[cdn-nucl-l] cdn-nucl-l: poison injection as a fast shutdown system

[Simon Day <dayse@mcmail.cis.mcmaster.ca>]

Friends, colleagues, fellow listers,
	Being one of the unwashed and uneducated masses (i.e., not working
for the power industry) I have a question regarding soluble poison
injection as a shutdown system.
	Is this means of shutdown used in PWRs and if so, how is the
injection done into a high-pressure system?  OR is this approach limited
to use as a slow reactivity balancing effect via pump makeup water etc?
	It is my understanding that in CANDU the poison injection is into
the low pressure moderator.  Is this a fast shutdown system?  How fast?
Now, in CANDU I believe that the poison is Gadolinium, what form is this
in and are there any issues with high temperature insoluble compound
decomposition (probably not as the moderator doesn't run very hot)?
	Thanks.  Answers on a postcard,
Simon

* Simon Day
* NRB-128A, McMaster University
* Hamilton, ON, Canada L8S 4K1
* tel: (905)-525-9140 x 23191
* fax: (905)-528-4339