You will have to go through DOEs registration and acceptance process to get access.
S-

Ralph

I'm getting a "403 forbidden" for that link. Do you have another one?

Thanks

Dave Lane


On 3/15/23 10:37 AM, Ralph Stuart wrote:

https://doeopexshare.doe.gov/OPEXShareFiles/pdf/39073_2023-AMSO-AMES-0002.pdf

Lessons Learned: Nitrogen Dewar Tip-over Incident
Lesson ID: 2023-AMSO-AMES-0002
Originator: Ames National Laboratory
Date: February 27, 2023 Contact: Ryan Wyllie/515-294-9769

Lessons Learned Statement: When performing material handling of potentially awkward and heavy items, users need to be aware of the route of travel and the ability to identify any hazards that may exist. Wheeled devices, surface transitions and passage through doorways with a large, top-heavy item can create a hazardous situation. It is imperative that staff bring any safety concerns to the attention of Environmental, Safety and Health (ESH) or Laboratory Leadership so potential issues may be addressed in a timely manner.

Event Details: On Monday, February 27, 2023, at 9:30 am, an Ames National Laboratory (Laboratory) contributor was moving a full 230 Liter (L) round base liquid nitrogen (LN2) Dewar from the Spedding Hall dock to inside the building. The contributor was pulling the Dewar across the door threshold when the caster stuck against the threshold bringing the Dewar to an abrupt halt. The more than 500-pound Dewar tipped over, knocking them to the ground. The user was temporarily pinned beneath the Dewar, but thankfully did not sustain serious injury.

Two Laboratory employees were on the second floor of Spedding Hall near the stairwell when they heard pleas for help. Upon arrival the contributor was already freed from under the Dewar, one staff member took the contributor to the Laboratory’s occupational medicine for evaluation. The other employee contacted the ESH Coordinator and cryogen facility personnel to assist with the incident. The scene was assessed and no emergency was declared: the Dewar was on its side, was located inside the building in the stairwell adjacent to the loading dock, the relief valve was not venting, and there was no indication of damage to the vacuum jacket.

When Laboratory staff began moving the Dewar the safety relief valve was triggered, and the Dewar began to vent L2N into the stairwell. The Dewar was moved outside onto the dock and returned to a vertical position. Once upright the Dewar stopped venting. There was no visible damage to the Dewar.

A Laboratory Industrial Hygienist measured the oxygen content in the stairwell with a 4-gas monitor to ensure that the atmosphere was safe. The monitor indicated normal oxygen levels in the stairwell. The Dewar was secured to the dock and taken out of service until it could be evaluated for operability. The contributor was transported to McFarland Clinic and offsite medical facility by personal vehicle for further evaluation, where x-rays were taken.

Further evaluation indicated that there were no fractures or other serious injury. The contributor was sent home and asked to return for follow-up evaluations.

Ames National Laboratory considered this incident a near-miss because several factors which could have been controlled contributed to the event.

Ames National Laboratory submitted this incident in the Occurrence Reporting Program System (ORPS) as Management Concerns and Issues, Level 2,
  Informational.

Analysis: The Dewar was a standard vessel with 5 casters located directly under the vessel, none of which were damaged or inoperable. There are only two Dewars with this configuration in use at the Laboratory; all other Dewars have a wider base or are on a cart providing a more stable configuration.
During the investigation, several experienced personnel provided feedback that the two Dewars in question were awkward to handle, though no accidents or other near misses had been reported. L2N  Dewars typically have a high center of gravity.

This Dewar type contributed to the incident because the positioning of the casters under the unit, the total weight of the Dewar, and the location of the casters in relationship to the handles and force exerted when pulling the Dewar (Image 1 and 2) create handling issues. When pulling the Dewar via the handle in Image 1, the handle is located directly above the single caster; if the caster’s forward motion is stopped this creates a vertical pivot point whereby the force applied may cause the Dewar to become unbalanced. In Image 2, there are two casters located between the handle at the bottom of the Dewar; if one caster is stopped the force applied would cause the rest of the casters to pivot sharply around the obstruction and keep rolling. Ames National Laboratory delivery staff indicated that the Dewar should be pulled via the handle in Image 2, or pushed when possible.

The contributor and their supervisor were not aware of special handling procedures with this type of Dewar. The contributor had previous experience moving these Dewars along this route with no reportretd issues. They had completed ‘Safe Use of Cryogen’ training through the Laboratory, which covers the  transport of Dewars and indicates that Dewars should be pushed versus pulled when possible.

Corrective Actions:
- Dewars of this style (230L round caster base) will no longer be used at Ames National Laboratory. Immediately following the incident, ESH placed a tag on the single caster side of the Dewar indicating not to pull from that side, and the research group instituted a policy that these types of Dewars need two people to move. The two Dewars utilized by this research group will be exchanged for Dewars with a square caster base (Image 3) which affords greater stability.
  - The on-line Helium Handling training identified gaps regarding the movement of Dewars. A new lesson on 'Transporting Dewars' was added to increase content on proper hand and body placement, identify incorrect methods, and increase situational awareness (two-person, best route). Transporting a Dewar alone is acceptable if the move is on smooth, even surfaces. It was identified that these updates were not incorporated into the ‘Safe Use of Cryogens’ training, but are now scheduled to be added.

The Ames National Laboratory Director will remind staff to bring any concerns to the attention of ESH or Laboratory Leadership so potential issues may be addressed in a timely manner.

The route of travel has been evaluated and the 1⁄2” threshold will be replaced with 1⁄4” plate. This reduces the height obstacle, allowing the caster to more easily bridge the obstacle. A plan is being developed to install an electromagnetic holder on the interior fire door.



Ralph Stuart, CIH, CCHO
ralph**At_Symbol_Here**rstuartcih.org

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