# In-Situ Seawater Gamma Spectrometry with LaBr\({}_{3}\) Detector at a Nuclear Power Plant Outlet  
[PERSON]  
1 Department of Engineering Physics, Tsinghua University, Beijing 100804, China;  
[EMAIL_ADDRESS] (D.D. ); [EMAIL_ADDRESS] (Z.Z. ); [EMAIL_ADDRESS] (M.Z. ); [EMAIL_ADDRESS] (H.M.); [EMAIL_ADDRESS] (J.L. )1  
[PERSON]  
1 Department of Engineering Physics, Tsinghua University, Beijing 100804, China;  
[EMAIL_ADDRESS] (D.D. ); [EMAIL_ADDRESS] (Z.Z. ); [EMAIL_ADDRESS] (M.Z. ); [EMAIL_ADDRESS] (H.M.); [EMAIL_ADDRESS] (J.L. )1  
[PERSON]  
2  
[PERSON]  
3 Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, China;  
[EMAIL_ADDRESS] (W.M. ); [EMAIL_ADDRESS] (F.L. )4  
[PERSON]  
3 Third Institute of Oceanography, Ministry of Natural Resources, Xiamen 361005, China;  
[EMAIL_ADDRESS] (W.M. ); [EMAIL_ADDRESS] (F.L. )4  
[PERSON]  
1 Department of Engineering Physics, Tsinghua University, Beijing 100804, China;  
[EMAIL_ADDRESS] (D.D. ); [EMAIL_ADDRESS] (Z.Z. ); [EMAIL_ADDRESS] (M.Z. ); [EMAIL_ADDRESS] (H.M.); [EMAIL_ADDRESS] (J.L. )1  
[PERSON]  
4 College of Nuclear Science and Technology, Beijing Normal University, Beijing 100875, China;  
[EMAIL_ADDRESS] (Correspondence: [EMAIL_ADDRESS] 4  
[PERSON]  
1 Department of Engineering Physics, Tsinghua University, Beijing 100804, China;  
[EMAIL_ADDRESS] (D.D. ); [EMAIL_ADDRESS] (D.Z. ); [EMAIL_ADDRESS] (M.Z. ); [EMAIL_ADDRESS] (H.M.); [EMAIL_ADDRESS] (J.L. )1  
[PERSON]  
1 Department of Engineering Physics, Tsinghua University, Beijing 100804, China;  
[EMAIL_ADDRESS] (D.D. ); [EMAIL_ADDRESS] (Z.Z. ); [EMAIL_ADDRESS] (M.Z. ); [EMAIL_ADDRESS] (H.M.); [EMAIL_ADDRESS] (J.L. )1  
Footnote 1: email: {j.li  
network consisting of 11 ocean observation buoys and a control center, was established in Greece. The buoys transmit data collected by NaI(Tl) detectors to the Hellenic Marine Research Center through satellite communication or GSM cell phone communication, and the single acquisition time of the spectrometer system is 3 h [5; 6; 7; 8]. The German Federal Ministry of the Environment established a monitoring network including 13 fixed stations at sea and on the seashore to monitor radioactive contamination in the German Gulf and the Western Baltic Sea. The sea stations are set up on buoys, and the seaside stations on tide gauges. In addition, four sets of equipment are installed on vessels of the Federal Maritime and Hydrographic Agency of Germany (BSH) to inspect hotspots of artificial radioactivity when needed. Gamma-ray detection in seawater is carried out from 2 to 6 m below the water surface. The data recorded by fixed stations are transmitted to the central computer of BSH via satellite (offshore stations) or telephone (seaside stations) [9]. The Kurchatov Institute of the Russian Research Center developed the REM-10 series of highly sensitive underwater \(\gamma\)-energy spectrometers based on NaI(Tl) scintillators for effective monitoring of radioactive contamination of various waters. This series of underwater gamma energy spectrometers were used in the investigation of the wrecked nuclear submarines \"Komsomolets\" and \"Kursk\" as well as at two radioactive waste dumping sites in the Kara Sea and Novaya Zemlya bays [10]. In China, a seawater radioactivity monitoring device was developed using a NaI(Tl) scintillator, which can be suspended either on a buoy for fixed-point measurements or on the bottom of a vessel for cruising monitoring, with an energy resolution of 14.8% for \({}^{137}\)Cs (at 662 keV) [11]. From the above introduction, it can be seen that NaI(Tl) detectors are commonly used in seawater in-situ \(\gamma\) spectrometers. NaI(Tl) detectors have the advantages of high detection efficiency, wide applicable temperature range, and low price. Nevertheless, it also has an apparent deficiency of low energy resolution. Typically NaI(Tl) detectors can only achieve an energy resolution as good as 7.5%, and the energy spectrum peak position drifts during long-time operation.