It has recently been reported in a number of blogs that Xe-131 has “blanketed” The US. There is enough to worry about during this event and Xenon is not one of them.
Pacific Northwest National Laboratory measured and reported the Xenon. Their lab has the most sensitive instrument in the world measuring specifically for Xenon around-the-clock. They are set up to provide Nuclear Test Treaty verification. They are not set up to warn for un-healthful levels during a radiation event.
Here is a report from the lab that first measured the very miniscule levels. PACIFIC NW LABS XENON-131 STATEMENT
Most of the “articles” include a moving map from WeatherOnline as proof of the blanket of Xe-131 covering us all. These are predictive dispersion models of where radioactive isotopes might go if they were in the atmosphere at that time. They are basically weather maps – not radiation predictors and should be treated as such.
Here is a disclaimer from the WeatherOnline website to amplify my assertion: “ATTENTION: These products are highly uncertain based on limited information for the source terms. Please use with caution and understand that the values are likely to change.”
HALF-LIFE: 5.29 days
Hazard category: C- level (low hazard ) : 0.100 to 10 mCi
B – level (Moderate hazard) : > 10 mCi to 1000 mCi
A – level (High hazard) : > greater than 1000 mCi
EXTERNAL RADIATION HAZARDS AND SHIELDING:
The gamma exposure rate at 1 cm from 1 mCi of Xe133 shielded for betas is 150 mR/hr, and at 1 foot will be 0.17 mR/hr. The half and tenth values of lead for this gamma are 0.003 and 0.015 cm respectively. This means that lead sheets or regular lead shipping pig will be sufficient for shielding the material.
The maximum range of the betas is about 0.002 inches in lead. Therefore, the use of the lead shield for storage will provide adequate shielding for the beta particles. If skin is uniformly contaminated with Xe133, 1 microcurie /cm2 deliver a dose of 4200 mrems/hr to the basal cells of the skin.
HAZARDS IF INTERNALLY DEPOSITED:
It is important to avoid ingestion, inhalation and/ or skin contamination.
The NCRP MPC for Xe133 is 10E-5 uCi/ml for 40 hr/wk.
SPECIAL PROBLEMS AND PRECAUTIONS:
1. Xe133 is heavier than air and hard to be kept in solution form, therefore, one should work in well ventilated areas.
2. Survey frequently. Change gloves often.
3. Limit of soluble waste to sewer: 100 microcuries per day per lab
TEPCO Press Release – Apr 6
“As part of monitoring activity of the surrounding environment, we conducted analysis of plutonium contained in the soil collected on March 21st and 22nd at the 5 spots in Fukushima Daiichi Nuclear Power Station.As a result, plutonium 238, 239 and 240 were detected. (previously announced)
Subsequently, from the 3 spots where periodic sampling was conducted on March 25th and 28th and from another spot which was supplemented on 25th, we conducted analysis of plutonium contained in the soil. As a result, plutonium 238, 239 and 240 were detected.
In addition, we conducted nuclide analysis of gamma ray contained in the soil collected on March 21st and 22nd at the 5 spots in Fukushima Daiichi Nuclear Power Station. Such analysis was also conducted on soil collected on March 25th and 28th at the 4 spots. As a result, radioactive materials were detected as described in the exhibit.
Accordingly, we have reported the result of analysis to Nuclear and Industrial Safety Agency and Fukushima Prefecture. We will continue the radionuclide analysis contained in the soil.”
UPDATE – TEPCO Press Release – April 7
“Additionally Iodine, Cesium, Tellurium, Barium, Niobium, Ruthenium, Molybdenum, Technetium, Lanthanum, Beryllium, Silver have been detected from the sample of soil at the site of Fukushima Daiichi Nuclear Power Station collected on 21st, 22nd, 25th and 28th of March.”
Today we have received a letter of protest from National Federation of Fisheries Cooperative Associations (NFFCA) with regard to the discharge of the low level radioactive wastewater from Fukushima Daiichi Nuclear Power Station to the sea. We, as the operator of the power station, received the letter with sincerity, being painfully aware of the feelings and concerns of people in the fishery industry.
While the water discharge was an unavoidable emergency measure implemented after the consultation with the national government in order to prevent the spread of high level radioactive substances, protect the essential safety facilities from inundation and maintain the cooling functions of Units 5 and 6, we would like to make our deepest apologies for the concerns and anxieties caused by our insufficient explanation in advance.
With regard to the compensations related to the water discharge and other issues, we will follow the Act on Compensation for Nuclear Damages and sincerely address them with support from the government. We would highly appreciate it if NFFCA could understand the above.
Working closely with the government, we will make every effort toward the earliest resolution of the situation.
April 6, 2011
The Tokyo Electric Power Company, Incorporated