Symmetricon — Hazardous Materials Safety Interpretation

Page 1U.S. Department of Transportation Pipeline and Hazardous Materials Safety Administration 1200 New Jersey Ave, SE Washington. D.C. 20590 MAR 1a 2010 Ms. Susan Durr Sr. Logistics Manager S ymmetri con 2300 Orchard Parkway San Jose, CA 95131 Ref. No. 10-0018 Dear Ms. Durr: This responds to your January 15, 20 10 letter concerning the applicability of the Hazardous Materials Regulations (HMR; 49 CFR Parts 171-180) to a device containing non-radioactive cesium metal (Cs-133). Specifically, you askwhether a device containing ten micrograms (Ilg) or less of cesium, a Division 4.3 dangerous when wet material, is subject to the HMR. According to information provided with your letter, the device is a chip scale atomic clock (CSAC) that contains ~ ten Ilgs of cesium metal enclosed in a hermetic cell filled with inert gas at < four psig (0.26 atm». The cesium in the CSAC is contained within four layers of mechanical protection. A worst case scenario analysis of the temperature and pressure if the cesium is exposed to oxygen or water indicates about a 1°C temperature increase in the cell and about a six psig (0040 atm) pressure rise. You also provide video evidence of destructive testing indicating no perceptible hazardous effects. Based on your analysis and based on a prior interpretation provided to your company by PHMSA that less than one gram of rubidium (also a Division 4.3 dangerous when wet material) contained in an atomic clock does not pose a hazard during transportation, it is the opinion of this Office that a CSAC containing ~ ten Ilgs of non-radioactive cesium metal does not pose a hazard during transportation. Therefore, provided the material does not meet the definition of any other hazard class, the CSAC is not subject to the HMR. I hope this information is helpful. If you have further questions, please contact this office. SinCerelY'~ t~.Be~ ~dards Development Office of Hazardous Materials Standards#

Page 2..----:9 Symmetri~orT" l)er lLlndt~ ~ January 15, 2010 U.S Department ofTransportation PHH-l0 1200 New Jersey Avenue, SE East Building, 2nd Floor Washington, DC 20590 Attantion: Mr. Edward T. Mazzullo ~Kceff-'()~s 10 - GO 1'3 Dear Mr. Mazzullo, Symmetricom, Inc. has developed a new chip scale atomic clock (CSAC) which is more than 100 times smaller than existing atomic clocks. The CSAC contains a very small amount (10 microgram) of cesium metal. Because of the very small quantity of cesium and the inherent hermetic construction of the CSAC product within the scope of 49 CFR § 173.13. Symmetrlcom seeks a DOT Special Exemption Letter to define the CSAC as exempt from HAZMAT transport regulations within the Continental USA and Its territories/lslands. Symmetricom has conducted analysis and testing on the CSAC which confirm its non-hazardous properties, as documented in the attached analysis. We provide the analysis with an accompanying movie ( CSAC_cel'-fracture_20091222.avi ) of testing; this movie may be viewed using most media viewers (eg Windows Media Player). Should you have any questions please do not hesitate to contact the following individuals for further clarity and/or information: Administrative: Susan Durr sdurr@symmetrlcom.com voice: 408-964-7624 Technical: Dr. Michael Garvey rmgarvey@symmetricom,com voice: 9782321417 We look forward to a favorable decision from the Department ofTransportation. ~/73·J3 Susan Durr Sr. logistics Manager Symmetricom 2300 Orchard Parkway San Jose, California 95131#