燃煤電廠周圍大氣微粒、底灰及飛灰之天然放射性核種活度特性

Characteristics of natural radioactivity in atmospheric particulates, bottom ash and fly ash around coal-fired power plants

陳信良(Chen Hsin-Liang)

指導教授 ： 林志忠 ； 黃益助

國立屏東科技大學/工學院/環境工程與科學系所/碩士(2022年)

https://doi.org/10.6346/NPUST202200251

摘要

燃煤鍋爐為台灣目前最倚重之發電方式，為了瞭解燃煤電廠周圍大氣微粒、底灰及飛灰之天然放射性核種活度特性，本研究以四部高流量採樣器採集大氣懸浮微粒，分別於4月、9月及10月在中部及南部燃煤電廠進行採樣，分析大氣總懸浮微粒濃度及微粒上金屬濃度。並以高純度半導體純鍺偵檢器(HPGe)進行放射性核種活度之分析，研究結果顯示：採樣期間南部電廠大氣懸浮微粒(TSP)平均濃度範圍為68.6~88.4 µg/m3；中部電廠TSP平均濃度範圍為134~204 µg/m3，電廠周圍大氣總懸浮微粒以主要金屬地殼元素（Mg、Al、Ca、Fe）所佔之比例最高（達90%以上）。大氣總懸浮微粒上金屬主要影響來源為燃煤機組、鋼鐵廠、港口船隻、海洋飛沫及地表揚塵，而微粒上天然核種活度皆小於純鍺偵檢器之偵測極限。南部電廠煤炭中K-40、Th及Ra-226天然放射性核種活度分別依序為27.9、9.68及8.70 Bq kg-1，而中部電廠混合亞煙煤中K-40、Th-232及Ra-226的平均活度分別依序為33.63、6.66和4.47 Bq kg-1。發電程序產生飛灰及底灰具有輻射濃縮之現象，其天然核種K-40、Th-232及Ra-226平均活度分別依序為284、61.9、60.1 Bq kg-1及244、65.1、61.1 Bq kg-1，輻射濃縮比例約在4.8~15.8之間。廠區內土壤易受到煤塵影響其天然核種活度K-40之平均活度較高，核種活度範圍在61.39~657.59 Bq kg-1之間，Th-232活度在10.68~40.62 Bq kg-1之間，而Ra-226之活度在9.20~23.57 Bq kg-1之間，越靠近煤倉其天然核種活度越低。飛灰微粒主要集中在粒徑小於105 µm，其天然核種活度約為粒徑大於105 µm飛灰微粒的1.25~1.87倍。大氣懸浮微粒、飛灰、底灰、土壤輻射危害皆小於其規範值，並不會對人體造成危害。

關鍵字

燃煤鍋爐 ； 天然放射性核種 ； 高純鍺偵檢器 ； 金屬 ； 總懸浮微粒 ； 飛灰 ； 底灰

並列摘要

Coal-fired power generation was the most important way of generating electricity in Taiwan. To uses HPGe to measure the natural radionuclides in total suspended particulate (TSP) and exposure doses of radiation around the Central Power Plant and South Power Plant of Taiwan. We collected TSP by 4 High-volume air samplers to analyze mass concentrations, metal compositions, and activity of natural radionuclide in the coal-fired power plants in winter and summer, respectively. These results indicate that the TSP concentrations in the South Power Plant were ranged from 68.6 to 88.4 µg/m3 and 134 to 204 µg/m3 in the Central Power Plant. The TSP around the power plants are mainly composed (over 90%) of crustal elements (Mg, Al, Ca, and Fe). The TSP particles were found to contain more of coal-fired power plant, steel mill, cargo ship, sea spray and dust, respectively. The activity concentrations of natural radionuclides in TSP are below the detection limit, indicating that the TSP around thermal power plants does not pose a radiation threat to humans. Natural materials were concentrated in the fly ash and bottom ash by thermal power plant combustion. The activity concentrations of K-40, Th-232 and Ra-226 natural radionuclides in the coal of the South Power Plant are 27.9, 9.68, and 8.70 Bq kg-1, respectively. The average activity concentrations of K-40, Th-232, and Ra-226 in the mixed sub-bituminous coal from Central Power Plant were 33.63, 6.66 and 4.47 Bq kg-1. The activity average value of K-40、Th-232、Ra-226 on fly ash were 284 Bq kg-1, 61.9 Bq kg-1, 61.1 Bq kg-1. Both of the fly ash and bottom ash enrichment ratio ranged from 4.8 to 15.8. The average activity concentration of K-40 in the soil around the power plant is high, the activity concentration of natural radionuclide was between 61.39 and 657.59 Bq kg-1, the activity of Th-232 is between 10.68 and 40.62 Bq kg-1, and the activity concentration of Ra-226 ranges from 9.20 to 23.57 Bq kg-1.the closer to the coal bunker, the lower of natural radionuclides in soil. Fly ash in the Power Plant was mainly distributed in particle size less than 105 µm. The activity concentration of particle size less than 105 µm was 1.25~1.87 time as big as particle size higher than that of 105 µm. TSP, fly ash, bottom ash and soil radiation hazards are all less than their specified values, and does not pose a radiation threat to humans.

並列關鍵字

Coal-fired boiler ； Activity concentration of natural radionuclide ； Metal ； High-Purity Germanium ； TSP ； Fly ash ； Bottom ash

參考文獻

台灣電力公司，煤灰海事工程應用手冊(2021年): 取自台灣電力公司網頁https://www.taipower.com.tw/tc/page.aspx?mid=216&cid=169&cchk=0e5c6c12-2e67-4350-980d-5cc312ce43da

台灣電力公司統計資料，歷年發購電量占比(2021年):取自台灣電力公司網頁https://www.taipower.com.tw/tc/page.aspx?mid=212&cid=120&cchk=f3a1b1e0-03e5-45fa-b72e-b28c5cb94f37

行政院原子委員會統計資料，生活環境中的輻射(2019年):取自行政院原子委員會網頁https://www.aec.gov.tw/%E7%B7%8A%E6%80%A5%E6%87%89%E8%AE%8A/%E5%B0%8D%E4%BA%BA%E7%9A%84%E5%BD%B1%E9%9F%BF/%E7%94%9F%E6%B4%BB%E7%92%B0%E5%A2%83%E4%B8%AD%E7%9A%84%E8%BC%BB%E5%B0%84--5_40_869.html

行政院環境保護署，空氣品質標準法規(2020年) :取自行政院環境保護署網頁https://airtw.epa.gov.tw/cht/Information/Standard/Rules.aspx

Adachi, K. and Buseck, P.R., 2015, “Changes in Shape and Composition of Sea-Salt Particles Upon Aging in an Urban Atmosphere,” Atmospheric Environment, Vol. 100, pp. 1-9.