NISP-RP-08 Use of HEPA Equipment

Chapter 8 covers high Efficiency Particulate Air (HEPA) equipment. This plays a crucial role in nuclear facilities and operations to control and mitigate the spread of radioactive particles and contaminants. Here are some specific uses of HEPA equipment in the nuclear industry:

Nuclear Power Plants: HEPA filters are extensively used in nuclear power plants to maintain clean and controlled environments. They are employed in various applications, including:

Containment Systems: HEPA filters are used in the containment building to prevent the release of radioactive particles into the environment in the event of a reactor accident or other incidents. They ensure that the air inside the containment remains free of radioactive contaminants.

Ventilation Systems: Nuclear facilities use HEPA filters in their ventilation systems to remove radioactive particulates from the air before it is released into the environment. This helps ensure compliance with strict environmental regulations and protects workers and the public from exposure.

Gloveboxes and Hot Cells: In laboratories and facilities where radioactive materials are handled, HEPA-filtered glove boxes and hot cells are used to provide a controlled environment. These enclosures allow researchers to work with radioactive materials while preventing the release of airborne contaminants.

Nuclear Waste Management: HEPA filters are used in systems that handle and process nuclear waste, such as in waste treatment facilities and during the handling of contaminated materials. These filters help prevent the release of radioactive particles during waste processing and disposal.

Decontamination and Decommissioning: During the decommissioning of nuclear facilities or the cleanup of contaminated areas, HEPA equipment is used to remove radioactive contamination from surfaces and the air. HEPA vacuums, air filtration systems, and decontamination units equipped with HEPA filters are employed to capture and contain radioactive particles.

Radiological Emergency Response: In the event of radiological emergencies, such as nuclear accidents or incidents involving the release of radioactive materials, HEPA equipment can be rapidly deployed. HEPA air filtration units can be used to purify the air in emergency response centers, decontamination stations, and temporary shelters.

Nuclear Medicine: In healthcare settings, HEPA filters are used in nuclear medicine facilities that handle radioactive materials for diagnostic and therapeutic purposes. These filters help maintain clean environments and protect healthcare workers and patients from exposure to radioactive contaminants.

Laboratory Research: HEPA filters are used in research laboratories that work with radioactive isotopes and materials to prevent the release of radioactive particles into the surrounding environment.

In all these applications, HEPA equipment is a critical component of nuclear safety and radiation protection measures. HEPA filters have the capability to capture and contain airborne radioactive particles, thus reducing the risk of radiation exposure to workers and the public and preventing the spread of contamination. Regular testing, maintenance, and replacement of HEPA filters are essential to ensure their continued effectiveness in these critical roles within the nuclear industry.

1.1           Purpose

This procedure provides instructions for the selection, operation and monitoring of HEPA ventilation and vacuum equipment used for radiological protection.    

1.2           Scope and Applicability

This procedure does not apply to HEPA ventilation or vacuum units used for other industrial hazards such as lead/asbestos abatement.  Documentation will be completed using site specific forms, electronic processes, or the attachments to this procedure.

 Member utilities are expected to use this standard to enable supplemental workers to transition between nuclear power plants with minimal site-specific training.  Compliance with these instructions is expected without additional site requirements or process deviations being imposed that may require additional training or challenge the performance of supplemental workers.

This procedure will be used to train and instruct supplemental radiological protection technicians.  Member utilities will implement these process requirements in site procedures and update site procedures whenever requirements or process steps in this Nuclear Industry Standard Process (NISP) are revised.  Current revisions are maintained on the INPO website.

Terms, acronyms, and definitions are provided in NISP-RP-13, Radiological Protection Glossary.

Clarifying notes for requirements and process steps are provided in Section 4.0 using superscript numbers in the preceding sections.

2.0          General Requirements

2.1         Only HEPA and vacuum units with a current DOP/PAO test can be used to control airborne radioactivity.

2.2         HEPA and vacuum units shall be DOP/PAO tested based on the manufacturer recommendations but as a minimum will be tested once every 24 months or when HEPA filter media is changed.  Date for retesting will be displayed on the unit.

2.3         Only HEPA certified vacuum units can be used inside the RCA.

2.4         Physical inspection is required for all HEPA and vacuum units prior to being placed in service.  Specific attention is to be made to electrical connects and power cords, hoses and connections, and equipment guards.  Do not operate any equipment with potential safety defects.

2.5         All HEPA and vacuum units used inside the RCA must be tagged as internally contaminated and cannot be opened without Radiation Protection oversight.  If the unit has been used in an alpha Level 3 area it must be indicated on the tag as possibly containing alpha contamination.

2.6         Contact Industrial Safety prior to using a HEPA ventilation unit any time that volatile substances, vapors or fumes are expected to be generated during the work activity. ¹

2.7         Portable HEPA ventilation does NOT eliminate the requirements for air quality or confined space monitoring.

2.8         Only those vacuums labeled as wet vacuums, or wet/dry vacuums or systems designed for this purpose, shall be used to remove liquids. 

2.9         HEPAs that require an operating voltage greater than 120V AC will require maintenance support for electrical connections. HEPA’s requiring multi-phase wiring (e.g., 480V 3 phase) should have proper rotation checked prior to placing the unit into service

2.10     All HEPA units and vacuums used in the RCA, while not in use, will be controlled in a manner to prevent unauthorized removal and use.

2.11     When not in the use, the openings of the HEPA ventilation unit and hoses will be covered to prevent access to any potentially contaminated surface or component. 

2.12     An Out of Service tag will be attached to any HEPA ventilation or vacuum unit removed from service due to equipment failure or retesting due date.

2.13     Radiation levels should be monitored on the HEPA units and vacuums while they are in service.  Where available, and based on the potential for increase in radiation levels, telemetry units should be placed on the filter housing to provide a continuous method of monitoring.

2.14     Fire zone loading should be considered when installing HEPA equipment.

2.15     Spark arrestors shall be used on all HEPA units for work activities that generate sparks such as grinding on metal. ²

2.16     Do NOT operate HEPA units with the end of the suction hose covered as this will damage components, over heat the unit, and may result in fire.

2.17     Site guidance should be utilized for the removal and replacement of HEPA filters based on unit type and model available.

3.0          Process Instructions

1.1           Selection of HEPA  and Vacuum equipment

1.1.1      The decision to use HEPA ventilation or vacuum equipment, and the type required, will be made based on the work activity and the expected radiological conditions and the implementing instructions will be included in the RWP or ALARA plan.

1.1.2      Prior to determining the proper engineering controls the potential airborne activity will be projected during the TEDE ALARA process used by the station.  The potential airborne generation takes into consideration the work methods being used, plant ventilation systems, and environmental conditions (e.g. wet surfaces).  Once the airborne generation rate has been projected the proper equipment can be selected.

1.1.3      Unless site specific information is provided, use Attachment 1, Capture Velocity Chart, to determine the capture velocity needed based on the work activity.  If the work activity has been completed successfully in the past then historical information can be used to determine the capture velocity requirements.

1.1.4      Unless site specific information is provided, use Attachment 2, Effective Capture Velocity and Distance Chart, to determine the ventilation hose size requirements for the work activity. 

1.1.5      Select the proper ventilation equipment by taking into consideration the following additional factors:

a.      Weight loading of the equipment on floor or grating

b.       Ability to position the hose at the required distance to provide proper capture velocity and allow the workers the visibility to perform the task.

c.       Spark arrestors should be installed for all spark producing work activities.  Consider the use of fire resistant hose material if available.

d.      Consider the use of a noise suppressor on the discharge of the unit to facilitate a better work environment.  

1.1.6      Select the proper vacuum unit depending on the following conditions

a.      Wet or dry conditions are expected during the work process

b.      Distance the material will have to be transported through the hose from the suction point to the receptacle. 

c.       Potential dose rates on the material being vacuumed

1.1.7      In applications where iodine gas is expected, charcoal filters should be considered/ utilized. ³

1.1.8      If a charcoal filter bank is being used take additional steps to monitor for iodine at the discharge of the unit.  Several factors contribute to the charcoals ability to remove iodine including humidity which can change over the course of a work activity. 

1.2           HEPA/Vacuum Setup

1.2.1      Verify the HEPA or vacuum unit DOP/PAO testing is current prior to setup in the field.

1.2.2      Verify the tamper proof seal or equivalent is in place on the unit.

1.2.3      Validate the current radiological conditions of the unit are indicated on the RAM label or tag.

1.2.4      Check the physical condition of the unit including the condition of the power cord.  Do not plug into an electrical power source if the cord shows signs of damage. 

1.2.5      Each HEPA and vacuum unit shall have a unique numbering system and should be signed out to the work location using Attachment 3, HEPA/Vacuum Issue and Return Log, or electronically using site specific processes.

1.2.6      Use caution when removing end covers of hoses or HEPA units due to the potential for internal contamination.  Proper contamination control measures should be implemented prior to removing the covers.

1.2.7      Ensure exhaust of the HEPA unit is directed away from a contamination area boundary to prevent the potential for airborne generation.

1.2.8      Ensure the HEPA exhaust screen is intact which prevents personnel injury from rotating equipment.

1.2.9      Use the following guidance to route the ventilation hose

a.      Minimize the amount of hose used to prevent the potential collapsing of the trunk.  Keep the hose as straight as possible from the unit to the work site

b.      Make sure the suction of the hose is located in the proper location to provide the capture velocity necessary to provide the proper ventilation

c.       Minimize sharp bends or curves which can reduce the suction flow and prevent the desired CFM from being achieved.  If sharp bends are necessary consider the use of fabricated joints.

d.      Route hose in low traffic areas or in the overhead to prevent trip hazards to personnel.  As appropriate use safety flagging to make personnel aware of the hazard.

e.      If the hose is being routed vertically consider the need for hose supports based on the weight of the HEPA hose being used

1.2.10   If a charcoal filter is required install the device in the suction of the HEPA unit or per the manufacturer’s instructions.

1.2.11   After inspection and installation of the HEPA hose, connect the unit to power source.  If the unit uses greater than 120V AC the unit must be connected by a qualified individual. 

1.2.12   Power up the unit and observe the magnehelic gauge, if equipped, and ensure it falls within the band established for that unit.  If the magnehelic gauge is outside the band then secure the unit and take the following actions

a.      Validate the hose did not collapse while the unit was in operation.

b.      Validate the magnehelic gauge connections are not loose

c.       The end of the hose is open and free

d.      There are no sharp bends in the hose which could reduce the air flow

e.      If no issues were found during a-c above consider the need to replace the HEPA and/or Pre-filters using site guidance.

f.        For units operating on 3 phase 220/480V AC it may be necessary to verify the rotation of the unit upon initial startup.

1.2.13   For operation of vacuum units individuals should review the requirements in Attachment 5, Worker Instructions for Vacuum Operation.

1.3           Monitoring HEPA/Vacuum Operations

1.3.1      Dose rates monitoring frequency for HEPA and vacuum units should be based on the potential for changing conditions.  In most cases the units should be checked daily when in use or at a survey frequency determined by RP supervision.  Survey frequency is documented on attachment 4.

1.3.2      Consider installing a telemetry device, if available, and there is the potential for the HEPA or vacuum unit to become a source of exposure.  Install the monitoring device on the inlet of the filter assembly. 

1.3.3      Use Attachment 4, HEPA Shift/Daily Inspection, to validate the operation of the unit once per Day/Shift or at the frequency determined by RP supervision while in operation.

1.3.4      The effectiveness of HEPA unit operation should be monitored based on the risk associated with failure of the unit.  For high risk activities (i.e. Steam generators ventilation) consider the use of continuous air monitors to provide a quick indication of equipment failure.  For other medium to low risk activities smear the discharge of the unit and/or obtain air samples to validate the units operation.

 

1.4           Storage of Equipment

1.4.1      HEPA and Vacuum equipment should be stored in a controlled manner to prevent unauthorized personnel from placing equipment in service.

1.4.2      RP personnel will maintain the control of HEPA and vacuum units by issuing equipment using Attachment 3, HEPA/Vacuum Issue/Return Log, or site electronic processes or forms.

1.4.3      Fire loading should be considered before storing HEPA ventilation equipment inside the plant.

1.4.4      HEPA and vacuum equipment shall be clearly tagged in accordance with NISP-RP-04,Radiological Posting and Labeling.

1.4.5      Charcoal filtration units should be stored to prevent damage from moisture based on manufactures recommendations.

2.0          Clarifying Notes

1      HEPA ventilation equipment could transport harmful vapors or fumes to other areas of the plant or the HEPA media could be damaged.  Ensure a proper safety evaluation has been completed prior to using HEPA ventilation equipment when other industrial hazards are present.

2      Due to the flow of oxygen a fire in a ventilation hose can spread rapidly.  Ensure proper precautions are taken if spark producing work is taking place in the area.

3      At some sites the discharge of the HEPA units may be directed towards, or attached directly to, the plants containment purge or ventilation system.  Ensure the equipment is installed according to site specific documents and tested as required prior to use.

3.0          References

3.1         INPO 05-008, Guidelines for Radiological Protection at Nuclear Power Stations

3.2         NISP-RP-13, Radiological Protection Glossary

3.3         NISP-RP-04, Radiological Posting and Labeling

Attachment 5 – Worker Instructions for Vacuum Operation – Sample

 

1.       If at any time you are uncertain about your responsibilities, place work in a safe condition and immediately contact RP for guidance.

2.       Only use a vacuum unit that has been DOP/PAO tested within the last 24 months

3.       Do NOT open a vacuum unit without contacting RP.

4.       Do not use the vacuum for any other job or task than the one for which the vacuum was issued.

5.       Do not use wet vacuums for dry work or dry vacuums for wet work

6.       If a dry vacuum inadvertently collects liquids, then stop work, shut off unit and contact RP.

7.       Ensure that the vacuum cleaner and associated equipment has a yellow radioactive material label or tag with dose rate information.  If the tag is not attached, contact RP prior to use for surveying.

8.       If you have reason to believe that dose rates or contamination levels on the vacuum cleaner or attachments have changed during use, then contact RP to perform a radiological survey and update the radioactive material label or tag

9.       Verify the unit has a tamper proof seal or equivalent installed and is intact.

10.   Cover the openings on the suction lines after use, or between uses, to prevent release of contamination.

11.   Immediately discontinue the use of vacuum cleaner(s) that do not perform properly, have safety issues, or appear to be leaking or discharging at any location other than the normal discharge port.

12.   If the vacuum becomes full and needs to be emptied, then contact RP

13.   Return vacuum cleaner to issue station when no longer needed.