2011年3月20日星期日

To Sun Bin: 核的疑惑

Sun Bin,

你貼的文章解不了我的一些疑惑﹐就是三號反應堆的鈽核廢料如果被燒燬﹐會出現什麼問題。我的理解是﹐如果鈽核廢料被燒燬﹐有毒物質會被排放出來﹐造成遠比堆芯融化嚴重的後果。而且這些鈽核廢料的存量是多少﹐存儲狀態如何﹐也是問題的關鍵。

看到日本不顧一切地只往三號堆射水﹐而不管外表看起來破裂得更為嚴重的四號反應堆﹐似乎更能加深這個印象。

堆芯融化最多只能毀掉週圍幾十公里範圍﹐但鈽的排放﹐損害可以沒有上限。我的理解是否正確﹖

盼能解惑。

如果上述猜測是成立的話﹐那說明整個核危機和硬件﹐設計﹐技術﹐採用什麼型號﹐第二代第三代技術﹐沒有關係。

由鈽核廢料引出來的危機﹐不管用什麼樣的技術﹐都可能發生﹐如果沒有完善體制的話。

6 条评论:

依馬打 说...

科學松鼠會這篇文,能否給你釋疑?

http://kexuesongshuhui.blog.163.com/blog/static/93596567201121913456347/

Sun Bin 说...

http://lewis.armscontrolwonk.com/archive/3711/fepc-statement-320#more-1321

Prof. Jeffrey Lewis is an expert in nuclear weapon. He has offered his view on the apparent confusion in the past few days.

regarding your quesion. the simple reason is. No 4 is not operating at the time of the quake and only waste is stored. EVEN IF there is fire, the damage will be very limited. No 3 has the risk (albeit very low) of a comprise in the primary container, and hence a meltdown of the core.

I don't understand why HK's media chose to emphasize Pu fuel.
For example, the Apple Daily article contains basically garbage, eg, when talking about the fuel element,they didn't even bother to mention the isotope (i.e. atomic number), which shows how ignorant the reporters are. There are many isotopes for each element, and some are more 'radioactive' than others.

Yes, there is the an issue of getting Weapon grade ready (and i don't disagree with you regarding this), which I think is very likely true and a very legitimate suspicion for us -- but there is totally beside the point of this disaster.
To be honest I haven't studied Pu vs other fuel in detail, but I do not think using non-Pu fuel means the risk is lower.

Sun Bin 说...

"堆芯融化最多只能毀掉週圍幾十公里範圍﹐但鈽的排放﹐損害可以沒有上限。我的理解是否正確﹖"

I think this statement is not right. Core meltdown, regardless what fuel is used, U235 or Pu, could be disastrous if it is the graphite (Chernobyl) type. A meltdown and explosion could shoot the waste up to high altitude and blown further away.
The issue is graphite vs water. not U vs Pu. I think the new scientist article explained that point.

I see no reason that Pu fuel damage area could be larger than that of other fuel. Where is your source about "no upper bound of damage"? in what measure is 'upper bound"? area affected? or radiation level?

Sun Bin 说...

thanks for yimada's link about. i think the scientific squirrel link is very informative.

Pu 239 is used mainly because it can be enriched form U235 waste -- and re-enriched/recycle from Pu239 waste.

Simply put, Pu or not is really not the point. it is the amount of radioactive element that is exposed that is the key. In fission, all types of elements will be released, though further fission and sometime recombination. e.g U235 reactor would produce Pu239 as waste. in fact most of the Pu239 in reactor No4 are derived from waste of U235 reactors (to higher concentration). So i really do not see why U235 reactor is better, because it also produces Pu239.

量子 说...

谢谢Sun Bin 和伊马打,

我的这个问题的理解,大多来自内地网上讨论和台湾的电视媒体。这本来就是一个很容易充满偏见的议题,而这两个都是很有偏见的信息渠道。你们似乎解释清楚了。

一些基础的科学事实,如果不解释不清楚,真是很容易受到扭曲。

依馬打 说...

Sun Bin 之前的介紹及松鼠科學會網誌外,這兩個網站也值得看看 :

- 對 mark 1 反應堆設計解讀最詳細,首選這個網站

http://allthingsnuclear.org

- 如果想再弄清楚一些核電物理的基礎知識,如 isotope,化學反應與核反應之分別等,

http://www.mitnse.com