CAUTION: This interim order is specific to the facility requesting it. Do NOT use these measures at your facility!!!
If I had a nickel for every time I have heard the excuse… “its more dangerous to do these isolations than it is to do the entry with lesser isolations,” I would not be writing this article instead, I would be on my yacht deep-sea fishing somewhere off the coast of Bora Bora!!!! If you have been involved in Permit-Required Confined Space entries I am sure you have had this debate with management/entry supervisor(s). OSHA had originally stated that the facility could “feasible to install two 5,000 pound blank flanges to isolate the system”, but they have granted the facility an interim order that permits it to continue operations (WITHOUT blinding/blanking) while OSHA continues to consider the application for a permanent variance. The facility has proposed “… drilling four (4) holes into the 99.75-inch diameter upper valve flange, and fabrication of twenty (20) three-fourth inch diameter mechanical stops (stop pins), which will be installed to block the movement of the butterfly valve disc to ensure isolation of the water boxes during maintenance work.” Here is the debate taking place… what do you think?
NOTE: I have had this debate in many power plants regarding their isolation practices for entry into their condensers/water boxes. I have never dealt with blinds that weigh 5,000 pounds or that are 99.5″ in diameter, 2.5-inch thick and weighing 5,563 pounds; however, single valve isolation for water flows that would almost immediately incapacitate the entry is not acceptable in my book. This same debate is taking place for entry into Ammonia Evaporative Condensers with NH3 still in the coils and using single valve isolation.
On February 18, 2019, a facility submitted under Section 6(d) of the Occupational Safety and Health Act of 1970 (“OSH Act”)and 29 CFR 1905.11 (“Variances and other relief under section 6(d)”) an application for a permanent variance from the provision of the OSHA standard that regulates ensuring isolation of permit-required confined spaces, as well as a request for an interim order pending OSHA’s decision on the application for variance (OSHA–2020–0001–0001) at its Wadsworth, Texas facility.
Specifically, the facility seeks a variance from the provision of the standard that requires “isolation of permit space,” meaning the process by which a permit-required space is removed from service and completely protected against the release of energy and material into the space (29 CFR 1910.146(b)) and (29 CFR 1910.146(d)(3)(iii)).
The facility also requests an interim order pending OSHA’s decision on the application for a variance. According to the application, the facility operates two Pressurized Water Reactor nuclear power plants at its Wadsworth, Texas, location. The facility’s description of its operation indicates that these nuclear power plants use steam to drive turbine generators, which is cooled by circulating water through a condenser to convert the steam back into water.
- The facility uses a Circulating Water System (CWS) that cools the steam by pumping water from the Main Cooling Reservoir (MCR), through the condenser and back to the reservoir.
- The MCR is 7,000 acres and includes an intake structure where pumps that provide cooling to the units are located.
- These pumps include the circulating water (CW) pumps, of which there are a total of eight (four per unit).
- The flow from each CW pump discharges through a motor-operated valve into a 96-foot diameter pipe which passes over the reservoir embankment at 59 feet elevation.
- The four (4) pump discharge pipes combine into two 138-inch underground pipes that feed a manifold in the Turbine Generator Building (TGB).
- The circulating water flows through condenser tubes inside what the facility refers to as the “water box.”
- The manifold supplies water to each of the six main condenser water boxes with an 84-inch motor-operated valve at the inlet and outlet of each water box.
- The water exiting the water boxes enters a discharge manifold which then splits into two (2) underground 138-inch pipes returning the water to the MCR, passing over the reservoir embankment at 58 feet elevation.
The applicant asserts that the design of the CWS is such that it cannot be completely removed from service for water box cleaning or tube repair and that maintenance activities occur when one of the two Power Plants is removed from service for refueling, which happens once every eighteen months.
The condenser water box is a PERMIT-REQUIRED CONFINED SPACE that, under the facility’s procedures, requires a confined-space permit and security alerts prior to entry. Employees can enter the water boxes to clean condenser tubes and to repair or plug leaking tubes only after being cleared by the Entry Supervisor in accordance with its confined space procedure.
The facility performs maintenance on condenser water boxes prior to the summer months to ensure maximum efficiency and, therefore, maximum generation during the peak electric generating period in Texas. This maintenance activity (tube cleaning) minimizes fouling and blocking of the condenser tubes. Employees entering the water box to perform maintenance and repair activities could be exposed to the hazard of engulfment by water that could flow into the water box if condenser isolation valves were to rotate or otherwise fail during the maintenance or repair activity.
The facility asserts that without frequent maintenance, the condenser tubes could leak and introduce contaminants, such as sodium, into plant systems that can erode barriers that prevent the release of radioactive materials. Further, it asserts that if the water box cannot be timely isolated to repair tubes, it may have to shut down the nuclear power plant, which will cause an interruption to the power supply.
The facility previously believed that procedures already in place — lockout/tagout of the isolation valve, continuous monitoring for leakage past the valve, and standby attendant — were adequate to protect employees.
On March 22, 2018, OSHA received a complaint alleging that the facility failed to ensure isolation of the condenser water box as required by OSHA’s permit-required confined space standard. In response to this complaint, the facility submitted a letter, dated March 28, 2018, to OSHA’s Corpus Christi, Texas Area Office (OSHA– 2020–0001–0002), asserting its belief that they are in full compliance with 29 CFR 1910.146 and describing their current practices to comply with the standard.
On April 20, 2018, the Corpus Christi, Texas OSHA Area Office provided a response explanation stating that it was feasible to install two 5,000 pound blank flanges to isolate the system and directed the facility to take corrective action (OSHA–2020–0001–0003). In the facility’s February 18, 2019, variance application, the applicant asserts that isolating the water box using blank flanges creates a greater hazard and significant risk for injury. Further, the applicant believes that installing blank flanges has the potential to compromise the structural integrity of the system.
To ensure isolation of the condenser water box prior to maintenance activities, the facility proposes in its variance application an alternative safety measure — drilling four (4) holes into the 99.75-inch diameter upper valve flange, and fabrication of twenty (20) three-fourth inch diameter mechanical stops (stop pins), which will be installed to block the movement of the butterfly valve disc to ensure isolation of the water boxes during maintenance work.
OSHA initiated a preliminary technical review of the facility’s variance application and developed a set of follow-up questions on June 9, 2019 (OSHA–2020–0001–0003), regarding the assertions of equivalent worker protection included in the application.
On June 27, 2019, the facility provided written answers to the follow-up questions, (OSHA–2020– 0001–0004) as well as supplemental materials to support the variance application including:
- a Hazard and Operability Study report and recommendations (hazard analysis using a ‘‘HAZOP’’ methodology);
- a copy of all detailed procedures used when employees are entering or inside the water box; and
- a copy of emergency procedures and equipment used while employees are working inside the water box.
In reviewing the application, OSHA evaluated the use of two (2) blank flanges, a 99.5-inch diameter, 2.5-inch thick steel blank weighing 5,563 pounds each to isolate the condenser water boxes during maintenance activities.
The applicant asserted in the variance application that installing a blank flange to isolate a condenser water box creates a greater hazard and significant risk for injury to both personnel and the physical building. The facility asserts that installing a blank flange requires removal of the water box inlet and outlet expansion joints and installation of two steel blanks. Installing the blank flanges as described above entails a high degree of risk, as it would require moving these heavy objects from the building entrance to the water box, using rigged chain falls to trapeze the blanks to the water box, as well as the construction of a support structure for the water box, in order to support the additional weight of the 5,563-pound blanks and ensure the water box and/or inlet pipe does not misalign from the removal of the expansion joint.
Further, OSHA carefully reviewed the administrative and engineering controls outlined in the variance application and supplemental materials as part of its proposed alternative work practices identified in the variance application. Following this review and discussions with the facility, OSHA determined that the facility proposed an alternative that will provide a workplace as safe and healthful as that required by the permit-required confined space standard. OSHA is granting the facility an interim order that permits it to continue operations while OSHA continues to consider the application for a permanent variance.
Source:https://www.osha.gov/sites/default/files/laws-regs/federalregister/2020-09-01.pdf
