ML20217G964

Insp Rept 70-1257/97-06 on 970915-19.No Violations Noted. Major Areas Inspected:Selected Aspects of Operations & Radiation Protection

ML20217G964
Person / Time
Site:	Framatome ANP Richland
Issue date:	10/08/1997
From:	NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION IV)
To:
Shared Package
ML20217G956	List: ML20217G951 ML20217G964
References
70-1257-97-06, 70-1257-97-6, NUDOCS 9710140310
Download: ML20217G964 (13)

Text

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o ENCLOSURE U.S. NUCLEAR REGULATORY COMMISSION REGION IV Docket No.: 70-1257 I License No.: SNM-1227 Report No.: 70 1257/97-06

' Licensee: Siemens Power Corporation Facility: Siemens Power Corporation

. - Location: Richland, Washington Dates: September 15-19,1997 Inspector: C. A. Hooker, Senior Fuel Facility inspector Approved By: Frank A. Wenslawski, Chief Materials Branch

Attachment:

Supplemental Inspection Information 9710140310 971000 PDR ADOCK 07001257 C PDR

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. 2-f EXECUTIVE

SUMMARY

Siemens Power Corporation

• NRC Inspection Report 701257/97-06 This routine, announced inspection included a review of selected aspects of operations and radiation protection. The inspection also included a review of the circumstances involved with a reportable criticality safety event that occurred during the inspection and followup on open items from previous inspections.

Ooerations

. No discrepancies were identified between the process system and components analyzed in the criticality safety analysis (CSA) for the new mop water processing system. The licensee was systematically proceeding in the development of the process (Section 1.1).

• Operations personnel were adequately implementing the criticality safety limits and controls for the uranyl nitrate hexahydrate (UNH) process. Modifications to the 901' process line were considered an enhancement to the criticality safety of the process (Section 1.2).

. Operations personnel responded appropriately to the identification of wet uranium powder in the Dry Conversion Pilot Plant (DCPP) Management appropriately instituted

, an incident investigation team to review the event, identify the causes, and define corrective actions prior to any restart of the DCPP (Section 1.3).

Radiation Protection

. The licensee was adequately implementing its in-plant radiation protection controls (Section 2).

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- Reoort Details Summarv of Plant Status The plant was operating both of its wet chemical conversion lines and the existing DCPP. Fuel pellet production, fuel rod snd fuel bundle assembly operations were also in progress. The new Dry Conversion Facility (DCF) was not operating at the time of this inspection.

1 Plant Operations i

' 1,1 Plant Modifications Moo Powder Olssolution Process

a. insoection Scoon (88020)

Inspection Reports 70-1257/97-01 and 04, described the licensee's installation of a new l mop powder processing system located in the Engineering Laboratory Operations l Building. This inspection included a review of the current status of the system with l cognizant licensee personnel and a review of CSA, " Mop Powder Dissolve Facility,"

Revistor: 0, dated June 25,1997, and a walkdown of this system with the respective criticality safety specialist to discuss and verify system design features utilized and analyzed in the CSA.

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b. Observations and Findinas At the time of inspection, the licensee had not received NRC approval of a Ilcense amendment request for use of unfavorable geometry poisoned rotary drum filters included in the process. The licensee had testod the system using a non-uranium chemical compound to evaluate the operational aspects of the process. These tests did not reveal any operational problems with the process.

The inspector did not identify any discrepancies between the process system and components analyzed in the CSA, nor any discrepancies from the information submitted to the NRC by letters dated April 16, May 21, and July 10, .1997, to support the licensee's amendment request At the time of the inspection, the licensee was cevising the CSA to include additiona; Nenses for certain accident scenarios. The inspector did not identify any safety concems Juring a walkdown of the system.

The criticality safety specification (CSS) form (transcribes the limits, controls, design features, instrumentation and surveillances, and actions for accident conditions defined in the CSA) had not been completed at the time of this inspection. The licensee informed the inspector that the CSS would be finalized upon revision of the CSA and approval of the license amendment request . Enriched uranium would not be introduced into the system prior to completing these actions.

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c. Conclusions No discrepancies were identified between the process system and components analyzed in the CSA. The licensee was systematically proceeding in the development of the

, process, 1.2 UNH ProrgJig

a. Insoection Scooe (88020)

The inspector reviewed selected aspects of modifications that had been made to the UNH 901 processing system located in the Uranium Dioxide (UQ) Building. The .

Inspection included a walkdown of the system and a review d ine applicable CSA, CSS, 4

operating procedure, and records of preventive maintenance (PM) for the system safety interlocks. - Discussions were held with the members of de uticality safety group and operators. Specific <iocuments reviewed were:

- CSA No. U120, "UNH Reprocessing," Revision 2, dated August 11 - 1997.

- CSS No. P97,120 "UNH Reprocessing," Revision 3, dated September 5,1997.

• Standard Operating Procedure No. P66,531, "UNH Powder Dissolution,"

Revision 26, Dated September 24,1997.

• PM C120P004, "UNH Interlocks," Revision 2, dated June 25,1997.

b. Observations and Findinas The UNH processing ' system is comprised of two parallel dissolution systems

! (901 and 902) where oxidized scrap uranium powder is dissolved as UNH, sent to i storage, and reprocessed to UO2 powder. Oxidized scrap dry powder containing less than 1.0 weight percent (wt.% ) moisture is vacuum transferred from drums or buckets (at floor level) to a powder receiver vessel located on an elevated platform ah.;ve each dissolve (favorable geometry). The powder receivers operate in conjunction with an e interlocked scale system to control the quantity of powder batched to the dissolvers.

Prior to the modification, the powder receiving vessels and associated feed hoppers that fed the dissolvers were located in a hood. Attematively to the vacuum transfer system, the feed system could be loaded from safe batch containers placed in the hood for each i respective system. The receiving vessel for each syster: vas geometrically unfavorable, and the 901 system had an unfavorable geometry feed hopper while the while the 902 system's feed hopper was geometrically favorable. Criticality controls for the powder portion of the process consisted of a mass limit of 20 kilograms (kg ) of UQ and moderation control.

The modification to the 901 system included replacement of the powder receiving and 4

feed system with a new self contained geometrically favorable system, and elimination of i

5-the hood. Similar modifications were planned for the 902 system. Although the 901 system was geometrically favorable, the CSA retained the 20 kg UQ mass limit.

According to the criticality safety specialist, since the two systems are side by side on the same platform, the mass limit was retained to eliminate any operator errors associated with the current 902 system.

During the review of the CSA and CSS, the inspector noted a discrepancy where the CSA specified a 20 kg UQ limit for the 901 system while the CSS only noted the controls (password protected scale set point) for limiting the transfer of 20 kg of UQ to the receiving vessel. The licensee acknowledged this observation and initiated a change to the CSS to correct the matter. With the exception of the above discrepancy, the inspector noted that the criticality safety limits and controls, instruments and interlocks specified in the CSA were incorporated in the CSS. The criticality safety limits and controls were adequately incorporated in the operating procedure. The inspector also verified that required instruments and safety interlocks for each of the system had been incorporated in the PM system and were tested at the frequencies specified in the CSS.

During a watkdown of the system, the inspector did not identify any safety concems. The operators interviewed were cognizant of the changes and the. criticality safety limits and controls for each of the systems.

c. Conclusions Operations personnel were adequately implementing the criticality safety limits and controls required by the CSA and CSS. Modifications to the 901 process were considered an enhancement to the criticality safety of the process.

1.3 Ooerational Event - Drv Conversion Pilot Plant (DCPP)

A primary component of the DCPP is a pyrohydrolysis vessel (called a reactor ) where vaporized uranium hexabluoride (UF. ) is converted to UQ by reacting the UF. with a steam-nitrogen-hydrogen atmosphere in a fluidized bed at elevated temperatures to form dry UO, powder. The reactor vesselis of a slab tank design. The upper portion of the reactor vessel where the UF is introduced is geometrically unfavorable. The lower portion of the vessel (UQ bed) is geometrically favorable and contains the majority of uranium powder during the process. The upper portion of the reactor vessel contains internal metal filters to prevent the carryover of UQ into the reactor off gas treatment system. The UO, transfer system from the reactor to a rotary calciner includes a spool piece at the bottom of the reactor that connects to a rotary airlock valve (RAL), where UO2is picked up by an encased screw conveyor and fed to the calciner. The feed system and calciner are geometrically favorable. The calciner is used to reduce the fluoride content of the UQ, and operates at temperatures from 600 to 800*C in an atmosphere of steam and hydrogen.

Criticality safety of the reactor vesselis based on moderation control by limiting the uranium powder in the reactor to less than 1.0 wt.% moisture. The process design and

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operating parameters used, with installed safety inteccks, are configured to limit the uranium powder to less than 1.0 wtS moisture.

The licensee's DCPP has been operating since 1985. Prior to 1994, UQ from the reactor wh collected in 5 gallon buckets in a ventilated enclosure, in 1993, the licensee installed the UO, feed conveyor and calciner which were placed in full operation in January 1994,

a. insoection Scone (88020)

At approximately 6:30 a.m. on September 17,1997, while onsite, the shift s'Jpervisor informed the inspector of an event involving wet UQ powder that had been found in the feed system between the DCPP's reactor vessel and the calciner, Subsequent to the disc Jsslon with the shift supervisor, the inspector diverted his attention from a routine onsite Inspection to review the circufnstances surrounding and matters germane to the event.

The review of this event included discussions with cognizant licensee staff and a review of sequences relative to the event, moisture sample results, actions being taken by the licensee, previous events, and the licensee's notification of a NRC Bulletin 91-01 reportable event (No 32949). The inspeitor also toured the DCPP system to witness existing conditions.

Since the ilcensee's dry conversion process is proprietary, specific technical details are not described in the below discussions.

b. ObseNstions and Findinas Summary of Events At 7:30 p.m. on September 15,1997, while the DCPP was operating, the licensee experienced a drop in the differential pressure (DP) of the reactor fil?.ers and suspected a plugging of the UF, feed nozzle, The enrichment of the UQ in the process was 4.2 wtS U 235. Using routine procedures, the licensee made several attempts to free the suspected plugged nozzle. With no improvement in the filter DP, the licenses shut off the UF, and initiated a normal shutdown and cool-down with a maintained nitrogen flow into the reactor. The calciner was operating at normal parameters to tall out the UQ(n the system, which is normal to the process. At 2:45 a.m. on September 16,1997, the tall out of the calciner was completed, and the steam and dissociated ammonia (hydrogen supply) to the calciner were shut off.

At 4:40 a.m. on September M 1997, the licensee inspected the internals of the reactor and found some powder trapped on one side of the upper poriion of the reactor. The physical condition of the powder was indicative of a feed nozzle problem.

7 At 7:40 a.m. the powder buildup at the top of the reactor was brushed down, cleaning ports closed and nitrogen purge initiated. At 7:54 a.m. the calciner was operated to remove UO, from the reactor (50 kw was removed).

At 10:00 a.m. the fluidizing nitrogen, RAL, and feed conveyor were shutdown, and the upper portion of,the reactor was brushed down. The reactor insoection/ cleaning ports were sealed and the fluidizing nitrogen was rt utablished and the RAL was restarted to discharge the remalt,Ing UO, from the reatic. , but the material would not discharge. .

1 At 10:25 a.m. the reactor was operiod to clean out the remaining UQ. At that time the powder appeared dry to the operator. By J:00 p.m., utilizing three safe batch containers, approximately 28 kg of UO, was cleaned from the reactor bed.

At 6:30 p.m. the calciner gases were shut down. During the day, the calciner had experienced everal pressure spikes. From 10:25 a.m. until 6:30 p.m , there was no nitrogen flow to the reactor. Also, during previous cleaning, there were 20 to 30 minute periods from the time the reactor was closed and the nitrogen purge was initiated.

At 10:05 p.m. with the process shut down, while cleaning out the UQ transfer system between the DCPP and rotary calciner, operating personnel found that the UQ powder was damp Further cleaning of the transfer system identified wet UQ powder in the

- spool piece at the bottom of the reactor.

At 2:20 a.m. on September 17,1997, while continuing the clean out of the system, wet powder was found in the feed tube to the calciner. At 2:45 a.m., by telephone, the shift supervisor notified the Lead Criticality Specialist. All operations with the Mean out were terminated. Samples of the uranium powder removed from the reactor vs,ssel and other portions of the system were submitted to the analyticallaboratory for a moisture analysis.

At 9:30 a.m. on September 17,1997, the sample results indicated that some of the uranium powder from the lower portion of the reactor vessol exceeded the 1.0 wt.%

moisture limit. The sample results from a container with a mix of UQ powder from the -

reactor vessel (6.12 kg) and spool niece (6.4 kg) indicated 1.6 wt % molsture. Sample results from two other containers ol other material removed from the reactor were 1.099 wt.% moisture for a 11.4 kg batch and 0.9279 wt % moisture for a 10.29 kg batch. .

(Under optimura conditions [ fully moderated and reflected with 30 centimeters of water),

at the enrichment [4.2 wt.% U 235) of the material being processed,28 kg represents approximately 59 percent of a critical mass of material.)

At 1:45 p.m. on September 17,1997, the licensee tr.ade a 4 hour4.62963e-5 days <br />0.00111 hours <br />6.613757e-6 weeks <br />1.522e-6 months <br /> report under the requirements of NRC Bulletin 91-01 to the NRC Operation Officer. The licensee considered that the matter was reportable because the CSA had been deficient since November 1993 when the calciner was installed and a potential moisture pathway from the calciner into the reactor was not evaluated,

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8 During facility tours the inspector noted that the licensee had dismantled the feed system. The RAL and transition section at the bottom of the conveyor evidenced caked UO, powder. The screw auger (large flat shaped wire) from inside the conveyor evidenced that significant binding had occurred in the system. One section had been broken off and the remaining section was heavily coiled together as opposed to the normal straight spiral condition.

Prevlous Event The inspector noted that on April 21,1997, the licensee had a similar event where liquid was observed dripping from an inspection cap at the lower end of the screw conveyor. A total of 4.93 kg of wet UO, was cleaned from the lower end conveyor while 3.65 kgs of dry powder was cleaned from the upper end. Approximately 105 kg of UQ in seven batches was removed from the reactor. Sample results of each of the seven containers indicated that the moisture content ranged from 0.0708 to 0.0918 wt.%. Prior to the April event,- there were several evolutions of reactor startup and shut down, and calc!ner start and restart due to upset conditions involving reactor un stabilized temperatures, calciner exhaust blower problems, and pressure differentials during operation.

The licensee's investigation report,

• Pilot Plant Dry Conversion Auger llB,' dated May 7, 1997, indicated that the root causes of the high moisture in the conveyor were :

' Equipment Difficulty, Design, Design Specifications, Problem Not Anticipated in that if there is no powder in the screw conveyor, the rotary air lock or the reactor discharge tube to isolate the atmosphere of the calciner from the atmosphere of the reactor, the reactor blower will produce enough vacuum to pull the calcinar atmosphere over to the reactor. The nitrogen purge installed in the bottom of the screw conveyor does not have enough flow to isolate the two atmospheres as designed."

During discussions with cognizant licensee personnel, the inspector was informed that under normal operating conditions, with fluidizing gases on, the reactor side of the RAL is positive in pressure while the calciner side of the RAL is negative in pressure. Under cold reactor shutdown conditions, with no UO,in the reactor bed, no nitrogen purge on, and the exhaust blower is on, the reactor side of the RAL is more negative in pressure than the calciner.

The licensee determined that the April event was not reportable under the requirements of NRC Bulletin 9101, because the conveyor and calciner are controlled by geometry, and wet UO, was only observed in the geometrically favorable conveyor system. The UO, removed from the reactor was less than the 1.0 wt.% moisture limit.

The inspector noted that a licensee internal memorandum 'Startup Council Meeting Dry Conversion Pilot Plant,' dated May 1,1997, stated,in part, that it was agreed that a change to the operating procedure to assure that fluidizing gases were present in the reactor before steam is turned on to the calciner would preclude a repeat of the incident.

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9 The inspector noted that Operating Procedure No. P66,699, ' Dry Conversion Startup,"

Revision 4, dated May 1,1997, incorporated the initiation of fluidizing gases in the reactor before introducing steam into the calciner.

Operating Procedure No. P66,1002, ' Dry Conversion Pilot Plant Process Shutdown,'

Revision 8, dated June 17,1997, was revised to include procedures for downloading the reactor bed which contained a special note. ' Powder remaining in the feed convevor will maintain a seal between the reactor and calciner keeping the calciner gases from flowing into the reactor.'

During discussions with the criticality safety staff and the process engineer, the inspector was Informed that the liquid in the conveyor tube for the April event was thought to have been from moisture condensing in the calciner's oowder receiver vessel and draining to the bottom of the conveyor tube.

The inspector noted that CSA No. UDRY 3.0, ' Dry Conversion Modification Project F 339,' dated November 22,1993, for the calciner 'nstallation and a subsequent replacement CSA No. U110,

• Dry Conversion Pilot Plant," dated August 2,1995, did not address the potential moisture pathway from the calciner into the reactor, as !:lustrated by this event.

Current Status Relative to the September 17,1997, event, the licensee initiated an incident investigation to determine the cause and corrective actions, prior to any restart of the DCPP.

Regarding a restart time, the licensee informed the inspector that following this past production run, there were no scheduled production runs with the DCPP as all future production of UO, powder would be from the new DCF. Production using enriched uranium in the new DCF was tentatively scheduled for the second week in October 1997.

The licensee also informed the inspector that they were reserving the DCPP for any potential future experimental activities, Regarding operating the new DCF, the applicable CSA had not been completed at the time of the inspection. The licensee Informed the inspector that the findings from the DCPP event wouid be addressed in the CSA for new DCF.

Since the licensee had not completed its investigation, the inspector informed the licensee that a subsequent NRC Inspection would be conducted to independently assess licensee management decision-making, root cause analysis, corrective actions, and overall event analysis relative to the DCPP April and September 1997 events. The inspection would also include the adequacy of the CSAs for the new DCF prior to startup using enriched uranium. The results of NRC's review will be documented in a subsequent inspection report and is considered as an inspection followup item (IFl 701257/9706-01).

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c. Conclusigag I

Operations responded appropriately and the criticality safety component was promptly  !

notified. Licensee management appropriately instituted an incident investment team to i I

review the event, identify the causes, and define corrective actions prior to any restart of the DCPP, and to identify generic implications relative to the new DCF. l 1.4 Miscellaneous ooerational Issues (92702)

(Closed) Violation 701257/9705-01: Fallure to maintain criticality spacing requirements for storage areas on the mezzanine in the gadolinium fuel production area. Based on discussions with cognizant licensee personnel, a review of licensee training records, and a walkdown of the subject storage area, the inspector verified that the licensee had completed the corrective actions described in the licensee's letter dated August 7,1997. ,

No additional cor, , erns were identified by the inspector.

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.2 Radiation Protection

a. insoectinn Scone (83822)

Inspection Report 701257/97-05, dated July 8,1997, documents the review of the 4 licensee's radiation protection program. This inspection (70-1257/97 06) was confined to 1 observations of radiation safety practices during facility tours.  ;

b. Observations and Findinas

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During facility tours, the inspector noted that personnel were appropriately attired in protective clothing as specified on their respective posted radiation job permits and/or as required by the licensee radiation work procedures.- The inspector did not observe any l unsafe radiation safety practices during multiple in plant tours.

Radiation survey instruments at personnel checkout stations appeared to be operating properly and were within their current calibration period. Radiation areas, radioactive materials, and airborne radioactive materials areas were potted as required by 10 CFR Part 20,

c. Conclusions The licensee was adequately implementing its in plant radiation protection controls.

3 Transportation laaue (92702)

(Closed) Violation 70-1257/9704-04: Failure to provide cushioning material in NT IX shipping packages. Based on discussions with cognizant licensee personnel, a review of revised Traffic and Warehousing Procedure No. P43,108,

• Packaging, Shipping and Receiving UO, Powder in NT-IX Shipping Containers,' Revision 7, dated August 21, 1997, a review of training records, and observing the loading of the subject shipping

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I 11 j packages, the inspector verifed that the licensee completed and implemented the  !

corrective actions described in its letter dated June 18,1997. No additional concems t were identified by the inspector. I r

Exit Meeting Summary The inspector presented the inspection results to members of licensee management at the conclusion of the onsite inspection on September 19,1997. The licensee acknowledged the -

findings presented.

Although proprietary information was reviewed during this inspection, such information is not knowingly described in this report.

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ATTACHMENT SUPPLEMENTAL INSPECTION INFORMATION PARTIAL LIST OF PERSONS CONTACTED L!rdtusta B. F. Bentley, Manager, Plant Operations

- J. M. Delst, Criticality Safety Specialist J. B. Edgar, Senior Engineer, Licensing B. N. Femreite, Vice President, Manufacturing D. C. Killan, Manager, Process Engineering L. J. Maas, Manager, Regulatory Compliance C. D. Manning, Lead Criticality Safety Specialist J. H. Phillips, General Supervisor, Chemical Operations T. C. Probasco, Manager, Safety

1. J. Urza, Manager, Manufacturing Technology G. N. Ward, Manager, Manufacturing Engineering L. O. Washington, Process Engineer l

INSPECTION PROCEDURES USED IP 88020: Operations Review  ;

IP 83822: Radiation Protection IP 92701: Followup lP 92702: Followup on Conective Actions for Vic,lations and Deviations ITEMS OPENED, CLOSED, AND DISCUSSED Ooened 70 1257/9706 01 IFl Review of the licensee's investigation of NRC Bulletin 91-01 reportable event (No. 32949)

Closed 70-1257/94 04 VIO Failure to follow transportation packaging requirements 70 1257/9705-01 VIO Failure to implement criticality safety spacing requirements LIST OF ACRONYMS USED CSA criticality safety analysis CSS criticality safety specification DCF Dry Conversion Facility DCPP Dry Conversion Pilot Plant kg kilograms RAL rotary air lock SI International System of Units UF. uranium hexafluoride UNH uranyl nitrate hexahydrate UO, . uranium dioxide wt % weight percent

y. v ATTACHMENT SUPPLEMENTAL INSPECTION INFORMATION PARTIAL LIST OF PERSONS CONTACTED l Licensee B. F. Bentley, Manager, Plant Operations J. M. Delst, Criticality Safety Specialist J. B. Edgar, Senior Engineer, Licensing B. N. Femreite, Vice President, Manufacturing D. C. Kilian, Manager, Process Engineering L. J. Maas, Manager, Regulatory Compilance C. D. Manning, Lead Criticality Safety Specialist J. H. Phillips, General Supervisor, Chemical Operations T. C. Probasco, Manager, Safety

1. J. Urza, Manager, Manufacturing Technology G. N. Ward, Manager,

• Manufacturing Engineering L. O. Washington, Process Engineer INSPECTION PROCEDURES USED lP 88020: Operations Review IP 83822: Radiation Protection IP 92701: Followup IP 92702: Followup on Corrective Actions for Violations and Deviations ITEMS OPENED, CLOSED, AND DISCUSSED Ooened 70-1257/9706-01 IFl Review of the licensee's investigation of NRC Bulletill 91-01 reportable event (No. 32949)

Cloind 70-1257/94-04 VIO Failure to follow transportation packaging requirements 70-1257/9705-01 VIO Failure to implement criticality safety spacing requirements LIST OF ACRONYMS USED CSA criticality safety analysis CSS criticality safety specification DCF Dry Conversion Facility DCPP Dry Conversion Pilot Plant kg kilograms RAL rotary air lock SI International System of Units U F. . uranium hexafluoride UNH uranyl nitrate hexahydrate UO, uranium dioxide wt.% weight percent

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