Targeted Domain Review: NRC Written Exam and OSHA 10 Content

Why Targeted Domain Review Matters

You have spent months learning reactor physics, plant systems, radiological protection, and safety regulations. This lesson pulls those threads together with one goal in mind: performing well on the written examinations that lead to your credentials. The NRC Non-Licensed Operator and Reactor Operator written exams, the NRRPT examination, and the OSHA 10 assessment each test specific domains with specific weighting. Knowing which domains carry the most questions — and drilling those areas deliberately — is the most efficient path to a passing score.

NUREG-1021, Operator Licensing Examination Standards for Power Reactors, is the NRC's public guidance document that defines how written and operating tests are structured, what knowledge areas are sampled, and what passing standards apply. Review it as a map, not as reading material to memorize. It tells you which technical areas will appear and at roughly what depth.

NRC Written Exam Domain Review

Reactor Physics and Neutron Behavior. Understand the four-factor formula conceptually, the roles of delayed neutrons in making a reactor controllable, and why reactor period matters operationally. Know the difference between prompt criticality and delayed criticality, and why operators must never allow the former. Understand reactivity coefficients — moderator temperature coefficient, fuel temperature coefficient (Doppler), and void coefficient — and whether each is positive or negative in your reactor type, since a negative coefficient provides inherent safety feedback.

Reactor Coolant and Auxiliary Systems. Trace the flow path of primary coolant from reactor vessel through the steam generator (PWR) or directly to the turbine (BWR). Know the function of the pressurizer in a PWR — how heaters and spray maintain pressure — and what happens to reactor safety if pressure limits are exceeded. Understand the purpose of the Emergency Core Cooling System (ECCS), including high- and low-pressure injection trains, and the conditions that actuate them automatically.

Electrical Systems. Nuclear plants require multiple independent AC power trains and reliable DC power for instrumentation and control. Know how offsite power, onsite standby diesel generators, and station batteries relate to each other. A loss of offsite power (LOOP) event requires diesel generators to start and load automatically; delayed generator start is a reportable condition. Understand bus alignments and why certain loads are safety-related.

Instrumentation and Control Logic. Most reactor protection system (RPS) trips use two-out-of-four or two-out-of-three logic to balance reliability against spurious trips. Know what each common trip signal — high neutron flux, low coolant flow, high reactor coolant temperature, low pressure — protects against. Understand the difference between an analog protection channel and a digital logic channel, and why channel calibration and surveillance testing are required by technical specifications.

Radwaste Systems. Liquid, gaseous, and solid radioactive waste streams are processed separately. Know the general flow of each: liquid waste through demineralizers and evaporators, gaseous waste through delay beds or charcoal adsorbers, and solid waste packaged per NRC and DOT requirements. Effluent monitoring ensures releases remain within limits established in the plant's license.

Radiological Fundamentals. Review the three basic types of ionizing radiation — alpha, beta, and gamma — and the shielding material appropriate for each. Understand exposure, dose (rem or sievert), dose rate, and the ALARA principle (as low as reasonably achievable). Know how time, distance, and shielding work together to reduce dose. Understand what a declared pregnant worker's dose limit is versus the general occupational limit under 10 CFR Part 20, and know that limits are set by regulation, not by plant preference.

Technical Specifications (Tech Specs). Technical specifications are legally binding conditions of the operating license. Know the structure: Limiting Conditions for Operation (LCOs), Surveillance Requirements (SRs), and Action statements. When a system or component is found outside its LCO, the operator must enter the applicable Action and restore operability within the allowed outage time or take the specified compensatory action. Violating an Action statement is a reportable event. Practice reading LCO tables quickly, since the written exam tests this skill directly.

Emergency Operating Procedures (EOPs). EOPs are symptom-based procedures that direct operators to stabilize critical safety functions — reactivity control, reactor coolant inventory, reactor heat removal, radioactive release control, and containment integrity — regardless of the initiating event. Know the five or six critical safety functions used at most plants and understand that EOP entry is triggered by plant parameter thresholds, not by event identification.

OSHA 10 Domain Review

The OSHA 10 card certifies that you have completed ten hours of federally recognized safety training. The assessment covers key topics from 29 CFR 1910 (general industry) and 29 CFR 1926 (construction). For nuclear plant work, the most testable topics are:

• Hazard recognition: Identifying physical, chemical, and radiological hazards in the workplace.
• Lockout/Tagout (LOTO): Per OSHA standards, energy control procedures must be written, machine-specific, and followed before any servicing of equipment with hazardous energy. Verify zero energy state before work begins.
• PPE selection: Match the PPE to the hazard — hard hats for overhead hazards, chemical-resistant gloves for corrosives, respirators selected by the type of airborne contaminant. PPE is the last line of defense after engineering and administrative controls.
• Electrical safety: Work on or near energized equipment above established voltage thresholds requires specific safe work practices; unqualified workers must maintain a safe approach boundary.
• Confined space entry: Permit-required confined spaces require atmospheric testing, continuous monitoring, an attendant outside the space, a rescue plan, and an entry permit. Never enter without proper authorization.
• Fall protection: At heights meeting the applicable threshold in general industry or construction, fall protection systems — guardrails, personal fall arrest systems, or safety nets — must be in place.
• HazCom/GHS: Safety Data Sheets (SDS) follow a standardized 16-section format. Labels must include the signal word, hazard pictograms, and precautionary statements.

Safety Emphasis

Lockout/tagout errors cause fatal accidents. In every practice scenario involving maintenance or equipment clearing, identify the energy source, isolate it, apply the lock, and verify zero energy before proceeding — no exceptions. ALARA is not optional in radiation work; it is a regulatory requirement under 10 CFR Part 20 and a professional habit you must build now.

Study Strategy for This Lesson

Complete each NRC domain review session and score your practice questions immediately. Record every missed item in your study notebook with the correct answer and a one-sentence explanation. Do not move on until you reach 75 percent in a domain; a second attempt on an alternate set is required if you fall short. For OSHA, treat the 40-question timed practice quiz as a dress rehearsal: closed book, timed, reviewed thoroughly afterward. Your instructor initials each passed domain on the tracking spreadsheet — that record is your evidence of readiness.