This incident illustrates the danger of hydrogen being inadvertently released through blown water seals. Similar incidents have occurred in non-nuclear industrial facilities, but offgas systems present a special hazard because of the…

The lessons of this event fall into five categories: (1) proper in-plant communications during events, (2) proper valve application for use with hydrogen, (3) excess flow check valve set point, (4) heating and ventilation and air conditioning (…

These events show the importance of preventing combustible gas mixtures from accumulating in piping. In both of the above described events, hydrogen and oxygen gases apparently accumulated to a combustible level which then catastrophically failed…

Personnel should be properly supervised, and supervisors should be aware of the activities of their personnel. Personnel must be motivated to adhere to established policies and procedures. All personnel associated with potentially hazardous work…

Because of the near invisibility of a hydrogen flame in daylight and hydrogen's extremely low ignition coefficient, if a known leak is present (e.g., an audible hissing), ignition should always be presumed. The primary cause of this incident…

The tube was 403 stainless steel, which is subject to hydrogen embrittlement. It is requested that all gauges that have bourdon tubes be replaced with 303 stainless steel.

A web-based resource developed by Sandia National Laboratories to…

1. The dilution water for making a polythionic acid aqueous solution was changed from industrial water to pure water to lower the chlorine concentration in the piping.
2. Water that accumulated in the drain was removed before heating…

1. The plant tried to increase production and decrease workload, but failed to notice the potential negative outcomes of this change.
2. It is necessary to thoroughly simulate all potential negative outcomes of a change in procedures…

• Operation and management of the hydrodesulfurization unit should be strengthened to account for abnormal phenomena such as local corrosion.
• The safety review system for remodeling existing equipment and facilities should be…

For the use of mechanical fittings in hydrogen service, administrative controls should be in place, as in this case, to ensure that leak testing is conducted on a regular basis. It should never be assumed that every fitting is tight. Additional…

To prevent a similar flashback, the following measures have been taken:

1. The valve is opened slowly to avoid a major leading shock into the venting line.
2. A special nozzle (Laval or similar) is mounted directly after the…

Recommendations:

1. The using organization should define necessary activities in order to place hydrogen systems in long-term periods of inactivity. The defined activities should address requirements for rendering inert, isolation (i.…

• Active GH2 sensors should be installed and continuously monitored in all enclosed buildings near GH2 sources. All buildings near areas where hydrogen is used should be designed to preclude GH2 entrapment (e.g., sloping roof with…

1.  Combustible gas detectors calibrated for hydrogen can falsely report hydrogen alarms due the presence of other gases the detector may pick up, such as carbon monoxide from engine exhaust or other sources. Since this event occurred, two…

Based on the results of the company investigation and analysis of an amateur video, the company determined that the incident could have been caused by the failure of one of the following plant components:
· pipes leading to the reactor…

In addition to the probable causes listed above, the lack of a standard operating procedure for hydrogen leak detection was one of the probable causes of this incident. Additional contributing factors included the following:
- Severe pipe…

The following actions were proposed as a result of this incident:

•  The company in charge of valve calibration and maintenance will be subject to approval of the plant service inspection team.
•  Plant operating…

1. Carbon steel Nelson curve methodology cannot be depended on to prevent HTHA equipment failures and cannot be reliably used to predict the occurrence of HTHA equipment damage. Revisions to recommended practices should be considered…

An investigative communication notes that "mechanical integrity programs at refineries repeatedly emphasize inspection strategies rather then the use of inherently safer design to control the damage mechanisms that ultimately cause major process…