Industry SNM Operating Experience

Industry SNM Operating Experience

Tom Morello and Nicole WalkerConstellation Energy

Overview

Introduction SNM Operating Experience Cause Compliance Conclusion

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Incore Detector Containing Special Nuclear Material Inappropriately

Released From Storage (OE24386)

February 12, 2007 Event:• Maintenance removed an incore detector from its

storage location without prior notification to Radiation Protection.

• The incore detector contained SNM, but there were no labels signifying this on the detector storage area.

• The area housing the detector was controlled with a Radiation Protection key.

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Event Continued:• Assumed that detector was not under RWP control

(not labeled SNM)

Causes:• SNM storage areas not labeled, but required by

procedure

• The supervisor of storeroom maintained a key which RP should have had instead

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Ensuring Compliance:• Label SNM storage areas

• Train personnel about SNM storage and accountability (Radiation Protection, Security, etc)

• Ensure SNM is stored separately from other non-SNM materials

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Inadequte Control of Special Nuclear Material Located Outside Protected

Area (OE29504)

December 6, 2008 Event:• An intermediate range nuclear instrument detector

was found in a storage area outside the plant’s Protected Area, but within the Owner Controlled Area.

• The detector contained about 7.12 g of U-235

• The SNM custodian understood SNM requirements:– Stored in a locked, radiologically-controlled area

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Area (OE29504)

Event Continued:• SNM custodian unaware SNM required by

procedure to be in Protected Area (PA)

• Security review of procedures in 2009 led to discovery of the source’s location

• The SNM was relocated inside the PA and tamper-indicating tape was placed on container

Cause:• Procedure for SNM Control- inadequate

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Area (OE29504)

Ensuring Compliance:• Correct procedure use

• Procedure should only allow storage of SNM in ICA’s in the protected area

8

Loss of Accountability of Less Than 1 Gram of SNM (OE24760)

April 4, 2007 Event:• In 1990, an assembly was disassembled for rod

inspections

• One of the rods was confirmed failed, but bent and snapped while in fuel inspection funnel.

• A bucket placed under the broken fuel rod segments contained small dark particles and a small piece of material

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Event Continued:• The small piece of material was suspected to be less

than 10% of a single pellet’s worth (less than 1 gram).

• Greater than 400 Rad/hr on contact- most likely a piece of fuel pellet

• The bucket and its contents were hung on a wall in the Spent Fuel Pool

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Event Continued:• The next refueling outage, the bucket was knocked

into the pool resulting in a loss of control of licensed material.

• This was reportable under 10CFR20.2201

Causes:• Not understanding the requirements for tracking less

than 1 gram of SNM

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Ensuring Compliance:• Understand reporting requirements for all SNM

• Do not use an open container, like a bucket, to store SNM

12

Reportable Quantity of SNM Was Not Being Reported (OE29634)

August 4, 2009 Event:• Audit showed the Plutonium-Beryllium(PuBe)

source was not being reported on the annual NRC form 742.

• The source had material type 83 (Pu-238).

• The source contained 0.33 g of Pu-238. Type 83 material should have been tracked to the nearest 0.1g (NuReg/BR-0007)

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Event Continued:• There was no form 741 because there was less than

1.0 g of SNM.

• Radiation Protection manuals processed the receipt of the source; documentation is limited

• The source was tracked and verified semiannually.

• A form 741 will be generated, and the source will be added to the yearly Material Balance Report.

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Cause:• Lack of understanding of tracking and reporting of

requirements of material type 83.

Ensuring Compliance:• Report type 83 material to nearest 0.1g.

• Ensure understanding of material types in any sources on site.

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Special Nuclear Material Reporting Requirements Not Met on Reactor

Vessel Head (OE25343)

June 19, 2009 Event:• Comanche Peak agreed to notify NMMSS within 30

days of plant start up of it’s new Japanese reactor vessel head.

• Because part of the vessel head was made in Japan, CPNPP had new SNM tracking requirements.

• After 59 days of operation, there was still no report on the change in obligations.

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Event Continued:• CPNPP also discovered errors in their obligation

codes for the fuel that was in the core.

• Upon agreement between NMMSS, Reg Affairs, and the NRC, CPNPP had to submit the corrections from the fuel receipt, and then submit the Japanese obligation.

Causes:• Errors in tracking and documenting SNM

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Ensuring Compliance:• Report head obligation material in accordance with

the agreement with the NRC.

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Plutonium and U234/U235 Sources Not Tracked by the SNM Program

(OE24419)

February 2, 2007 Event:• Radiation Protection asked to identify any non-fuel

SNM.– Discovered 14 electroplated Pu-239 disk sources and 6

U234/U235 sources

• RP procedures require inventory every 3 months, so the detectors were accounted for and controlled as licensed material

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(OE24419)

Event Continued:• The sources were never part of the SNM inventory

(already inventoried by RP procedures)

• All non-fuel SNM are required to be included in the SNM inventory

Causes:• Lack of understanding of the SNM reporting

requirements for non-fuel SNM.

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(OE24419)

Ensuring Compliance:• Update procedures to include any sources (even

ones owned by RP) in the SNM physical inventory.

• Incorporate RP so that they report SNM inventory to the SNM custodian.

• Track check sources (either SNM custodian or RP)

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Special Nuclear Material Inventory Error (OE24314)

February 6, 2007 Event:• Failed source range monitors, intermediate range

monitors, and TIP detectors were stored in a designated location in Radwaste Building

• In November 2000, a non-irradiating traversing in-core probe (TIP) was documented as being in storage drum 471 with tamper proof seal.

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Event continued:• A source range monitor (SRM) documented to be in

a drum numbered 742 with tamper proof seal.

• Storage drum 742 was shipped off-site.

• Reactor engineering was performing inventory and noticed that the TIP detector was not in its specified location in the SNM Inventory Account.

• A radioactive material bag labeled “TIP cables” was found in drum 471, instead.

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Event Continued:• The tamper proof seal on drum 741 was not

breached from 2000-2007.

• A radioactive material bag labeled SRM cable had an SRM. The SRM was not included in the annual inventory.

Cause:• Site personnel relied on the description and date of

the RAM tag to identify the contents.24


Ensuring Compliance:• Follow procedures and SNM inventory requirements

• Update procedures to label/tag storage areas better.

• Do not rely on tags/labels

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Tamper Indicating Devices on Detector Storage Containers Inadequate

(OE25059)

June 14, 2007 Event:• An NRC Material Control and Accountability Audit

performed.

• Locks on storage areas for fission chambers not adequate.

• A controlled key is not an acceptable substitute even though site personnel argued the locks would have to be physically broken for an unapproved access.

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Tamper Indicating Devices on Detector Storage Containers Inadequate

(OE25059)

Ensuring Compliance:• Install tamper evident devices on storage containers

used to store non-exempt detectors

• Perform a piece count of the detectors.

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Special Nuclear Material Movement Authorization Sheet did not Specify Correct

Location for Fuel Assembly in SFP During MPC Loading (OE29837)

June 25, 2009 Event:• After first ISFSI campaign, there were

supplemental moves that needed to be done before the 2nd loading.

• The supplemental moves were not completed until a week later, so only the first ISFSI loading move sheets were updated in the fuel accountability database.

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Event continued:• The second cask loading move sheets were issued

without first completing the supplemental moves.

• The supplemental moves were completed that same day, as was the database.

• During the 2nd cask loading, the fuel handling supervisor noticed that there was not an assembly in the location specified by the move sheet.

• Work stopped until the issue was resolved.

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Event Continued:• The SFP map was accurate, not the move sheets for

the 2nd cask loading.

Cause:• Move sheets were made before the previous set of

move sheets were retrieved and used to update the fuel accountability database.

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Ensuring Compliance:• Procedures should allow only one set of move sheets

at a time (except for core alterations)

• Update database before planning more moves.

• Require that all move sheets be returned to the SNM custodian at the end of shift for database updates (except for core alterations)

• Use a database or procedure that ensures plant configurations are up to date.

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Special Nuclear Material Inventory Discrepancy (OE29563)

July 22, 2009 Event:• A SFP cleanup campaign held in February 2005. It

staged detectors into a shipping cask for disposal. No LPRM canisters were shipped offsite.

• An unirradiated local power range monitor detector was expected to be stored in a canister in a SFP drum.

• The detector continued to be on the SNM inventory32


Event continued:• The detector could not be located during an SNM

inventory.

• SNM Tracking Sheet STS-1-14-21 showed the detector being shipped to Barnwell, SC in February 2005.

Causes:• Assuming the detector was stored in the detector

canister. 33


Ensuring Compliance:• Adhere to procedure to properly store SNM in

identifiable containers.

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Industry SNM Operating Experience

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