A quantitative, probabilistic risk modeling tool used for more than a decade by the National Aeronautics and Space Administration (NASA) might help the offshore industry prevent low-probability but high-impact incidents, a NASA safety official told a breakfast audience on 4 May at the Offshore Technology Conference in Houston.
David Kaplan, who is in charge of partnership development for NASA’s Safety & Mission Assurance Directorate, said that over a long period — but accelerated by the 2003 loss of the space shuttle Columbia — the space agency has embraced and advanced a quantitative tool called probabilistic risk assessment (PRA) to model and manage risk in the space shuttle program and for the International Space Station (ISS). PRA was also used for the now-terminated Constellation lunar exploration program and is currently in use on the Orion capsule that will one day carry humans to Mars.
“All of NASA’s manned space programs have used PRA to keep aware of these kinds of low-probability, high-consequence events,” Kaplan said. Encompassing hardware performance and human reliability assessment, PRA models are continually updated as changes take place and milestones are met.
Origins in the Nuclear Industry
PRA was developed by the nuclear power industry in the mid-1970s. Like many new programs, it sat on the shelf for several years. But after the 1979 Three-Mile Island accident, the industry took it up and began to apply it.
“People in the industry concluded that the defect that led to the incident could have been predicted, could have been stopped,” Kaplan said. Today, the licensure of every US nuclear power plant is based in part on PRA modeling.
NASA had “dabbled with” PRA before the Columbia disaster, Kaplan said. But the loss of the spacecraft, which disintegrated upon re-entry into the earth’s atmosphere, killing all seven crew members, led to the agency’s full adoption of the probabilistic assessment tool. Although the future of the space shuttle program was thrown into doubt for an extended period, when shuttle flights resumed in mid-2005, NASA was able to complete its remaining missions because of PRA, Kaplan said. The NASA space shuttle fleet was retired in 2011 as construction of the ISS was completed.
The Loss of Columbia
PRA has helped NASA understand risks that arise from small deviations from standards and that increase as the deviations become accepted, Kaplan said. Over many missions, NASA had grown used to small amounts of foam insulation breaking loose from the spacecraft during the launch phase, he said. Although this had never caused problems previously, foam that broke off of Columbia’s propellant tank just after takeoff on 16 January 2003 struck and damaged the protective covering on the orbiter’s left wing tip. During re-entry on 3 February, hot gas penetrated and destroyed the wing, which caused Columbia to lose control and disintegrate.
Kaplan described the evolution of the foam issue in the years before the disaster as “a deviation that became normalized,” resulting in a slow erosion of safety. To address these types of problems, hiring more people or redeploying them would not be an adequate response, he said. NASA needed a system that could provide leading indicators of low-probability, high-impact risks and adopted PRA for that purpose. PRA modeling also “will show you where you should spend your money,” Kaplan said.
In suggesting that PRA could help the oil industry to improve risk management, Kaplan noted the similarity in size and isolated operating environment between the ISS and a facility such as a spar or mobile offshore drilling unit. In all of these facilities, maintenance is critical and repair of critical components is essential. They also must be regularly resupplied.
Parallels Between Deepwater and Space
“NASA does have experience dealing with complex facilities operated in hostile, isolated environments, frankly where single mistakes can have extreme consequences,” Kaplan said. Given the nature of these operations, “failure is not an option,” he said. “In certain ways, it strikes me that the oil and gas industry, particularly in offshore deepwater activity, has many parallels [with NASA’s ISS activity].”
As a quantitative tool, PRA builds on the framework of qualitative tools used by the oil industry and NASA, such as failure modes and effects analysis, hazard and operability studies, fault trees, event trees, and bow-tie assessments, Kaplan said.
Through last year’s SPACE Act, the US Congress allows NASA to engage in partnership agreements with the external community, including private companies, to share expertise, assets, or information potentially beneficial to both parties, if NASA has excess resources available. Kaplan noted a SPACE Act agreement with Anadarko Petroleum to study the potential of PRA to mitigate operational risks in blowout preventers. Results of the study will be made available through the American Petroleum Institute and a planned technical paper this fall.
Kaplan said he was “certainly looking forward” to creating SPACE Act agreements with other oil industry participants to examine PRA’s applicability to industry activity. He encouraged the industry to form such partnerships. He also said that NASA has a 5-year inter-agency agreement with the US Bureau of Safety and Environmental Enforcement to determine if PRA would be a useful tool for the offshore regulatory bureau.