ML20151J542

Supplements Amend Request Re Spent Fuel Pool Special Ventilation Sys Specifications.Responses to NRC RAI Dtd 970710,provided

ML20151J542
Person / Time
Site:	Prairie Island
Issue date:	07/29/1997
From:	Richard Anderson NORTHERN STATES POWER CO.
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
NUDOCS 9708050170
Download: ML20151J542 (6)

Text

Northern states Power Company 1717 Wakonade Dr. E.

Welch, MN 55089 Telephone 612 388-1121 July 29,1997 l

10 CFR Part 50  !

Section 50.90 U S Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555 1

PRAIRIE ISLAND NUC' EAR GENERATING PLANT Docket Nos. 50-282 License Nos. DPR-42 1 50-306 DPR-60 I License Amendment Request Dated May 7,1997 Supplement to the Amendment of Spent Fuel Pool Special Ventilation Systegl Specifications This letter is submit;sd to supplement the subject license amendment request pursuant to discussions witi the NRC Staff and provide NSP responses to the NRC request for additional informaiion dated July 10,1997. The document entitled,

" Answers to the NRC Request for Additional Information for Review of the Amendment of the Spent Fuel Pool Special Ventilation Zone Technical Specifications", is included as Attachment 1.

The original license amendment request stated on page 3 in Exhibit A, " Prairie Island has also upgraded the west hoist on the spent fuel pool bridge crane to meet the design criteria of NUREG-0612." Pursuant to discussions with the NRC Staff this statemant ic c!arifiec' as follows. The spent fuel pool bridge crane is a wheel-mounted walkway, spanning the spent fuel pool which carries elecu monorail hoists on an overhead structure. The spent fuel pool bridge crane has two hoists, designated the East Hoist and the West Hoist. In 1990, NSP replaced the spent fuel pool crane bridge and West Hoist with a model that meets the single-feilure-proof criteria of NUREG-0554. The East Hoist is a 2-ton capacity non-single-failure-proof  ;

hoist used for general fuel handling and Unit 1 refuelings. The West Holst is a ,

single-failure-proof, 3-ton design rated load, 3700 pound maximum critical load hoist l used for general fuel handling, Unit 2 refuelings, and heavy load lifting. The West

' i Hoist is specifically designed for moving heavy loads in the spent fuel pool D j l

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.P"g3 2 cf 2 enclosure. In addition, the West Hoist has the capability to transfer out to the New Fuel Crane located outside the spent fuel pool enclosure for movement of new fuel assemblies from the new fuel containers to the New Fuel Pit.

NSP requests that the subject license amendment request be issued by September 10,1997. Our previous supplement, dated May 30,1997, to this license amendment request, requested NRC review and approval by August 15,1997. The new date is possible through adjustment of the new fuel shipping schedule.

A revised SL. ty Evaluation, Significant Hazards Determination and Environmental Assessment have not been submitted with the additional information provided by this letter since these evaluations, as originally presented in the May 7,1997 submittal, continue to bound the proposed license amendment as modified by this supplement.

If you have any questions related to this information in support of the subject license amendment request, please contact Dale Vincent at 612-388-1121.

f h Ro O. Anderson Director, Nuclear Energy Engineering Attachments:

Affidavit

1. Answers to the NRC Request for Additional Information for Review of the Amendment of the Spent Fuel Pool Special Ventilation Zone Technical Specifications c: Regional Administrator-lil, NRC NRR Project Manager, NRC Senior Resident inspector, NRC I State of Minnesota Attn: Kris Sanda J E Silberg

i l . .

UNITED STATES NUCLEAR REGULATORY COMMISSION l

NORTHERN STATES POWER COMPANY PRAIRIE ISLAND NUCLEAR GENERATING PLANT DOCKET Nos. 50-282 50-306 REQUEST FOR AMENDMENT TO OPERATING LICENSES DPR-42 & DPR-60 LICENSE AMENDMENT REQUEST DATED May 7,1997 Amendment of Spent Fuel Pool Special Ventilation System Specifications Northern States Power Company, a Minnesota corporation, by this letter dated July l

29,1997 provides supplemental information in support of the subject license amendment request dated May 7,1997. Attachment 1 provides responses to the NRC request for additional information dated July 10,1997.

l This letter and its attachments contain no restricted or other defense information.

i

! NOR ERN STATES P WER COMPANY By en  % _

Rdger,D. Anderson Director, Nuclear Energy Engineering i

On this 2_#1 day of 34^ !v l99) before me a notary public in and for said County, personally 6ppeared, Roger O. Anderson, Director, Nuclear Energy Engineering, and being first duly sworn acknowledged that he is authorized to execute this document on behalf of Northern States Power Company,

, that he knows the contents thereof, and that to the best of his knowledge, l

information, and belief the statements made in it are true and that it is not inter-l posed for delay.

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ATTACHMENT 1 l-Supplement dated July 21,1997 License Amendment Request Dated May 7,1997  ;

Amendment of SDent Fuel Pool Special Ventilation System Specifications j Answers to the NRC Request for Additional Information for Review of the I

- Amendment of the Spent Fuel Pool Soecial Ventilation Zone Technical Specifications i

The NRC Staff request for additional information dated July 10,1997 asks questions on spent fuel storage cask unloading operations as they relate to the spent fuel pool  ;

special ventilation system operability. The license amendment request to amend the spent fuel pool special ventilation system specifications, dated May 7,1997, does not alter the cask unloading process described in the Prairie Island independent spent fuel storage installation (ISFSI) safety analysis report (SAR) or operating procedures. The cask unloading process described in the SAR was reviewed during ISFSI licensing

(

Reference:

SNM-2506, October 19,1993). The cask loading and unloading procedures were reviewed in detail by the NRC during a pre-operational inspection

(

Reference:

Inspection Report No. 50-282/95002(DRP),50-306/95002, 72-10/95002(DRP). Cask handling activities at Prairie Island have also been reviewed i by the NRC under two previous license amendments (Amendment 74,6/26/85 and l Amendment 99,7/9/92). Both of these amendments were explicit in ngt tal ing credit for the spent fuel pool special ventilation system. The following responses summarize the previous NRC reviews of these areas.

l Question 1 Step 8.27 of D95.2, "TN-40 Cask Unloading Procedure" directs the cask to be filled with water. The caution prior to step 8.27 reads, "The water / steam mixture from the vent port hose may contain some radioactive gas. The area directly above where the hose is discharging shall be closely monitored to determine if there is a radiological hazard." is the spent fuel pool special ventilation system operable during the performance of this step of the unloading procedure? If the spent fuel pool special ventilation system is inoperable during this step and other portions of the unloading procedure because the overhead crane is supporting the cask through the open spent fuel pool enclosure slot doors, discuss why an inoperable i ventilation system does not pose a radiological hazard and give any

! precautions and protections that ensure that 10 CFR Part 20 and Part 100

. requirements are not exceeded.~ ,

j Ans 1.The spent fuel pool special ventilation system is inoperable during this step of )

j the cask unloading. The inoperability of the spent fuel pool special ventilation

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system does not pose a radiological hazard because no radioactive gases are  !

postulated to be present during cask refilling operations. The Caution prior to l Step 8.27 was included as a prudent, general precaution to alert the unloading i personnel to monitor the vent line for any unexpected radiological condition.

The cask seal integrity is monitored during storage and would alert the Praine  :

Island staff to any problem before oxidation of any cladding could occur. Cask )

seal integrity monitoring alone is considered adequate by the NRC staff to ensure that no damaged or oxided fuel exists in the cask (Ref: NUREG-1567, Page 5-8, item 4) and thus the absence of radioactive gases is assured. In addition to cask seal integrity monitoring, the Prairie Island cask unloading l procedure includes a step to sample the cask cavity gas to verify that no '

radioactive gases are present. If any radioactive gases were detecteo, appropriate measures, such as purging of the cask cavity to a filtered, monitored flow path, would be incorporated. Plant management review is required of any such precautions prior to continuing with the unloading process.

The discharge of the cask vent line during refilling operation is routed below the spent fuel pool surface in order to condense any steam generated. This will preclude the possibility of any significant radiological conditions. This conclusion is shared by the NRC as described in a letter from Gail Marcus (Project Director, Project Directorate 111-3) to Mr. George Crocker, dated February 25,1997.

Question 2 Section 5.5 of the Prairie Island ISFSI (independent spent fuel storage installation) safety analysis report (SAR) states in part, "After moving the cask into the fuel pool area, the cavity will be depressurized and the cask lowered into the spent fuel pool." However, Step 8.4 of procedure D95.2 directs the cask to be depressurized while it is still located in the rail bay area. Explain the discrepancy between the two documents. Also, what is the basis for the SAR requiring the cask to be moved to the spent fuel pool area prior to depressurizat!on? Does the SAR assume that the spent fuel pool special ventilation system will be operable during the cask depressurization evolution?

Ans 2.The SAR does not assume that the spent fuel pool special ventilation system is i

operable during the cask venting. The cask unloading procedure directs the L cask venting to be performed in the cask decontamination area (rail bay) in order to perform this step prior to lifting the cask with the auxiliary building crane. This was done to allow this evolution to be performed in a more controlled manner

( without the cask suspended from the crane hook. It also allows the cask bolts to j be de-torqued before the cask is suspended from the hook. An additional i benefit of this sequence is that it allows the cavity contents to be vented through i

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a tube into the spent fuel pool with the spent fuel pool special ventilation system l operable, in case any unexpected radiological gases were to be found in the cask.

As described in the NRC SER for the ISFSI, the SAR provides a " general description of the operational procedures for loading the cask and preparing it for storage" and " detailed procedures for loading, draining and drying the cask,

... should be developed before NSP loads fuel into the first cask". Cask unloading procedures were prepared to provide those specific detailed instructions prior to loading the first cask.

l Question 3 i

When the spent fuel cask is filled with water prior to unloading the fuel (per Step 8.27 of D95.2,"TN-40 Cask Unloading Procedure"), discuss the  ;

l likelihood that this will result in cracking of the spent fuel rods due to the l interaction of the cool spent fuel pool water with the hot fuel elements. If l any fuel cracking is predicted, list the expected radionuclides and l quantitles that will be released into the cask and into the fuel building when the cask is vented. If the filtered ventilation system is not operating i during cask venting, describe how you plan to detect and prevent these radioactive gases from being released into the environment. I

3. No cracking of the spent fuel rods due to the interaction of the cold spent fuel pool water with the hot fuel elements is expected to occur during cask refilling.

Therefore a filtered vent system is not needed. This expectation for lack of fuel damage during refilling is based on extensive experience with safely unloading Transnuclear shipping casks. These shipping casks typically have much higher fuel temperatures than the TN-40 cask. For example, the TN-12 transportation cask has a fuel cladding design temperature of 531 C (987 F), compared to the i TN-40 maximum normal cladding temperature of 317 C (602 F). Transnuclear and their parent company, Transnuclaire, Paris, maintain a shipping cask fleet of approximately 100 shipping casks that are in constant use throughout the world. l The above referenced February 25,1997 letter from the NRC to Mr. George l Crocker supports the conclusion that spent fuel rod cracking is not expected, stating "The fuel is also expected to maintain its integrity during the refilling of

! the cask during the unloading process". The vented gases are monitored as a further precaution and remedial filtering would be established if required.

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