Fail-Safe and Fault-Tolerant Design

DOE-STD-6002-96

4.5 Fail-Safe and Fault-Tolerant Design

The fail-safe principle shall be applied to items performing public and worker safety func-

tions; that is, if an item were to fail, it would pass into a safe state without a requirement to initi-

ate any actions. The design of systems shall also, to the extent feasible, be tolerant to faults.

4.6 Human Factors

Human factors and human-machine interfaces shall be considered in the design of items

performing safety functions for fusion facilities.

4.7 Remote Maintenance

The design shall make provisions early in the design process, where necessary, for

accessibility, adequate shielding, and remote handling of items performing safety functions to

facilitate maintenance and repair, taking into account the need to keep worker exposures

ALARA.

4.8 Quality Assurance

A quality assurance process shall be considered in the design, selection of materials,

specifications, fabrication, construction, installation, operating procedures, maintenance, and

testing of fusion facilities. The requirements of 10 CFR 830.120, Nuclear Safety Management,

shall be used for development of the program.

4.9 Codes and Standards

Applicable codes and/or standards shall be identified for use on items performing safety

functions when available. Justification for the applicability of the code for use on the compo-

nents performing the safety functions shall be provided. For items performing safety functions in

fusion facilities for which there are no appropriate established codes or standards, an approach

for selecting the requirements that must be met to accomplish those safety functions shall be

developed and justified.

4.10 Safety Analysis

The safety of fusion facilities shall be analyzed to demonstrate that the facility meets the

evaluation guidelines presented in Section 3. The development of the safety analysis and the

design of the facility are complementary processes that should be carried out interactively.

The evaluation of the safety of the facility shall include a hazard analysis and an analysis

of the response of the facility to a range of PIEs under each mode of facility operation, including

maintenance and shutdown. These PIEs shall include equipment failures and malfunctions,

operator errors, and external events that could lead to either anticipated operational occur-

rences or off-normal conditions. These analyses shall be used as the basis for the selection of

operational limits and conditions for the facility.