External Event Probabilistic Risk Assessment for the High Flux Isotope Reactor (HFIR).
External Event Probabilistic Risk Assessment for the High Flux Isotope Reactor (HFIR).

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Published: 1989

Total Pages: 24

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The High Flux Isotope Reactor (HFIR) is a high performance isotope production and research reactor which has been in operation at Oak Ridge National Laboratory (ORNL) since 1965. In late 1986 the reactor was shut down as a result of discovery of unexpected neutron embrittlement of the reactor vessel. In January of 1988 a level 1 Probabilistic Risk Assessment (PRA) (excluding external events) was published as part of the response to the many reviews that followed the shutdown and for use by ORNL to prioritize action items intended to upgrade the safety of the reactor. A conservative estimate of the core damage frequency initiated by internal events for HFIR was 3.11 x 10−4. In June 1989 a draft external events initiated PRA was published. The dominant contributions from external events came from seismic, wind, and fires. The overall external event contribution to core damage frequency is about 50% of the internal event initiated contribution and is dominated by seismic events.

The Use of PRA (Probabilistic Risk Assessment) in the Management of Safety Issues at the High Flux Isotope Reactor
The Use of PRA (Probabilistic Risk Assessment) in the Management of Safety Issues at the High Flux Isotope Reactor

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Published: 1990

Total Pages: 9

ISBN-13:

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The High Flux Isotope reactor (HFIR) is a high performance isotope production and research reactor which has been in operation at Oak Ridge National Laboratory (ORNL) since 1965. In late 1986 the reactor was shut down as a result of discovery of unexpected neutron embrittlement of the reactor vessel. In January of 1988, a level 1 Probabilistic Risk Assessment (PRA) (excluding external events) was published as part of the response to the many reviews that followed the shutdown and for use by ORNL to prioritize action items intended to upgrade the safety of the reactor. A conservative estimate of the core damage frequency initiated by internal events for HFIR was 3.11 x 10−4. In June 1989 a draft external events initiated PRA was published. The dominant contributions from external events came from seismic, wind, and fires. The overall external event contribution to core damage frequency is about 138% of the internal event initiated contribution and is dominated by wind initiators. The PRA has provided a basis for the management of a wide range of safety and operation issues at the HFIR. 3 refs., 4 figs., 2 tabs.

Risk Management at the Oak Ridge National Laboratory Research Reactors
Risk Management at the Oak Ridge National Laboratory Research Reactors

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Published: 1994

Total Pages: 7

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In November of 1986, the High Flux Isotope Reactor (HFIR) was shut down by Oak Ridge National Laboratory (ORNL) due to a concern regarding embrittlement of the reactor vessel. A massive review effort was undertaken by ORNL and the Department of Energy (DOE). This review resulted in an extensive list of analyses and design modifications to be completed before restart could take place. The review also focused on the improvement of management practices including implementation of several of the Institute of Nuclear Power Operations (INPO) requirements. One of the early items identified was the need to perform a Probabilistic Risk Assessment (PRA) on the reactor. It was decided by ORNL management that this PRA would not be just an exercise to assess the ''bottom'' line in order to restart, but would be used to improve the overall safety of the reactor, especially since resources (both manpower and dollars) were severely limited. The PRA would become a basic safety tool to be used instead of a more standard deterministic approach to safety used in commercial reactor power plants. This approach was further reinforced, because the reactor was nearly 25 years old at this time, and the design standards and regulations had changed significantly since the original design, and many of the safety issues could not be addressed by compliance to codes and standards.

Risk Analysis of Environmental Hazards at the High Flux Beam Reactor
Risk Analysis of Environmental Hazards at the High Flux Beam Reactor

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Published: 1994

Total Pages: 6

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In the late 1980s, a Level 1 internal event probabilistic risk assessment (PRA) was performed for the High-Flux Beam Reactor (HFBR), a US Department of Energy research reactor located at Brookhaven National Laboratory. Prior to the completion of that study, a level 1 PRA for external events was initiated, including environmental hazards such as fire, internal flooding, etc. Although this paper provides a brief summary of the risks from environmental hazards, emphasis will be placed on the methodology employed in utilizing industrial event databases for event frequency determination for the HFBR complex. Since the equipment in the HFBR is different from that of, say, a commercial nuclear power plant, the current approach is to categorize the industrial events according to the hazard initiators instead of categorizing by initiator location. But first a general overview of the analysis.