Wednesday, September 29, 2010

Reactivity Coefficients

The title sounds too technical?
Hmm.. it is just a title after all..
This blog is designed to be fun!
Turning technicals into something that is easy to be digest by the majorities.

Ever heard of Chernobyl accident?
Chernobyl Power Plant located in Ukraine (Soviet Union at that time) was hit by disaster in 1986.
One of the reactor exploded and cause major catastrophe.
The accident is said to be caused by the combinations of the design and operating characteristics of the reactor and human error.
Yeah, human do make mistake.

Chernobyl reactor have a feature known as Positive Reactivity Feedback.
When the output power increase, the temperature and multiplication factor increase.
In short, Positive Reactivity Feedback Effect enhances the effect that produced it and is destabilizing.

The RBMK reactor design used at chernobyl is a pressurized water cooled reactor which uses boiling water as the coolant and using graphite as its moderator.
It is very different from most other power reactors in the world, as it is derived from a design that produce both plutonium and power generation.
When the coolant water temperature increase, the boiling increase, which creates voids.
In RBMK reactor, the void coefficient is positive thus making it less stable.
As the accident showed, positive void coefficient is fairly unsafe.
Major modifications have been made to RBMK reactors to solve these problems.
The last unit of reactor at Chernobyl were still used until the year 2000.

As for now, there is nothing to worry about.
The flawed design characteristics of the RBMK reactor is seen as one of several cause of Chernobyl accident.
Those were 1970s design reactors after all. :)

Reactors design nowadays is far more safer!




8 comments:

Unknown said...

Good. You are listeing Mr Shamsul's lectures wel, I reckon.

Pelajar IPTS said...

Yes we are concentrating in class..
The lectures are very interesting and full of knowledge.. :)

vimalan said...

As far as we know the reactor are not just specified to the nuclear there are plenty of them to a matter of fact.such an example will be The Advanced Boiling Water Reactor (ABWR) .so by comparing withh all the other reactor which one will give the highest percentage of efficiency.thanks ( VIMALAN A/l GENASAN vimalan_12@yahoo.com )

Pelajar IPTS said...

hmm..Efficiency is subject to the manufacturers specification actually.

As far as i know, the efficiency of the Gen3/3+ reactors is roughly about 34% - 37%. The highest efficiency is the EPR reactors made by AREVA, which is 37%.

:)

Anonymous said...

Really good blogging. You said that human error was one of the causes of the Chernobyl incident years back. There's even been talks of Malaysia's very own nuclear reactors to generate energy. Undisputed, humans do make mistakes, But mistakes in this case can be fatal and very destructive. Malaysia probably has the fundamentals for good and efficient professionals, but in this case efficiency means concentration and people with no carelessness. I believe our country has to bring out the best out of the attitude and mindsets of engineers and laborers working in the field if we are ever to be successful in this nuclear energy field.

Roshen James
Me084283
james_thierry@hotmail.com

Pelajar IPTS said...

Yes you're right.
To be the best, u must beat the rest. Beat the carelessness in us. Always keep in minds that safety is the first priority.

:)

Anonymous said...

hello you had mention earlier that
the highest efficiency is the EPR reactors made by AREVA, which is 37%.Is this mean the nuclear power plant can only convert 37% of the input to some useful energy.thanks
( VIMALAN A/l GENASAN vimalan_12@yahoo.com )

Anonymous said...

you have mention that,reactors nowsdays are much safer,but can explain the safety feature of reactors that are install in modern reactor,to avoid disasters like u mention above.?

vaageesan ganeesan
macha15_swimfaster@yahoo.com