative). On the other hand, if it tries to potter along with long-dormant infrastructure, it is an accident waiting to happen. Damned either way.

4 ( +4 / -0 )

And with all the extra-strigent safety checks, no one noticed that there was seawater in one of the pumps? What exactly were they checking? Simply that a major earthquake wasn't actually in progress as they flipped the switch?

Incompetence, on a stellar level. This is what happens when all eyes are on them - what happens when it's back to business as usual and they start to get lax?

1 ( +5 / -4 )

Don't get fooled by the word "secondary". It indicates that the water circulation is separated from the primary cycle, but both have to work in order to cool the reactor. Corrosive salt water in the secondary cycle is a serious issue with regard to long term reliability.

3 ( +5 / -2 )

Japan why the HELL are you so willing to play Russian Roulette!!??!!??

And I have a feeling there is more than one bullet in the chambers!!

If there is another Fukushima the costs for the entire country are likely to far exceed what Fukushima is going to cost, seems like nuke plants are Japans new kamikaze!!! INSANE

1 ( +3 / -2 )

Don't get fooled by the word "secondary". It indicates that the water circulation is separated from the primary cycle, but both have to work in order to cool the reactor. Corrosive salt water in the secondary cycle is a serious issue with regard to long term reliability.

I'm very curious as to how seawater ever got in anywhere in the plant, but the secondary cooling system is used to draw heat off the primary circuit for power generation. If the secondary circuit loses all its water, heat will not be drawn from the primary circuit, and the reaction will actually slow down because the water is hotter and less good a moderator and the temperature remains constant.

-1 ( +1 / -2 )

Wasnt the IAEA suppose to fully check and OK the reboot, which means, shouldnt the reactor be 100% in tip top shape?

You can't check that the integrated systems work 100% without running the whole system together under operating conditions.

(to stop a meltdown)

No, to condense the steam. There is a seperate system to cool the reactor water to keep the core below meltdown temperatures.

If the secondary circuit loses all its water, heat will not be drawn from the primary circuit, and the reaction will actually slow down because the water is hotter and less good a moderator and the temperature remains constant.

It is known as the Temperature Coefficient of Reactivity and in all Western reactor designs it is negative. So as you say, as the reactor heats up the increased temperature actually works to shut down the reaction. It is a designed in safety feature to prevent a run-away increase in the reaction.

1 ( +3 / -2 )

Pump no go-nuclear juices flow and flow......

-2 ( +0 / -2 )

A pump going bad is news? What the... pumps go bad. Next news will be "sendai reactor laint is chiping"

1 ( +2 / -1 )

The public are too frightened, it's just a minor problem that can be easily fixed. These tests are done in order to double check if it's safe to run these power plants fully. With that glitch discovered, the power plant is actually much safer than if it didn't happen since were able to replace existing components and improve performance. I say keep testing until were 100% sure its safe and then and ONLY THEN can we start operations!

0 ( +2 / -2 )

Don't worry, Shinzo Abe said nuclear reactors are safe, so it must be true.

-2 ( +2 / -4 )

Sendai nuclear plant seems too old to be operated as many parts are corroding by using salt water in the plant for decades.

-1 ( +1 / -2 )

Engineers and regulators have warned that the utility may encounter equipment problems and failures as the Sendai No. 1 reactor has been idled for more than four years.

You can't check that the integrated systems work 100% without running the whole system together under operating conditions.

Both of those statements are nonsense. The problem described here should be or should have been discovered with serious inspection of the installation. Apparently it wasn't done in that way which puts a serious doubt on the qualification and honesty of the company running this power plant and of NRA. And frankly I am not surprised, this is Japan.

Sea water making it inside the secondary calling system is not something that should have been missed. Period.

It is known as the Temperature Coefficient of Reactivity and in all Western reactor designs it is negative. So as you say, as the reactor heats up the increased temperature actually works to shut down the reaction. It is a designed in safety feature to prevent a run-away increase in the reaction.

Humm this is not a totally correct description. It is more refered as void coefficient of reactivity or just void coefficient. Yes void coefficient is negative on BWR and PWR designs, which means that an increase of void content results in a decrease of the reactivity. PWR (pressured water reactor) is safer since there is relatively a small amount of voids and thus a large negative void coefficient ensures that if the water boils, power will drop.

BWR (boiling water reactor), the design mostly used in Japan has also a negative void coefficient. If the water boils, voids (steam bubbles) are formed, reducing the moderation which in turn reduces thermal power. The problem with BRWs is that an increase of the reactor pressure leads to less voids and then to a potential increase of power. Additionally negative void coefficient with this design produces power oscillations with reduced core flow in case of a failure of the recirculation pump.

0 ( +1 / -1 )

Nuclear faces political barriers, dishonest fear-mongers/pathological liars, fraudulent green lobbyists and sensationalist mass media, while wind and solar that is provoking more fatalities and environmental impacts than nuclear per gigawatt produced, aside intermittences compensated by fossil fuels, is still heavily rewarded with governmental subsidies.

0 ( +2 / -2 )

while wind and solar that is provoking more fatalities and environmental impacts than nuclear per gigawatt produced,

This is one of the dumbest thing I have ever read in the forum of JapanToday, ever. And I can tell you that I have seen some pretty delirious posts.

Give us a break, please.

-3 ( +2 / -5 )

Before making statements like that you may want to Google it. Deaths per KW of power produced are substantially higher for solar, wind and Hydro than nuclear.

1 ( +2 / -1 )

"opinion polls show a majority of the public oppose the move after the nuclear crisis triggered by the earthquake and tsunami four years ago." article

Since the public is now the financial backstop for any failure in Nuclear Power, why should they have any worries? Pumps don't always work and when they don't work the public will pay for the clean up.

It's not as if the public has some stake or say in this debacle.

Oddly, after four years of getting ready to switch on the juice, it would seem Kyushu Electric Power would be keenly aware of the condition of all systems and their state of readiness.

0 ( +2 / -2 )

People just fear that an invisible magic energy gives them cancer. But to this day. Nuclear power is the safest way to get energy

1 ( +3 / -2 )

Humm this is not a totally correct description. It is more refered as void coefficient of reactivity or just void coefficient.

Humm void and temperature coefficients are two different (although slightly related) terms.

Moderator temperature coefficient of reactivity - As the moderator (water) increases in temperature, it becomes less dense and slows down fewer neutrons, which results in a negative change of reactivity. This negative temperature coefficient acts to stabilize atomic power reactor operations.

Void coefficient of reactivity - A rate of change in the reactivity of a water reactor system resulting from a formation of steam bubbles as the power level and temperature increase.

The temperature coefficient works even without boiling and/or voids, it occurs (as the NRC explains) as a result of the fact that water's density decreases with increased temperature, even without boiling.

2 ( +3 / -1 )

Mike o'brien. Water density doesnt change before boiling points. Its a liquid. Not a gas

0 ( +0 / -0 )

@overchan

Water density doesnt change before boiling points. Its a liquid. Not a gas.

It certainly does change before boiling. That's very basic physics. Look it up....

1 ( +1 / -0 )

Lucabrasi While water is in its liquid state it doesnt change. Ice and steam are less dense than water. Water stays the same. I have a steam boiler and it doesnt change before boiling point

0 ( +0 / -0 )

@overchan

Think about a domestic water-heater. The water at the top is always hottest; the water at the bottom is coldest.

Why? As Mike says, the density of hot water is less than that of cold water. It's true. Seriously, google it if you don't believe me....

1 ( +1 / -0 )

@overchan

At 4 degrees C water has a density of 1000 kg/m3 and it slowly drops. At 50 degrees C it is 988 kg/m3 and at 100 degress C (immediately before boiling) it has dropped to 958 kg/m3.

I have a steam boiler and it doesnt change before boiling point

Then you have a steam boiler in which water violates the physics that water everywhere else on the planet follows.

1 ( +1 / -0 )

Sendai Nuclear Plant, Thank you for being cautious in your ramp up to full power. It shows that safety is uppermost in your mind.

2 ( +2 / -0 )

Sendai plant has no power after huge storm hits area..

Did the back up generators work?

Should we send over car batteries?

-1 ( +0 / -1 )

opinion polls show a majority of the public oppose the move after the nuclear crisis triggered by the earthquake and tsunami four years ago.

What are the income brackets of this so-called 'majority'? With a weak yen and high cost for alternative energy. . . what is plan B?

Funny how before 3/11 japan was cool with nuclear energy. (Yet, protesting nuke powered US subs/USS) when near a Japanese Port.

Ohh- but lord forbid one of those US ships provide "umbrella" peace/security to a region of japan from a foreign threat.

1 ( +1 / -0 )

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