# In-Situ Seawater Gamma Spectrometry with LaBr\({}_{3}\) Detector at a Nuclear Power Plant Outlet
## 5 Conclusions  
In the context of the rapid development of nuclear power and the increasing importance of marine environmental protection, it is necessary to establish a real-time online monitoring network of radioactivity in Chinese coastal waters.  
In this study, the energy scaling of the lanthanum bromide detector was carried out using its naturally occurring radioactivity. The detection efficiency of the detector for radionuclides was obtained by spiking experiments and Monte Carlo simulations, and the relationship with \(\gamma\)-ray energy was derived by fitting. The energy resolution of the detector was determined using standard radioactive point sources. In this study, an in situ measurement of the gamma energy spectrum of seawater at the nuclear power plant discharge outlet was also conducted in the field for four months. The results show that the lanthanum bromide detector has excellent energy resolution and detection efficiency performance and can be used at environmental temperature. It could become another choice besides sodium iodide detectors for in situ gamma energy spectrometry of seawater in regular situations and emergencies.  
\begin{table}
\begin{tabular}{c c c} \hline
**Date** & **Weather (Day/Night)** & **Increase in 609 keV Peak Count?** \\ \hline April 12 & medium rain/medium rain & Yes \\ April 14 & Medium Rain/light rain & No \\ April 23 & thunderstorm/thunderstorm & Yes \\ May 31 & medium rain/heavy rain & Yes \\ June 6 & rainstorm/medium rain & Yes \\ June 14 & light rain/mostly cloudy & Yes \\ June 18 & medium rain/light rain & No \\ June 21 & heavy rain/light rain & Yes \\ July 2 & heavy rain/mostly cloudy & No \\ July 4 & mostly cloudy/mostly cloudy & Yes \\ July 7 & light rain/mostly cloudy & Yes \\ July 10 & mostly cloudy/heavy rain & No \\ July 11 & rainstorm/light rain & No \\ \hline \end{tabular}
\end{table}
Table 5: Dates with precipitation during the test period and the relevant increase in 609 keV peak count.  
**Author Contributions:** Conceptualization, Z.Z. and W.Y.; methodology, D.D., M.Z. and Z.Z.; software, D.D. and M.Z.; validation, W.M., F.L., and W.Y.; formal analysis, W.Y.; investigation, W.M., F.L.; resources, J.C.; data curation, H.M.; writing--original draft preparation, D.D. and W.Y.; writing--review and editing, Z.Z. and W.Y.; visualization, D.D.; supervision, J.C., and J.L.; project administration, Z.Z.; funding acquisition, Z.Z. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by the NATIONAL KEY SCIENTIFIC INSTRUMENT AND EQUIPMENT DEVELOPMENT PROJECT, grant number 2016 YFF0103902 and the PUBLIC SCIENCE AND TECHNOLOGY RESEARCH FUNDS PROJECTS OF OCEAN, grant number No.201505005.  
**Institutional Review Board Statement:** Not Applicable.  
**Informed Consent Statement:** Not Applicable.  
**Data Availability Statement:** Not Applicable.  
**Conflicts of Interest:** The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results.