Fort Calhoun Station has seen a considerable shift in average plant gamma
energy during our extended shutdown. The major contributor in our case was the
decay (over 10 half-lives) of the Co-58 that was just over 40% of our gamma
activity when on line. This energy shift has driven us to adjust our
electronic dosimeter bias a couple times to keep them reasonably close to the
OSLN.
Our method of keeping up with this is to trend all record dosimeter results
relative to the electronic dosimeter results. We do this every time we get
record dosimeter results. This has provided data that has identified a few
distinct locations and times where an adjustment of the electronic dosimeter
bias is warranted. Examples include normal on-line, in containment inside the
bio shield the first week of an outage, and the balance of the outage.
Extended shutdowns are a special case I hope none of you get to experience.
My longer term goal is to use a portable gamma spectrometer (Inspector 1000 w/
2x2 NaI) to provide the data needed to adjust the electronic dosimeter bias
before the high-dose jobs start.
David Brehm
Radiological Engineer
Office: 402.533.7582
Radiation Protection - Nuclear Operations
Cellular: 402.237.9840
Omaha Public Power District - Fort Calhoun Nuclear Station
Pager: 402.561.3310
9610 Power Lane, Blair, NE 68008
[email protected]
From: [email protected] [mailto:[email protected]] On Behalf Of
Liesl K Germann
Sent: Tuesday, July 09, 2013 1:17 PM
To: [email protected]
Subject: Powernet: Higher TLD Dose Trend.
Hello All,
At Millstone, we recently discovered a trend where a majority of individuals
working on our ECCS sump strainer cover installation had TLD doses higher than
the ED estimates (ICES #305595). A couple follow-up questions:
1. Have you ever seen higher TLD results for a majority of workers on any
particular job(s)? If so, which one(s)?
2. Have you ever required that the TLD and ED be kept together (for
example in a bag) for a particular job to eliminate placement differences?
Thanks!
Liesl
Liesl Germann
Health Physicist
Millstone Power Station
Rope Ferry Road
Waterford, CT 06385
860-447-1791 Ext. 6511
CONFIDENTIALITY NOTICE: This electronic message contains information which may
be legally confidential and/or privileged and does not in any case represent a
firm ENERGY COMMODITY bid or offer relating thereto which binds the sender
without an additional express written confirmation to that effect. The
information is intended solely for the individual or entity named above and
access by anyone else is unauthorized. If you are not the intended recipient,
any disclosure, copying, distribution, or use of the contents of this
information is prohibited and may be unlawful. If you have received this
electronic transmission in error, please reply immediately to the sender that
you have received the message in error, and delete it. Thank you.
----------------------------------------------------------------------
This e-mail contains Omaha Public Power District's confidential and proprietary
information and is for use only by the intended recipient. Unless explicitly
stated otherwise, this e-mail is not a contract offer, amendment, or
acceptance. If you are not the intended recipient you are notified that
disclosing, copying, distributing or taking any action in reliance on the
contents of this information is strictly prohibited.
