NEUTRON ACTIVATION ANALYSIS WITH THE NIGERIA MNSR (NIRR-1)

NEUTRON ACTIVATION ANALYSIS WITH THE NIGERIA MNSR (NIRR-1) S.A. Jonah REACTOR FACILITY SECTION CENTRE FOR ENERGY RESEARCH AND TRAINING, AHMADU BELLO UNIVERSITY, ZARIA, NIGERIA Jonah

OUTLINE OF PRESENTATION • INTRODUCTION • STATUS OF NIRR-1 FACILITIES FOR NAA • PLAN FOR THE CRP • PRELIMINARY RESULTS • DISCUSSION & RECOMMENDATIONS Jonah

INTRODUCTION-NIRR-1 Design Parameters • No. of fuel rods installed: 347 with 3 Al dummies • No of extra fuel rods: 3 • Fuel integrity check: periodic gamma ray spectrometry • Clean Cold Core ρex: 3.77 mk (< 50 cents) • Special Feature: SRR (Cd absorber) ρ =-1.2 mk • Total U-235: 1 kg. • Nominal power: 31 kW • Nominal flux: 1.0  1012 cm-2 s-1. • Uses NAA, Training/Teaching, Research and limited Isotope Production Jonah

INTRODUCTION-NIRR-1 Parameters for NAA • NIRR-1 is 8th commercial MNSR • Criticality Feb. 03, 2004 • Licensed June 01, 2004 • It is designed specifically for NAA and RI • Has 6 irradiation sites connected for NAA • Suitable flux for NAA is 7x1010 – 1x1012 n/cm2.s • Reactor flux stabilizes 15 min after start-up • Radial and axial flux variation around core is 3% • Flux variation inside irradition vial is 1% • Max. Temp., inner site is 55 °C, thus suitable for liquid & biological samples Jonah

Jonah

IRRADIATION FACILITIES • Irradiation via 2 Pneumatic Transfer Systems (A & B) • A connected to a small inner site (A1)&large outer site (A2) • B is connected to 3 small inner sites (B1, B2, B3) and a small outer site (B4) • B is for short and medium irrad. With Channel B1 designed for cyclic NAA • B can tranfer sample from reactor to det., stripper, Pb box • A works in auto/manual for long irradiation with a timer Jonah

Jonah

GAMMA-RAY COUNTING FACILITIES • GEM Series HPGe Coaxial Detector (GEM-30195), p-type • Resolution is 2.0 keV @ 1.33 MeV, 60Co, HV = +1500 V • Pb shield cuts background and suitable for MARINELLI • 2 sets of plexi-glass sample holders for samp-source posns. • Amp settings adjusted for compatibilty with ‘WINSPAN’ • ‘WINSPAN’ performs peak ident., evaluatn; & calc. of conc. • Efficiency curves have been determined for the sample holders Jonah

NEUTRON SPECTRUM PARAMETERS OF SLOWPOKE & MNSR Jonah

ROUTINE UTILIZATION PROCEDURES Jonah

CRP PLAN • Improve and validate methods for n-spectrum parameters • Acquisition of codes (MCNP5, SAND) • Develop methodologies for accurate measurement of fission neutron ave • Comparison with data libraries • Re-measure constants (o, Io) for NAA • As specified by CRP • Testing of the k0-IAEA software • Using CRMs Jonah

PRELIMINARY RESULTS- fission f by single comparator method Jonah

PRELIMINARY RESULTS- Fast neutron flux by threshold reactions Jonah

DISCUSSION & RECOMMENDATIONS • NIRR-1 is used routinely by relative NAA • MNSRs´n-spec parameters are in-consistent • Cd-covered method with Io(Au) is ok for fiss. ave • Fast n-spec in MNSR is a pure fission spec • The Al-0.1%Au is ok for fast flux monitoring • Coordinated n-spec charact.program for MNSR • Inter comparison exercises Jonah

NEUTRON ACTIVATION ANALYSIS WITH THE NIGERIA MNSR (NIRR-1)