RADIOLOGICAL PROTECTION TECHNICIAN INITIAL TRAINING Use and Control of Portable HEPA Systems.

RADIOLOGICAL PROTECTION TECHNICIAN INITIAL TRAINING

Use and Control of PortableHEPA Systems

Terminal ObjectiveTerminal Objective

Upon completion of this course, the participants will demonstrate their knowledge and understanding of the information presented during RADCON Technician training by obtaining a score equal to or greater than 80% on a written examination. The information presented in this lesson plan may be part of an overall exam or be the only information for which the student is examined.

Enabling ObjectivesEnabling ObjectivesThe technician will be able to identify the following on a multiple choice examination.

Define the following terms.• HEPA• Pre-filter • Decontamination • Dry radioactive dust• Filter integrity test• Reference Survey Point

State the procedure that provides direction for the use and control of portable HEPA ventilation units and vacs.State the purpose for using HEPAs in the RCA.

Enabling Objectives (continued)Enabling Objectives (continued)

Identify the hazards associated with using portable vacuum cleaners and ventilation units in the RCA.

State the type of survey performed to indicate the presence of a specific hazard.

Identify the major components of a HEPA filtration system.

State the RadCon form used to track the issue and use of HEPA ventilation units and vacs.

Enabling Objectives (continued)Enabling Objectives (continued) State the survey requirements when a HEPA ventilation

unit or vacuum is returned.

State the conditions that would require a portable vacuum cleaner or ventilation unit to be taken out of service.

Discuss the proper technique for changing out a HEPA vacuum’s dust bag and filters.

Discuss the proper technique for changing out a HEPA unit’s filters.

INTRODUCTIONINTRODUCTION

High Efficiency Particulate Air handling units and vacuum cleaners, respectively referred to as HEPA units and HEPA vacs, are essential tools for dealing with contamination in the routine activities of the plant.

HEPA units are often the engineering control of choice for controlling potentially high airborne work areas such as Steam Generator Bowls, Reactor Coolant Pump Seals, Decontamination Hoods and Tents, etc.

HEPA vacs are generally used for RCA housekeeping, deconning and to provide negative ventilation for small contamination containments such as glove bags.


It is easy to see how HEPAs can benefit rad workers in their day to day activities in the RCA by reducing and controlling contamination, making clean up easier and helping maintain exposure ALARA.

This lesson will discuss the benefits in using this equipment, the hazards associated with this equipment, the radiological surveys that protect us from the hazards, the major components of the system, when to remove the equipment from service, how to issue and track HEPA equipment, and when and how to change out the filters.


Why should Rad Workers care about HEPAs?

How do they make our job easier? - They reduce / control contamination, reduce our exposure, make cleanup easier and help maintain work ALARA.


The proper issue use and return of HEPA units is critical. Always use self checking and STAR principles when issuing these units. If you are setting the unit up, employ peer checking to ensure you have completed all the necessary prerequisite steps for safe and efficient use. Once the systems is in place and ready for use, use the 2 minute rule as a final step in ensuring that all personnel and related equipment are ready. When removing and returning the unit to storage, again use self checking and peer checking to ensure the units are handled correctly. Improper handling, use or storage can have significant effects on workers and the workplace.

HUMAN PERFORMANCE ISSUES

Definitions Obj. 1Definitions Obj. 1

High Efficiency Particulate Air (HEPA) filter: A filter that provides highly efficient filtration of particulates in the air with a minimum of 99.97% efficiency for 0.3 micron sized particles.

Pre-filter: A filter that provides first stage air filtration to remove larger particulates and prolong the efficient use of the HEPA filter.

Decontamination: The removal of contamination from equipment and structure surfaces.


Dry Radioactive Dust: The small particles of radioactively contaminated material that have high potential to become airborne.

Filter Integrity Tests: A test performed on the HEPA filters to identify any damage to or leakage around the filter. Techniques used to conduct this test may be differential pressure checks or measurements of particles in the exhaust. Filter integrity tests should include specific quantitative acceptance criteria.


Reference Survey Point: A marked location where contact dose rates are consistently measured and recorded.

Special Use Vacuum Cleaner (SQN def.): A vacuum cleaner approved by RADCON for use inside the Radiologically Controlled Area (RCA). A special use vacuum cleaner is generally small capacity, and its use inside the RCA will not create any radiological hazards.


Note: While there are no industry standards on portable units, dioctylpthalate (DOP) testing is considered a good practice by many manufacturers and ventilation experts. However, during a random survey of other nuclear plants as part of a 1998 Beaver Valley Power Station self assessment on its portable HEPA unit program, it was found that some plants either did not perform DOP testing, or had discontinued it. Their rationale was that as long as the equipment was used in a RCA that was exhausted via site ventilation, a leak in a HEPA unit was not a significant problem.

Uses For HEPAs and Vacuums Procedures

BFN – RCI-24; Control of Vacuum Cleaners and Portable HEPA Units Within the RCA (Radiologically Controlled Area).

SQN – RCI-18; Vacuum Cleaner Control Within the Radiologically Controlled Area (RCA).

WBN - RCI-119; Use and Control of HEPA Ventilation Units and Vacuum Cleaners

These procedures provide direction for the use and control of portable HEPA ventilation units and vacuums.

Uses For HEPAs and Vacuums Obj. 2

Used to reduce the need for respiratory protection.

Reduces the spread of surface contamination when established engineering controls are inadequate or unavailable.


general cleaning in the RCA

post job cleanup and decontamination

spill cleanup

removal of debris for FME purposes following such maintenance as grinding or filing.

providing negative pressure for small glove bags

HEPA vacs may also be used for:


Only vacuum cleaners with pre-filters, a HEPA filtered exhaust and approved for use with radioactive materials are allowed in the RCA.

Only vacuum cleaners approved by the manufacturer for use with liquids shall be utilized for this purpose. Precautions should be taken to prevent tip-over and spillage when using vacuum cleaners for liquids. In the event a vacuum cleaner containing liquids is turned over, the unit shall be removed from service and the HEPA filter inspectedreplaced as necessary.


All vacuum cleaner HEPA filters must be DOP tested and documented (prior to approval by RADCON) when the HEPA filters are initially installed and anytime the filter assembly is disturbed. It is not necessary to repeat the DOP test after emptying the canister, if the filter assembly is not disassembled.

A seal or locking device shall be placed on the vacuum cleaner canister and HEPA filter housing to indicate unauthorized tampering. This device shall only be removed with RADCON supervision.

Uses For HEPAs and Vacuums Obj. 2 Joints in hoses should employ seals such as O-rings

to prevent leakage, or the joints should be taped.

After the HEPA filter has been installed and DOP tested, a DOP tag shall be placed on the unit with the serial number, the date tested, and the initials of the individual performing the test.

Fifty-five gallon drums with approved transfer lids may be utilized in conjunction with HEPA vacuum cleaners. The HEPA vacuum cleaners are the power source and the 55-gal drums act as the collection container for the debris.


The intake, and any other potentially contaminated opening of HEPA ventilation units, HEPA vacuum cleaner, or hoses used with these units should be covered when not in use and upon job completion.

NOTE: Extremely high levels of contamination could be present inside the suction side hoses.

NOTE: Used HEPA filters can not be unconditionally released as clean material.

Uses For HEPAs and Vacuums Obj. 2 Joints in hoses should employ seals such as O-rings

to prevent leakage, or the joints should be taped.

After the HEPA filter has been installed and DOP tested, a DOP tag shall be placed on the unit with the serial number, the date tested, and the initials of the individual performing the test.

Fifty-five gallon drums with approved transfer lids may be utilized in conjunction with HEPA vacuum cleaners. The HEPA vacuum cleaners are the power source and the 55-gal drums act as the collection container for the debris.

Hazards and Required Surveys Hazards and Required Surveys When HEPAs are Used Objective 3When HEPAs are Used Objective 3

Can cause airborne radioactivity.

Create readily dispersible loose surface contamination.

Surveys must be performed during and following the use of HEPA ventilation units and vacuum cleaners.

NOTE: Do not use a HEPA if an explosive atmosphere may exist. The electrical motor could trigger an explosion.

Surveys Will Indicate When Surveys Will Indicate When Conditions Start to Degrade. Conditions Start to Degrade.

Objective 4Objective 4 Performed periodically when in use.

Frequency depends on the specific use.

Ensure that the radiological condition in the area will be known and posted correctly.

It will also indicate when the HEPA should be changed out due to excessive dose rates.

Surveys Will Indicate When Conditions Surveys Will Indicate When Conditions Start to Degrade. Objective 4Start to Degrade. Objective 4

whenever a HEPA unit or vacuum is removed from a contaminated area

whenever hoses or internals are breached periodically when a HEPA unit or vacuum is in

use Contamination surveys of the HEPA unit

exhaust will monitor filter performance and indicate if a filter has failed.

Contamination surveys should be performed:

Surveys Will Indicate When Conditions Surveys Will Indicate When Conditions Start to Degrade. Objective 4Start to Degrade. Objective 4

whenever a HEPA unit or vacuum is used in a highly contaminated area,

whenever the exhaust is not already being monitored by plant effluent monitors.

Airborne radioactivity should be monitored:

Major Components of the HEPA Major Components of the HEPA Filtration System Obj.5Filtration System Obj.5

• Pressure Blower: Generates air flow through the filtration system.

• HEPA filter: Provides highly efficient filtration of particulates from the air.

• Pre-filter: Provides first stage filtration of large particles to prolong the life of the HEPA filter.

• Filter Housing: Provides a containment and sealing surface for the filters that creates proper flow path of air through the filters.

Issuing and Tracking HEPAs Obj. 6Issuing and Tracking HEPAs Obj. 6

• HEPA Ventilation Units and Vacuums should be issued and tracked by RadCon using a tracking form. In addition, an inspection tag should be placed on the unit verifying inspection of components and operational readiness of the unit.


• Personnel to which the equipment is issued to are responsible for:Notifying RadCon if HEPA filter system fails

• Notifying RadCon prior to disconnecting hoses or breaching the unit

• Ensuring the hose openings are covered and sealed when the unit is not in use


• Unit is properly labeled. Each site has their own labeling requirements.

• Dust bag and/or filter housing access points are locked or sealed to prevent an inadvertent breach of the unit.

• If it is a vacuum that is issued, ensuring that it is labeled as being designated for either wet or dry use

RadCon Technician issuing the equipment is responsible for ensuring:


• All joints in hoses/hose ends are sealed or taped.

• Personnel to which the unit is issued are briefed on their responsibilities and understand the purpose of the HEPA fail light and Differential Pressure Gauge

• Unit has an inspection tag affixed

RadCon Technician issuing the equipment is responsible for ensuring:

Returning HEPAs Obj. 7Returning HEPAs Obj. 7

• Ensuring the hose openings are covered and sealed.

• Documenting whether the unit is either ready for refurbishment or re-issue.

• Ensuring wet vacs are staged to be emptied prior to re-issuing.

• Surveying the unit and updating the rad tag and area postings as necessary

RadCon Technician signing in the equipment is responsible for:

Considerations When Setting Up a HEPA Unit for Use. Obj. 8

• physical size of area is large enough to accommodate the unit without hindering work.

• exhaust air blows in the least contaminated location possible, preferably, the unit itself will remain in a clean area.

• hoses are not damaged.


• hose sections are EITHER joined with a coupling device and hose clamps, OR joined with at least 4 ty-wraps and sealed with tape.

• duct hose is no longer than necessary. Resistance from the wall surface of the duct will reduce the flow.

• vertically hung hose is supported at approximately 15’ intervals to prevent hose separation at the joints.


• HEPA has a dedicated power supply if it’s use is critical.

• exhaust is monitored with an effluent monitor such as the auxiliary building exhaust monitors or air samples of the exhaust are taken by RadCon.

• A seal or locking device shall be placed on the vacuum cleaner canister and HEPA filter housing to indicate unauthorized tampering. This device should only be removed with RADCON supervision.


• Adhere to site radiation and contamination limits on HEPA units and vacs prior to issuance and use.

• Lengths of attachment hoses should not exceed that recommended by the vacuum manufacturer. Hose lengths greater than 25 feet may severely restrict suction flow rate.

• Vacuum cleaners used for asbestos removal and cleanup within the RCA shall meet the requirements of this procedure. These vacuums shall be used for asbestos work only and will be labeled accordingly.


• Vacuum cleaners used for activities involving lead shall be used exclusively for lead work only. The vacuum cleaner and associated attachments will be labeled accordingly.

• HEPA units used for the filtration of radioactive gases shall have charcoal trays installed. Attachment 2 will be noted to reflect that the HEPA unit contains a charcoal filter for this purpose.


• Vacuuming liquids or wet solids can result in damage to the HEPA filter or motor presenting radiological and electrical hazards. A vacuum specifically designed to collect liquids shall be used for this purpose. When performing these operations, the following requirements and guidelines shall apply.


• Catch tank level shall be monitored and the catch tank emptied when full to minimize liquids entering the vacuum cleaner.

• Anytime an electric vacuum is used to collect liquids without an external catch tank, the vacuum shall be fitted with a float switch to de‑energize the motor when the vacuum canister becomes full.

• Electric vacuums shall not be used to collect flammable or combustible liquids.

HEPA Filter Replacement and Canister Change Out Obj. 10

If the HEPA fail light is on or the differential pressure (D.P.) across the HEPA filter exceeds the specifications noted on the side of HEPA ventilation unit or HEPA vacuum cleaner, the prefilter should be replaced or the vacuum cleaner emptied. The prefilter may be replaced several times prior to replacing HEPA filter.

If the prefilter has been replaced and the HEPA fail light is still on or the gauge indication (D.P.) does not meet the specifications on the side of the HEPA ventilation unit or vacuum cleaner, the HEPA filter should be replaced.


Appropriate radiological surveys should be performed prior to handling filters.

Personnel changing prefilters or HEPA filters shall be briefed on the proper method of filter replacement and radiological hazards if applicable.

Filters should be bagged upon removal from the unit housing.


Bagged filters shall be tagged/marked radioactive material and should be transported to the waste packaging area in a timely manner.

The housing should be examined for dents or cracks in welding seals and sealing surfaces. Report any discrepancies to the RADCON Shift Supervisor and place unit out-of-service if necessary.


New filters should be examined for damage prior to installation.

Update the HEPA/VAC logs to reflect filter replacement and availability of unit.

See Appendix 2 for canister change out instructions.


If the date on the charcoal absorber has expired or it is suspected that the charcoal absorber is no longer capable of iodine removal, replace the charcoal absorber.

Appropriate radiological surveys should be performed prior to handling charcoal absorbers.

Bag or wrap the charcoal absorber as it is removed. The bagged filter shall be tagged/marked radioactive material and should be transported to the waste packaging area in a timely manner. After an appropriate amount of decay time, charcoal absorbers may be returned to service.

Charcoal Filter Replacement


The housing should be examined for dents or cracks in welding seals and sealing surfaces. Report any discrepancies to the RADCON Shift Supervisor and place unit out-of-service if necessary.

Charcoal absorbers should be examined for damage prior to installation.

Update the appropriate documentation to reflect filter replacement and availability of unit.

Charcoal Filter Replacement

Conditions That Require a HEPA to Conditions That Require a HEPA to be Removed From Service Obj. 9be Removed From Service Obj. 9

smearing the unit exhaust.

surveying for increasing contamination levels in the area the HEPA discharges to

taking air samples in the vicinity of the exhaust

Filter Leakage – may be detected by:


Elevated Dose Rates

Contact dose rate on HEPA unit high creates exposure problem in the HEPA’s vicinity.

Clogged Filter Filter is clogged - units performance is reduced to an

unacceptable flow rate.


High Differential Pressure

Differential pressure across filters has increased above the manufacture’s suggested limit for the unit.

NOTE: Filter change out requirements are posted on

the housing on the unit.

Return and StorageReturn and Storage

All vacs are to be surveyed and tagged prior to return to storage. Vacs exceeding the site radiation and/or contamination limits shall remain in storage until the deficiency is corrected, unless otherwise exempted.

Vacs shall be stored in designated storage areas only.

HEPAs are essential tools in dealing with contamination. They are often the engineering control of choice for controlling potentially high airborne work areas. HEPA systems benefit the radiation worker in his/her day to day activities in the RCA by reducing and controlling contamination, making clean up easier and helping maintain exposure ALARA.

Summary

While there are serious hazards associated with the use of HEPA systems, recognizing and performing the necessary surveys will give an early indication of degrading conditions.

Summary

RADIOLOGICAL PROTECTION TECHNICIAN INITIAL TRAINING Use and Control of Portable HEPA Systems.

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