[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
RE: Cross Post: Radioactivity in Watches?
- To: "radsafe@romulus.ehs.uiuc.edu" <radsafe@romulus.ehs.uiuc.edu>
- Subject: RE: Cross Post: Radioactivity in Watches?
- From: "Edward A. Tupin 301-594-4752 Fax 594-4760" <EAT@FDADR.CDRH.FDA.GOV>
- Date: Tue, 25 Apr 1995 09:44:45 EST
- A1-Type: MAIL
- Alternate-Recipient: prohibited
- Hop-Count: 0
- Importance: normal
- In-Reply-To: <abc26e2f040210048c0b@[35.8.104.89]>
- Mr-Received: by mta CVAX3; Relayed; Tue, 25 Apr 1995 10:00:25 -0500 (EST)
- Posting-Date: Tue, 25 Apr 1995 10:00:00 EST
- Priority: normal
- Ua-Content-Id: D220ZVSREAU2C
- X400-Mts-Identifier: [;52000152405991/399008@FDADR]
One possibility is Promethium (Pm-147). It has a 0.24 MeV Beta (no
gamma) and a 2.6 year half life. It is usually accompanied by some
Pm-146 (0.78 MeV beta [35%]; Electron Capture followed by 0.453 MeV and
0.75MeV gamma [65%]. Pm has been used in various luminous compound for
a number of years.
The preceeding was from NUREG/CP-001, Radioactivity in Consumer
Products, USNRC, August 1978.
Also, NCRP Report 95, Radiation Exposure of the U.S. Population from
Consumer Products and Miscellaneous Products, lists Pm-147 as a major
luminant, estimating production at 1 million watches per year in 1978.
If you really want to know what Seiko is using, the NRC license under
which the watches are manufactured or imported/distributed will have the
details. The licenses are public documents. Contact the NRC Regional
office where Seiko claims to have U.S. headquarters.
Ed Tupin
RSO, CDRH
EAT@fdadr.cdrh.fda.gov