A Survey On Radiation Protection Status Of Ray Thickness Gauge At Anshan Iron&Steel Group Corporation

Objective: To know about the radiation dose level of ray thickness gauge, theexposure dose and occupation health conditions of radiation workers, providingtechnical support for company about radiation protection management.Methods: The radiation dose level of108ray thickness gauges (including5profilegauges) was monitored, the personnel monitoring and occupational health examinationof412radiation workers were carried out, and some statistical analysis were done ofthese results.Results:①The application status of ray thickness gauge: the108ray thicknessgauges (including5profile gauges),isotope thickness gauge account for52.8%(57/108), X ray thickness gauge47.2%(51/108, including5profile gauges).At hot thick plate rolling lines, classification II137Cs sealed source (10.19%,11/108) was used in penetrating thickness gauge；at hot rolling sheets, Ⅲ X rayapparatus (9.26%,10/108) was used in penetrating thickness gauge；at cold rollingsheets, classificationⅢ,Ⅳ241Am sealed source (37.04%,40/108)and III X rayapparatus (23.15%,25/108) were used in penetrating thickness gauge, V147Pm in betabackscattering thickness gauge (5.56%,6/108), Ⅲ X ray in coating fluorescencethickness gauge (14.81%,16/108).②Radiation protection facilities of ray thickness gauge: the ray switch wasremote and servo control, there were multiple interlocking protection device, and thework status lights, protective doors, fences, proper shielding room protection facilitiesand warning signs " Caution, ionizing radiation " et.③Results of dose monitoring in radiation workplace of ray thickness gauge:the maximum ambient dose equivalent rate of isotope thickness gauge was0.66μSv/h, the X ray device was4.38μSv//h. In normal conditions, the hot thick plate rolling lines and sheethot-rolling line workers can remain out of3meters regional, and remaining productionlines out of1meter.④Results of personnel monitoring: The personal dose range of412workers was0.04mSv/a~12.76mSv/a, less than1mSv/a as98.54%, the per capita effective dose was0.21mSv/a, conforms to the national occupation standard of limit values. Under thethickness gauge ray beam was normal, the per capita effective dose of workers whohave been needed to maintain equipment was（0.51±0.30）mSv/a.⑤Results of occupational health examination: hypertension prevalence rate was6.55%(27/412), the abnormal rate of ECG was4.85%(20/412), routine urinalysis2.67%(7/412), renal functions3.64%(15/412), color weakness1.94%(8/412), chestradiograph0.24%(1/412), opacity of the lens1.46%(6/412). Lymphocytemicronucleus rate was within2‰of the normal range, no abnormal about the routineblood. Physical examination conclusion was:405people might continue to engage inexternal exposure radiation workplace,7people were not suitable for, except1peoplesuffering from tuberculosis, the other6people suffering from a bit flaky or strip opacityof binocular or monocular lens,and having worked at the cold rolling sheets mill line.From2006to2011, there were25radiological workers were removed from theformer position, ocular lens changes were found for the rotation first cause, a total of16people, and were the cold rolling mill workers.⑥Analysis according to the type of production line: the workplace estimationresults of the hot thick plate rolling, hot rolling sheet and cold rolling sheet in turn were0.15mSv/a,0.71mSv/a,0.59mSv/a; the workers actual exposure dose were:0.15mSv/a,0.25mSv/a,0.21mSv/a. In various production line,the result of the estimation greaterthan the actual dose was consistent，and also all results was below constraint value ofthe annual dose limit. The incidence rate of single dose equivalent>0.25mSv, there wasstatistical difference (X~2=6.47, P=0.039) between the three production line, theabnormal rate of occupation health examination there was no statistical difference(X~2=0.46, P=0.795) between them. Conclusion: Under normal production status，the workplace of ray thickness gaugeis relatively safe, no health and safety hazards to the public and the radiationpersonnel’s.Henceforth, we should limit online maintenance of ray thickness gauge andstrengthen management to the pre examination and supervision to radiation protectionproducts，like lead glasses, moreover，radiation personnel’s health status also should besystematically investigated and analysed.The results were obtained basing on existing protection facilities, so we shouldfully know about the results’ appropriateness when popularizing them. Currently，owning lack of specialized monitoring standards in X ray thickness gauge, the resultsonly reflected the radiation personnel’s dose level. In the future, we should establish therelevant monitoring standards on X ray thickness gauge.