NSN3 Neutron Survey Meter

Proportional Gas Counter

Fuji Electric NSN3 Neutron Survey Meter

Fuji Electric’s lightweight and durable NSN3 Neutron Meter features an innovative, robust meter to meet all neutron measurement needs. The streamlined unit only weighs approximately 7 pounds (3kg). The NSN3 offers a wide range of measurement, able to measure thermal and fast neutrons with an energy range up to 15MeV. Measurement capabilities boast H* (1cm dose equivalent). The outer shell is fabricated from premium, high strength polyurethane that has endured rigorous testing.

Neutron measurements are generally taken in harsh environments. Workers face risks such as heat stress, steep ladders, and confined spaces. The lightweight NSN3 is ideal for these conditions.

Operational Theory

The NSN3’s Detection Principles Proportional Gas Counter consists of an organic gas mixture of methane and nitrogen gas (the neutrons are measured using this mixed gas). Fast neutrons are detected by the elastic scattering reaction of hydrogen from the methane gas. Slow, thermal neutrons are detected using the 14N(n, p) 14C reaction of nitrogen gas. The proton energy in this reaction is 626 keV. By using these two reactions, the neutron ambient dose equivalent can be obtained from thermal neutrons up to approximately 15 MeV.

NSN3 Specifications

Radiation Detected: Neutron

Measurement Quantity: 1cm dose equivalent

Detector: Gas detector

Sensitivity: 0.2 s-1 / μSv/hr ±20 %, ref. 252Cf

Measurement Range Dose Rate: 1 urem/hr to 9.99 rem/hr ( 0.01 μSv/hr to 99.99 mSv/hr) Dose: 1 urem to 9.99 rem ( 0.01 μSv to 99.99 mSv)

Accuracy Dose Rate: ≤ ±20 % at 1 mrem/hr (10 μSv/hr) Dose: ≤ ±20 % at 0.1 mrem (1 μSv)

Energy Range: 0.025eV to 15 MeV Energy Dependency ICRP74 compliance (Response Curve of H*(10)/ɸ)

Angular Dependence: ≤ ±25 % (±90°from standard direction)

Dose Rate Characteristic: ≤ ±20% (1 mrem/hr or 10 uSv/hr reference)

Gamma Ray Sensitivity: ≤ ±1% of indication at 1 rem/hr (10 mSv/hr)

Battery Life: Displays continuously 31 hours or more Displays intermittently 17 hours or more (displays 1min, during 5min.)

Response Time: Time constant automatically switches depending on the dose rate. Less than 5sec: over 5 mrem/hr (50 uSv/hr) at "Medium" time constant

Display: Five-digit display (Dose rate, Integrating dose)

Power Supply: 3-way / Primary battery or secondary battery (AA type, 6 cells) AC Adaptor (IN: 100 to 240V AC) (option)

Operating Temperature: -10 to +45 °C / +14 to +113°F Operating Humidity 35 to 90 % (non-condensing)

Size: Φ 164 (without the handle) × 289.5 mm / Φ 6.46×11.4 in. Mass 3 kg / 7 lb approx. (including batteries)

Interface: USB

Compliance Code: IEC61005(2014), JIS Z4341 (2006)