Document: NRC Regulatory Guide
Document ID: 688895c2-d1d9-44f3-9c79-3cf0daa88510
Document Type: regulatory_guide
Title: 
Source: NRC Regulatory Guide Division 4
Source URL: https://www.nrc.gov/docs/ML0037/ML003739541.pdf
Revision Date: 2023-06
Chapter: 
Section ID: RG-4.5
CFR Part: 
CFR Title: 

Content:
nding several centimeters into the ground, and it is rarely possible to remove an intact core les than 5 cm in depth. A. Site Selection When soil is sampled as part of a preoperational survey around a plant, it is desirable to select areas that can be resampled at a later time should it become necessary. Figure I shows a suggested distribution of PREDOMINANT WIND II VECTOR Mils 0 1 2 3 4 5 10 Kiloine rs; 0 l.6 3.2 4.8 6.4 8.0 16 Figure 1. PRELIMINARY SOIL SAMFLING SITES NEAR A NUCLEAR FACILITY 4.5-2 sampling sites covering the area surrounding the plant, with emphasis on the downwind direction. About 13 siles, with the furthest extending 16 km (10 miles) downwind, should give an adequate picture of background levels in the environs of a plant. If necessary, sampling at this same array of sites would promide a preliminary picture of the contamination pattern.following a release. It is also suggested that one or more samples be taken close to the center of the most heavily populated area in the vicinity of the plant. The procedure described here is designed to obtain samples that will measure the total amount of an initially airborne contaminant that has fallen out in a given area. It will not evaluate the unusual case where excessive accumulations occur in low spots, at the foot of slopes, or in flooded areas. The site should be nearly level with moderate to good permeability. There should be little or no runoff during heavy rains and no overwash at any time. Such a site is frequently found on smooth ridge crests, level virgin land, and well-kept lawns and grounds around institutional buildings. The site should not be near enough to buildings or trees to be sheltered during blowing rains. Soils having very high earthworm activity should be avoided because of uneven mixing of the soil to considerable depths. B. Core Method Experience has shown that a total sample area of 460 to 930 cm2 (1/2 to I ft2) will provide d reasonably good estimate oftotal deposit if the area