Safety Basis Analysis - STD-1128-98master0312

DOE-STD-1128-98

Guide of Good Practices for Occupational Radiological Protection in Plutonium Facilities

should be based on a documented safety evaluation that compares the risks versus the

benefits. Filtration should be provided to limit the concentrations of radioactive material in

recirculated air to ALARA levels. The design should allow for in-place testing of HEPA

filters or filter banks.

Continuous sampling and monitoring of recirculated air for airborne radioactive material

should be provided downstream of fans and filters. Monitoring should be provided for the

differential pressure across the filter stages and for airborne radioactive material behind the

first HEPA filter or filter stage. The means for automatic or manual diversion of airflow to a

once-through system or stage should be provided. The monitoring system alarm should

result in the automatic diversion of airflow to a once-through system or a parallel set of

filters if an automatic system is used.

The secondary confinement barrier encloses the room or compartment in which the primary

confinement barrier is located, and provides contamination protection for plant personnel

who are outside of the secondary confinement area. High-efficiency particulate air filtration

should be required for air supplied to and exhausted from a secondary confinement barrier.

Secondary confinement rooms, compartments, or cells should be separated from each other

by fire doors or stops. Both the barrier walls and the fire doors should be constructed of

materials that are capable of withstanding a design-basis accident. The secondary

confinement should be designed for pressures that are consistent with the criteria for the

ventilation system. The secondary confinement area should be at a positive air pressure with

respect to the primary confinement areas and at negative pressure with respect to the outside

environment and adjacent building areas that are not primary or secondary barriers.

The building is the structure that encloses both the primary and secondary confinement

barriers, as well as the offices, change rooms, and other support areas that are not expected

to become contaminated. It is the final barrier between the potential contamination and the

outside environment. The building structure or any portion thereof may serve as the

secondary confinement barrier if the requirements for both structure and confinement are

met. The portion of the structure that houses activities involving radioactive material in a

dispersible form should be able to withstand design basis accidents, site-related natural

phenomena, and missiles without a breach of integrity that would result in releases of

radioactive material from the structure in excess of DOE guidelines.

C.2.3 Safety Basis Analysis

A contractor who is responsible for the design, construction, or operation of DOE nuclear

facilities, as designated in writing by the Program Secretarial Officer, is required to perform

a safety analysis. The safety analysis shall evaluate the adequacy of the safety basis for each

facility. Safety basis is defined as the combination of information relating to the control of

hazards at a nuclear facility (including design, engineering analyses, and administrative

controls) upon which DOE depends for its conclusion that activities at the facility can be

conducted safely. The level of safety analysis to be performed must be commensurate with

the magnitude of the hazards being addressed, the complexity of the facility and/or systems

being relied upon to maintain an acceptable level of risk, and the stage of the facility life

cycle. The safety analysis report (SAR) defines the safety basis, document the logic of its

derivation, demonstrate adherence to the safety basis, and justify its adequacy. Included in

this process is evaluation of the design features and their contribution and/or mitigation to

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