[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
RE: A Question for Power Reactor Types and others with portal monitors.
Hi All,
Several people have pointed out my mistake. I'll blame it on my outage induced haze.
The Tl-201 and Tc-99m numbers are reversed. It's usually less than a week for Tc-99m and 1-3 weeks (usually 2 weeks) for Tl-201. Also, regarding our "portal pass" they do list a time period after which the pass has expired.
Linda
-----Original Message-----
From: owner-radsafe@list.Vanderbilt.Edu
[mailto:owner-radsafe@list.Vanderbilt.Edu]On Behalf Of Sewell, Linda
Sent: Thursday, April 08, 2004 9:32 AM
To: Peter.Vernig@MED.VA.GOV; Radsafe@list.Vanderbilt.Edu
Subject: RE: A Question for Power Reactor Types and others with portal
monitors.
Greetings All,
Nuclear Medicine patients have been an issue at power plants for years since most of us have portal monitors at the exit to our protected area, not just the radiologically controlled areas. We've had 16 folks in our "portal pass" program in the past year and we employee approximately 1100 people.
We have found that Tc-99 alarms our portals for 1-3 weeks. I think it really depends on how much Mo-99 there is as a contaminant.
Tl-201 is typically less than a week but is dependent on what it's being used for.
I-123 used for thyroid scans is gone pretty quickly, within a few days.
I-131 for partial or complete thyroid ablation is a problem for 1 - 3 MONTHS and a dose rate issue for closely located co-workers for a few days.
We are starting to see F-18 and Ga-67 a bit now, but don't really have any good data yet.
Another one that is generally only an issue if your lower energy thresholds are set below 80 KeV or so are the prostate cancer seeds. The I-125 seeds are fairly straightforward but the Pd-103 seeds have a significant Zn-65 contaminant which can cause problems. If the monitors "see" that low, the seeds are an issue for 1-3 years.
Several of our workers have indicated that they were setting off the incoming gate alarms at our local landfill.
A common thread throughout which confuses the matter is that the folks doing the tests routinely tell the people that we'll never see it or that it will be gone in just a day or two. The bottom line is, as well all know, if you start off with a BUNCH of activity (millicuries) you still have a BUNCH of activity (from a portal or gate monitor standpoint) even after 7-10 half-lives.
Regarding Peter's issue on homeland security, it's a very valid point. As I recall, I think the current plan is to start having nuc med groups issue the equivalent of our "portal pass" that indicates that the person has had a nuclear medicine treatment. Also, if homeland security sticks with the FEMA alarm setpoints of 1 uCi that will reduce the impacts. Most power plants set their portals to alarm at somewhere around 100 nCi.
Hope this provided some useful information.
Linda
Linda Sewell, CHP
Dosimetry Supervisor
Diablo Canyon Power Plant
MS 119/1/122
PO Box 56
Avila Beach, CA 93424
805.545.4315 (voice)
805.545.2618 (fax)
mailto:lms1@pge.com
-----Original Message-----
From: owner-radsafe@list.Vanderbilt.Edu
[mailto:owner-radsafe@list.Vanderbilt.Edu]On Behalf Of
Peter.Vernig@MED.VA.GOV
Sent: Tuesday, April 06, 2004 12:26 PM
To: Radsafe@list.Vanderbilt.Edu
Subject: A Question for Power Reactor Types and others with portal
monitors.
Group,
I have been pondering the issue of Nuclear Medicine patients setting off
Homeland Security radiation detectors.
There apparently have been scattered incidents so far but NRC published an
information notice on it suggesting a verbal explanation and a business card
be given to patients that could set off such alarms.
I did an impromptu, very quick and VERY dirty test using about 850 uCi of
Tc-99m behind my back [to simulate in the body rather than a point source
and set off waste alarms at about ten feet (3m).
Among the challenges in trying to inform patients and security personnel is
how long a patient may set off an alarm. We have had personnel here receive
a heart study using Tl-201, usual dose 4 or 5 mCi, trip our waste alarm at
"almost a month" after the procedure.
I am slow on the uptake but I just realized this is something I have heard
about at power plants and DOE facilities using portal monitoring systems.
Can any of you out there give me any information about how long people that
have had NM studies continue to trip portal monitors. Any publications that
address this?
Any opinions expressed in this message are mine alone and do not necessarily
represent those of the Eastern Colorado VA Health Care System, The
Department of Veterans Affairs, or the United States Government.
Peter G. Vernig
Radiation Safety Officer, VA Eastern Colorado Health Care System, 1055
Clermont St. Denver, CO 80220, ATTN: RSO MS 115; peter.vernig@med.va.gov;
personal peter_vernig@hotmail.com; 303.399.8020 ext. 2447, FAX: 303.393-5026
Alternate fax 303-377-5686
"...whatever is true, whatever is noble, whatever is right, whatever is
pure, whatever is lovely, whatever is admirable, if anything is found to be
excellent or praiseworthy, let your mind dwell on these things."
Paul of Tarsus
************************************************************************
You are currently subscribed to the Radsafe mailing list. To
unsubscribe, send an e-mail to Majordomo@list.vanderbilt.edu Put the
text "unsubscribe radsafe" (no quote marks) in the body of the e-mail,
with no subject line. You can view the Radsafe archives at
http://www.vanderbilt.edu/radsafe/
************************************************************************
You are currently subscribed to the Radsafe mailing list. To
unsubscribe, send an e-mail to Majordomo@list.vanderbilt.edu Put the
text "unsubscribe radsafe" (no quote marks) in the body of the e-mail,
with no subject line. You can view the Radsafe archives at
http://www.vanderbilt.edu/radsafe/
************************************************************************
You are currently subscribed to the Radsafe mailing list. To
unsubscribe, send an e-mail to Majordomo@list.vanderbilt.edu Put the
text "unsubscribe radsafe" (no quote marks) in the body of the e-mail,
with no subject line. You can view the Radsafe archives at
http://www.vanderbilt.edu/radsafe/