ML20116C129

Rev 0 to Action Plan to Address Fuel Loading Incident at Plant

ML20116C129
Person / Time
Site:	Point Beach
Issue date:	06/04/1996
From:	Chechelnitsky, Dixon G, Wenner T SIERRA NUCLEAR, INC.
To:
Shared Package
ML20116B333	List: ML20116C129 ML20116C264 ML20116C347 ML20116C358
References
FOIA-96-244 WEP04-08, WEP4-8, NUDOCS 9607310020
Download: ML20116C129 (11)

Text

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- Scotts Valley, CA 95066 Roswell, GA 30075 Phone (408F438 6444 Phone (404)-518 7785 Fax (408) 438 5206 Fax (404F518 7883 DOCUMENT NO. WEP04-08 REVIS10.1NO. 0 DATE: June 4,1996 PREPARED BY: T. J. Wenner PAGE 1 OF 6 TITLE: Action Plan To Address Fuel Loading incident at Point Beach I

Reviewed and

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BfA) Chechelnitsky ', Engineering Manager c/4/%

6 ate Reviewed and 3 $lf" Q#.W-T. J. Mnner, Vice President Operations

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Reviewed and

^ f" R1 G.N. Dixo'n Jr.,'Vice fresgat, Quality Assurance! Control duIn Da'te Reviewed and By:- / S 9!94 A. J. McSherry, Pfent Da'te M ONLY File: eAlicense\rnisc\actptn.2

, SIERRA NUCLEAR CORPORATION i

i DOCUMENT NO. Anachment 1 CAR-96-07 REVISION No. O PACE 2 OF 6 TITLE: Action Plan To Address to the Fuel Loading Incident at Poira Beach

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1.0 Purpose The purpose of this document is to establish the actions to be completed during the investigation of the fuel loading incident of a VSC 24 MSB at Wisconsin's Point Beach Nuclear Plant on May 28,1996. SNC will work with WEPCO personnel and will sham all information collected and/or developed.

As this incident has been determmed to be potentially reportable in accordance with 10CFR Part 21, Corrective Action Request CAR 96-07, his been issued for processing in accordance with QAP 15.2.

2.0 Reference (s) 2.1 Corrective Action Request CAR 96-07 3.0 Responsibility The Vice President of Operations shall be responsible for ensunng implementation and completion of this action plan.

) 4.0 Schedule The planned schedule for completion is June 30,1996.

5.0 Documentation All actions shall be documented in the form of written reports. Where analysis activities are required they shall be completed and documented in accordance with SNC's Design Control Tro:edure QAP 3.0.

f9 Action (s) 6.1 Send letters to VSC clients formally advising them of the incident and advising them that their procedures should include venting of the air space in the MSB prior to performing any activity such as welding, cuttmg, grinding etc. on the shield lid.

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SIERRA NUCLEAR CORPORATION DOCLIMENT NO. Attaciunent 1 CAR.%07 REVISION NO. O PAGE 3 OF 6 !

TrTLE: Action Plan To Address to the Fuel Loading incident at Point Beach l

I l l 6.2 Research the design process and data used to select the carbo zine coating.  !

Assemble a package containing this information for review / discussion with the

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NRC and clients. '

6.3 Assess the potential sources for generating hydrogen in the MSB.

6.3.1 Reaction of carbo zine with pool water 1

a. Determine how carbo zine reacts with pool water, i.e. what 1 chemical compounds will be produced. I

b. Calculate the estimated rate of hydrogen generation.

c. Calculate how long it would take (at the calculated rate of hydrogen generation) to reach the hydrogen concentration in the air l space necessary to cause ignition.

l d. Compare this time with the actual time between shield lid l placement and the time that the incident occurred.  !

c. Assess if the carbo zine reaction makes sense as the primary source (or a contributing source) for the hydrogen in the MSB. 1 1

i 6.3.2 Radiolysis

a. Estimate the hydrogen generation rate from radiolysis within the MSB.

b. Calculate how long it would take (at the calculated rate of 1 l hydrogen generation) to reach the hydrogen concentration in the air space necessary to cause ignition.

c. Compare this time with the actual time between shield lid placement and the time that the incident occurred.

d. Assess if the radiolysis makes sense as the primary source (or a contributing source) for the hydrogen in the MSB.

6.4 Evaluate observations from the incident and their possible consequences.

l l 6.4.1 Evaluate effect of chemical reactions on boron concentration in the MSB.

a. Determine if boron concentration is reduced as a result of carbo zine reaction.

b. Determine solubility of resultant compounds.

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SIERRA NUCLEAR CORPORATION DOCUMENT NO. Attachment I CAR 96-07 REVISION NO. O PAGE 4 OF 6 TITLE: Action Plan To Address to the fuel Loading incident at Point Beach

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c. Determine effects, if any, on criticality analysis.

6.4.2 Evaluate effect ofincident on fuel assemblies.

a. Visually inspect assemblies.

b. Determme loads (pressure) experienced by assemblies.

c. Evaluate effects of pressure on assemblies.

6.4.3 Evaluate white substance found in pool after MSB was unloaded.

a. Determine what substance is composed of.

b. Determine how it was produced.

c. Evaluate the effect/ consequences ofits presence.

6.5 Assess the effects of this incident on previously loaded casks.

6.5.1 Assess potential for continued hydrogen generation in casks ilmt have been drained and dried.

a. From residual water, y

b. From any residue generated during loading.

6.5.2 Evaluate possible formation of precipitate during the loading process from the pool water / carbo zine reaction.

a. Determine if precipitate will form.

b. If so, determine which compounds are formed.

c. Determine effect on MSB performance.

6.5.3 Assess any residual effects from possible burn in previously loaded casks.

a. Evaluate effects of combustion products /rcsidue on MSB performance.

b. Evaluate possible coating damage and effects on MSB performance.

c. Evaluate pressure stresses.

SIERRA NUCLEAR CORPORATION DOCUMENT NO. Attachment 1 CAR-96-07 REVISION NO. O PACE 5 OF 6 TITLE: Action Plan To Address to the Fuel Loading Incident at Point Beach

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6.5.4 Evaluate the possibility and consequences of hydrogen contamination of shield lid weld.

6.6 Develop actions to preclude similar incidents.

6.6.1 Loading procedures

a. Use previously successful loadings at Palisades as a base.

b. Identify measures taken by Palisades which precluded a similar

- incident.

c. Investigate possible measures to prevent similar incidents.

- Increase amount of water pumped out prior to welding.

- Create negative pressure in air space prior to and during welding.

- Check for combustible gas prior to and during welding.

- Others as appropriate.

6.6.2 Design improvements - future casks

a. Investigate ways to mitigate hydrogen generation.

- Possible installation of hydrogen " getters".

- Investigate altemate coatings or application of a suitable topcoat.

b. Investigate way.s of decreasing hydrogen generation rate.

- Changes in paint procedure.

- Possible acid wash.

6.63 Advise clients /NRC of actions necessary to prevent a similar incident.

6.7 Evaluate the suitability for future use of the MSB involved in the incident.

l 6.7.1 Structural integrity

a. Calculate the pressure that the MSB was subjected to.

b. Evaluate the effect of this pressure on the MSB.

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SIERRA NUCLEAR CORPORATION DOCUMENT NO. Attachment 1 CAR-96-07 REVISION NO. O PAGE 6 OF 6 TITLE. Action Plan To Address io the Fuel Loading locident at Point Beach

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6.7.2 Effects of possible residue

a. Check MSB for presence of residue.

b. Remove residue or evaluate to confirm that its presence does not affect MSB performance.

6.8 Complete 10CFR21 evaluation 6.8.1 Determine whether or not incident is reportable under 10CFR21.

6.8.2 Advise NRC and clients of the conclusion from this evaluation and the basis for this conclusion.

6.9 Assist utilities with evaluations required to address confirmatory action letters.

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SELECTION OF CARBO ZINC 11 FOR USE IN COATING MSBs

• MSBs require coating to protect the spent fuel pool from corrosion products of the carbon steel shell and intemals.

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• An evaluation was completed in 1990 of available coating materials that could meet VSC operational requirements.

. Resistance to radiation.

• Maintain intergity at relatively high 700'F temperature inside MSB.

e Using all information sources available at the time including paint vendors, operators of nuclear power plants, and relevent nuclear industry )

experience, zine based inorganic coatings were selected.

1 e Carbo Zine 11 l I

e Dimetcote 6 I e Carbo Zinc 11 was selected because it was extensively used in the I nuclear industry and significant testing confirmed its performance.

. Carbo Zinc 11 was the only coating approved for use in the Palisades spent fuel pool at the time of coating selection.

e Main focus of selection involved performance in the spent fuel pool.

• Discussions with several nuclear organizations did not identify concerns with hydrogen generation due to contact with spent fuel pool water.

e Hydrogen generation in a closed spent fuel cask filled with fuel l pool water was never identified as a concern.

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SELECTION OF CARBO ZINC 11 FOR USE IN COATING MSBs (continued) a Until ircident at Point Beach, SNC was not aware of any combustible gas conc,trns with the VSC.  ;

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• SNC has put together an action plan to address hydrogen generation within the MSB during loading operations.

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• Preliminary conclusion is that procedural changes will eliminate the potential for combustible concentrations of hydrogen being I

present during MSB closure operations.

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. i RELEVANT DIFFERENCES IN LOADING PROCEDURES PALISADES VS. POINT BEACH Point Beach e Vent in shield lid closed prior to and during welding.

. 30 Gals. of water pumped out prior to welding shield lid. ,

- Amount of water pumped out determined by pumping time. '

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• MSB #3 sat for 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> niter pumpdown prior to start of welding.

1 e Appearance ofloose Carbo Zinc on surface of spent fuel pool.

- Increases potential for hydrogen generation e Shims for shield lid installed using pneumatic tool (tighter fit).

J Palisades

) e Vent in shield lid open prior to and during welding.

• Slight negative pressure created in air space prior to and during welding, e 75 gals. of water pumped out prior to welding shield lid.

- Amount of water pumped out is measured.

. Lid welding activities started immediately after pumpdown.

• No appearance ofloose Carbo Zine on surface of spent fuel pool.

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= Shims for shield lid installed by hand (looser fit).

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RECOMMENDED ACTIONS TO PREVENT l RECURRENCE l

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j e Follow approach used in 13 previously successful loadings at Palisades.

• Assure loose Carbo Zine is removed from interior of MSB.

• Pump out at least 75 gals. of water prior to welding shield lid.

- Measure amount ofwater pumped out to assure accuracy.

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• Keep vent in shield ild open until water is completely removed.

• Maintain slight negative pressure in air space prior to and during l

welding.

. Check for combustible gas in area of welding prior to start of welding.

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• Start shield lid welding activities immediately after pumpdown.

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~h-i TOTAL P.05 4

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