ML081020400
| ML081020400 | |
| Person / Time | |
|---|---|
| Site: | Nine Mile Point  |
| Issue date: | 04/10/2008 |
| From: | Polson K Constellation Energy Group |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| GL-08-001 | |
| Download: ML081020400 (8) | |
Text
Keith J. Polson Vice President-Nine Mile Point 0::***\\ Constellation Energyto to Nine Mile Point Nuclear Station U. S. Nuclear Regulatory Commission 11555 Rockville Pike Rockville, MD 20852 P.O. Box 63 Lycoming, New York 13093 315.349.5200 315.349.1321 Fax April 10, 2008 ATTENTION:
SUBJECT:
REFERENCE:
Document Control Desk Nine Mile Point Nuclear Station, LLC Unit No. I; Docket No. 50-220; License No. DPR-63 Three Month
Response
to NRC Generic Letter 2008-0I, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems" NRC Generic Letter 2008-01, dated January II, 2008, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems" The Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 2008-01 (Reference) to request that each licensee evaluate the licensing basis, design, testing, and corrective action programs for the emergency core cooling systems, decay heat removal system, and containment spray system, to ensure that gas accumulation is maintained less than the amount that challenges operability ofthese systems, and that appropriate action is taken when conditions adverse to quality are identified.
The NRC, in GL 2008-01, requested each licensee to submit a written response in accordance with 10 CFR 50.54(f) within nine months ofthe date ofthe GL to provide the following information:
(a)
A description of the results of evaluations that were performed pursuant to the requested actions of the GL. This description should provide sufficient information to demonstrate that you are or will be in compliance with the quality assurance criteria in Sections ill, V, XI, XVI, and XVII of Appendix B to 10 CFR Part 50 and the licensing basis and operating license as those requirements apply to the subject systems ofthe GL; (b)
A description of all corrective actions, including plant, programmatic, procedure, and licensing basis modifications that you determined were necessary to assure compliance with these regulations; and, (c)
A statement regarding which corrective actions were completed, the schedule for completing the remaining corrective actions, and the basis for that schedule.
Additionally, the NRC requested that if a licensee cannot meet the requested response date, the licensee "shall provide a response within 3 months of the date of this GL." In the 3 month response, the licensee
WITNESS my Hand and Notarial Seal:
Document Control Desk April 10, 2008 Page 2 was requested to describe the alternative course of action that it proposes to take, including the basis for the acceptability ofthe proposed alternative course ofaction. to this letter contains the Nine Mile Point Nuclear Station, LLC three month response to the requested information in NRC GL 2008-01 for Nine Mile Point Unit 1. to this letter contains a listing ofcommitments made in this document.
Should you have any questions regarding this submittal, please contact T. F. Syrell, Licensing Director, at (315) 349-5219.
Very truly yours,
~~
STATE OF NEW YORK TO WIT:
COUNTY OF OSWEGO I, Keith J. Polson, being duly sworn, state that I am Vice President-Nine Mile Point, and that I am duly authorized to execute and file this response on behalf of Nine Mile Point Nuclear Station, LLC. To the best of my knowledge and belief, the statements contained in this document are true and correct. To the extent that these statements are not based on my personal knowledge, they are based upon information provided by other Nine Mile Point employees and/or consultants. Such information has been reviewed in accordance with company practice and I believe it to be reliable.
Subscribed and sworn before m~ary Public in and for the State ofNew York and County of Oswego, this (0+clay of
, 2008.
J-..L)f(~
Notary Public My Commission Expires:
It>/2S/6 "
Date
/G SANDRA A. OSWALD KJP B
Notary PUblic, State of New Vork No. 01086032276 qual,ified in Oswego qq,u!1tv Jommlsslon Expires lOji6f/o1
Document Control Desk April 10, 2008 Page 3 Attachments:
- 1. Nine Mile Point Unit 1 Three Month Response to GL 2008-01
- 2. Regulatory Commitment List cc:
R. V. Guzman, NRC Project Manager S. J. Collins, NRC Regional Administrator, Region I Senior NRC Resident Inspector
ATTACHMENT 1 NINE MILE POINT UNIT 1 THREE MONTH RESPONSE TO NRC GL 2008-01 Nine Mile Point Nuclear Station, LLC April 10, 2008 Nine Mile Point Unit 1 Response to NRC GL 2008-01 This response to Generic Letter (GL) 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," addresses the Nine Mile Point Nuclear Station, LLC (NMPNS) three month response for Nine Mile Point Unit 1 (NMP1).
This response discusses:
1)
The required evaluations that will not be complete by October 11, 2008 (nine months from the date ofGL 2008-01),
2)
The alternative course ofaction planned, and 3)
The basis for acceptability ofthe alternative course of action.
The evaluations requested by the GL require physical walkdowns to confirm locations ofhigh point vents, as-built configurations (such as pipe locations, elevations, and slope), and performance of non-intrusive examinations, such as ultrasonic testing, of piping suspected to contain accumulated gases. Portions of these piping systems are located inside the drywell and, during power operation, are inaccessible due to radiation environments and/or an inerted drywell atmosphere (less than 4% oxygen concentration).
Additionally, piping sections may require installation of scaffolding for access, which would not be possible during power operations due to risks to other nearby equipment during its erection and disassembly (for example, instrument racks with sensitive equipment that could cause system isolation).
Currently, NMPI does not have a planned outage to conduct the required walkdowns in the inaccessible areas within the nine month period requested in the GL. The next scheduled outage is currently planned for early 2009 (next NMPI refueling outage).
Plans are currently being formulated to complete preliminary "scoping" walkdowns in case an opportunity does develop providing limited access to these areas prior to the planned refueling outage.
Such scoping walkdowns would be used to confirm design information on drawings, identify obstructions or clearance problems that could interfere with detailed inspections at a later date, and identify areas where scaffolding would be required to gain access.
The information acquired from "scoping" walkdowns will assist in the performance ofthe more detailed evaluation walkdowns required for the GL response during the next refueling outage.
Based on the above, sections of inaccessible piping will be deferred until the next refueling outage for the following systems included in the GL evaluation scope:
Shutdown cooling Core spray NMPl, being a boiling water reactor, does not rely upon nitrogen or air-charged accumulators as part of the design of the piping systems for the shutdown cooling or core spray systems. Thus, there are limited scenarios where significant gas entrainment is possible, particularly in the suction piping ofthe pumps for the systems requiring inspection. For example, one potential scenario would be failure to properly fill and vent piping after maintenance. Although this scenario (and other emergency core cooling system-related pipe voiding scenarios) is considered highly unlikely given that there are written procedures for its avoidance (including multiple verifications of key procedure steps, administrative work controls, and post-maintenance testing for such restorations), NMPNS does acknowledge the concerns identified in the GL.
The core spray system is routinely tested in accordance with technical specifications and the in-service testing program, and no significant issues with accumulated gas have been identified.
Test flow is achieved within the assumed accident recovery times and no obvious equipment issues associated with 10f2 Nine Mile Point Unit 1 Response to NRC GL 2008-01 accumulated gas voiding (such as net positive suction head, water hammer, and pump cavitations) have been noted during these tests. The on-line tests and routine evolutions conducted during refueling outages (injection into the vessel) cover most of the design basis alignments of this system for both suction and discharge piping, and consistently demonstrate system operability.
The potential to form vortices and entrain air at the suction pipe inlets and their effect on the core spray system pump performance has been evaluated. Calculations verify that air will not be ingested into the core spray strainers from the water surface of the suppression chamber (torus). In addition, the suction piping for the core spray pumps exits the torus and has no other high points (by design) from that point to the actual pump inlet.
On the discharge side, the core spray system has a keep-fill system and high points vents. The high point vent for each core spray loop consists of a line from the core spray piping just upstream of the inside isolation valve, which discharges to the reactor building equipment drain tank. The purpose of the high point vent is to purge air out of the piping and allow it to be maintained full of water by the keep-fill system.
Similarly, the shutdown cooling system operating procedures require venting when placing the system in service, including venting of the shutdown cooling pump casing.
The shutdown cooling piping is maintained full of water at all times, thus the likelihood of water hammer effects are significantly decreased.
NMPNS remains confident that the NMPI core spray and shutdown cooling systems can fulfill their required functions based upon almost 40 years of operating experience, including system walkdowns and detailed evaluations. NMPNS will complete as much of the requested GL actions within the requested nine month period as is practical, based upon accessibility ofthe subject systems.
Based upon the above, NMPNS believes that performance and completion ofthe detailed walkdowns and subsequent evaluations of those portions of piping at NMP1, outside the requested nine month period, is an acceptable alternative course of action. Within six months after the end of the next scheduled NMPI refueling outage, NMPNS will submit a written response informing the NRC of the activities performed consistent with the actions and information requested by Generic Letter 2008-01.
20f2
ATTACHMENT 2 REGULATORY COMMITMENT LIST Nine Mile Point Nuclear Station, LLC April 10, 2008 Regulatory Commitment List Regulatory Commitments The following table identifies actions committed to in this document by Nine Mile Point Nuclear Station, LLC.
Any other statements in this submittal are provided for information purposes and are not considered to be regulatory commitments.
Direct questions regarding these commitments to T. F. Syrell, Licensing Director, at (315) 349-5219.
REGULATORY COMMITMENT DUE DATE Perform and complete required plant walkdowns and inspections Completion of Spring 2009 associated with NRC Generic Letter 2008-01 that cannot be completed refueling outage with plant online for Nine Mile Point Unit 1.
Submit written response to the NRC informing them ofthe activities Within six months after the performed consistent with the requested actions and information completion ofthe NMP 1 required by Generic Letter 2008-01.
Spring 2009 refueling outage 1 of 1