[ RadSafe ] What's a "T unit?"

Thu Oct 19 15:13:56 CDT 2006

Thanks, Dave. 

I should have stated that it couldn't be the "tritium unit," since I
don't think the tritium unit wasn't invented until the 1950s
(environmental monitoring following atmospheric nuclear weapons tests),
and it doesn't make sense in this context (measurements at a uranium
plant).

Anyone know when the tritium unit was introduced?

- Dan Strom 

The opinions expressed above, if any, are mine alone and have not been
reviewed or approved by Battelle, the Pacific Northwest National
Laboratory, or the U.S. Department of Energy.

Daniel J. Strom, Ph.D., CHP 
Environmental Technology Directorate, Pacific Northwest National
Laboratory 
Mail Stop K3-56, PO BOX 999, Richland, Washington 99352-0999 USA 
Overnight: Battelle for the U.S. DOE, 790 6th St., Richland WA 99354
ATTN: Dan Strom K3-56 
Telephone (509) 375-2626 FAX (509) 375-2019 mailto:strom at pnl.gov 
Brief Resume: http://www.pnl.gov/bayesian/strom/strombio.htm 
Online Publications: http://www.pnl.gov/bayesian/strom/strompub.htm 
Pagemaster for  http://www.pnl.gov/bayesian   http://qecc.pnl.gov
<http://qecc.pnl.gov/>    http://bidug.pnl.gov <http://bidug.pnl.gov/>  

________________________________

From: WHILLANS David -NUCLEAR [mailto:david.whillans at opg.com] 
Sent: Thursday, October 19, 2006 12:05 PM
To: Strom, Daniel J
Subject: RE: [ RadSafe ] What's a "T unit?"

Dan,

As you probably know, a T unit was an old environmental measure of
tritium concentration, 

See http://toxics.usgs.gov/definitions/tritium.html

"The unit of measure of tritium in water is the tritium unit (TU). One
tritium unit equals 1 tritium atom in 10(18) hydrogen atoms. In SI
units, one tritium unit is about 0.118 bequerels per liter (Bq/L), where
the bequerel is one decay per second. In picocuries per liter, 1 TU is
approximately 3.19 pCi/L. Tritium occurs in very small quantities
naturally, being produced in the upper atmosphere by cosmic rays.
Natural (pre-nuclear age) levels of tritium in precipitation are on the
order of 1 to 5 TU. Nuclear-weapons testing during the 1950s and 1960s
created relatively large amounts of tritium in the atmosphere that can
be detected in ground water that was recharged during this period.
Greatly elevated levels of tritium can be present in ground water
contaminated with radioactive wastes." 

I don't see how that fits the measurements ("beta plus gamma") you
reference but it is curious that you are talking about a company that
presumably had interests in Metal Hydrides (tritides?).

Regards,

Dave Whillans

D. W. Whillans, Senior Scientist

Health Physics Department

Nuclear Protection Programs and Training Division

Ontario Power Generation-Nuclear

1549 Victoria Street East (P58)

Whitby, Ontario L1N 9E3

Phone 905-430-2215 ext3201

FAX 905-430-8583

david.whillans at opg.com

-----Original Message-----
From: radsafe-bounces at radlab.nl [mailto:radsafe-bounces at radlab.nl] On
Behalf Of Strom, Daniel J
Sent: Thursday, October 19, 2006 1:54 PM
To: radsafe at radlab.nl
Subject: [ RadSafe ] What's a "T unit?"

I need to interpret a declassified report dated June 15, 1944 concerning

a company called (at the time) Metal Hydrides. Here's what one finds at

http://www.eh.doe.gov/advocacy/faclist/showfacility.cfm :

-------------*------------

Ventron Corporation 

Also Known As: Metal Hydrides Corp. 

Also Known As: Ventron Div., Morton Thiokol, Inc. 

State: Massachusetts Location: Beverly 

Time Period: AWE 1942-1948; Residual Radiation 1949-1995; DOE 1986;

1996-1997 (remediation) 

Facility Type: Atomic Weapons Employer Department of Energy 

Facility Description: From 1942 to 1948, Metal Hydrides Corp. was under

contract to the Manhattan Engineer District and the Atomic Energy

Commission to convert uranium oxide to uranium metal powder. This work,

as well as later operations to recover uranium from scrap and turnings

from a fuel fabrication plant at Hanford, was conducted at a foundry at

the site. During this period, Metal Hydrides was the AEC's primary

uranium scrap recovery contractor. 

Cleanup activities at this location included the removal of an

underground storage tank in 1986. Further remediation was performed

between May 1996 and August 1997 by Bechtel National Inc. and a number

of local subcontractors as part of the Formerly Utilized Site

Remediation Action Program (FUSRAP). 

The plant is currently owed by the Ventron Division of Morton

International. 

----------*-----------

The report gives one pair of readings as "0.04 r/8-hr. day (gamma)" and

"0.5 T units (beta and gamma)" at "1/2 foot from 14000 pounds of scrap

metal." For measurements reported in "T units," the report states,

"Shield was removed from chamber, hence both beta and gamma radiation,

if present was measured with no differentiation possible."

In those days, the "Tolerance Dose" was 0.1 "r/day." It is possible that

a "T unit" was simply a fraction of the tolerance dose, when the beta +

gamma [open window or shield off] reading was interpreted as simply the

r/d divided by 0.1.

The limit for extremities was evidently 5 times higher, because there

are a whole series of readings inside of a left glove and a right glove

from 10 Apr. 1944 such as "Beta Rad. R/8 hr." of 0.15 and "Times

Tolerance" of 0.3, indicating a Tolerance Dose for the hands of 0.5 r/d

(usually one sees "r" and sometimes "R", as in a column heading where

all words or abbreviations began with an uppercase letter). I would

infer that these measurements must have been made with film, the only

contemporary technology that would fit into a glove. "Times Tolerance"

values ranged from 0.1 ("inside-back of hand") to 0.5 ("inside-base of

3rd and 4th fingers").

Intriguingly, a paragraph states, "The above figures indicate that these

gloves were not contaminated beyond the tolerance limit with beta

radiating materials as of 21 March 1944 or within a week prior to that

date. Corrections for the decay of radioactive materials were made to

the 21st of March, because that is when the gloves were shipped, but if

most of the radioactive contamination was accumulated two or three weeks

before the 21st, the beta radiation to the hands of the wearer at that

time was in the neighborhood of tolerance." This would imply a half-life

of a few weeks. The material in question may have been U-238 alpha decay

product Th-234, with a 24.1-day half-life, if it had been chemically

separated from uranium for some reason.

I would be grateful for any references to information that can confirm

what a "T unit" was.

- Dan Strom

The opinions expressed above, if any, are mine alone and have not been

reviewed or approved by Battelle, the Pacific Northwest National

Laboratory, or the U.S. Department of Energy.

Daniel J. Strom, Ph.D., CHP

Environmental Technology Directorate, Pacific Northwest National

Laboratory

Mail Stop K3-56, PO BOX 999, Richland, Washington 99352-0999 USA

Overnight: Battelle for the U.S. DOE, 790 6th St., Richland WA 99354

ATTN: Dan Strom K3-56

Telephone (509) 375-2626 FAX (509) 375-2019 mailto:strom at pnl.gov

Brief Resume: http://www.pnl.gov/bayesian/strom/strombio.htm

Online Publications: http://www.pnl.gov/bayesian/strom/strompub.htm

Pagemaster for  http://www.pnl.gov/bayesian   http://qecc.pnl.gov

http://bidug.pnl.gov

_______________________________________________

You are currently subscribed to the RadSafe mailing list

Before posting a message to RadSafe be sure to have read and understood
the RadSafe rules. These can be found at:
http://radlab.nl/radsafe/radsaferules.html

For information on how to subscribe or unsubscribe and other settings
visit: http://radlab.nl/radsafe/

________________________________

THIS MESSAGE IS ONLY INTENDED FOR THE USE OF THE INTENDED RECIPIENT(S)
AND MAY CONTAIN INFORMATION THAT IS PRIVILEGED, PROPRIETARY AND/OR
CONFIDENTIAL. If you are not the intended recipient, you are hereby
notified that any review, retransmission, dissemination, distribution,
copying, conversion to hard copy or other use of this communication is
strictly prohibited. If you are not the intended recipient and have
received this message in error, please notify me by return e-mail and
delete this message from your system. Ontario Power Generation Inc. 