See the St. Lucie response below ...
1. A flow chart is used to drive the method to perform neutron monitoring
of personnel. The process evaluates whether the work involves containment
entry, ISFSI, a neutron source, or in areas outside the containment (such as by
the escape hatch), etc.. For the most part, neutron to gamma ratios (vs.
gamma to neutron) are used, that are based on historical surveys by location,
component ID, standardized survey points, and evaluation of historical
estimated to DLR dose. Once determined, a neutron correction factor (NCF) is
entered into Sentinel (the RP computer system software), which automatically
calculates the estimated neutron by multiplying the NCF by the SRD gamma value.
We have found this to be very accurate at determining neutron dose. However,
it does get a little tricky when going to multiple areas of containment (due to
the varying neutron to gamma ratios), but we have NCFs to apply in those
situations also. If the survey during the work activity indicates a neutron
to gamma ratio different than the NCF in Sentinel, we have supervision evaluate
whether to use the Sentinel NCF or manually override the NCF using the survey
ratio.
2. The criteria above is specific for the work performed and area to be
entered.
3. No
4. Yes ... guidance for moderated and unmoderated sources
5. Monthly in accessible areas outside of containment (including the
ISFSI pad), and upon entry (or use) in containment or with source use.
Good luck!
[cid:[email protected]]
Brent L. Robinson
TECHNICAL RP SUPERINTENDENT
Florida Power & Light
St. Lucie Plant
6501 S. Ocean Drive
Jensen Beach, Florida 34957
(772) 467-7308
[email protected]<mailto:[email protected]>
From: Powernet [mailto:[email protected]] On Behalf Of Beth
Heyeck via Powernet
Sent: Monday, April 16, 2018 3:33 PM
To: [email protected]
Cc: Beth Heyeck
Subject: [Powernet] Neutron dose tracking
CAUTION - EXTERNAL EMAIL
We are looking at streamlining our neutron dose tracking and are wondering how
other plants are performing it.
1. Which do you use for determining neutron dose for workers in Neutron
Exposure Areas:
a. Stay time tracking
b. Gamma to neutron ratios
c. Neutron sensitive SRDs
d. Other
2. Do you have specific criteria for using any of the above?
3. Are there any exemptions to tracking neutron doses in Neutron Exposure
Areas, and how are those documented?
4. Do you track neutron dose outside of Neutron Exposure Areas/when
handling neutron sources?
5. How often do you perform neutron surveys of Neutron Exposure Areas?
Elizabeth Heyeck, CHP
Senior Health Physicist
D.C. Cook Nuclear Plant
269-466-2545
[email protected]<mailto:[email protected]>
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