Re: Criticality monitor at power reactors

["Scott E. Bradley" <sbradle1@tuelectric.com>]

Chul Lee wrote:
> 
> I would like to know what type of criticality monitors
> are set up at power reactors per 10 CFR 70,(to monitor
> 20 rad to soft tisuues at 2 meters from neutrons and gamma
> combined)
> 
> Thanks
> 
> Chul Lee - > chullee@umich.edu
 
Area Detectors: G-M Tubes with a range of 0.1 to 1000 mR/hr.
Two (2) above each Spent Fuel Pool and two (2) above each reactor
cavity.  Since in both instances the special nuclear material is
shielded in water, the detectors do not need to be neutron sensitive.

Source Range Detectors: two (2) BF3 Ion Chambers with a range of 1 to
1,000,000 counts/second around the reactor vessel for when the reactor
is subcritical (they are deenergized at power).  Additionally, two (2)
intermediate range compensated ion chambers with a range of 10-11 to
10-3 amps are used for approaching criticality.
-- 
Scott E. Bradley  
Rad Protection Supervisor  
Comanche Peak 
sbradle1@tuelectric.com
http://www.flash.net/~brad