EFFLUENT

ABOVE PL

DISCHARGE

ION-EXCHANGE

TREATMENT PLANT

permissible discharge level, they are released to the laboratory wastetreatment plant. If they are above the permissible level, they are pumped into a tank truck and hauled to the waste-processing building for treatment before release.

The Brookhaven National Laboratory (BNL) flow sheet is given in Fig. 3.4. At BNL wastes are segregated at the source in special containers. Each area in which liquid wastes are produced is provided with holdup tanks and provisions for monitoring. Where wastes exceed specified limits, they are sent to the evaporator for volume reduction and subsequent packaging of evaporator concentrates for sea disposal.

An analytical result cannot be better than the sample from which it is derived; therefore great care should be exercised in collecting a sample representative of the volume and composition of the waste. In planning a sampling program, one must determine what should be sampled and where, how, and why the sample should be taken. Where the amount of radioactivity contributed by short-lived radionuclides is to be determined, analyses of samples collected and composited over a period of time yield less meaningful information than grab samples collected at random and analyzed immediately. On the other hand, if information is needed on levels of long-lived radionuclides, frequent analyses may not be warranted; a monthly or quarterly composite may be sufficient. When operations are fairly constant, continuous long-time sampling may not be as necessary as in cases where major short-term fluctuations are known to take place. Frequency of collection and analysis is determined by fluctuations in the levels of radioactivity and by the nature of the radionuclides present. The sample-collection program should be reviewed from time to time and altered as necessary to provide the kind of data needed to evaluate operations and to ascertain radiation effects downstream.

The sampling program should be designed to answer two basic questions: What materials are released into the environment and at what concentrations? What effect does release of these materials have upon the environment? The first question can be answered by taking samples as close to their source of production as possible. Obtaining samples at the source minimizes subsequent analytical difficulties arising from admixture and dilution of the wastes.

The second is a more difficult question to answer and requires a more extensive sample-collection program. Elements of the aquatic environment should be sampled to determine the predischarge condition of the receiving stream, the volumes available for dilution, the species of biota present, the chemical character of the stream, etc.

The extent of sampling required depends on the downstream uses of the stream into which the wastes are to be released. Furthermore, interpretation of sampling results from the aquatic environment is more difficult because all samples do not provide quantitative data. Some of the aquatic media sampled to determine the fate of radioactive materials released into the hydrosphere are listed in Table 3.1 along with the advantages and disadvantages associated with their collection.28

Of the media mentioned, only water provides quantitative information. If the mass of organisms (plankton, algae, fish, etc.) can be determined as a function of the quantity of water with which they have had contact, it may be possible to accurately evaluate results. The productivity of the medium should be known. However, it is recognized that the levels of activity associated with these organisms, TABLE 3.1-ADVANTAGES AND DISADVANTAGES OF SAMPLING SPECIFIC MEDIA

*Signifies removal from water by surface adsorption, ion exchange, precipitation, etc.

as well as the silt and bottom muas, are aпесteа ру levels of activi

in the streams. They represent dynamic systems, and an exchang of activity between the liquid and solid phases will take place in eithe direction depending upon the levels occurring in each. Thus, durin periods of low stream activity, one may assume that under certai conditions activity will be returned to the stream from plankton an bottom silts where it was temporarily stored during periods of highe water activity. Below uranium-milling operations, for example, wher quantities of radium may be associated with particulate matter, thi particulate matter will settle to the bottom of the stream, and radiur may be released slowly to the surrounding water for long periods o time. 29

Even though fish in many cases provide little information on level of activity existing in the aquatic environment, it may be necessary t sample such material to satisfy the public that levels of activity ar low. The determination of activity levels in such samples permits more accurate evaluation of the potential exposure to downstream populations resulting from the consumption of such fish.

Sampling techniques can be divided into two broad categories manual sampling and mechanical sampling. These techniques are discussed in the following sections, and a description of the various instruments employed with each is given.

(a) Manual Sampling. Manual sampling has the flexibility desired in exploratory work and in spot-check surveys. It may be useful in providing a record of unusual occurrences and is used sometimes in setting up specifications for automatic sampling and continuousrecording equipment. Its disadvantages are that it is expensive, time consuming, and frequently toilsome. Manual sampling also is used to collect grab samples from well-mixed batch collection and treatment systems.

Very simple devices are used in manual sampling. With homogeneous waste solutions a stainless-steel dipper or wide-mouth polyethylene bottle mounted on a rigid light-weight rod can be used. If waste characteristics differ with depth, a weighted bottle can be used. The bottle is lowered to the desired depth, the stopper is removed, and the bottle is held in place until filled. For cross-sectional sampling a tube approximately 2- or 3-ft long and about 2 in. in diameter, open at both ends and with provisions for stoppering the lower end at the desired depth, can be used.

Samples of biota, bottom muds, fish, etc., are generally collected manually. Continuous sampling in the sense that it is used in sampling water cannot be applied. The kinds of samples named are integrated samples in that they reflect the influence and effects of a