ML17056B549
| ML17056B549 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 11/19/1991 |
| From: | Brinkman D Office of Nuclear Reactor Regulation |
| To: | Sylvia B NIAGARA MOHAWK POWER CORP. |
| References | |
| TAC-M80214, NUDOCS 9112040068 | |
| Download: ML17056B549 (10) | |
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November 19, 1991 Docket No. 50-220 Hr. B. Ralph Sylvia Executive Vice President, Nuclear Niagara Mohawk Power Corporation 301 Plainfield Road
- Syracuse, New York 13212
Dear Mr. Sylvia:
DISTRIBUTION:
PDI:1 Reading JCalvo DBrinkman
- GBagchi, 7/M/15 RACapra Plant File ACRS (10)
NRC 5 Local PDRs SVarga CVogan
- CPTan, 7/M/15 CCowgill OGC
- EJordan, HNBB, 3701
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION CONCERNING NINE MILE POINT NUCLEAR STATION UNIT NO.
1 TORUS STRESS ANALYSIS (TAC NO. 80214)
By letter dated May 14, 1991, Niagara Mohawk Power Corporation (NHPC) submitted Teledyne's technical report TR-7353-1, Revision 1, in suppot t of NHPC's proposal to decrease the calculated stresses in the Nine Mile Point 1 torus shell due to reductions in condensation oscillation loads.
The NRC staff has determined that additional information, as identified in the enclosure, is required for the NRC staff to complete its review of the May 14, 1991, submittal.
I provided an advance copy of the enclosure to Hr. Nick Spagnoletti of your staff on November 15, 1991.
In order for us to complete our review of your Hay 14, 1991 submittal in a timely manner, we request that you respond to this request for additional information within 30 days of receipt of this letter.
This requirement affects one respondent and, therefore, is not subject to Office of Management and Budget review under P.L.96-511.
Sincerely,
Enclosure:
Request for Additional Information cc w/enclosure:
See next page Original Signed By:
Donald S. Brinkman, Senior Project Manager Project Directorate I-1 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation WO ~ >>
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Docket No.
50-220'NITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 November 19, 1991 Hr. B. Ralph Sylvia Executive Yice President, Nuclear Niagara Mohawk Power Corporation 301 Plainfield Road
- Syracuse, New York 13212
Dear Hr. Sylvia:
SUBJECT:
REQUEST FOR ADDITIONAL INFORMATION CONCERNING NINE MILE POINT NUCLEAR STATION UNIT NO.
1 TORUS STRESS ANALYSIS (TAC NO. 80214)
By letter dated May 14, 1991, Niagara Mohawk Power Corporation (NMPC) submitted Teledyne's technical report TR-7353-1, Revision I, in support of NMPC's proposal to decrease the calculated stresses in the Nine Mile Point 1 torus shell due%to reductions in condensation oscillation loads.
The NRC staff has determined P
that additional information, as identified in the enclosure, is required fork the NRC staff to complete its review of the Hay 14, 1991, submittal.
I provided an advance copy of the enclosure to Mr. Nick Spagnoletti of your staff on November 15, 1991.
In order for us to complete our review of your May 14, 1991 submittal in a time'ly manner, we request that you respond to this request for additional information within 30 days of receipt of this letter.
This requirement affects one respondent and, therefore, is not subject to Office of Management and Budget review under P.L.96-511.
Sincerely,
Enclosure:
Request for Additional Information cc w/enclosure:
See next page Donald S. Brinkman, Senior Project Manager Project Directorate I-1 Division of Reactor Projects - I/II Office of Nuclear Reactor Regulation
Mr. B. Ralph Sylvia Niagara Mohawk Power Corporation Nine Mile Point Nuclear Station Unit No.
1 CC.
Hr. Hark J. Wetterhahn, Esquire Winston' Strawn 1400 L Street, NW.
Washington, D.C.
20005-3502 Supervisor Town of Scriba Route 8, Box 382
- Oswego, New York 13126 Mr. Joseph F. Firlit Vice President - Nuclear Generation Niagar a Mohawk Power Corporation Nine Mile Point Nuclear Station Post Office Box 32
- Lycoming, New York 13093 Resident Inspector U.S. Nuclear Regulatory Commission Post Office Box 126
- Lycoming, New Yor k 13093 Mr. Gary D. Wilson, Esquire Niagara Mohawk Power Corporation 300 Erie Boulevard West
- Syracuse, New York 13202 Regional Administrator,'egion I
U.S. Nuclear Regulatory Commission 475 Allendale Road King of Prussia,'ennsylvania 19406 Ms. Donna
- Ross, New York State."Energy Office 2 Empire State,"Plaza 16th Floor
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- Albany, New York 12223 Hr. Kim Dahlberg Unit I Station Super intendent Nine Mile Point Nuclear Station Post Office Box 32
- Lycoming, New Yor k 13093 Mr. David K. Greene Manager Licensing Niagara Mohawk Power Corporation 301 Plainfield Road
- Syracuse, New York 13212 Charlie Donaldson, Esquire Ass is tant Attorney Genera 1
New York Department of Law 120 Broadway New York, New York 10271 Mr. Paul D. Eddy State of New York Department of Public Service Power Division, System Operations 3 Empire State Plaza
- Albany, New York 12223
Enclosur e RE(VEST FOR ADDITION INFORMATION REGARD SHELL NINE NO. I The following information is requested to continue our review of your May 14, 1991, submittal.
In Teledyne's technical report, TR-7353-1, Revision 1, Section 5.1, it is stated that the Design Basis Accident (DBA) pressure used is 26 psig.
However the design pressure of the torus was originally 35 psig.
Explain these two different pressures and indicate the conditions under which the DBA pressure and design pressure are used respectively.
2.
3.
4.
In section 6, on page 13 of TR-7353-1, the actual stresses and allowable stresses for various conditions for free shell element 19 are listed.
It is indicated that the stresses are from event combination 20, which consists basically of DBA, earthquake, dead load, and condensation and oscillation loads.
The components of the resultant stress of 16,150 (16025) psi were given in the April 29, 1991, presentation.
It is understood that the stresses given are the maximum principal stress which may be the hoop stress or meridional stress.
Provide the hoop stress and the meridional stress for each loading.
Note that the location of element 19 has not been clearly identified.
In an attempt to check the stress values as given in TR-7353-1, the stresses as shown in FIG XVI-14 in Section B, Pressure Suppression Containment; of the Nine Mile Point 1
FSAR were reviewed and compared by the staff.
The staff has reservations on the validity of the stress values indicated therein.
It appears that a check of the values in this figure is necessary.
In order to evaluate the structural integrity of a corroded steel containment such as the drywell of the Oyster Creek Plant and the torus of Nine Mile Point Unit 1, the staff has established a position.
The staff position is enclosed.
The position can only be applied when, the corrosion is highly localized, the reduction in shell thickness is not moreChan 10K; and there is a program of periodic UT measurements.
If the l,icensee finds these conditions can be met and the staff's position is applicab1e to Nine Mile Point 1 to~us, the licensee should submit to the staff for review a figure of the torus showing, as accurately as ractical; the locations of localized corrosion and the thickness of the ase metal remaining for each area together with the critical stresses (general primary membrane stress or local primary membrane) identified at and around each of the corroded areas.
On the basis of the review and evaluation of the information thus provided, the staff will determine the adequacy of the actions to be taken by the licensee.
The above review comments are based on the original analysis without considet fng the condensation oscillation load reduction.
NRC STAFF POSITION ON EVALUATION OF STRUCTURAL INTEGRITY OF A DEGRADED STEEL CONTAINMENT ASME Section XI Subsections IWE-3519.3 and IWE-3122.4 state that a steel containment is acceptable if the thickness of the area of degradation discovered is reduced by not more than 10%.
This is acceptable only on the basis of considering the area of degradation as a form of discontinuity as stipulated in ASME Section III, Division I, Subsection NE-3213.10.
The area of degradation, where the stress intensity exceeds l.l Smc, is stipulated in NE-3213.10 in terms of the square root of the product of R and t as defined therein.
The code requires such a discontinuity be localized.
This is due to the fact that the load on a highly stressed and localized area will be transferred to the adjacent area.
If the area of degradation is localized, the effect on the overall behavior of the containment will be minimal or neg 1i gib le.
The code does not specify the limit of the extent of the support region in which the stress intensity varies from 1.0 Smc to 1.1 Smc.
However, the limit can be determined from the analysis for load combinations with the internal pressure as the major load.
On the basis of the above observations, the staff has established the following position:
1.
The corroded or degraded ar ea with a reduction in thickness of not more than 10$ should be considered in accordance with NE-3213.10 as a
discontinuity with the limits of its extent as prescribed therein.
2.
For a'orroded containment shell where the thicknesses of the corroded areas are obtained through UT measurements, the extent of each corroded area should be determined as accurately as practical.
3.
Except in the support zone* of the discontinuity where the stress intensity value may vary from 1.0 Smc to 1.1 Smc, the primary membrane stress should be in accordance with the stress intensity limits.as stipulated in Table NE-3221-1, Su@vary of Stress Intensity Limits.
The support zone is a region contiguous to and supports the discontinuity.
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