ML081020695
| ML081020695 | |
| Person / Time | |
|---|---|
| Site: | Monticello  |
| Issue date: | 04/11/2008 |
| From: | Sawatzke B J Nuclear Management Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| GL-08-001, L-MT-08-026 | |
| Download: ML081020695 (5) | |
Text
1 Committed to Nucisar Excellence Operated by Nuclear Management Company, LLC April 1 1, 2008 U. S. Nuclear Regulatory Commission ATN: Document Control Desk Washington, DC 20555 Monticello Nuclear Generating Plant Docket 50-263 Renewed Operating License No.
DPR-22 Generic Letter 2008-01 : Three Month Response to Genetic Letter 2008-01
Reference:
- 1) U.S. NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," dated January 11,2008. On January 1 1, 2008, the U.S. Nuclear Regulatory Commission (NRC) issued Generic Letter (GL) 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," (Reference 1). The generic letter requested each licensee to evaluate the licensing basis, design, testing, and corrective actions for the Emergency Core Cooling Systems (ECCS), Decay Meat Removal System, and Containment Spray System, to ensure that gas accumulation is maintained less than the amount that challenges operability of these systems, and that appropriate action is taken when conditions adverse to quality are identified.
The NRC in GL 2008-01 further requested that if a licensee cannot meet the requested nine month response date, the licensee "shall provide a response within 3 months of the date of this GL." In the three month response, the licensee was requested to describe "the alternative course of action that it proposes to take, including the basis for the acceptability of the proposed alternative course of action." The enclosure to this letter provides the Nuclear Management Company three month response to Generic Letter 2008-01 for the Monticello Nuclear Generating Plant.
2807 West County Road 75 Monticello, Minnesota 55362-9637 Telephone:
763.295.51 51 Fax: 763.295.1 454 Document Control Desk Page 2 This letter contains the following new commitments:
- 1. Complete the detailed walkdowns of inaccessible sections of the Generic Letter 2008-01 subject systems prior to startup from the 2009 Refueling Outage. 2. Complete evaluations of the Generic Letter 2008-01 subject systems within 90 days following return to full power from the 2009 Refueling Outage. A summary of the evaluation results will be forwarded to the NRC. I declare under penalty of perjury that the foregoing is true and correct. Executed on April I I, 2008. Bradley J. Sawatzke Plant Manager, Monticelle Nuclear Generating Plant Nuclear Management Company, LLC Enclosure cc: Administrator, Region Ill, USNRC Project Manager, Monticello, USNRC Resident Inspector, Monticello, IISNRC Minnesota Departrt~ent of Commerce ENCLOSURE NINEN DAY RESPONSE TO GENERIC LEIT'ER 200841 On January I I, 2008, the U.S. Nuclear Regulatov Commission (NRC) issued Generic Letter (GL) 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems,', (Reference I). The GL requested each licensee evaluate the licensing basis, design, testing, and corrective actions for the Emergency Core Cooling Systems (ECCS), Decay Heat Removal System, and Containment Spray System, to ensure that gas accumulation is maintained less than the amount that challenges operability of these systems, that appropriate action is taken when conditions adverse to quality ate identified, and provide a "description of the results of evaluations that were performed" to the NRC. The NRC further requested that if a licensee could not complete all evaluations within the nine month response date (October A I, 20081, that the licensee "provide a response within 3 months of the date of this GL." In the three month response, the licensee was requested to describe the required evaluations that will not be complete within nine months indicating, "the alternative course of action that it proposes to take, including the basis far the acceptability of the proposed alternative course of action." For the Montfcello Nuclear Generating Plant (MNGP), the scope of evaluations required to support the response to GL 2008-01 includes the following systems: HighPressureCoolantInjection(HPC1)System Core Spray (CS) System a Residual Meat Removal (RHR) System (following modes of operation:
Low Pressure Coolant Injection (LPCI), Torus Cooling, Shutdown Cooling, and Containment Spray) Automatic Depressurization system(') (ADS) Scope The Nuclear Management Company, LLC (NMC) will review and evaluate the licensing and design bases, system operating and test procedures, technical specifications, design drawings and corrective actions pertaining to the above systems. Detailed walkdowns will be performed to confirm items such as adequate vent capability for system high points and verification of the design drawings.
Completion of these evaluations within the schedule provided by the GL will not be possible since portions of the systems (due to the Boiling Water Reactor design) are inaccessible during power operation.
In addition, establishment of the proper conditions
- 1. The ADS rernotelly operates Safetykelief valves (SRVs) to depressurize the reactor pressure vessel to allow low pressure ECCS system injection.
The SRVs are attached to the Main Steam lines, and discharge steam. There is no concern with gas accumulation in either the upstream or downstream lines of the SRV's. Page 1 of 3 ENCLOSURE NINETY DAY RESPONSE TO GENERIC LElTER 200801 (e.g., installation of scaffolding and shielding]
requires planning resources typically associated with an extended duration outage, such as a refueling outage. The following are some of the considerations:
Walkdowns of these systems would require entry into areas of high radiation or inerted atmosphere (less than 4 percent oxygen concentration inside the Drywell) during power operations.
Erection of some scaffolding during power operations is impractical due to locations in high radiation areas, or near sensitive or safety related equipment.
Installation and removal of scaffolding and insulation in the upper levels of the Drywell is prohibited during fuel movements.
Surveying of areas not routinely accessed, such as overheads, and installation of shielding to reduce exposure to personnel performing inspections would be required.
Walkdowns of the accessible portions of the subject systems will be performed within the nine-month timeframe prescribed by GL 2008-01. Alternative Course of Action Planned The NMC does not have a scheduled(2) outage prior to the requested completion date of October 1 ?, 2008. The NMC proposes to complete walkdowns for those portions of the subject systems that cannot be perFormed by October 11, 2008, by the end of the next refueling outage (RFO), scheduled for the spring 2009. The NMC will evaluate the findings of these walkdowns upon completion and enter the findings into the Corrective Action Program. Therefore the NMC is making the following commitments:
- 1. Complete the detailed walkdowns of inaccessible sections OF the Generic Letter 20138-01 subject systems prior to startup from the 2009 Refueling Outage. 2. Complete evaluations of the Generic Letter 2008-01 subject systems within 90 days following return to full power from the 2009 Refueling Outage. A summary of the evaluation results will be forwarded to the NRC. 2. A shutdown to replace a leaking fuel assembly may occur before the 2009 RFO. Access to the upper levels of the Drywell is prohibited during fuel movement, therefore, this outage is not expected to be of sufficient duration to allow establishment of the conditions necessary to perform detailed walkdowns of these systems. Page 2 of 3 ENCLOSURE NINETY DAY RESPONSE TO GENERIC LElTER 200841 Acceptability of the Alternative Course of Action: This alternative course of action is considered acceptable because MNGP is continuously evaluating for (and resolving if found) gas accumulation issues as a result of site and industry operating experience. Surveillance testing is routinely performed on the subject systems and has demonstrated acceptab te performance. Routine evolutions during plant shutdowns and refueling outages, e.g., RHR shutdown cooling mode for decay heat removal, demonstrate system operability. Operating procedures include monthly venting of the low pressure systems to ensure the systems are maintained sufficiently filled.
No current issues have been identified during perFormance of these procedures.
e Venting procedures were improved and vent valves were added in the early 1990's to ensure adequate system venting and filling as part of corrective actions for previous gas accumulation issues. A HPCl "keep-fill" system was installed during the last refueling outage 20 specifically address a gas voiding issue. Based upon the preceding, the NMC believes that completing performance of the detailed walkdowns on those portions of the subject piping systems requiring refueling outages and subsequent evaluations outside the requested nine month period is an acceptabje alternative course of action for the MNGP. Conclusion Based on operating experience, testing (performance and surveillance), and prior corrective actions, the NMC has a high confidence that the systems discussed in GL 2008-01 can perform their required design functions at the MNGP. The NMC will complete all of the generic letter requested actions by October 11, 2008 except for the detailed walkdowns and analysis of inaccessible portions of the subject systems, as previously discussed.
REFERENCES I U.S. NRC Generic Letter 2008-01, "Managing Gas Accumulation in Emergency Core Cooling, Decay Heat Removal, and Containment Spray Systems," dated January 11,2008. Page 3 of 3