Description of Event:
On Friday, February 4, 2022, there was a planned outage at Beta Pumped Storage Plant (PSP) that included turbine (Francis type) runner restoration work – grinding and welding – to repair cavitation on the stainless steel runner vanes. The scope of work included runner repairs on Unit 2, Unit 3, and Unit 1, in that order.
Unit 2 repairs were completed and during this event the contract crew were near completion of Unit 3. The work was being performed in a confined space with the appropriate permits and ventilation. In order to complete all the work, a Turbine Maintenance Platform (TMP) was used.
The TMP was custom designed and built for the plant in the 1980s and has been used since that time. The TMP comprises of a lower deck (dance floor) and an upper platform (runner deck). There is an 18” x 2’ access hatch located on the upper platform which is a multi-purpose component used for access and egress from the lower platform, ventilation, rescue, and the access hatch cover is the only barrier to protect workers from a fall from the upper platform to the lower platform. The TMP is moved from unit to unit as needed, to perform repair work, and stowed away when not in use. The turbine runner restoration work was a maintenance work (expense) project which was contracted out to a company, who has experience performing other work at the site and who has a positive safety rating.
At approximately 2235 hours, a contractor worker (Contactor Worker #1) returned from break and searched the runner vanes for a work light in order to replace the battery so they could resume grinding work. Contractor Worker #1 ascended three vanes looking for the light. When descending a third vane marked Vane #1, the contractor worker became disorientated as to the correct vane he was located in. The worker realized too late he was descending the vane which was directly over the hatch opening with its hatch cover left in the open position. The worker sustained a 7 foot fall resulting in non-life-threatening injuries and exited the confined space without assistance after initial first aid.
Contractor Worker #1 was immediately transported to a medical facility by the foreman for additional treatment and was released from the medical facility. Immediate corrective actions were taken to stand down work while the contractor company completed an initial investigation and corrective actions were taken. Work re-commenced 6 days later.
Actions Taken:
Method & Findings:
HFACS tool was primarily designed to examine unsafe acts, identify the pre-conditions for the act to occur, and determine if supervisory or organizational level influences present that allowed the event to occur. The HFACS analysis is summarized below. Based on the HFACS analysis, several key factors were identified that influenced this event
Unsafe Acts:
Inadequate action/response:
Information was provided to close the hatch when ventilation was not needed, but contractor made decision not to close the hatch. Contractor Worker #1 expressed in the post accident interview that there were tailboards regarding the process of closing the hatch dependent on ventilation needs.
Excessive risk taking
Individual climbed up the vane knowing there was a fall hazard with an open hatch. Fall protection was not utilized.
Preconditions for Unsafe Acts:
Inadequate design:
The design and placement of the platform/hatch. The fall occurred because the design of the hatch was directly below vane one. Once working in the vane, it is not clear which vane you are currently working in.
Inadequate monitoring/backup
There was no defined spotter role who oversaw watching the hatch.
Supervisory Factors:
Failure to provide adequate guidance
There were not clear directions and procedures regarding the hatch. The Safety Plans and JSAs did not specify protocols regarding the hatch. Tailboard discussions were made revolving slip, trips, and falls regarding housekeeping, but nothing documented regarding the hatch cover as a fall barrier.
Organizational Factors:
Policies/Procedures
There were no policies/procedures in place regarding hatch process to indicate when the hatch was to remain close
Barrier Analysis:
Failed, Missing, or Disabled Controls:
Supporting Materials:
Corrective Actions:
• Develop and implement a site-specific Job Hazard Analysis (JHA) for the plant’s TMP. The site specific JHA should include requirements, instructions, and mitigating actions for keeping the plant’s TMP with hatches covered or closed for exposed workers in the absence of alternative fall protection systems. The JHA shall be provided to contractors or employee workers utilizing TMPs, when planning and executing work. The requirement for a JHA will be documented In the PSSP and CWA
· Perform fall protection engineering and fall potential design evaluation of all Hydro TMPs with hatch covers or manways, exposing workers to fall from heights hazards
Sequence & Completion Dates for Actions Listed:
Lessons Learned:
Recommendations: