ML19331B713

Forwards Molybdenum Decontamination & Surveillance Rept Describing Decontamination Technique & Surveillance of Approx 1,200 Lb Molybdenum Scrap.Results Indicate Surface Contamination Well Below Acceptable Levels

ML19331B713
Person / Time
Site:	Westinghouse
Issue date:	05/29/1980
From:	Reitler E WESTINGHOUSE ELECTRIC COMPANY, DIV OF CBS CORP.
To:	Crow W NRC OFFICE OF NUCLEAR MATERIAL SAFETY & SAFEGUARDS (NMSS)
References
16518, NUDOCS 8008120651
Download: ML19331B713 (3)

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'30H May 29, 1980

'U. S. Nuclear Regulatory Commission Uranium Fuel Licensing Branch Division of Fuel Cycle and Material Safety Washington, D. C. 20555 ATTENTION:

Mr. W. T. Crow, Section Leader Uranium Process Licensing Branch

SUBJECT:

Molybdenum Decontamination and Surveillance Report, License SNM-1107, Docket 70-1151 Gentlemen:

Westinghouse Electric Corporation hereby submits the attached Molybdenum Decon-tamination and Surveillance Report in accordance with the requirements of Annex C of SNM-1107. The report describes the decontamination technique and surveillance of approximately 1,200 pounds of molybdenum scrap which was formerly used as boats to transfer low-enriched uranium pellets through our sintering furnaces.

The molybdenum scrap is in the form of one to two pound pieces of broken molyb-denum boats which have been decontaminated and subjected to 100% alpha and beta-gamma surveys. The results of this surveillance are given in the enclosure to this letter.

Survey results indicate that surface contamination levels are well below accept-able levels as defined in Annex C, Table I of SNM 1107. Consequently, Westing-house plans to release the molybdenum as scrap for unrestricted use on or after June 30, 1980.

If you have any questions regarding this matter, please write to me at the above address or telephone me on 803 776-2610.

Very truly yours, k

Edward Reitler Fellow Engineer T 108 f*S 80Y

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ER/ff A66IS Attachment cc: USNRC Office of Inspection and Enforcement, Region II 8008120

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ENCLOSURE TO TRANSMITTAL OF MAY 29, 1980 SNM-1107, DOCKET 70-1151 j

MOLYBDENUM DECONTAMINATION AND SURVEILLANCE REPORT 1

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IDENTIFICATION The material consists of approximately 900 pieces of molybdenum, each piace weighing from approximately one to two pounds. The molybdenum originally con-sisted of boats used to transport low-enriched uranium pellets through our re-duction furnaces. During routine operations, boats become damaged or broken and must be scrapped. When this occurs, the boats are broken into smaller pieces to facilitate decontamination and surveillance.

DECONTAMINATION TECHNIQUE Uranium contamination of the molybdenum was restricted to the exterior surfaces; consequently, an electro-chemical process was chosen as the most efficient method of contamination removal to reduce uranium levels to As-Low-As-Reason-ably-Achievable. The technique involved complete immersion of the molybdenum pieces in an electrolytic bath containing a strategically located cathode.

The passage of electric current resulted in a progressive smoothing of the surfaces and the removal of a thin layer of surface material. Following this treatment, the material was thoroughly rinsed, dried, and surveyed to determine decontamination effectiveness.

SURVEILLANCE PROCEDURE Ee:h piece of molybdenum was thoroughly surveyed for total direct alpha and total direct beta gamma on all surfaces, front, back and edges. Removable alphacontamingtion.surveyswereperformedforthosepiecegwhichexceeded 400 dpm/100 cm total direct alpha and/or 1,000 dpm/100 cm' total direct beta '

gamma.

Special precautions were taken to assure that all surfaces of the molybdenum were accessible to the detector; probes. This resulted in essentially flat pieces of molybdenum with minimal surface cracks or crevices.

For total direct alpha surveys, the folloiwng instruments were used: Eberline PAC 4G with an AC-21 alpha probe and Eberline RM-19 with an AC-3 alpha probe.

For total direct beta-gamma surveys, an Eberline E-120 with an HP-210 probe was used. Surveys were performed by slowly scanning aLL surfaces of the molybdenum at a scanning speed of approximately 1 cm/sec. When contamination was detected, the probe was held stationary until equilibrium was attained. This method pro-vided a high degree of confidence that no contamination was undetected. Instru-ments were calibrated with appropriate alpha and beta check sources and checked periodicatty during the surveillance to assure operability.

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molybdenum with a Whatman 41 filter paper using moderate pressure and counting with either of the alpha instruments described above.

i SURVEILLANCE FINDINGS For each piece of molybdenum, the fgtlowing information was recorded:

(1) average (2) maximum alpha results per piece alpha resulgs per piece (dpm/100 cm ),

2 (dom /100 cm ), (3) aversge beta gamma results per pigce (dam /100 cm ), and (4) maximum beta gamma results per piece (dpm/100 cm').

Summary data are presented below:

TotalAlphg TotalBeta-Gagma (dom /100 cm )

(dom /100 cn )

Average Maximum Average Maximum Range 8kgd - 800 Bkgd - 1,000 Bkgd - 2,250 Bkgd - 3,750 Average 240 400 750 1,200 Removable gontamination surveys were performed for those pieces exceeding 400 2 beta-gamma. The average thosepiecessurveyedwas68dpm/100cm,withamaximumof160dpm/100cm{ce dpm/100 cm' total alpha and/or 1,000 dom /100 cm 2

alpha.

Gamma measurements were performed with a Victoreen 444 portable ionization chamber. Based upon comparison data, it was concluded that the beta gamma results as measured by the Eberline E-120 with the HP-210 probe were the limiting factor. For example, a beta gamma reading of approximately 10,000 2

dpm/100 cm ontheHP-210probecorrespondedtoapproximatelyg.2mr/hron the Victorcen 444 with an unshielded window (less than 3 mg/cm window). As shown above, the maximum beta-gamma result was 2,500 dom /100 cm2 Spot check measurements with the Victoreen 444 indicated no results above background; i.e., less than 0.1 mr/hr.

Detailed survey data are available for each piece of molybdenum, consisting of survey results, date of survey, signature of the surveyor and a certification that the surveillance was performed in accordance with the above procedure.

This information will be retained indefinitely for your review.

For both alpha and beta gamma, survey results are well below Annex C, Table I acceptable levels.

Consequently, we feel that the molybdenum decontamination meets the As-Low-As-Reasonably-Achievable philosophy.

The of f-site shipment of the molybdenum shall meet all applicable federal and state regulations.

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