1. NPL Environmental Radioactivity Comparison 2005 Results from LNGS

2. NPL Environmental Radioactivity Comparison 2005 The LNGS LBL has participated (not formally) to a comparison exercise promoted by NPL (National Physical Laboratory, UK) SAMPLE: Type GL: sample consists of 500 g of 2 M HCl/0.1 M oxalic acid with 50 ppm of Ba, Co, Na, Nb, Sb, Y and Zr, containing a mixture of ten gamma-emitting radionuclides: 22 Na, 60 Co, 88 Y, 95 Zr, 95 Nb, 125 Sb, 133 Ba, 134 Cs, 137 Cs, 152 Eu The activity concentration of each nuclide was in the range 1-20 Bq/kg. Nuclide 22 Na 60 Co 88 Y 95 Zr 95 Nb 125 Sb 133 Ba 134 Cs 137 Cs 152 Eu Activity [Bq/kg] 3.718 (14)18.84 (6)3.843 (14)1.836 (19)3.84 (4)6.48 (4)5.74 (4)5.30 (4)2.884 (20)4.19 (3) Reference time: October 1, 2005

3. Results Deviation [%] 22 Na 60 Co 88 Y 95 Zr 95 Nb 125 Sb 133 Ba 134 Cs 137 Cs 152 Eu Measurement: GeMi Detector 124.5 g volume: d70mm h40mm measuring time 92.6 h Deviation from NPL reference results: D[%] = 100*(Meas/Ref-1) Mean Value -2.84%

4. Conclusions Problems with 95 Nb: 95 Zr  95 Nb or 95m Nb 95m Nb  95 Nb or 95 Mo 95 Nb  95 Mo