ENTRY 32820 20230912 3282000000001 SUBENT 32820001 20230912 20240316 3282000100001 BIB 13 63 3282000100002 TITLE Measurement of the prompt neutron number distribution 3282000100003 probability of U235 fission induced by thermal neutron 3282000100004 AUTHOR (Huang Shengnian,Wang Yusheng,Liang Qichang, 3282000100005 Zhang Peishu) 3282000100006 INSTITUTE (3CPRAEP) 3282000100007 REFERENCE (J,CST,3,585,1961) 3282000100008 FACILITY (REAC,3CPRAEP) Heavy water reactor 3282000100009 INC-SOURCE (REAC) The reactor power was 100 kW and the neutron 3282000100010 flux was about 5E3 n/s/cm2. 3282000100011 SAMPLE 20% enriched uranium is plated on both sides of the 3282000100012 aluminum foil using a neutral alcohol solution 3282000100013 electroplating method, with a thickness of 0.5 3282000100014 mg/cm2. There were 14 sheets in total. 3282000100015 METHOD Neutrons were moderated by heavy water and measured 3282000100016 by the BF3 detector.The container for heavy water was 3282000100017 a large cylinder made of Al, with an outer diameter 3282000100018 of 800 mm, a length of 700 mm, and a wall thickness 3282000100019 of 5 mm. The center of the cylinder was a cylindrical 3282000100020 cavity for placing a fission ionization chamber, with 3282000100021 an inner diameter of 65 mm. Around the cavity, 40 Al 3282000100022 tubes with a diameter of 37 mm were symmetrically 3282000100023 arranged (divided into three circles, each with 8, 12, 3282000100024 and 20 tubes), and BF3 were placed inside. A graphite 3282000100025 reflector with a thickness of 500 mm was stacked 3282000100026 around the system. At the end of the horizontal 3282000100027 transport channel, a graphite pillar(phi 145 * 600 3282000100028 mm) was place to the active zone. The cadmium ratio 3282000100029 of the neutron beam increased from 10 to 56. The 3282000100030 collimator placed in the horizontal channel is made 3282000100031 of boron containing paraffin, with a central aperture 3282000100032 of 6.5 mm, an outer diameter of 200 mm, and a length 3282000100033 of 1200 mm. The lead protective layer(600*600*600 3282000100034 mm3) was at the orifice, with a central square hole 3282000100035 size of 20*20 mm2. Paraffin layer containing B (100mm 3282000100036 thick) and Cd sheet are used to shield the entire 3282000100037 system. The system efficiency was 14.72 %. The 3282000100038 measurement time was about 50 hours. 3282000100039 DETECTOR (BF3) 2 groups of BF3 were used. One group was 12 CHM- 3282000100040 8 (B-10 concentration of 80%, 35 mm in diameter, 1000 3282000100041 mm long, inflation pressure of 400 millimeters of 3282000100042 mercury, working voltage 2400 V, flat width 300 V). 3282000100043 The other was 19 CHM-7 (B-10 concentration of 90%, 35 3282000100044 mm in diameter, 550 mm long, inflation pressure of 3282000100045 400 millimeters of mercury, working voltage 2600 V, 3282000100046 flat width 100 V). Total content of boron was 4.33 3282000100047 grams. 3282000100048 (FISCH) The fission ionization chamber was entirely 3282000100049 made of Al, with a diameter of 60mm and a length of 3282000100050 150mm. The thickness of the front and back walls was 3282000100051 less than 1mm. The ionization chamber was filled with 3282000100052 Ar gas with a height of 600 mm of mercury, and the 3282000100053 working voltage was negative 200 V. 3282000100054 ASSUMED (ASSUM,92-U-235(N,F)0-NN-1,PR,NU) 3282000100055 Hughes,J,NUC,17,11,1959 3282000100056 ERR-ANALYS (DATA-ERR) The first source of uncertainty was from 3282000100057 statistics, especially the statistical uncertainties 3282000100058 of 5, 4 and 3 neutrons emission probability. The 3282000100059 second source of uncertainty was from detector 3282000100060 efficiency. The uncertainties from instrument 3282000100061 instability and electronic gate width instability 3282000100062 were ignored for far less than statistical uncertainty.3282000100063 STATUS (TABLE) TABLE 2 of At.En.Sci.Technol,3,585,1961 3282000100064 HISTORY (20230912C) Compiled by Xi Tao (CNDC) 3282000100065 ENDBIB 63 0 3282000100066 COMMON 2 3 3282000100067 ASSUM ASSUM-ERR 3282000100068 PRT/FIS PRT/FIS 3282000100069 2.43 0.02 3282000100070 ENDCOMMON 3 0 3282000100071 ENDSUBENT 70 0 3282000199999 SUBENT 32820002 20230912 20240316 3282000200001 BIB 1 1 3282000200002 REACTION (92-U-235(N,F),NUM,NU,,SPA) 3282000200003 ENDBIB 1 0 3282000200004 COMMON 1 3 3282000200005 EN-DUMMY 3282000200006 EV 3282000200007 0.0253 3282000200008 ENDCOMMON 3 0 3282000200009 DATA 3 6 3282000200010 PART-OUT DATA DATA-ERR 3282000200011 NO-DIM NO-DIM NO-DIM 3282000200012 0. 0.076 0.008 3282000200013 1. 0.139 0.026 3282000200014 2. 0.262 0.044 3282000200015 3. 0.346 0.057 3282000200016 4. 0.147 0.043 3282000200017 5. 0.030 0.014 3282000200018 ENDDATA 8 0 3282000200019 ENDSUBENT 18 0 3282000299999 ENDENTRY 2 0 3282099999999