ML20149D795
| ML20149D795 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 07/10/1997 |
| From: | Kim T NRC (Affiliation Not Assigned) |
| To: | Richard Anderson NORTHERN STATES POWER CO. |
| References | |
| TAC-M97781, NUDOCS 9707170255 | |
| Download: ML20149D795 (4) | |
Text
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July 10, 1997-Mr. Roger 0. Anderson Director
~ Distribution:
Licensing and Management Issues Docket File OGC-1
. Northern States Power Company PUBLIC-AGill 414 Nicollet Mall PD3-1 Rdg.
JKudrick l.
Minneapolis, MN 55401 JRoe KKavanagh l
EAdensam(EGA1)
ACRS JMBarapr. DITI
SUBJECT:
MONTICELLO NUCLEAR GENERATING PLANT - REQUEST FOR ADDITIONAL INFORMATION ON REVISION NO. 2 TO LICENSE AMENDMENT REQUEST DATED JANUARY 23, 1997. ENTITLED " UPDATE OF DESIGN BASIS ACCIDENT CONTAINMENT TEMPERATURE AND PRESSURE RESPONSE" (TAC N0..M97781)
Dear Mr. Anderson:
By letter dated June 19. 1997. Northern States Power Company (NSP) submitted l
Revision No. 2 to the subject license amendment request for staff review and approval of an update to the design-basis accident containment temperature and pressure response.
Based on our review of the June 19. 1997, submittal, the staff has determined that additional information is necessary to complete its review.
The contents of the enclosed request for additional information was communicated to your staff on July 3.1997.
Please provide your response within 30 days of the date of this letter.
If you need additional time, or if you have any questions, please contact me at (301) 415-1392.
Sincerely.
ORIGINAL SIGNED BY 1
Tae Kim. Senior Project Manager I
Project Directorate III-1 Division'of Reactor Projects III/IV Office of Nuclear Reactor Regulation Docket No:
50-263
Enclosure:
As stated cc w/ enc 1:
See next page
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DOCUMENT NAME:
G:\\WPDOCS\\MONTICEL\\ MON 97781.RAI To receive a copy of this document, Indicate in the box: "C" = Copy without enclosures "E". = Copy with enclosures "N" =
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Mr. Roger O. Anderson, Director Monticello Nuclear Generating Plant 4
Northem States Power Company cc:
J. E. Silberg, Esquire Kris Sanda, Commissioner Shaw, Pittman, Potts and Trowbridge Department of Public Service 2300 N Street, N. W.
121 Seventh Place East
' Washington DC 20037 Suite 200 St. Paul, Minnesota 55101-2145 U.S. Nuclear Regulatory Commission Resident inspector's Office Adonis A. Nebiett 2807 W. County Road 75 Assistant Attomey General Monticello, Minnesota 55362
. Office of the Attomey General 445 Minnesota Street Plant Manager Suite 900 Monticello Nuclear Generating Plant St. Paul, Minnesota 55101-2127 ATTN: Site Licensing Northem States Power Company 2807 West County Road 75 Monticello, Minnesota 55362-9637 4
Robert Nelson, President Minnesota Environmental Control Citizens Association (MECCA) 1051 South McKnight Road St. Paul, Minnesota 55119 Commissioner Minnesota Pollution Control Agency 520 Lafayette Road St. Paul, Minnesota 55119 Regional Administrator, Region lil U.S. Nuclear Regulatory Commission 801 Warrenville Road Lisle, Illinois 60532-4351 Commissioner of Health Minnesota Department of Health 717 Delaware Street, S. E.
Minneapolis, Minnesota 55440 Darla Groshens, Auditor / Treasurer Wright County Govemment Center 10 NW Second Street 2
Buffalo, Minnesota 55313 l
January 1995 s
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t REQUEST FOR ADDITIONAL INFORMATION MONTICELLO NUCLEAR GENERATING PLANT 1.
Page A-5 of the June 19. 1997, submittal states that "the figures in
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Exhibit E demonstrate graphically the amount of ccntainment pressure required and the minimum containment pressure available to supply the required NPSH [ net positive suction head).for the emergency core cooling 1
system (ECCS) pumps in the limiting pump combinations evaluated." These l
i.
evaluations are for both short-and long-term periods under minimum containment pressure conditions.
For the short-term case, please state the requested over)ressure and respective time periods to ensure that no 4
cavitation of the ECCS pumps occurs.
This request should be in the i
submittal and shown graphically on the figures in Exhibit E.
Examples of such requests are available in the recent requests from the licensees of Dresden and Pilgrim Nuclear Power Stations.
2.
For the long-term case, the submitted analysis does not extend to the time when the required containment overpressure for the core spray aumps returns to atmospheric conditions.
Please extend the analysis to slow this point. Also, state the requested overpressure and respective time periods to ensure that no cavitation of the ECCS Jumps occurs.
This request should be in the submittal and shown grap11cally on the figures in Exhibit E.
3.
On page A-2 of the submittal the Northern States Power Co. proposed to j
change section 3.7.A of the Bases to the following:
For an initial maximum suppression chamber water temperature of 90*F and conditions which lead to minimum containment pressure, adequate net positive suction head (NPSH) is maintained for the core spray.
RHR. and HPCI pumps under loss of coolant accident conditions.
The staff believes that when the amendment request is approved that the approved containment overpressure and respective time periods should be stated in section 3.7.A of the Bases.
This should avoid any~ confusion in the future regarding Monticello's credit for use of containment overpressure.
4.
For the long-term NPSH case, what factors contribute to the relatively high requirement of containment overpressure in comparison to other BWRs
[ boiling water reactors] of the same vintage? The staff has recently approved credit for long-term containment overpressure on the order of 2.5 psig.
However, the calculations presented in the submittal imply that Monticello will need approximately 5.7 psig to meet the long-term NPSH requir'ements.
ENCLOSURE
2 5.
In Appendix A of Exhibit D. it is stated that the "HXSIZ" code can only model the long-term response for only the DBA-LOCA [ design-basis accident-loss-of-coolant accident] and only with assumptions which maximize drywell and suparession chamber airs) ace pressure. State and justify the differences
)etween using the "SHEX" code to analyze for minimum versus maximum containment pressure.
6.
Please saecify under what conditions that the containment venting is allowed )y the )lant procedures, and discuss the ramifications for the adequacy of NPSi during containment venting.
7.
At what containment pressure do the E0Ps [ emergency operating procedures] require manual initiation and manual shutoff of containment sprays?
8.
Provide your verification that equipment qualification (EO) evaluation included an analysis which confirmed that all accident and post-accident temperature and pressure (not just peak) were bounded.
Provide a representative of the E0 test profile curve to demonstrate that the E0 test profile continues to bound the new containment response profile resulting from the reanalysis.
9.
For Case 3. the GE analysis assumes that after 10 minutes, one of the RHR [ residual heat removal] pumps is turned off to allow start of a RHRSW [ residual heat removal service water] pump. The remaining RHR pump is aligned to containment spray mode.
One core spray (CS) pump would be injecting into the vessel.
Based on our review of the applicable sections of the E0Ps, the staff came to the following conclusions.
In E0P Section C.5.1-1100, the operators are instructed to maintain level between +9 and +48 inches.
Under this scenario however, this band is not achievable.
The next allowable band is top of active fuel. -126 inches. The E0Ps instruct the operators to establish two injection paths (CS and RHR with a heat exchanger in LPCI [ low pressure coolant injection] mode under this scenario.) Again, the level band is not attainable.
The operators would proceed into C.5-2004. "Drywell Flooding."
Concurrently with the Reactor Pressure Vessel Pressure / Level Control, the operators would be entering Primary Containment Control C.S.1-1200.
The torus temperature and drywell pressure branches instruct the operators to place RHR in torus cooling mode only if not required for core cooling. A RHR pump will be placed in drywell spray / torus cooling mode only if the pressure cannot be maintained below 56 psig.
(In Figure B-6 of the submittal, pressure is less than 40 psia.)
Therefore, it appears that there may be some discrepancies between assumptions made in the GE analysis and E0Ps.
The staff believes that this question also applies to Cases 4 and 6.