Design of the Sampling Measurement and Radiochemistry Lab in the Nuclear Island of HTR-PM

Abstract

Radiation monitoring system is very important to the safe operation of the nuclear power plant. The radiation monitor, including the on-line type and the off-line type, can provide the radioactive level for a given system, certain areas, or unique substance promptly. However, as a supplementary method, the sampling measurement can supply more accurate information about the source term. In this paper, we present the design of the sampling measurement in the nuclear island of HTR-PM. The sampling measurement contains the helium sampling from the primary coolant, the radioactive dust sampling from the primary loop, the liquid sampling from the tritiated water and some process systems, the gas sampling from certain areas, etc. The frequency of the sampling measurement depends on regulatory requirements and actual operational demands. The control values of the samples are settled on the basis of the source term analysis and regulatory requirements. The radiochemistry lab has been designed to meet the requirement of the sampling measurement, in which the main instruments include a NaI γ spectrometer, two high-purity germanium γ spectrometers, a four-channel ultralow background α/β analyzer, and a low background liquid scintillation counter. The characteristics of these instruments will be described in details in the paper.

Design of the Online Gross γ Monitoring Instrument at the Exit of the Helium Purification System in HTR-PM

“…The process and effluent radiation monitoring system in HTR-PM was designed based on the source term research of HTR-10, including the experimental measurement of the activity concentration of H-3 and C-14 in the primary loop [11], radioactive dust concentration in the primary loop [12][13][14], and types and distributions of typical nuclides in the irradiated graphite spheres from the core [15][16][17]. The source terms in the primary loop of HTR-PM, which contains fission and activation products, radioactive dust, H-3, and C-14, have been designed to be monitored using the online monitoring instrument and/or the sampling measurement [10,18,19].…”