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Comments on 国际热核聚变实验堆是实现人类可持续发展的理想洁净能源吗？

Dear Dr. Fang

It is interesting to read a recent posted article by
何祚庥 on
国际热核聚变实验堆是实现人类可持续发展的理想洁净能源吗？

Although Dr. 何's calculation on the radioactive
dosage of tritium is correct, It seems that he had
exaggerated the potential hazardous of tritium. I
don't think he provided a good picture to general
public on ITER and nuclear power in general. 

Tritium has half lifetime of 12.3 year, and it is a
beta-emitter (high-energy electron), with an average
energy of 7.9 keV. Comparing with other heavey metal
isotopes, tritium is generally considered much SAFER.
This is because

1. 7.9 keV electron has very limited penetration depth
in human tissue. There is no evidence to my knowledge
that electron at this energy will pose harm to human
organ. 

2. tritium in gaseous form cannot be absorbed by
human, tritium in water form only stay in human body
for ~10 days and will be recyled together with other
water out of human body by metalobalism. This is in a
sharp contrast to other heavy metal isotopes, which
will stay in human body for the rest of life span. 

3. Further most of heavy metal isotopes produce Gamma
radiation, which are far more dangerous at much much
lower dosage. 

Because of these, tritium powered lighting devices are
widely used in air plane, emergency exits, and
military facilities. Tritium powered watch is
astandard gear for every GI in US army. 

These information is based on my own practices and
research on tritium and I feel sorry that I cannot
write Chinese.
 
Kevin 

Note: 1 Curie=3.7 x 10^10 nuclear decay events per
second. It does not specify the decay products nor
energy.

(XYS20040329)

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