RNEO

• Alpha: helium nucleus, heavy, travels a few cm in air. Stopped by paper or dead skin. Harmless outside the body; the most dangerous of the four if inhaled, swallowed, or in a wound. Not visible to your meter. Needs a probe held within a quarter inch of the surface; hazmat carries it.
• Beta: a fast electron. Inches to a few feet in air. Stopped by thin plastic or aluminum, heavy clothing. Skin and eye burns on contact. Serious internalized.
• Gamma / X-ray: photons. No mass, no charge. Whole-body hazard, goes straight through turnouts and suits. Slowed by dense mass, never fully stopped. This is what your PRD and dose-rate meter read.
• Neutron: no charge, so only a nuclear collision slows it. Shield with water, concrete, polyethylene, wet earth. Rare on the street (moisture/density gauges, well logging, reactors, nuclear yield). A GM tube does not read it.

• Ionizing has enough energy to knock electrons off atoms. That is the biological damage. Alpha, beta, gamma, X-ray, neutron.
• Non-ionizing cannot. Radio, microwaves, infrared, visible light, most UV. Most of it is invisible. It can heat tissue; it cannot ionize it.

A radiation detector is an ionization detector. Cell towers, radar, and microwave dishes read background on it because there is nothing to detect. The meter is right.

• R (roentgen): exposure in air. What most field meters actually measure.
• rad / gray: absorbed dose in tissue. 100 rad = 1 Gy.
• rem / sievert: dose weighted for biological harm. 100 rem = 1 Sv.
• Field rule: for gamma, 1 R = 1 rad = 1 rem, close enough for response decisions.
• Rate vs dose: "per hour" is a rate (mR/hr) and is what a survey meter shows. No "per hour" is accumulated dose (mR) and is what a dosimeter shows.
• 1,000 mR = 1 R. Watch the prefix; a decimal-point error is a factor of a thousand.

Reference points: US background about 620 mrem per year. Chest X-ray about 10 mrem. EPA emergency worker guidance (EPA 400-R-92-001): 5 rem all activities, 10 rem protecting valuable property, 25 rem lifesaving.

• The time for half of a radioisotope to decay. Fixed for each isotope. Cannot be sped up, slowed down, or switched off, sealed or not.
• After one half-life 50% remains. Two: 25%. Three: 12.5%. Ten: about 0.1%. It halves what is left. It never subtracts to zero.
• Common ones: I-131 8 days. Ir-192 74 days. Co-60 5.3 years. Cs-137 30 years. Am-241 432 years.

• Exposed: radiation passed through them. Nothing on them. Not a hazard. No decon. Record who and for how long; they may need medical follow-up.
• Contaminated: material on skin, clothing, or inside them. A spread hazard until removed.
• Emergency decon, in order: (1) outer clothing off, cut not pulled over the head, bagged and tagged; that removes most of it. (2) Rinse exposed skin with water. (3) Gentle wash, mild soap, no scrubbing; abraded skin is an open door. (4) Re-survey when hazmat has the probe. (5) Document.
• Never: hose down a clothed person (drives it in and spreads it), brush dust off (resuspends it for inhalation), or hold a contaminated but stable person in dusty clothing waiting for a corridor.
• Life over decon. A patient with a life threat goes to definitive care with contamination managed en route. There is no documented case of a contaminated patient harming a clinician. Untreated injuries kill.

• Time. Dose = dose rate x time. Stay time = allowed dose / dose rate. Plan the task outside the hot zone. Log entry and exit for everyone.
• Distance. Inverse square. The cheapest control you have and the first one you reach for.
• Shielding. Match it to the type: anything stops alpha; plastic or aluminum first for beta; dense mass (engine block, water tank, concrete, earth) for gamma; water, concrete, or polyethylene for neutrons.
• PPE on a radiological scene is contamination control. No suit stops gamma. Lead aprons attenuate low-energy photons and beta; they are not protection from an industrial source and they cook the wearer.

• Radiation from a point source falls with the square of distance. Half the distance: x4. Double it: divide by 4. Triple it: divide by 9.
• 20 mR/hr at 20 ft becomes 80 mR/hr at 10 ft and 5 mR/hr at 40 ft.
• A reading means nothing without the distance it was taken at. Log both.
• The gradient check: take a second reading 50 ft from the first. A point source falls off hard. A reading that does not change over 50 ft is either contamination everywhere or a very strong source a long way off. Either way it is not a nuc-med patient.

• 5 rem - all activities (normal).
• 10 rem - protecting valuable property.
• 25 rem - lifesaving or protecting large populations; voluntary and fully informed.
• 50 rad - the withdrawal DECISION dose, not a limit.

These are guidelines, not hard limits - an IC may raise them for an IND. Track occupancy and dose. Source: EPA 400-R-92-001; FEMA ND Guidance Ch. 2.2.

• Search/rescue, fire, and triage are the priority. Radiation does not delay a rescue.
• Missing radiological PPE never prevents prompt lifesaving action.
• Body protection: duty uniform, goggles, gloves. Level A is unnecessary for contamination.
• Respiratory: SCBA early; half/full-face or N95 once airborne concentrations drop.
• Track occupancy time when you do not have dosimeters.

Dose = dose rate x time. The log is the record that outlives the call.

• PRD (personal radiation detector): alarms on gamma above background, gives a dose rate. Cannot identify the isotope. Cannot find alpha or beta contamination. Use it to confirm, set the perimeter, and figure stay time.
• Rig dose-rate meter (GM): a second, independent instrument for the two-instrument confirmation and for perimeter readings in mR/hr.
• Dosimeter: records the dose a person accumulates. Not a survey tool.
• What hazmat brings: pancake / alpha-beta-gamma frisker probes for contamination surveys in counts per minute (held within a quarter inch, moved about an inch per second), a scintillation meter for low-level surveys, and a RIID for isotope ID.
• Instrument discipline: battery, background, and a check source before use. Every reading logged with time, distance, and instrument.

Confirmation, two-two-two: two readings, two locations, two instruments, before you call a scene radiological. One reading can be a nuc-med patient, a NORM load, or a bad battery.

• Class 7 placard on the vehicle tells you radioactive material is aboard. Dose-rate information is on the package label, not the placard.
• Transport Index (TI) = the maximum radiation level in mrem/hr (about mR/hr) at 1 meter from the surface of a closed, intact package (49 CFR 173.403). Not a background multiple. Not the surface reading.
• White-I: TI 0, surface up to 0.5 mrem/hr. Yellow-II: TI up to 1.0, surface up to 50. Yellow-III: TI up to 10.0, surface up to 200.
• Intact package: TI plus inverse square predicts the reading at any distance. Open, crushed, or breached: the label is history and the live meter rules. Pass the TI up anyway; the Specialist uses it to back-calculate activity.
• ERG Guides 163 and 164: initial isolation at least 25 m (75 ft) in all directions. The meter refines it from there.

• Your PRD and the rig's dose-rate meter read gamma. They do not read neutrons.
• Fissile material - the heart of a nuclear device - emits neutrons while reading surprisingly low on gamma.
• So a low, unexplained gamma reading is not an all-clear. It can be a blind one.
• Only a RIID with a neutron channel (on the HazMat rig) can confirm neutron radiation and attempt an ID.

Low gamma + high neutron = fissile = the worst-case find. Get HazMat and their RIID.

• A RIID (Radio-Isotope Identification Device) is a field gamma spectrometer - it reads the gamma fingerprint and names the isotope(s).
• Most models also carry a neutron channel your PRD does not have.
• It drives scene/life-safety, medical, forensic, and categorization (innocent vs. threat) decisions.
• Reachback needs three spectra: an UNKNOWN, a BACKGROUND, and a KNOWN (check source).

Ops role: recognize the need, protect the scene, request the Technician. You do not operate the RIID at the Operations level.

• FH-40 G-L survey meter: counter tube, sound/light generators, logarithmic bar display, internal/external probe designator.
• Pancake probe: detects alpha, beta, and gamma; used to locate contamination; directional for alpha/beta; reads gamma from any direction; range ~30-60 cpm background up to 600,000 cpm.

The instrument is what proves "clean" - and only on dry skin.

• RED (exposure device): a source placed to expose people. No explosion, no dispersal. Point-source readings that fall off with distance. No contamination.
• RDD (dispersal device): spreads radioactive material, usually with an explosive. Contamination everywhere plus exposure from the debris.
• IND (improvised nuclear device): a nuclear yield. Blast, thermal, prompt radiation, fallout. A different response entirely (Post-Nuclear-Detonation course).
• The discriminator: contamination spread. No spread and a point source: RED or a lost industrial source. Spread: RDD or an uncontained industrial accident. Placement and context tell you accident versus intent.

• Severe Damage Zone (SDZ) - about 1/2 mile. Few buildings standing; few survivors. Not an early priority.
• Moderate Damage Zone (MDZ) - about 1 mile. Significant damage but many survivors. This is the lifesaving priority.
• Light Damage Zone (LDZ) - broken windows, minor injuries. Staging and self-evacuation management.

Read them by sight. Your eyes and your meter are truth; models are estimates. Source: FEMA ND Planning Guidance, 3rd Ed. (2022), Ch. 2.

• The blast zones are fixed. The Dangerous Fallout zone is dynamic - it grows downwind over the first 1-3 hours, then shrinks as radiation decays.
• Fallout radiation decays fast: roughly 100 R/hr at 1 hour falls to about 1 R/hr by 48 hours.
• Shelter first, move later - 12 to 24 hours inside, then move on informed routes.
• Caught in the open with the plume overhead? Get behind mass - crawl under the engine's water tank for the first few hours.

A dark cloud top means heavy fallout; white means less. Fallout follows the wind. Source: FEMA ND Planning Guidance, Ch. 1-2, Fig. 14.

• A detonation's electromagnetic pulse can kill landlines, cell service, radios, vehicles, and your detectors.
• Assume degraded from minute one. Try a radio once, then fall back to the pre-plan and runners.
• No working meter does not mean no response - it means you read zones by sight and manage dose by time, distance, and shielding.

This is why "two types of responders" is an RDD/RED lesson - in a detonation, the EMP may leave everyone without a detector.

• Awareness: recognize the hazard, isolate from a safe distance, deny entry, notify. No PPE, no product contact.
• Operations (you): everything above, plus defensive actions: perimeters from the ERG and the meter, evacuation, emergency decon, dose-rate readings and a log, information for the hazmat team, requests for the right resources.
• Technician: arrives with contamination probes, isotope ID, and entry PPE. Makes entry, surveys people and objects for contamination, controls the source with the licensee or bomb squad, runs technical decon.
• Specialist: takes all readings and turns them into dose estimates and spread predictions for the IC. Advises through ICS. Oversees the Technicians.

NFPA 470 is the one standard for all hazmat/WMD responders, radiological included. Your lane is set by your qualification, not by the gear on the rig.

• Two readings - one is a question, not an answer.
• Two locations, at least 50 ft (15 m) apart, about 3 ft off the ground - rules out a passing nuc-med patient and shows you the gradient.
• Two instruments - if both agree, the instrument is not the problem.
• Each reading should be 3-5x natural background to confirm a real source.

Know your jurisdiction's normal background before the tone drops. Source: DHS/NUSTL RDD Immediate Response Guidance (2025), Tactic 2.

• Below Hot Zone - under 10 mR/hr. No restrictions; work and monitor.
• Hot Zone (HZ) - 10 mR/hr to 10 R/hr. Emergency operations only; minimize time (ALARA); track exposure.
• Dangerous Radiation Zone (DRZ) - over 10 R/hr. Lifesaving only, with informed consent.
• Initial footprint before you have readings: hot zone about 800 ft (250 m), shelter-in-place about 1,600 ft (500 m), in all directions.

Direction is unknown at first, so the initial zone is a circle. A 2 mR/hr boundary is for cleanup planning, not scene management. Source: RDD Guide Tactic 7; NCRP 2010.

Tap to enlarge — RREC Framework, CJ Scheil / REST LLC.

• Confirm (2x2x2), then read the gradient: a point source falls off sharply with distance.
• The single discriminator is contamination spread.
• No spread + a point-of-contact who can explain the source = contained industrial / orphaned source (RED-class).
• Spread confirmed = rules out RED; either an uncontained industrial accident or a malicious RDD.

RREC resolves an ambiguous reading. It does NOT apply to a detonation - a mushroom cloud has no ambiguity to resolve.

• OSHA 1910.120: PPE shields or isolates responders from hazards at a hazardous-substance site.
• PPE is a physical barrier between contaminant and person - it keeps material off skin and out of the airway.
• No PPE stops external penetrating gamma. That hazard is managed by time, distance, and shielding.
• Alpha and beta are stopped easily (see the widget); gamma is the one the suit cannot touch.

Match the protection to the hazard: barrier for contamination, distance for the field.

• Level A: highest protection - fully encapsulated, SCBA.
• Level B: high respiratory protection with splash protection.
• Level C: known contaminant - APR/PAPR with chemical suit.
• Level D: standard work uniform, no respiratory protection.

Radiological contamination with normal O2 is a Level C job. Source: RNEO Mod 3.

• Chemical-resistant suit: hooded, non-encapsulated outer garment.
• Respirator (APR/PAPR): full or half air-purifying respirator.
• Inner & outer gloves: double-layered hand protection.
• Protective boots: chemical-resistant footwear.

Standard when contaminant concentration is known and O2 exceeds 19.5%. Most common field-level rad ensemble.

• Use when: contaminant + concentration known, O2 above 19.5%, below IDLH, approved canister for the hazard, adequate warning properties, continuous atmospheric monitoring.
• Before use: medical evaluation, fit test, positive/negative pressure seal check.
• In use: maintain mask seal, apply anti-fog, do not break canister seals early.

An APR is NOT for oxygen-deficient or IDLH atmospheres - that is an SCBA (Level B/A) call.

• Consolidated area to inspect, prepare, and don PPE before entry.
• Position away from distractions and hazards.
• Clean tarp or salvage cover on the ground.
• Shelter from adverse weather.
• Lay out PPE in a uniform, standardized manner.

A disciplined donning area is where cross-contamination is prevented before it starts.

• Anything that enters contamination must be decontaminated to leave it - tools, radios, evidence, weapons, personal phones.
• Stage what you do not need. Decide before entry what is coming back out and how.
• The decon plan gates PPE selection and entry - not the other way around.

"What do you mean I can't take it out of here?" is a question you answer before you go in.

• Decon happens in the immediate aftermath; local responders will likely manage it under time pressure.
• Decon categorization follows medical triage closely.
• Radioactive contamination must not delay emergency medical response.
• Field decon addresses external contamination only.
• Plans must be flexible and scalable; notify receiving facilities early and follow their SOPs.

General population screened as resources allow. Pre-script messaging for medical screening and CRCs.

• Dry decon first: clothing removal strips the large majority of external contamination - no water required.
• Hybrid (damp wipes) for residual hot spots: lift and remove, leaving the skin dry.
• No gross water for rad: a single drop shields alpha, so wet skin cannot be surveyed - and runoff spreads contamination.
• Respiratory protection in every decon line.
• Evidence: track victims' clothing and property for investigation. Privacy corridors for all patients. Most good, most people.

Survey on dry skin. If it is wet, you cannot trust the reading.

• Dry (clothing removal) and hybrid (damp-wipe) decon handle the field. When residual contamination persists, escalate - do not reach for a hose.
• Alternatives: repeat targeted wipes, isolate/bag the contaminated item, or transport to a fixed facility for controlled decon.
• Effective when: clothing removed, dry-skin survey confirms levels at or near background, appropriate number processed, supervisors verify the pace.

Water is a last resort for rad - it shields alpha and spreads contamination. Dry / hybrid keeps the survey valid.

• Partial: focused survey of key body areas - time/resource limited; target the areas most likely contaminated.
• Full: comprehensive head-to-toe with instruments - thorough whole-body assessment.
• Self: ambulatory patient surveys themselves following written or verbal directions.

Always survey on dry skin - water shields alpha and gives a false clean.

• RED / Immediate (non-ambulatory): critical and unstable - remove from the area, wrap and transport. Do NOT delay for decon; clothing removal during packaging strips most contamination on the way out.
• YELLOW / Delayed (non-ambulatory): stabilized - two-station process; scope expands as resources arrive.
• GREEN / Minor (ambulatory): can follow directions; self-decon corridors; at-risk populations may need assistance.

The keystone: radioactive contamination never delays life-saving medical care.

• Station 1: clean face/mouth/nose first, don N-95 on the victim, maintain airway, remove clothing gently (cut, do not shake) to avoid resuspension, secure belongings as evidence, multiple glove layers for change-outs.
• Station 2: damp-wipe residual contamination - wipe, dry-survey, wipe, final dry-survey, transport. Persistent levels may mean impalement or internal contamination; dress wounds after decon.

Decon scope expands with arriving resources. Survey on dry skin.

• The last people on the line are you and your crew. Screen every responder to clear - dry-survey - before anyone leaves the controlled area.
• Doff correctly: outer layers first, roll contamination inward; bag and contain gear at the scene so it does not ride the apparatus back dirty.
• What a body screen will not catch: internal contamination from a resuspension breath. Document exposure; follow up medically.
• Make screen-to-clear the standard on every call, not just the big one.

Contamination reaches the people who come to help you. Close the loop on yourself.

• Get Inside - a sound building beats moving through fallout. Push it immediately; do not wait for authorization.
• Stay Inside - adequate shelter is the lowest level, most interior space. Basement or building core, not upper floors or vehicles.
• Stay Tuned - hold 12 to 24 hours for decay, then move on informed routes.
• Do not let people self-evacuate into the plume. Fire or collapse is the one exception that forces movement out.

Going outside too soon to evacuate can be fatal. Source: FEMA ND Planning Guidance, Ch. 3.

• The public message, made personal: get inside, lowest and most interior, do not drive toward me, stay put until it passes and officials clear movement.
• Build it before the day - EMP means you may not reach them: an agreed shelter, an agreed no-drive rule, an out-of-area contact everyone knows.

Teaching responders the family plan is how they internalize the public message. You hold your post.