View source for PNO-IV-99-036, on 990813,licensee Notified NRC Operations Ctr That Inaccurate Lab Analysis Method Resulted in Potential for Criticality Safety Limit to Be Exceeded by 23%.Affected Process Was Shut Down & Tagged Out.Region Will Conduct Insp

{{Adams
| number = ML20210U169
| issue date = 08/18/1999
| title = PNO-IV-99-036:on 990813,licensee Notified NRC Operations Ctr That Inaccurate Lab Analysis Method Resulted in Potential for Criticality Safety Limit to Be Exceeded by 23%.Affected Process Was Shut Down & Tagged Out.Region Will Conduct Insp
| author name = Britz W, Spitzberg B
| author affiliation = NRC OFFICE OF INSPECTION &amp; ENFORCEMENT (IE REGION IV)
| addressee name = 
| addressee affiliation = 
| docket = 07001257
| license number = 
| contact person = 
| document report number = PNO-IV-99-036, NUDOCS 9908200023
| document type = PRELIMINARY NOTIFICATION OF EVENT OR OCCURRENCE (PNO,, TEXT-INSPECTION &amp; AUDIT &amp; I&amp;E CIRCULARS
| page count = 2
}}
{{#Wiki_filter:a                                                     .
    ~                                                   August 18,1999 PREUMINARY NOTIFICATION OF EVENT OR UNUSUAL OCCURRENCE PNO-IV-99-036
           .This preliminary notification constitutes EARLY notice of events of POSSIBLE safety or public interest significance. The information is as initially received without verification or evaluation, and is basically all that is known by Region IV staff in Arlington, Texas on this date.
Facility                               Licensee Emergency Classification Siemens Nuclear Power Corporation                    Notification of Unusual Event
           . Siemens Nuclear Power Corporation                    Alert Richland, Washington                           Site Area Emergency Dockets: 07001257 License No: SNM-1227                 . General Emergency X Not Applicable

==Subject:==
CRITICALITY SAFETY SPECIFICATION LIMIT POTENTIALLY EXCEEDED On August 13,1999, Siemens Power Corporation (SPC) notified the NRC Operations Center that an inaccurate laboratory analysis method resulted in the potential for a
           = criticality' safety limit for surface density (mass per unit area) to be exceeded by 23 percent. The event concemed the Mop Powder Dissolver Facility and analytical laboratory measurements. The Mop Powder Dissolver Facility processes dirty uranium powder and uses a vacuum drum filter to separate dissolved uranium from dirt.
           . During normal processing in the Mop Powder Dissolver Facility, shavings from the vacuum drum filter are collected in small drums and sampled and assayed for uranium
           . content. When laboratory sample results are obtained, the material is transferred from 5 gallon containers into a 55 gallon waste drum. After the material is placed into a wat,tc drum, the drums are transferred to another building and receive a non destructive assay (NDA), using.a gamma counter, to confirm that the uranium-235 content of the material is low enough to allow transfer to the waste storage pad where the drums may be stacked
           . up to three high.
The initial discovery of a potentially inaccurate laboratory analysis method resulted from a radiatian protection technician performing a routine radiological survey. During a survey of a waste bag containing lab filter paper and other combustible waste, the radiation protection technician noticed that the filter paper had higher readings than expected. An investigation was subsequently initiated by SPC personnel. The investigation determined that the acid dissolution process used to dissolve uranium on the filter paper for subsequent analysis had not been completely effective in separating uranium from other solid material on the filter paper. Laboratory personnel initiated further investigations to determine whether the initial observations had led to lower analytical results for tests using this dissolution method. The investigation uetermined, through comparison of other
           - dissolution methods, that laboratory analysis using the acid dissolution method yielded uranium content results that were significantly lower that other methods. SPC personnel subsequantly investigated analytical results obtained for shavings from the vacuum drum filter in the Mop Powder Dissolver Facility and determined that the laboratory method normally used to analyze the shavings as described above had underestimated the total
           . uranium content.
The investigation into the laboratory analysis also revealed that the NDA value assigned                  .
to these waste drums may also be low. The expected cause of the low NDA v; lues is                      j attributed to differences _ between the geometry of the material as it is counted and the material being assayed are dissimilar enough that self-shielding that wr]
geometry of the NDA drum standard. Also, the material matrix of the standard and the
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PND-IV-99-036            PDR                                                                         j

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The parameters controlled for criticality safety of this material are surface density and
             . concentration. As a result of the potential measurement error, the surface density
            - parameter specified in the SPC Criticality Safety Specification may have been exceected for a three-tier array of drums storing solid material from the Mop Powder Dissolver Facility. A criticality accident is only possible if the concentration of uranium exceeds the minimum critical concentration. In this case, the maximum concentration of uranium in any drum was only about 20 percent of the concentration limit.
The corrective actions initially taken to restore criticality safety parameters were: 1) the
            . affected process was shut down and tagged out,2) the three-tier array of the 55 gallon drums were moved into a single-tier to ensure that surface density was below the safety limit, 3) additional multi-drum samplings were inititced to verify the actual uranium content, and 4) the affected process will remain shut down pending further investigation and completion of corrective actions.
Region IV will review the licensee's ongoing investigation and corrective actions during an
            ' inspection scheduled for the week of August 23,1999. The State of Washington and NMSS have been informed.
Region IV received notification of this occurrence by facsimile from the licensee who also notified the NRC Operations Center on August 13,1999.
This information has been discussed with the licensee and is current as of 3:00 p.m.
(CDT), August 17,1999.
Cented: Blair Spitzberg         Wayne Britz (817)860-8191        - (817)B60-8194
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