ML20036C469
| ML20036C469 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 06/08/1993 |
| From: | Richard Anderson NORTHERN STATES POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| IEB-93-002, IEB-93-2, NUDOCS 9306170143 | |
| Download: ML20036C469 (5) | |
Text
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J Northem States Power Company 414 Nicollet Mall Minneapolis, Minnesota 55401-1927 Telephone (612) 330-5500 June 8, 1993 US Nuclear Regulatory Commission 10 CPR Part 50 Attn:
Document Control Desk Section 50.54(f)
Washington, DC 20555 MONTICELID NUCLEAR GENERATING PLANT Docket No. 50-263 License No. DPR-22 Response to NRC Bulletin 93-02, " Debris Plugging of Emergency Core Cooling Suction Strainers" The following information is provided in response to the reporting requirements contained in NRC Bulletin 93-02, " Debris Plugging of. Emergency Core Cooling Suction Strainers".
Reporting Requirement No. 1 states:
Within 30 days of the date of this bulletin, a written response stating whether the actions requested [by the bulletin) have been or will be performed.
If the use of such material is identified, this written response shall also include the locations and quantity of use, any immediate compensatory measures taken, and the current schedule for removal of the material.
' Response The Monticello Nuclear Generating Plant does not have any fibrous air filters-or other temporary sources of fibrous material stored in the primary I
containment. Attachment 2 to this letter provides our response to the requested actions specified in NRC Bulletin 93-02, " Debris Plugging of Emergency Core Cooling Suction Strainers".
Reporting Requirement No. 2 states:
Within 30 days of completion of the requested actions, [ provide) a report confirming" completion.
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Response
All actions requested by the bulletin are complete, this letter satisfies Reporting Requirement No. 2 of NRC Bulletin 93-02.
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Reporting Requirement No. 3 states:
If an addressee proposes not to take the actions requested in this i
bulletin, provide to the NRC staff, within 30 days of the date of this bulletin, your proposed alternative course of action and a justification for any deviations from the requested actions.
Response
This item is not applicable to the Monticello Nuclear Generating Plant.
This letter contains no new NRC commitments, nor does it modify any prior commitments.
Please contact Marv Engen, Sr Licensing Engineer, at (612) 295-1291 if you require further information.
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' Roger 0 Anderson i
Director Licensing and Management Issues cc:
Regional Administrator - III, NRC NRR Project Manager, NRC Sr Resident Inspector, NRC State of Minnesota.
Attn: Kris Sanda J Silberg
. Attachments:
1)
Affidavit to the US Nuclear Regulatory Commission i
2)
Response to Requested Actions of NRC Bulletin No. 93-02 L
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1 ATTACHMENT 1 UNITED STATES NUCLEAR REGULATORY COMMISSION
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NORTilERN STATES POWER COMPANY j
l MONTICELID NUCLEAR GENERATING PLANT DOCKET No. 50-263
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DEBRIS PLUGGING OF EMFRGENCY CORE COOLING SUCTION STRAINERS Northern States Power Company, a Minnesota corporation, with this letter is submitting information requested by NRC Bulletin 93-02, Debris Plugging of Emergency Core Cooling Suction Strainers, pursuant to 10 CFR 50.54(f).
This letter contains no restricted or other defense information.
NORTHERN STATES POWER COMPANY l//Dfk -W fdm-7 ll By 7 jdger 0 Anderson l
l Director Licensing and Management Issues On this day of
/#93 before me a notary public in and forsaidCounty,pe/fonallyappeare'dRoger0 Anderson,DirectorLicensingand.
Management Issues, 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, information, and belief the statements made'in it are true and that it is not interposed for delay.
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June 8, 1993 j
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Response to Reauested Actions of NRC Bulletin No. 93-02 l
i Reauested Actions Identify fibrous air filters or other temporary sources of fibrous j
material, not designed to withstand a LOCA, which are installed or stored in your primary containment. Take any immediate compensatory measures which may be required to assure the functional capability of-the ECCS. Take prompt action to remove any such material.
Because of the low probability of a LOCA event, the staff considers removal of this material at the next shutdown,.or within 120 days, whichever comes first, to be sufficiently prompt.
If the facility is currently in a.
shutdown, you are requested to remove such material prior to restart.
Resoonse:
No fibrous air filters are used or stored within the Monticello primary containment. At one time this type of filter was utilized in the Drywell Cooling System, however; the fibrous type filter had been replaced with a cleanable stainless steel type of filter due to disintegration of the fibrous type, and subsequent plugging of the drywell cooling coils.
In addition, we 4
do not store any temporary fibrous material.in the primary containment.
The Monticello containment is of a General Electric Boiling Water. Reactor Mark I design.
The primary containment design consists of a drywell, which 1
encloses the reactor vessel and recirculation pumps, a separate enclosed torus pressure suppression chamber which-stores a large volume of water, and the connecting vent system between the drywell and the torus suppression chamber.
j The Monticello containment design is not vulnerable to inadvertent-introduction of foreign material to the torus during plant operation as the torus is-closed, with the manways bolted shut, and inerted with nitrogen.
- During periods of extended plant shutdown for refueling, the torus has been routinely opened for torus preservation and maintenance activities.
l Monticello has pursued. an aggressive program of torus preservation and
. cleanliness during past refueling outages.
This program has included the complete. drain down of the1 torus structure, visual inspection of the' torus-internal structures., torus shell surface preparation, torus shell preservation
. painting, and visual ~ inspection for cleanliness prior to reflood of the torus.
. i Cleanliness inspections have also been performed of the drywell. interior prior to closure following a refuel outage.
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In addition, the Monticello Emergency Core Cooling Systems (ECCS) pump suction design employs a common ECCS ring header to rupply suction to all ECCS pumps.
This ring header, encircling the torus exterior, is supplied with torus water which' passes through four ECCS suction strainers separated approximately 90 degrees apart. Suificient flow area is available to meet the combined flow requirements of the Core Spray and Low Pressure Coolant Injection systems with one completely plugged suction strainer.
The four ECCS suction strainers are visually inspected for cleanliness and integrity, and cleaned if necessary, l
during refueling outages when the torus is drained down.
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