Presentation Transcript

1. Contamination Control ACADs (08-006) Covered Keywords Beta/gamma contamination, alpha contamination, loose, airborne, fixed, wipe, smear, noble gases, particulate, vapors, hot particles, contamination limits, personnel monitors, loose survey, direct survey, RCA release survey, contamination control, inhalation, ingestion, absorption, personnel contamination protection, personnel contamination detection, plant area decontamination. Description Supporting Material Contamination Control Lesson Plan
2. CONTAMINATIONCONTROL
3. CONTAMINATION DEFINITION Valves Maintenance Activities Performed On A System Defective Pump Gaskets Defective Welds Flanged Connections Boric Acid Corrosion Reactor Coolant Leaks Contamination - Radioactive material in an unwanted place Escape piping or components Reactor Coolant Coolant Gases Activation Products Fission Products MAJOR SOURCES Fission Products Activation Products Activated Corrosion Products Spills Of Reactor Coolant
4. TYPES OF CONTAMINATION Beta/Gamma contamination – Isotopic make-up of the contamination releases beta and/or gamma during decay process a Alpha contamination – Isotopic make-up of the contamination releases alpha during decay process b g b g
5. fORMS OF CONTAMINATION LOOSE RADIOACTIVE MATERIAL TRANSFERRABLE SMEARABLE FIXED Contamination Embedded In Object Cannot Be Removed Through Normal Cleaning AIRBORNE RADIOACTIVE PARTICLES OR GASES SUSPENDED IN THE AIR Units Of Measure DPM/100 CM2 UNITS OF MEASURE CPM
6. CONTAMINATION SURVEY TECHNIQUES Wipe Chemically treated cloth Verify non-contamination 100 ft2 area Fold in route to survey instrument Frisker monitors for beta/gamma contamination Unit of measurement cpm Loose Contamination smearable, removable, transferable
7. CONTAMINATION SURVEY TECHNIQUES SMEARS - dpm/100cm2 Counting inst – cpm cpm / efficiency = dpm Frisker – 10% Lab counters – calibrate SMEARS Number represent total area Area surveyed – 100 cm2 Identify each smear Avoid cross-contamination 1 SMEARS Frisker or laboratory counter Frisker 1st Caution cross-contamination (count area & counter) Limit on laboratory counter Smear > frisker ion chamber w/o mrem/hr/100cm2
8. CONTAMINATION SURVEY TECHNIQUES Direct survey – frisker & pancake probe Contamination indication – audible count rate increase meter reading increase alarm sounds Survey technique – slowly total area surveyed transverse indicated area – define boundaries measure Unit of measurement – cpm Fixed Contamination – embedded in object
9. CONTAMINATION SURVEY TECHNIQUES Airborne contamination – suspended in air Noble Gases Particulate Vapors - Iodine Survey – sampler - draw air into or across media –media counted to quantify amount of radioactivity Unit of measurement – mCi/cc
10. Special Type Loose Contamination Definition Negative charged - Mobilize easily Beta emitters – High localized skin exposure HOT PARTICLES Single discrete particle difficult to see >0.1 mCi Activated corrosion product (stellite) Fuel fragment
11. HOT PARTICLE SURVEY TECHNIQUE Hot Particle contamination verifiedwith 1 cm or shielding mechanisms Hot Particle > or = 20000 cpm Hot Particle removed with tape & sent for gamma id Hot particles in area surveyed with sticky media such as tacky roller
12. CONTAMINATION SURVEYS Technicians shall: Adhere to requirements for entry into area Minimize radiation exposure Eliminate personal contamination potential Check all instruments used for proper operation up-to-date calibration perform source checks assignment to technician in HIS-20 Document survey in VSDS and/or HIS-20
13. Contamination Limits Beta/gamma : Alpha Alpha contamination levels correlated to beta/gamma contamination levels Apply ALI of beta/gamma to ALI of alpha 50:1 or lower - require alpha monitoring Isotopic analysis determines alpha potential based upon beta/gamma nuclides present correlates alpha potential to specific beta/gamma nuclides Beta/gamma : Alpha >50 : 1 No routine plant area alpha surveys No routine release alpha surveys Used to set alpha work area surveys based upon beta/gamma levels Used to set contamination limits Alpha – loose 20 dpm/100cm2, direct 30 cpm Beta/gamma – loose 1000 dpm/1oocm2, direct 100 cpm Alpha nuclides fuel failures high internal dose conversion factors difficult to measure directly gross alpha determines presence and levels limits based on internal deposition & stochastic ALI
14. LOOSE CONTAMINATION IDENTIFICATION Object/Item >1000 dpm/100cm2 (b,g) and/or >30 dpm/100cm2 (a) Object bagged or wrapped to control loose contamination Radioactive Material Tag (Rad Tag) to denote content contamination levels radiation levels tech performing survey Radioactive Material must be stored in a designated location
15. LOOSE CONTAMINATION IDENTIFICATION Plant Area >1000 dpm/100cm2 (b,g) and/or >30 dpm/100cm2 (a) Sign posting on boundaries installed stating “Caution Contamination Area” ‘Hot Particle’ High levels of Contamination Multiple SOPs Outer SOP only considered non-contaminated Designate and contain contamination by placing yellow and magenta chain, ribbon, or rope around area Proper procedures for crossing observed to prevent spread of contamination. All items/personnel enter and exit via SOP. Step-off-pad (SOP) designate entry/exit point line of demarcation between Contamination Area & RCA SOP part of barrier part of non-contaminated RCA
16. LOOSE CONTAMINATION IDENTIFICATION Plant Area >1000 dpm/100cm2 (b,g) and/or >30 dpm/100cm2 (a) Items Surveyed by Radcon verify <1000 dpm/100cm2 Bagged at SOP, sealed, and transported to Radcon Personnel Surveyed through use of nearest hand-held frisker or automated personnel monitors Items >1000 dpm/100cm2 Remain in Contaminated Area Bagged, sealed, tagged, & stored Items/personnel exiting Contamination Area considered contaminated until surveyed
17. Automated Personnel Contamination Monitor Inside RCA – PCM-1b RCA exits – PCM-1b PCM-2a PCM-1b/PCM-2a Beta detecting Proportional monitors PCM-2a PCM-1b Detector alarms normally consistent with area contaminated. Hot Particles or high contamination can instigate alarms beyond area contaminated. PM-7 “Door frame” type Gamma detecting Scintillation monitor PM-7 RCA exits Gatehouse exits Final check
18. Hand-held Frisker Personnel Monitoring Device Automated Monitor not available Precursor to Automated Monitor Proper Technique Probe detector window ½” from body Probe movement slow 1-2”/ sec Consistent movement no area missed Contamination Indication Audible count rate increase Alarm above preset limit audible & visual Meter display increase >100 cpm above bkg Operational Checks Verify AC (battery if no AC) Verify volume high (to right) Verify on X1 scale (to right) Verify slow response (down) Verify background <300 cpm Determine background Non-contaminated - <100 cpm above background
19. Direct Surveys Fixed Objects <1000 dpm/100cm2 loose Items exceeding the limits set forth in 10CFR20.1094 will be labeled/tagged unless exempt in 10CFR20.1905. Items >100 cpm beta/gamma Marked with magenta paint or tape Remain inside RCA AllRadioactive Material will be stored in a designated location. Non-contaminated <100 cpm
20. RCA Release Surveys Personnel Automated Personnel Monitor with preset alarms limits Items used in RCA only Process through Small Article Monitor with preset alarm limits All personnel and items exiting RCA to “clean” area require surveys for non-contamination verification for release for non-restricted use. Bulk items/liquids Gamma ID Surveys: Loose contamination Fixed contamination Items from Contamination Area Surveyed by Radcon “Clean release” results b,g <1000 dpm/100cm2, <100 cpm a <20 dpm/100cm2, <30 cpm)
21. Contamination Control Contamination - Radioactive Material in unwanted place Origin – fission & activation products from core & coolant Cause – release of fission/activation products from system Control – locate, stop/contain, limit spread, protect/monitor
22. Control Contamination Pin point the source Inspect/survey ASAP Review history Review activities Gamma ID’s Source undetermined Stop the release Implement site procedures Control & limit spread Cease release Contain release Confine release Clean-up release Conduct surveys
23. Control & limit spread Confine release Confinement benefits Reduces exposure potential Eases task of control Enhances clean-up Confinement mechanisms Isolate with barriers Control access Direct traffic flow Monitoring stations Protective clothing in area Items from area surveyed Clean-up Cease release Contain release Catch containments Glove bags Drain hoses Absorbents Clean-up release Conduct surveys Frequent identifies unknown release quickly Routine controls existing barriers
24. Control Contamination Pin point the source Inspect/survey ASAP Review history Review activities Gamma ID’s Source undetermined Stop the release Implement site procedures Control & limit spread Cease release Contain release Confine release Clean-up release Conduct surveys Protect & monitor personnel Barriers Requirements and guidance Surveys and monitoring devices
25. Contamination Control Contamination - Radioactive Material in unwanted place Origin – fission & activation products from core & coolant Cause – release of fission/activation products from system Control – locate, stop/contain, limit spread, protect/monitor Limit – strict procedure adherence limits to existing area Control loss– lack of cooperation & exceptions to procedures Control implementation – measures for systems breaches
26. Control Implementation Cover area - material to be placed over work area Caution – used around cracks, crevices, small openings Containment devices – install to contain contamination Completion – remove/dispose of covers & containments Clean-up – remove contamination through cleaning process
27. Personnel Contamination Protection and Detection Personnel Hazards in a Contamination Area require Protection Inhalation Ingestion Absorption Contamination on skin/clothing- Increase potential for internal deposition Efforts utilized to limit personnel contamination/intakes Extra efforts for areas with break in skin Excess contamination creates radiation exposure Entry to Contaminated Area requires protective clothing
28. Personnel Contamination Protection Entries to Contamination Area controlled with RWP Protective clothing and devices based upon: Radiological Hazards in area Work to be performed Form of contamination present (wet, dry, dust, hot particles) Work environment Gloves worn whenever potential for hand contamination Low level contamination/Low activity work- Labcoat Dressout Lab Coat Booties Overshoes Cotton inserts Rubber gloves
29. Normally a “Full Dressout” is required for entry
30. Personnel Contamination Protection High contamination levels & Hot Particles require Double Dressout – 2nd set coveralls usually disposable papers, 2 sets of booties, 2 sets of shoe covers, 2 sets of rubber gloves Wet contamination –Rain-suits Potential for facial contamination –Dust cups or face-shields Substantial Airborne contamination –Respiratory devices Utilize proper steps for donning and doffing clothing Inspect protective clothing for defects prior to use
31. Personnel Contamination Protection Proper utilization of SOP – limit spread of contamination Protective clothing removed prior to SOP Transfer items to/from Contaminated Area at SOP Items surveyed prior to exit or placed in bag at SOP Respiratory equipment -reusable Smearable b,g <1000 dpm100cm2 a <20 dpm/100cm2 Direct b,g <500 cpm a <30 cpm Protective clothing removed prior to exiting “Contamination Area” and placed in appropriate reusable or disposable hampers Reusable- magenta <4500 cpm (b,g) - <30 cpm (a) Disposable- yellow processed as Radioactive Waste
32. PERSONNEL CONTAMINATION DETECTION Upon exit Contamination Area proceed to nearest monitoring device Alpha direct results <30 cpm Utilize Automated personnel monitor (PCM-1b) when available – preset alarms <100 cpm If hand-held frisker is used ensure proper techniques with results <100 cpm Results >100 cpm and/or >30 cpm Require decontamination & documentation
33. Decontamination – Plant Area Performed with cleaning solutions, water, rags, and/or mops Review work area configuration, radiological conditions, and desired outcome to determine mechanism used Mechanisms for Decontamination of plant areas Work from boundaries inward reducing as decon is performed Decon from lowest levels to highest Fold rag, frequently turn to clean fold, all folds used - change rag Rinse mop and change water frequently Detail attention to equipment, cracks, crevices, and difficult places Ensure all equipment and walls is area are deconned Items used to decon considered contaminated until surveyed Place wet items in separate bag after excess water removed
34. Decontamination – Equipment Normally in designated facility with use of solution, water, and rags Notify Radcon prior to start - requirements based on survey results Equipment decon occurs when >1000 dpm/100cm2 & non-contamination is desired Need to use caution to ensure equipment not damaged All parts of equipment need deconned and surveyed Authorization from owner required to disassemble some equipment Post decon non-restricted release results - <1000 dpm/100 cm2, <100cpm
35. Decontamination - Personnel Personnel contamination – >100 cpm, 15 cm probe, not noble gas Clothing Survey inside and outside clothing Hot Particle – capture for gamma ID Decon techniques – tape, water, brushes Ineffective decon – confiscate clothing, complete form Complete Personnel Contamination Report
36. Decontamination - Personnel Skin – decon ASAP Capture for gamma ID Medical staff required – ear canal, eye, break in skin Adjacent to skin break – cover break Injured personnel – surveys/decon secondary Minor injuries inside RCA – notify Medical prior to arrival Off-site medical assistance – future lesson plan (MERT) WBC required – Facial contamination indicating intake Nasal contamination detected Ingestion of radioactive material Open wound contamination Decontamination through soap and water Tape used for capture – caution in areas with hair Ineffective decon – sweating used
37. Decontamination - Personnel Skin – decon ASAP (cont) Large area decon – showers Caution no entry into body opens Process start at head and progress downward Hair decon – shampoo & water Caution no entry to body through openings Ineffective decon – cut hair – Radcon Shift Supervisor Notification Radcon Shift Supervisor of difficult decons Transversal through RCA – containment clothing &pathway survey Pathway survey from incident area to monitoring area Incident area survey may be needed Complete Personnel Contamination Report, surveydocumentation, & notify Radcon Shift Supervisor Natural Products & noble gas contaminations notpersonnel contaminations
38. Just-in-Time – Hot Particles Important Points Radiation protection work planning and work practice were inadequate. Managers were aware of the potential for DRPs to be present; however, the magnitude of the dose rates that were encountered was not anticipated. There was previous plant experience with DRPs in excess of 100 rem per hour when this evolution was performed in 1991, but this information was not widely known, nor was it incorporated into planning for this evolution. The increase in hot particle contamination was attributed to the reduced scope of containment and scaffold decontamination. Relevant information about hot particles had been omitted from previous post-work ALARA reviews therefore, this information was not incorporated into the incore instrumentation work.
39. Just-in-Time – Hot Particles – cont Contributing Factors A radiation protection supervisor determined that the requirements of the hot particle program were not applicable because the definition of a hot particle area was not met, even though it was known that a hot particle existed within the valve for several years. The assigned radiation protection supervisor did not immediately stop work or urge the workers to leave the area when indication of general radiation levels increased from 15 mrem per hour to 250 mrem per hour. Contingency plans or actions to be taken if DRPs were encountered in other than controlled areas were not developed. Turnover to the evening shift occurred while work continued, potentially distracting individuals from receiving needed information. Clear expectations regarding DRP controls for the travel path during the transfer of the ACS were not established.
40. Just-in-Time – Hot Particles – cont Contributing Factors Although workers believed DRPs might be present, a DRP check of the unit was not required by the work package nor was one completed before the transfer of the ACS began. Because of the ACS design, and the inability to hydrolaze in an upward direction, portions of the unit could not be effectively cleaned. The ACS was not rinsed with demineralized water as it was raised from the fuel pool as had been the practice in the past to help remove potential DRPs. The personnel contamination monitors at the RCA exit were relatively insensitive to the higher energy cobalt-60 gamma radiation and may not detect beta radiation if shielded by clothing or in a location of poor geometry relative to the monitor.
41. Just-in-Time – Hot Particles – cont Contributing Factors Sticky pads were not used as prescribed by procedure. Less than adequate radiological work practices were identified. Lack of proper labeling existed at the job site. Less than adequate planning regarding communication methods when wearing certain protective equipment. Less than adequate training for identifying the location of special tags and equipment used for hot particles.
42. Just-in-Time – Hot Particles – cont Questions What contamination controls should be used when a contaminated piece of equipment is moved? What is the most effective way to communicate these controls to personnel involved with the task? What course of action should be taken if hot particles are anticipated? What course of action should be taken if hot particles are identified? What controls should be considered prior to retrieving a hot particle? How do we consider dose, particle movement, and difficulty of removal?
43. Just-in-Time – Hot Particles – cont Questions How do we capture radiological lessons learned at the completion of our task? What are the hazards associated with hot particles? How do we communicate the potential hazards to those involved? How do we ensure prejob briefs are sufficiently in-depth and inform workers of the radiological risks associated with the task to be performed? Under what conditions do we expect radiological technicians to stop work in the field? When should a hot particle control zone be established?
44. Just-in-Time – Hot Particles – cont Questions When should a check of hot particles be made? What monitors should be used considering the type of contamination anticipated? What training is required to support the task if hot particles are anticipated?