ML20003D667

Natural Environ Radioactivity Survey for Period of Sept 1979 Through Aug 1980.

ML20003D667
Person / Time
Site:	05000187
Issue date:	03/27/1981
From:	Avant D, Cozens G, Woods J NORTHROP RESEARCH & TECHNICAL CENTER
To:
References
NUDOCS 8103300261
Download: ML20003D667 (8)

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I NATURAL ENVIRONMENTAL RAD *3 ACTIVITY SURVEY FOR THE PERIOD OF SEPTEMBER 1979 THROUGH AUGUST 1980 l

- Prepared By:

Dan Avant George Cozens Joe Woods

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. NORTHROP RESEARCH AND TECHNOLOGY CENTER One Research Park Palos Verdes Peninsula, CA 90274 Telephone (213) 377-4811

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NORTHROP RESEARCH AND TECHNOLOGY CENTER I INTRODUCTION The health physics environmental sampling program includes a continuous evaluation of the levels of ' aturally occurring radioactivity in the irrediate environs, and out to a radius of five miles from the Northrop Reactor site.

I Fluctuations in the radioactivity content of the environmental samples occur from time to time due to seasonal and climatic conditions which ray effect the deposition of the atmospheric fallout or other airborne radioactive naterials.

These minor variations must be noted since the do add to the natural environ-mental background; therefore, it is quite important to compile the sample data and periodically compare it with the data from the previous sampling periods in order to establish the trend in the natural background.

The report is a compilation of the data derived fron the environmental samples collected and processed during the period of September 1979 throuch August 1980 which comprises the nineteenth annual report.

In order to maintain continuity in the overall sampling progran, the samol-ing sites have not been changed from those shown in Table I. All sample process-ing and handling techniques have remained the same as those stated in the preview reports.

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AIR ANALYSES A total of 89 continuous air samples were collected during the period from sites S-11 and S-12. The sampling time averaged 189 hours0.00219 days <br />0.0525 hours <br />3.125e-4 weeks <br />7.19145e-5 months <br /> per sample. A 72-hour decay period was permitted on each sample prior to counting to eliminate natural Radon-Thoron activities.

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NORTHROP RESEARCH AND TECHNOLOGY CENTER l

Figure 1 graphically displays the monthly averages from the two sampling stations.

RAINWATER ANALYSES A total of 30 samples were collected from sites S-11 and S-12. The radio-activity content of the rainwater, as shown in Figure 2, does not indicate any significant changes from the previous periods.

S0IL ANALYSES A total of 108 soil samples were collected from the sampling sites indi-cated in Table I. The radioactivity content of the soil samples, as shown in Figure 3, indicates a relatively stable trend.

VEGETATION ANALYSES A total of 108 vegetation samples were collected and processed from the same r eas as the soil samples. The samples indicated no increase in radio-

. activity content. The overall trend was quite typical. The monthly averages are shown in Figure 4.

WATER ANALYSES A total of 120 water samples were collected from the sites indicated in Table I. The combined monthly averages for drinking water and pond water are shown in Figure 5. The water samples indicated only a very slight variation in radioactivity.

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I NORTHROP RESEARCH AND TECHNOLOGY CENTER l

I DISCUSSION Analysis of the data for the overall environmental samples indicates a reasonably stable trend in their radioactivity content, with no significant changes from previous sampling periods.

At times the radioactivity content of the environmental samples changed due to climatic conditions, the prevailing winds (with the ch'nge in seasons),

and the temperature inversions in the los Angeles basin. The smog centent in the air during periods of temperature inversions tends to increase the natural background radioactivity of the air.

Since the overall radioactivity content of the environmental samples was reasonably stable, it is apparent that the Northrop Reactor and associated facilities have not contributed significantly to the natural radioactivity background.

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