ML043280420
| ML043280420 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 11/10/2004 |
| From: | Spina J Constellation Energy Group |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NMP1L 1883 | |
| Download: ML043280420 (5) | |
Text
Constellation Energy- RO. Box 63
- Nine Mile Point Nuclear Station Lycoming, New York 13093 November 10, 2004 NMP1L 1883 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Washington, DC 20555
SUBJECT:
Nine Mile Point Units 1 and 2 Docket Nos. 50-220 and 50410 Facility Operating License Nos: DPR-63 -and NPF-69 Response to NRC Request for Information Regarding the Offsite Power System Gentlemen:
On September 20, 2004, the NRC staff transmitted by e-mail a request for information regarding the offsite power system for Nine Mile Point Units I and 2. The Attachment to this letter contains the information request and the Nine Mile Point Nuclear Station, LLC response.
Very truly yours, Ja s A. Spina
. i.-.. ce President Nine Mile Point JAS/DEV/jm
-Attachment--- - x cc: Mr. S. J. Collins, NRC Regional Administrator, Region I Mr. G. K. Hunegs, NRC Senior Resident Inspector Mr. P. S. Tam, Senior Project Manager, NRR (2 copies)
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ATTACHMENT NINE MILE POINT UNITS 1 AND 2 RESPONSE TO NRC REQUEST FOR INFORMATION REGARDING THE OFFSITE POWER SYSTEM
Reference:
NRC Email to Nine Mile Point Nuclear Station, LLC (NMPNS) dated September 20, 2004 Request (repeated verbatim fromn the referenced email)
NIine Mile Point does not iizeet NJRC's safety requirementsformulti-unit stations. -
The two-unit Nine Mile Point Station is adjacent to the single-unit James FitzpatrickStation, separatedonly by a chain linkfence. Forallpracticaland safety purposes, Nine Mile Point and Fitzpatrickmeet the definition of a multi-three-unitstation, even though the license holder's of the tvo facilitiesare different. This issue becomes especially significant because the Nine Mile Point/Fitzpatrickcomplex share systems important to safety, and as such NRC regulationsmust be appliedto this as a three-unitcomplex when evaluating the Nine Mile PointLicense Renewal Application. Supporting details areprovided below.
Background
Both Nine Mile Point andFitzpatrickshare the same 115 kVpreferred offsite power supply that is requiredby GeneralDesign Criteria17 (GDC-1 7)for accident mitigation and safe shutdown.
Tie same 115 kVcircuit is utilized by all three units of this multi-station complex. This preferred offsite power circuit has marginalcapacity and capabilitysuch that it may be not be able to support an accident in one unit, an orderly shutdown and cooldown of the remainingtivo units, as requiredby GeneralDesign Criteria5.
Criterion 5 - Sharingof Structures, systems, and components, states:
"Structures,systems, and components important to safety shall not be sharedamongst nuclear power units unless it can be shown that such sharingwill not significantly impairtheir ability to perform their safetyfunctions, including, in the event of an accident in one unit, an orderly shutdown and cooldown of the remainingunits. "
The safety requirements invoked by GeneralDesign CriteriaS are applicable to all multi-unit stations that share systems important to safety; and these safety systems include the preferred offsite power supplies. 7he fact that ownership ofNine Mile Point and Fitzpatrickare different is incidentalto this safety concern, and the technicality ofseparateownership should not preclude the NRCfroin applying its regulationsto the three-unit complex.
In August/September 2001 both plants entered 7-day LCOs because it was determinedthat the common 115 kVlinesfeeding both stations did not have the capacity or capabilityrequiredby Page 1 of 4
each station's Technical Specifications (GDC-17 requirement). Though corrective actions were taken to resolve these Technical Specification non-compliance issues, the resolutionswere station specific, andfailed to address the three-multi-unit Nine Mile Point/Fitzpatrickcomplex.
Response
Nine Mile Point Unit 2 (NMP2)
The NMP2 115 kV offsite power sources, referred to as line numbers 5 and 6, are from the Scriba Substation, as shown on NMP2 Updated Safety Analysis Report (USAR) Figures 8.2-1 and 8.2-8.
The Scriba Substation has multiple sources of input power, including a fossil fuel generating unit and connection to the 345 kV grid. The power from the 345 kV grid is transformed to 115 kV and supplied to NMP2. There are no structures, systems or components associated with the IftM `ffsi e power sources that are shared with either Nine Mile Point Unit 1 (NMP1) or James A. Fitzpatrick (JAF). Thus, the remaining discussion addresses NMPI only.
Nine Mile Point Unit I (NMPI)
The NMP1 offsite power system is described in the NMPI Updated Final Safety Analysis Report (UFSAR)Section IX. The system consists of two 115 kV lines, referred to as line numbers 1 and
- 4. Line number 1 originates at the South Oswego Substation. Line number 4 arrives via the JAF switchyard. However, the power source for line number 4 is the Lighthouse Hill Substation and is not dependent on the operating status of the JAF station. Each of these 115 kV lines is capable of supplying all of the NMP1 auxiliary power loads. To minimize the possibility of a double-circuit outage, the lines are separated and supported on independent structures. The two lines are connected in a common bus in the NMPI switchyard by a normally closed motor-operated disconnect switch.
The current NRC requirements related to offsite power systems at nuclear power plants are contained in General Design Criterion (GDC) 17 in Appendix A to 10 CFR Part 50, which states in relevant part:
Electric power from the transmission network to the onsite electric distribution system-nhall'bcsupplied by tWo physically independent circuits (nhotneessadil separate rights of way) designed and located so as to minimize to the extent practical the likelihood of their simultaneous failure under operating and postulated accident and environmental conditions. A switchyard common to both circuits is acceptable. Each of these circuits shall be designed to be available in sufficient time following a loss of all onsite alternating current power supplies and the other offsite electric power circuit, to assure that specified fuel design limits and design conditions of the reactor coolant pressure boundary are not exceeded.
One of these circuits shall be designed to be available within a few seconds following a loss-of-coolant accident to assure that core cooling, containment integrity, and other vital safety functions are maintained.
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GDC 17 became effective after issuance of the construction permit for NMPI and, therefore, is not part of the current licensing basis for NMPl.
Both line numbers I and 4 are capable of handling a unit trip with loss-of-coolant accident (LOCA) loading. Also, although NMPI's two 115 kV offsite power lines are not entirely physically separate by virtue of the common motor operated disconnect switch in the NMP1 switchyard bus, the two 115 kV circuits are sufficiently functionally independent to meet the intent of GDC 17.
The NRC reviewed and verified the adequacy of certain aspects of the NMP1 emergency onsite and offsite power sources, including the capability of the 115 kV offsite power system, during the 1991 Electrical Distribution System Function Inspection (EDSFI). The NRC reviewed the configuration of the 115 kV transmission lines and determined that NMP1 met the intent of GDC 17 andthiat, iiitheleven vof a system disturbance that impairs both offsite power supplies, one of the offsite supplies could be restored within a reasonable time. Because each offsite source is part of the 115 kV grid, which has sufficient capacity and reliability to supply all required emergency loads, each NMPI offsite power source is capable of handling the expected unit trip with LOCA loading without the support of the other source.
On September 7, 2001, Niagara Mohawk Power Corporation (NMPC) [the previous licensee for NMP1] declared 115 kV line number 4 inoperable and entered the NMP1 Technical Specification 3.6.3.b Limiting Condition for Operation (LCO), allowing continued operation of NMP1 for seven days with line number 4 inoperable. This action was taken when NMPC determined that line number 4 could not provide the power required for a unit trip with LOCA when line number 1 is out of service. Specifically, the voltage on line number 4 during a unit trip with LOCA, with line number I out of service, would decrease and actuate the Degraded Voltage Relays (DVRs) transferring the NMP1 Emergency Core Cooling System (ECCS) loads to the diesel generators.
The voltage decrease is due to the additional load applied during a unit trip with LOCA as compared to normal plant operation. NMPC reported this condition to the NRC in Licensee Event Report (LER)01-002 dated November 6,2001. NMP2 was not affected by line number 4 being declared inoperable. As identified in Section IV of the LER, NMPC and Nine Mile Point Nuclear Station, LLC (NMPNS) have completed a number of corrective actions to ensure that line number 4 will provide adequate voltage to support the NMP1 emergency systems whenever line number-1is out of service and line number 4is-available. For example, voltage'tap settings-were changed on reserve station service transformers XF-1OlN and XF-I0lS, the 115 kV grid voltage estimator was fully implemented, training was provided to NMPC and NMP1 personnel, and applicable operating procedures were revised to address this issue.
As indicated above and illustrated on NMP2 USAR Figure 8.2-1, NMPI receives offsite power from the South Oswego and Lighthouse Hill Substations via 115 kV line numbers 1 and 4. These substations are connected to the 115 kV electrical power grid. As such, they have multiple sources of input power, including hydroelectric generating units and fossil fuel generating units.
JAF receives offsite power from the same two sources via line number 3 originating at the Lighthouse Hill Substation and line number 4 via the NMP1 switchyard. The 1 15 kV circuit components (e.g. disconnect switches, circuit breakers, transmission lines, etc.) that connect the South Oswego and Lighthouse Hill substations together via the NMPl and JAF substations have Page 3 of 4
I an MVA rating well in excess of the unit trip and LOCA loading associated with one nuclear unit plus the orderly shutdown and cooldown loading associated with the remaining nuclear unit.
Also, transmission system protection relays will not actuate under these loading conditions.
Thus, sharing of the 115 kV offsite power supplies between NMP1 and JAF satisfies the requirements of GDC 5.
In summary, there are no structures, systems or components associated with the NMP2 offsite power sources that are shared with either NMP1 or JAF. The NMP1 offsite power sources meet the current licensing basis requirements and have an MVA rating well in excess of the unit trip and LOCA loading associated with NMP1 plus the orderly shutdown and cooldown loading associated with JAF, thereby satisfying the requirements of GDC 5.
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