Radiation Workers Researchers obtain a New Personnel Packet Which Contains the TLD Application and Other Important Documents to obtain radiation- worker status. After Radiation workers demonstrate an understanding of safe practices in a radiation environment they are given lab access and are given a Thermoluminescent Dosimeter (TLD). –TLD’s Detect X & Gamma Radiation and also Fast Neutrons. –They Must Be Worn At All Times While In The Lab. –They Are Exchanged Every Three Months. –TUNL Provides A Rack In The Control Room For TLD’s. The TLD Reports Are Posted In The Control Room For Inspection.
Visitors and non-Radiation Workers Visitors and non-Radiation workers Are Permitted In Research Areas ONLY If No Radiation Is Present. Visitors Obtain A Card Pass From The Secretary In Room 414, Visitors must be escorted by a badged TUNL employee. Minors (under age 18) may accompany adults. TUNL provides Pocket Dosimeters For visitors and non-radiation workers –These Detect X & Gamma Radiation from Beam Activated Components or Sources. –They Must Be Signed Out on Entry and Back In On Exit. –The Difference Between The Sign Out and Sign In Readings Must Be Recorded.
Area Monitors Neutron and Gamma Area Monitors are Read Out In the Control Room. –Displays Read mRem/Hour. –Red Alarm Lamp Indicates Radiation in Excess of 2.5 mR/Hr. –Only the Control Room Audible Alarm is Connected.
Neutron Monitors Neutron Monitors are Located In each Experimental Area –They consist of white Polyethylene “Rem Balls” which simulate a human body’s response to neutrons - with BF3 tubes inside –A preamplifier sends the counts from the BF3 tube to the readout in the Control Room. Area Monitors are tested monthly and calibrated Annually.
Gamma-Ray Monitors Gamma-Ray Monitors are Located In Experimental Areas where either X-Ray Radiation or Gamma-Ray’s may be present from Activated Equipment or Sources. –They consist of small Tan Metal Boxes Mounted on the walls which contain a Geiger Muller Tube. –In Several Locations they are mounted alongside the Neutron Rem Balls. –A preamplifier sends the counts from the GM tube to the readout in the Control Room. Area Monitors are tested monthly and calibrated Annually.
Survey Meters All Experimental Areas Have Portable Geiger Counters at their Entrance Door. These Include: Eberline’s E-120 instrument, and Ludlum Model 2 & 3 Instruments. Geiger Counters are sensitive mainly to X & Gamma Ray Radiation. –Use Them To Survey for Activated Beamline Components When Entering. –Some probes have a Thin Window That Will Detect Energetic Beta Radiation. Additional Meters Are Kept In a Cabinet In The Control Room. TUNL has two portable neutron survey meters - called “Snoopy”. They consist of a heavy polyethylene cylinder with a BF3 counter inside. They are insensitive to gamma radiation.
Accelerator “ON” Illuminated Signs Illuminated “Accelerator On” Warning Signs are positioned near entrances to Radiation Areas. They are illuminated whenever the accelerator control power is on. These signs alert occupants that the accelerator is in operation and radiation may be present.
Klaxon Loud Klaxon warnings are sounded whenever the accelerator control power is turned on. These last for five seconds. They warn occupants of the laboratory of the potential for accelerator induced radiation.
Audible Warning State Regulations Require a Fifteen Second Audible Warning before Beam is Introduced Into any Area. Operators must Use the Control Console Mounted Microphone to make a Warning Page before Putting Beam through the Tandem Accelerator. –The Low Energy Faraday Cup Must be Kept In Until The Page is Completed. –This Allows Time for Researchers to Exit or to throw a kill switch.
Safety Circuit The Safety Circuit Located In The Control Room Monitors The Status of All Area Radiation Monitors, Door Interlocks, and Kill Switches. The Status Of These Devices Are Indicated On The Safety Circuit Panel Which Contains An Overlay Of The Lab Floor Plan. When A Door Interlock Is Tripped, The Interlock Must Be Reset On The Safety Circuit Panel After The Area Is Cleared And The Door Closed. Kill Switches Cannot Be Over-Ridden At The Safety Circuit Panel.
Door Interlocks Entry Doors and Gates To Experimental Areas are Equipped With Interlock Switches. When The Door Or Gate Is Opened, The Switch Signals The Safety Circuit. If The Radiation Level Beyond the Door/Gate is >2.5 mRem/Hr, The Low Energy Faraday Cup Will Be Inserted. Once Tripped, The Door/Gate Must Be Closed and The Interlock Reset At The Safety Panel. Interlocks Must NEVER Be Bypassed!
Kill Switches Kill Switches Are Located at Each Entrance To The Experimental Areas. They are located inside of a Red Painted Block on the Walls. When thrown - down - they interrupt beam from the ion sources at the tandem low-energy Faraday Cup. The Toggle Switch must be Up in order for the beam to be accelerated. They may not be over-ridden from any other location.
Warning Beacons Red Rotating Illuminated Warning Beacons are Located in each Experimental Area. They are activated when the local area monitor detects radiation in excess of 2.5 mRem/Hour. When a Beacon is active - personnel should not be present in the area. A “Kill” switch can be thrown to interrupt beam. Doors or gates opened to an area with an illuminated beacon will trip the safety circuit - interrupting beam to the tandem.
Triangle Universities Nuclear Laboratory Safety Concepts Radiation Areas
All Experimental Areas are Designated Radiation Areas. The Entry to Each Area is marked with Appropriate Signage. TUNL Provides Hand-Held Geiger Counters for Personnel Entering These Areas. These Detect X & Gamma Radiation from Beam Activated Components or Sources. Some Areas Include Remote Readouts for the Area Monitors in these Areas.
X-Ray Radiation Areas X-Rays are produced by high voltage equipment. TUNL has three areas where X-Ray Radiation may be produced. These are: the Atomic Beam Polarized Ion Source, The Direct Extraction Negative Ion Source, and the mini-tandem Accelerator. These areas are posted with “Caution X-Ray Radiation” Signs. Portable Instruments should be used to survey work areas around these areas when they are in operation.
Target Areas All Experimental Areas Where Accelerated Beam May Be Introduced Are Designated Target Areas. These Include: The Tandem High Energy End, Shielded Source Area, Target Room #1, The NTOF Room, & Target Room #4. Prior To Introducing Beam Into a Target Area: –A Sweep Must Be Made To Be Sure That No One Is In The Area. –The Area Must Be Secured By Closing All Entries & Exits. –Verify That The Entry Interlock Switch Is Closed At The Safety Panel –Page The Lab To Warn That Beam Is About To Be Introduced To The Specific Area. This Page Must Last A Minimum of 15 Seconds.
High Radiation Areas High Radiation is Defined as Greater than 100 mRem/Hour. TUNL has three areas where Neutron Radiation can exceed this level and in fact can approach 10 R/Hr. These locations are the 20-70 analyzing magnet vault, the Neutron time-of-flight room, and Target Room #1 at the 59- degree scattering chamber. The door and Gates at the approach to these areas are marked with “Caution High Radiation Area” signs.
Contaminated Beam Lines Two Beam Lines In The Tandem Laboratory Have Tritium Contamination. They are Marked With Yellow Warning Signs. Any Work Requiring Venting These Beam Lines Requires A Work Permit. Permit Applications Are Available At The Tandem Console. Applications Will Be Reviewed By the TUNL RSM or Designate. The Contaminated Beam Lines are the Low-Energy Capture Beam Line and the Neutron Time Of Flight Beam Line.
Radioactive Waste & Tritium Targets All Radioactive Contaminated Materials Are To Be Stored In The TUNL Radiological Fume Hood. Radioactive Waste Should Tagged, Dated and Placed In The Waste Receptacles In This Hood For Disposal By The TUNL RSM. Tritium Targets Are To Be Stored On The Shelves Provided In The Hood. The Hood Exhaust is Monitored For Tritium And The High Speed Fan Will Be Activated If The Preset Level Is Exceeded.
All Radioactive Sources Must Be Secured Against Unauthorized Access When Not In Use. Three Locations Are Provided: – A Well for Pole Sources, –A Locker for Small Check Sources, and –Two Safes for Activated Components and Larger Sources. Keys And Combinations To These Storage Locations Are Available Only To Authorized Personnel. A Signout Log Is Provided and All Sources Must Be Signed Out And Back In.
Radioactive Sources II A list of Radioactive Sources is posted near the TUNL Source Locker. Special Handling Instructions are Posted for 241Am sources. Sources must be signed out and back in on the form provided. Only Specific Locations are authorized for the use of Radioactive Materials, these are indicated on the “Authorized Locations” form which is posted. Radioactive Sources may not be transported off campus or on any public road without proper DOT packaging and labeling. Contact the TUNL RSM if you need to use a source off campus.
Handling Radioactive Sources Most TUNL Radioactive Sources are Sealed. Although Sealed Sources may be handled safely with Bare Hands, it is Prudent to wear Hand Protection. Check gloves for Activity after Use. Dispose of in ordinary Trash if “clean”. Alert the RSM or TUNL Director if a source is found to be leaking or is damaged. If a source is dropped or damaged - contact the RSM to do a leak test immediately.
Handling Radioactive Sources II Especially Strong Sources are mounted on long, 2 meter poles. The poles allow handling from a distance thereby reducing exposures. Never tamper with or open the source capsule on the end of the poles. Alert the RSM or TUNL Director if a pole source is damaged. If a source is dropped or damaged - contact the RSM to do a leak test immediately. Store pole sources in the special well behind the source lockers. Always post a RAM sign near these sources when in use.
Handling Radioactive Sources III TUNL Possesses several Americium-241 Sources that are not sealed. The Americium is plated onto a metal surface which permits the Alpha particles to be emitted without attenuation. Never tamper with or touch the Americium Surfaces. Alert the RSM or TUNL Director if an Americium source is damaged. If a source is dropped or damaged - contact the RSM to do a leak test immediately. Americium Sources are stored in a secondary containment and must be handled with gloves.