ML12339A486
| ML12339A486 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 03/30/2012 |
| From: | Environmental Protection Agency |
| To: | Atomic Safety and Licensing Board Panel |
| SECY RAS | |
| References | |
| RAS 22152, 50-247-LR, 50-286-LR, ASLBP 07-858-03-LR-BD01 | |
| Download: ML12339A486 (2) | |
Text
Cesium NRC000054 Submitted: March 30, 2012 United States Nuclear Regulatory Commission Official Hearing Exhibit In the Matter of:
Entergy Nuclear Operations, Inc.
(Indian Point Nuclear Generating Units 2 and 3)
ASLBP #: 07-858-03-LR-BD01 Docket #: 05000247 l 05000286 Exhibit #:
Identified:
Admitted:
Withdrawn:
Rejected:
Stricken:
Other:
NRC000054-00-BD01 10/15/2012 10/15/2012 c:..\\,.~p..R REGlI~;.
l~'~
0
~
~
....,,1-0....
?
~
- il The Basics Who discovered cesium and cesium-137?
In 1860, Gustav Kirchhoff and Robert Bunsen discovered nonradioactive cesium in mineral water in Germany. Radioactive cesium-137, and many other radionuclides that are used in nuclear medicine, was discovered in the late 1930s by Glenn T. Seaborg and his coworker, Margaret Melhase.
i'Top of page W here does cesium-13 7 come from?
Nonradioactive cesium occurs naturally in various minerals. Radioactive cesium-137 is produced when uranium and plutonium absorb neutrons and undergo fission.
Examples of the uses of this process are nuclear reactors and nuclear weapons. The splitting of uranium and plutonium in fission creat es numerous fission products.
Cesium-137 is one of the more well-known fission products.
i'Top of page What are the properties of cesium-137?
Cesium, as well as cesium-137, is a soft, malleable, silvery whit e metal. Cesium is one of only three metals that is a liquid near room temperature (83 OF). The half-life of cesium-137 is 30 years. It decays by emission of a beta particle and gamma rays to barium-137m.
i'Top of page What is cesium-137 used for?
Cesium-137 is one of the most common radioisotopes used in indust ry. Thousands of devices use cesium-137 :
- moisture-density gauges, widely used in the const ruction indust ry
- leveling gauges, used in industries to detect liquid flow in pipes and t anks
- thickness gauges, for measuring thickness of sheet met al, paper, film and many other products
- well-logging devices in the drilling industry to help characterize rock strata Cesium-137 is also used in medical therapy t o treat cancer.
i'Top of page Exposure to Cesium and Cesium-137 How does cesium-13 7 get into t he environment?
Cesium-137 in the environment came from a variety of sources. The largest single source was fallout from atmospheric nuclear weapons t est s in the 1950s and 1960s, which dispersed and deposited cesium-137 world-wide. However much of the cesium-137 from t esting has now decayed.
Nuclear reactor wast e and accidental releases such as the Chernobyl accident in the Ukraine release some cesium-137 to the environment. Spent nuclear fuel reprocessing plant wast es may introduce small amounts to the environment. However, the U.S. does not currently reprocess spent nuclear fuel.
Although hospitals and research laboratories generate wast es containing cesium-137, they usually do not enter the environment. Occasionally, industrial instruments containing cesium-137 are lost or st olen. Anyone who unwittingly handles them may be exposed. These devices are typically metal, and may be considered scrap metal and sold for recycling. If they find their way into a steel mill and are melted, they can cause significant environmental contamination. They may also be discarded and sent t o a municipal landfill, or sold for other reasons. These devices should be considered dangerous.
i'Top of page How does cesium-13 7 change in the environment?
Cesium-137 undergoes radioactive decay with the emission of bet a particles and relatively strong gamma radiation. Cesium-137 decays to barium-137m, a short-lived decay product, which in turn decays to a nonradioactive form of barium. The major dose from cesium-137 is from the barium-1 37. The half-life of cesium-137 is 30.17 years. Because of the chemical nature of cesium, it moves easily through the environment. This makes the cleanup of cesium-137 difficult.
i'Top of page How do people come in contact with cesium-13 7?
Everyone is exposed to very small amounts of cesium-137 in soil and wat er as a result of atmospheric fallout. In the Northern Hemisphere, the average annual dose from exposure to cesium-137 associated with atmospheric fallout is less than 1 mrem; this dose continues to diminish every year as cesium-1 37 decays.
People may also be exposed from contaminated sites:
Walking on cesium-137 contaminated soil could result in external exposure t o gamma radiation. Leaving the contaminat ed area would prevent additional exposure.
Coming in contact with waste materials at contaminated sites could also result in external exposure to gamma radiation. Leaving the area would also end the exposure.
If cesium-137 contaminated soil becomes air-borne as dust, breathing the dust would result in internal exposure. Because the radiation emitting material is then in the body, leaving the sit e would not end the exposure.
Drinking cesium-137 contaminated water, would also place the cesium-137 inside the body, where it would expose living tissue t o gamma and beta radiation.
People may also unknowingly handle a strong industrial source of cesium-137. For example, certain moisture gauges contain cesium-137 sources.
i'Top of page