ML20009A838
| ML20009A838 | |
| Person / Time | |
|---|---|
| Issue date: | 07/10/1978 |
| From: | Levine S NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | Minogue R, Casey Smith, Volgenau E NRC OFFICE OF INSPECTION & ENFORCEMENT (IE), NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS), NRC OFFICE OF STANDARDS DEVELOPMENT |
| References | |
| RIL-031, RIL-31, NUDOCS 8107140327 | |
| Download: ML20009A838 (8) | |
Text
-
p
- / ',
(
i e
2 JUL 101978 kM]RA9DUM:Robert B. MinogJe, Director i
Office of Standards Developoent Clifford V. Smith, Jr., Director Office of Huclear Material Safety and Safeguards i
Ernest Volgenau, Director Office of Inspection & Enforcement FROM:
Saul Levine, Director Office of Naclea; Regulatory Research SU3 JECT:
RESEARCli INF0PJ8.ATION LETTEP, f 31 ASSAY OF STANDARD REFEREtJCE MTERIAL (SPJ1) 950b t
~
j
,f i.
Ir'roduction
$6; This ceturande transmits the results of a completed phaseof research on the assay deterair.ation of uranium in Standard Reference Material (SRM) 9500, which is part of a continuing NRC research activity entitled
%asurements and Standards for fiuclear Materials safeguards." This study has perforr.ed by the National Bureau of Standards (NBS), for the Office of Nuclear Regulatory Researen (RES) in response to, a research request (50-77-3) froe. the Office of Standards Developnent identifying a need to improve the quality of measurerents mde on special nuclear mterial for coatrol and accounting purposes.
The parpose of this phase of the study was to develop and certify a uranium oxide U 0s assay standaro to replace the virtually de:>1eted 3
SPJ: 95Ca. The nca replacerent calibration standard, designated as uranium assay standard SPJi 9505, was certified through a cooperative effort of N3S I'
and tiew Brunswick Laboratory (NSL) using botn the suoified Davies-Gray mthod and coulometry.
The research results indicate that the newly developed SRM 950b calibration
- standard has a certified value of 99.97 + 0.02 percenturantuooxide(U0s)-
3 Re_s_ul _ts The results of the first phase of a series of SRMs to be developed under this research task have been cocpleted. Tables I and II sua:arize the resulting quantitative data that have been generated.
W 8107140327 PDR
_L J t
RIL f31 2
Additional efforts in the area indicated are continuing. The aim is to develop, test and certify a set of urants oxide (0 0s) assay SRMs and 3
the associated set of Nuclear Safeguards SP.Ms for nondestructive assay (NSA)use. The first set to be developed will cover the low enriched spectrun ranging froa 0.7 percent to 5.0 percent. Additional sets of low enriched standards will be developed over the next two years followed by the production of standards for hign enriched calibrations.
Research Infory.ation Letters (RIL's) will be prepared for distribution as each SRM standard or series of standards are developed, tested and i
certified.
The results of this work have been exposed to expert review through extensive collaboration with knowledgeable individuals in both private and goverrnent facilities and through numerous technical r.eetings (e.g.,
ASTM, A 151. INiti, international inforr.stion exchanges). SAFER's Measure-rents and Standards Research Reviet Group concluded that the work was sufficiently r.ature and technically sound that this Research Information Letter be prepared.g While the exact impact of this work on current i
licensing practices has not been identified, it is felt that there are truediate applications involving the verification of licensee inventory measurement data by NRC regional inspectors.
Since the issuance of SRM 953a in early 19G0, essential information about the use of calibration standards has been placed directly on the new certificates (See Enclosures II and III).
These results can best be utilized in estimting the uncertainty associated with "Haterial Unaccounted For" (MUF) deten:ination and other pertinent accountability peasurenents. The stated uncertainty associated with the certified value gives the limit of tne random error and tha estinated upper limit of conceivable systcoatic errors, including material variability.
RES concludas that this phase of ongoing research activity has achieved most of its initial objectives and that these findings will continue to 1
be evalusted and dissoainated as new SRMs becw available in the later stages of the progra=.
Minutes of the SAFER Haasurenent & Standard Review Group Maeting, May 4 1978. Washington, D. C., issued June 16, 1978.
G
. IELJ _
)
T
'9 RTL #31 3
Discussion SRP. 950b is a high purit/ natural uranium standard inter.ded te provide a reference c.aterial of knoen urentum content.
Tne certified value for this caterial is 99.950 1 0.020 percent urantun oxide (U 3 ) and is based 33 or, the r.aterial bein; ignited at a te.7perature of E00,C for on;- hour in an open crucible in a muffle furnace and cooled in a desiccator.
It is critical tnat the L4terial be freshly ignited in the prescribed manner to ottai.. accurate assay results.
59' PS2t is a good exancle tnat the certification of a reissue SRM does not always proceed in a scooth r~anner.
Despite the fact that bcth SPJi
,950s and b are materials of relatively hi9n purity. there are some sub-stantial dif[erences between the two.
For SRP. 9503, an ignition tenacr-ature of 9.?] C for onc houi was found to be satisfactory and gave re-of9);y.lcuraniumassayvalues.
For SRM 950t., an ignition tergerature projac C for one hour gave ignition 'oss variations of up to 3.05 percent dependjn, on the rate of cooling after ignition. An ignition temperature of 600 L for SD: 953b gave reproducible 19'nition losses to witnin 0.035 percent irrespective of cooline rates or even if tnc ignition tere,erature 0
was in error by as much as +59 C.
The titripetric assay of SDN. at N35 also sh~.eed that the type o? furnace used for ignition could influence tos asscy value by a stell but statistically significant amount.
As a r.sult, the certificate for 5!!" 950b states tnat the ignition is to be 8
7erforr.ed in a nuffle furnaca at 300 C for one hour (Enclosure Ill).
in2 original M35 assay of SRM 959b was performed using a coulotetric tecar.iqae and the assay of this caterial at Scw Brunswick Laboratory (NLL) us:c a titric.etric procedure. The results of the tuo analyses differed by
- r. ore than 0.03 percent.
Investigations of both the coulometric and titri-natric netnocs resulted in several modifications being m3de to the coulo-metric method which accounted for this difference.
Tne certificate for SMi 930b lists an uncertainty of t 0.02 percent whica reflects both a sr ll interltboratory uncertainty and some imprecision noted for the coulonetric r.ethod.
Reco.twnda tior.s Tne above results and discussion are offered for user office consideration for application to an tientified regulatory need. The princr/ significance of the work described is to inr. rove the standardization and calibration capability of both n?.C field inspectors and the nuclear industry as a whole.
RES believes that the reported results are lit.ely to have significant near-tera tapact on current 53 gJides that Will address the {CQlec.entation Of 10 CFR 70.57, Licensees I:easorce2nt control Plans.
a
_C[
t R1L #31 4
SU. 9500 is available to MP.C regional 1::spectors, :Pi contracters, D02 contractors, licensees anj foreign governments that have er.tered an agreevnt in cooperation wic'. r,ne U. S. Governr.ent concerning thc civil uses of ato.11c enery.
Tn: RES contact for any further clarificatiGn or evaluation of these rjsalts is Dr. R. L. SneparJ of tae Opert.ticnal Su:nort.? ranch.
orfginal signed br Saul Levine Saal Levine, Lirect:r i
Office of huclear Regulatory Research Enclosar:s:
(2) 1.
Tuo Tables l
4.
Certificate - Standard R forenc2 i
l'a tcri:1 9653 I
- .;5 Cer:.ificate - Standarc Referer.cc 4.
4ateri:1 E.::
l DIST:
G Eral File Circ C;1rono R. L. Shepard Rdg H. !!. iiaul. ins J. S. Durs t F. Arsenault C. P. Jupiter R. 11. Scroggins S. Levina RES C. P. Jupiter 6/ /78 RES: SAFER RES: SAFER RES: SAFER RES: SAFER RES: SAFER RES:DIR 427-4337 i!!;. aukins JSDurst FArsenault RMScroggins Stevine RLShepard:akb C/ /20 6/ /78 -
6/ /73 6/ /70 C/ /73 G/ /7S
.L J ENCLOSURE 1 Table 1.
Uranium Assay Results No. of Measured Concentration o, Value of SRf'.*
Assays of U 0 in Sample (%)
Standard Error (%)
3g 960 14 99.971 O.005 a
950s 4
99.938 0.003 a
950b B
99.969 0.006 b
950b 1C
- 99. 9.n 0.016 C
950b 6
99.958 0.022 a lgnition in muffle furnace.
[DeterminedbyNBL.
Determined by coulometry.
Standard reference material Table 2.
Comparison of Certified Values of Uraniuc. Assay SRMs s
Certified Velue of SRM*
Measured Concentration (i) 960 99.975 10.017 8
950a 99.93 10.0?
950b 99.97 10.02
Standard reference material.
- ~
" Corrected for change in atomic weight of chromium.
e
3
,e r s r>e w.=m at c""
ENCLOSURE II 4
m... a so,,
W Tr.':Str=
Cerft::ttafe STANDARD REFERENCE MATERIAL 950a Uranium Oxide (U 0 )
3 8
Uranium Oxide (C 0.)....... 99.94 percent 3
This sample consists of normal ura-Jum in the form of oxide, U 0a. It is 3
intended to provide a material of known cranium content. The indicated value is based on material heated at 900 'C for one hour in in open crucible and cooled in a desiccator. The material should be freshly ignited as ur,ed.
The assay is based on high. purity normaiurardum metal (dingot) using National Bureau of Standards Standard Potassium Dichromate 136a as the transfer reagent.
The atomic wei; hts used in the calculation are: uranium,238.03, oxygen, 15.9994.
It is estimated that the uncertainty in the assay does not exceed 0.02 percent.
Total impurities as determined by spectropaphic sn'a?ysis are less than 50 ppm.
The difference between the assay and calculated purity is considered to represent deviationgrom the nominal stoichiometric composition.
I{arry C. Aller Jr., Chief Washington, D. C. 20234 Didsion of Analvtical and December 1,1961
,e (reprinted October 27,1969)
Inorganic Chemktry 1
t i
I
\\
? f.a1l i;
i
.m l
g
- i..-
)
ENCLOSURE III I
C,7, 3 % ;" " "
l "D
i niaw-j#afional plureau of $fanc.arels (Certificate Standard Reference Materia 1950b Uranium Oxide (U 0 )
3 8 (In Cooperation with the Department of Energy, New Brunswick laboratory, Argonne, This material consists of normal uranium in the form of oaidc,UsOs. It is intended to provide a refer material of known uranium content.
CERTIFIED YALUE Uranium Oxide (U30s)... 99.968 10.020 percent The stated uncertainty of 10120 percent assocsated with the certified value is the linear sum of 0.0076 pe which is the limit of the random erTor of the anay measurements at the 99 percent confidence level (2.8 where S. is the standard error rdthe mean pith n = 24),and 0.012 percent,the estimated upperlimit of i
j able systematic errors including material vr.r{ ability. The above ccatified value is based on mat 800 'C for one hour in an open crucible in a muffle furnace and cc.n: led in a desiccator. It is importa ma:erial befreshly ignited in this manner to obtain accura:e result).
The total irnpurities as deie rmined by spectrochemi:a1 analysis are estimated to be less than 50 u mined iton content is -3 pg/g and the determined vanadium content ts ~ l ug/g The tuay of this mat as the oxidizing agent as described in the NBL bued on the use of NBS Potassium Dichromate (SRM 13g,Tbc assay values obtained are co titrimetric method for the precise assay of uranium metal.
those obtained from the assay of NB5 Uranium Mefal,(SRM 960) and NBS Uranium Oxide.(SRM 950 certified value for this lot of uranium oxide has also been confirmed uing a coulometric procedure.
The atomic weights used in the calculations are: uranium, 238.029, and oxygen, 15.9994.
This materia!was prepared under contract with the NationalLeaf Company of 0hio, Cincinnati. Ohio. A :
l of the material was performed by N. M.Trahey of the New Brunswick Labort. tory, Argonne,itiinois an Mood) and W. Koch of the NBS Analyti:a! Che.nistry Dhision. Iron and vanadiumwere measu l
Diamondstone and S. A. Wicks of the SBS Analytical Chemistry Dhision.
Overall directicn and coordination of the technical mersmements leading to toe certification were pe under the chairmanship of 1. L. Barnes.
The technica! and support aspects mvohed in the preparation, ceinfication, and issuance of this Sta Reference Material were coordinated throgh the Office of Standard Reference Materials by W. P. Re J. Paul Cali, Chief Washingtor. D.C. 20234 Office of Standard Reference Materials March 1,1978 (over)
-.U.
a 1.'
4 Ignition of Material Before Use To anay accurately, this rnaterial must be ignited in an open crucibic in a mume furnace at 800 *
~
and cooled in a desiccator ju't prior to use. Tbc ignition temperature,800 *C,was determined to be es this specific lot of material.
References
- 1. A. R. Eberle and M. W. Lett,er, NBL Annual Propess Report, No. 258, July 1969 - June 1970, pp 5-9.
- 2. A. R. Eberle and M. W. Lerner, NBL Annual Propess Report, No. 262, July 1970 -June 1971, pp. 516.
l b
.d r
l l
/
e W