Operational Controls - doe-std-1128-98

DOE-STD-1128-98

The final consideration in the design of air cleaning systems for plutonium

operations is the probability and consequences of accidents. In general, plutonium

air-handling systems are designed so that all probable accidents, including the

failure of a single HEPA filter, do not have measurable consequences offsite. It will

be necessary to design the system for all probable meteorological conditions,

including (for some regions of the country) tornados. The system must also be

designed so that some improbable (but not impossible) events (accidents) have

consequences that are less than catastrophic. For example, the simultaneous failure

of two HEPA filters in series is highly unlikely (without a common cause such as

high differential pressure from an explosion or meteorological event) but facilities

must be designed so that these events are not likely to cause fatalities offsite. The

minimum performance criteria for the air-cleaning systems are dictated by DOE

design criteria. Other design parameters are finalized during the Environmental

Impact and Safety Analysis processes. They will differ from facility to facility.

8.2.2

Operational Controls

Plutonium air-handling systems must be operated within the design safety envelope

of the system, designated by Operational Safety Requirements (OSRs). Beyond

that, there are measures that can further reduce the potential for airborne plutonium,

even in glovebox operations. Even within glove boxes, plutonium should be

containerized, preferably doubly encapsulated whenever possible. Spills should be

cleaned up promptly. If rags or tissues are contaminated, they should be bagged as

soon as possible.

8.2.3

Waste Treatments

The principal treatment for cleaning plutonium from air is HEPA filtration. There

are other technologies that can be used for pretreatment, but the most common is

filtration. Electrostatic precipitation, wet scrubbing, demisters to remove moisture,

and other technologies may have specific applications. (Treatment of the HEPA

filters, a solid waste, and the wet scrubber effluent, a liquid waste, are discussed in

Sections 8.3 and 8.4, respectively.)

8.2.4

Sampling and Monitoring

Sampling is the primary method used to achieve a complete and accurate legal

record of releases after they have occurred. The primary requirement for a

particulate air sample of any type is that it be representative of the stream being

measured. This translates into isokinetic sampling in a laminar flow section of the

exhaust duct. The parameters needed to achieve such a sample are given in

numerous references such as the DOE Implementation Guide. Workplace Air

Monitoring (DOE, 1999f), and ANSI N13.1-1969, Guide to Sampling Airborne

Radioactive Materials in Stacks and Ducts (ANSI, 1969b). For sampling, the

analytical methods are the same as those discussed in Chapter 3 of this document

for workplace sampling.

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