Integrated Safety Analysis

An integrated safety analysis (ISA):

  • Identifies potential accident sequences in a facility's operations,
  • Designates items relied on for safety (IROFS) to either prevent such accidents or mitigate their consequences to an acceptable level, and
  • Describes management measures to provide reasonable assurance of the availability and reliability of IROFS.

Applicants for new licenses and persons holding licenses under 10 CFR Part 70, "Domestic Licensing of Special Nuclear Material," on September 18, 2000, must perform an ISA and submit a summary (referred to as an "ISA Summary") to the U.S. Nuclear Regulatory Commission (NRC) for approval.

While the licensee maintains the full ISA and its supporting documentation at an existing licensed facility, the licensee annually submits the ISA Summary which is subject to NRC review.  The ISA Summary focuses on accident sequences with credible consequences that could exceed the criteria of 10 CFR 70.61, "Performance Requirements." The ISA Summary is a synopsis of the results of the ISA and contains information specified in 10 CFR 70.65(b).

The purpose of the review of the ISA Summary is to establish reasonable assurance that the applicant has performed the following tasks:


  • Conducted an ISA of appropriate detail for each applicable process, using methods and staff adequate to achieve the requirements of 10 CFR 70.62(c)(1) and (2).

  • Identified and evaluated, in the ISA, all credible events (accident sequences) involving process deviations or other events internal to the facility (e.g., explosions, spills, and fires) and credible external events that could result in facility-induced consequences to workers, the public, or the environment, that could exceed the performance requirements of 10 CFR 70.61. As a minimum, external events normally include the following:

    • natural phenomena such as floods, high winds, tornadoes, and earthquakes,
    • fires external to the facility, and
    • transportation accidents and accidents at nearby industrial facilities.
  • Designated engineered and administrative IROFS and correctly evaluated the set of IROFS addressing each accident sequence to provide reasonable assurance, through preventive or mitigating measures and the application of supporting management measures (discussed in Chapter 11 of this standard review plan), that the performance requirements of 10 CFR 70.61 are met.  Management measures (as described in NUREG-1520) are activities performed by a licensee that are applied to IROFS to provide reasonable assurance that the IROFS will perform their intended safety function when needed to prevent accidents or mitigate the consequences of accidents to an acceptable level.

The NRC determines the acceptability of the applicant's ISA by reviewing a portion of the ISA documentation and any supporting documentation maintained on site and by reviewing and approving the applicant's ISA Summary which, although not part of the license application, is placed on the public docket. Neither the ISA nor the ISA Summary is incorporated as part of the license.

Reviewers must confirm that an ISA Summary meets the regulatory requirements of 10 CFR 70.65, "Additional Content of Applications," and, specifically, that suitable IROFS and management measures have been designated for high-risk accident sequences and that programmatic commitments to maintain the ISA and ISA Summary are acceptable.

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