Adam, Simon:
In any of the reactors, SDS-2 (poison-injection) actuation gives a very high negative reactivity once the poison has spread throughout the moderator. A figure of >-300 mk is often quoted. A reactivity worth of 55 mk would correspond to a very short time (1 or 2 s) after actuation, with the poison still not mixed throughout the calandria, and perhaps with 1 or more injection nozzles assumed not functioning.
Benjamin Rouben, FCNS
Manager, Reactor Core Physics
AECL Sheridan Park
Tel: 905-823-9060 x 4550
Fax: 905-822-0567
e-mail: roubenb@aecl.ca <mailto:roubenb@aecl.ca>
Cell: 905-302-2054
-----Original Message-----
From: Adam McLean [mailto:adam.mclean@utoronto.ca]
Sent: 2002/mm/02 7:38 AM
To: 'Canadian Nuclear Discussion List'
Subject: RE: [cdn-nucl-l] cdn-nucl-l: poison injection as a fast
shutdown system
Hey Simon,
I can't help with most of the questions... But I do have the original
2-page design specs that OH produced for each set of reactors - the ones
for Bruce and Darlington mention the liquid injection system briefly
(both Pickering stations have boron injection into the moderator but
neither has liquid Gad).
In the Darlington one (dated June 1989):
"Shutdown system - Liquid Injection
Type: Gadolinium nitrate solution
Reactivity Worth: -55 mk
Injection method: Pressurized helium to drive solution into bulk
moderator through nozzles"
In the Bruce A one (dated September 1979):
"Liquid injection shutdown system
Purpose: Terminate reactor operation
Liquid poison: Gadolinium nitrate
Reactivity worth: -675 mk
Injection: Pressurized helium to drive gadolinium nitrate into bulk
moderator through injection nozzles"
In the Bruce B one (no date printed):
"Poison injection nozzles
Safety devices to quickly terminate reactor operation
Quantity: 8
Liquid poison: Gadolinium nitrate
Reactivity depth: >-300 mk with one nozzle out of service"
That's all I got :) I'd note the various measures of reactivity worth
are quite significant, although the liquid and method of injection is
the same (with the same backing pressure?) on all three systems.
Perhaps this is using different times to allow the liquid to diffuse
around the entire Calandria and take effect? I'd also mention that it's
pretty surprising OH would even include a figure with a unit of "mk" and
hand it out to a general audience... (there are also worth's of all the
other control and shutdown systems on it), but I have used them quite a
bit to refer to over the years :)
Adam
-----Original Message-----
From: cdn-nucl-l-admin@informer2.cis.McMaster.CA
[mailto:cdn-nucl-l-admin@informer2.cis.McMaster.CA] On Behalf Of Simon
Day
Sent: Thursday, August 01, 2002 12:49 PM
To: Canadian Nuclear Discussion List
Subject: [cdn-nucl-l] cdn-nucl-l: poison injection as a fast shutdown
system
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
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