Instrumentation Considerations

DOE-STD-1136-2004

Guide of Good Practices for Occupational Radiological Protection in Uranium Facilities

Radiological control personnel should use the facility reporting system to identify discrepancies

and abnormal trends and should summarize the data review results in their monthly reports to the

radiological control manager. Survey data trends should be investigated when either an upward trend

occurs, causing a significant increase (10% or more), or an abrupt change in conditions occurs that cannot

be directly correlated to normal activities.

3.2.5.2 Instrumentation Considerations

Instrumentation performance criteria are necessary for portable, fixed, and emergency

monitoring instrumentation. There are also requirements for instrument calibration and testing.

General Performance Criteria for Instruments

Programs for in-plant monitoring of uranium consist mainly of airborne and surface contamination

surveys and dose rate surveys. The general and specific performance criteria for the instrumentation needed

to conduct these programs are described in ANSI N317-1991, Performance Criteria for Instrumentation

Used for In-Plant Plutonium Monitoring (ANSI, 1980). Performance specifications are also given in ANSI

N323-1993, Radiation Protection Instrumentation Test and Calibration (ANSI 1993), ANSI N42.17A,

Performance Specifications for Health Physics Instrumentation - Portable Instrumentation for Use in

Normal Environmental Conditions (ANSI 1988a), and ANSI N42.17C-1989, Performance Specifications

for Health Physics Instrumentation - Portable Instrumentation for Use in Extreme Environmental

Conditions (ANSI 1987a) for portable radiological control instrumentation and IEC Publication 325, Alpha,

Beta, and Alpha-Beta Contamination Meters and Monitors (IEC 1981) for alpha and beta contamination

meters and monitors. Criteria for air monitoring instrumentation are provided in ANSI/HPS N13.1-1999,

Sampling and Monitoring Releases of Airborne Radioactive Substances from the Stacks and Ducts of

Nuclear Facilitie s (ANSI/HPS 1999b), IEC Publication 761-2, Equipment for Continuously Monitoring

Radioactivity in Gaseous Effluents (IEC 1983), and ANSI N42.17B-1989, Performance Specifications for

Health Physics Instrumentation - Occupational Airborne Radioactivity Monitoring Instrumentation (ANSI

1987b). Criticality alarm systems are discussed in ANSI/ANS 8.3-1986, Criticality Accident Alarm System

(ANSI 1986a). The criteria discussed in the following sections are specified in these standards as

referenced.

Portable Monitoring Instruments

ANSI N317 discusses several criteria related to the performance of portable monitoring

instruments:

The overall accuracy should be within 20%, and the precision should be within 10% at

the 95% confidence level.

The response time (i.e., the time for the instrument reading to go from zero to 90% of full

scale) should be <10 seconds on the most sensitive scale and <2 seconds at readings of

100 mrem/h, 100 mR/h, and 500 dpm or greater. (This criterion is unrealistic with current

neutron instrument capabilities. Response time is typically 30 to 60 seconds.)

The instrument should be able to maintain accuracy and precision for a minimum of 24

hours of continuous operation.

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