ML101800052

Generic Letter

ML101800052
Person / Time
Site:	Point Beach
Issue date:	06/30/2010
From:	Beltz T Plant Licensing Branch III
To:	Meyer L Point Beach
beltz T, NRR/DORL/LPL3-1, 301-415-3049
References
TAC MC4705, GL-04-002
Download: ML101800052 (6)

Text

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 June 30, 2010 Mr. Larry Meyer Site Vice President NextEra Energy Point Beach, LLC 6610 Nuclear Road Two Rivers, WI 54241

SUBJECT:

POINT BEACH NUCLEAR PLANT, UNIT 1 - GENERIC LETTER 2004-02 EXTENSION REQUEST APPROVAL (TAC NO. MC4705)

Dear Mr. Meyer:

The U.S. Nuclear Regulatory Commission (NRC) staff has evaluated the information provided in NextEra Energy Point Beach, LLC's (the licensee) letter dated June 11, 2010 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML101650080),

supporting a request for an extension of the Point Beach Nuclear Plant (PBNP), Unit 1 sump clogging corrective actions due date of June 30, 2010, as approved by the NRC by letter dated June 30, 2009 (ADAMS Accession No. ML091800430).

The NRC has determined that for PBNP Unit 1, it is acceptable to extend the due date for completion of Generic Letter 2004-02 "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors," corrective actions as described in the enclosed NRC staff evaluation of the extension request, until 90 days following Commission direction to the NRC staff based on their review of the information submitted by the NRC staff to address the NRC Staff Requirements Memorandum (M100415) dated May 17, 2010. The licensee committed to submit to the NRC an updated resolution plan, including milestones, within 60 days beyond receipt of the above noted Commission direction.

The NRC will then review the licensee's submittal and determine whether an additional extension is appropriate. Enclosed is the NRC staff evaluation.

If you have any questions, please contact me at (301) 415-3049.

Sincerely,

~~~'----

Terry A. Beltz, Senior Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-266 and 50-301

Enclosure:

As stated cc w/encl: Distribution via ListServ

UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20555-0001 EVALUATION OF EXTENSION REQUEST FOR CONTAINMENT SUMP CORRECTIVE ACTIONS ASSOCIATED WITH GENERIC LETTER 2004-02 POINT BEACH NUCLEAR PLANT, UNITS 1 AND 2 DOCKET NOS. 50-266 AND 50-301 By letter dated June 11, 2010 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML101650080), NextEra Energy Point Beach, LLC (the licensee),

requested an extension of time to complete actions to address Generic Letter (GL) 2004-02, "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors," for the Point Beach Nuclear Plant (PBNP), Unit 1.

In a letter dated June 12,2009 (ADAMS Accession No. ML091660326), the licensee had previously requested an extension to the corrective action due date until June 30, 2010, for PBNP Unit 1, and June 30, 2011, for PBNP Unit 2. The U.S. Nuclear Regulatory Commission (NRC) granted the extension to the dates requested (NRC letter dated June 30, 2009, ADAMS Accession No. ML091800430) in order to support the licensee's plans to complete fibrous insulation removal for both units.

Recent NRC and industry discussions have revealed that a number of issues remain unresolved for Generic Safety Issue (GSI) 191, "Assessment of Debris Accumulation on Pressurized Water Reactor (PWR) Sump Performance," and that a clear and acceptable path needs to be defined to resolve the issues. On April 15, 2010, the Commission was briefed by an industry panel and the NRC staff on the ongoing efforts to resolve GSI-191. Because of the number of significant matters that remain unresolved, the Commission directed the NRC staff via Staff Requirements Memorandum (SRM) M100415 (ADAMS Accession No. ML101370261) not to transmit letters to licensees under Section 50.54(f) of Title 10 of the Code of Federal Regulations on the subject of GSI-191 pending further direction from the Commission. Additionally, the staff has been directed to submit to the Commission a Notation Vote policy paper on potential approaches to bring GSI-191 to closure. The discussion of the options will, among others, address such factors as the Commission's ALARA policy concerning radiation dose, worker hazardous material exposure, and risk-informed versus deterministic treatment of remaining elements.

During a teleconference held on June 7,2010, between NextEra and the NRC, the licensee stated that an updated resolution plan, including milestones, would be submitted to the NRC within 60 days following Commission direction to the NRC staff based on their review of the information submitted by the NRC staff to address the SRM dated May 17, 2010. Following the NextEra submittal, the licensee assumed the NRC would take an additional 30 days to review Enclosure

- 2 and respond to this approach. Therefore, the licensee requested an extension of 90 days from issuance of the Commission direction.

The NRC staff uses the criteria stated in SECY-06-0078 to evaluate requests for extending the due date for completion of GL 2004-02 corrective actions. Specifically, an extension may be granted if:

• the licensee has a plant-specific technical/experimental plan with milestones and schedule to address outstanding technical issues with enough margin to account for uncertainties, and

• the licensee identifies mitigative measures to be put in place prior to December 31,2007, and adequately describes how these mitigative measures will minimize the risk of degraded emergency core cooling system (ECCS) and containment spray system (CSS) functions during the extension period.

SECY-06-0078 also states that for proposed extensions beyond several months, a licensee's request will more likely be accepted if the proposed mitigative measures include temporary physical improvements to the ECCS sump or materials inside containment to better ensure a high level of ECCS sump performance.

With regard to the first extension criteria the licensee has made the following commitment as stated in its June 11, 2010, letter:

Within 60 days following establishment of sufficient Commission direction to resolve the remaining GSI-191 issues, PBNP will submit to the NRC a plan with milestones to achieve final resolution.

Given the significance of GSI-191 open issues and the direction provided by the Commission in SRM M100415, the staff has determined that it is acceptable for the licensee to provide the plan for resolution 60 days after the Commission has made its decision, as communicated during the June 7, 2010, teleconference.

With regard to the second extension criterion, the licensee has implemented mitigative measures which minimize the risk of degraded ECCS and CSS functions during the proposed extension period.

The licensee stated in its letter dated June 12, 2009, that during the spring 2007 refueling outage a new strainer design was installed on the ECCS system in containment. This design increased the available flow area from approximately 21 square feet (ft2) to approximately 1,500 ft2 for each of two redundant strainers on the ECCS recirculation piping. This design also reduced the size of the flow openings from 0.125-inch to 0.066-inch diameter and greatly reduced the approach velocity of the openings to allow for increased settling of particulates and fiber. As a result of the July 2008 large flume testing, performed with the latest Performance Contracting Inc. protocols, additional hardware modifications have been made. These modifications increased each strainer train area from approximately 1,500 ft2 to approximately

- 3 1,900 ft2 and structurally reinforced the strainer assemblies to accommodate an increased differential pressure. Lastly, debris interceptors designed to reduce the quantity of suspended debris that could be transported to the screen surface were installed and the refueling cavity drain piping was rerouted to direct debris suspended in containment spray water from these areas to upstream of the debris interceptors. These changes were implemented during the fall 2008 refueling outage.

The licensee stated in its letter dated June 12, 2009 that, during the fall 2006 refueling outage, a new strainer design was installed on the ECCS system in containment. This design increased the available flow area from approximately 21 fe to approximately 1,500 fe for each of two redundant strainers on the ECCS recirculation piping. This design also reduced the size of the flow openings from 0.125-inch to 0.066-inch diameter and greatly reduced the approach velocity of the openings to allow for increased settling of particulates and fiber. A prototype of this design was successfully tested during May 2006 with scaled flow and debris. During the fall 2009 refueling outage, the licensee installed three (3) additional strainer modules to increase each strainer train area from approximately 1,500 fe to approximately 1,900 fe, structurally reinforced the strainer assemblies to accommodate an increased differential pressure, and initiated the fibrous insulation reduction effort.

With regard to the third extension criterion, the licensee stated that it has completed various significant plant modifications to address GL 2004-02. These include the improved monitoring of containment coatings condition, improved monitoring and control of containment cleanliness, and procedural action in the unlikely event of sump screen blockage. The licensee also stated that the PBNP containment sumps incorporate design features that help to minimize the possibility of strainer blockage. First, the containment sump is the lowest full containment floor elevation. Second, the screens are located outside the reactor coolant system (RCS) loop compartments to minimize the potential for damage from a high energy pipe failure. Third, there are two redundant trains to minimize the potential for a single failure resulting in loss of function.

Fourth, the sump screens rest on supports that are slightly off the sump floor, rather than mounted in a depressed sump that could collect debris and obstruct active screen area.

In the June 12, 2009, letter, the licensee discussed the structural integrity of the piping with problematic insulation. The licensee examines the RCS piping in accordance with PBNP's American Society of Mechanical Engineers Boiler and Pressure Vessel Code (Code),

Section XI, in-service inspection (lSI) program. The licensee further states that it ultrasonically examined 100 percent of the RCS welds during the third inspection interval ending in 2002, and subsequently performed examinations following the NRC-approved risk-informed lSI program during the fourth inspection interval. The licensee has not detected any rejectable indications.

The licensee also performs the Code-required visual examinations for thru-wall leakage at the end of each refueling outage, and has not detected any leakage. For the purpose of the extension, the licensee adequately discussed primary water stress corrosion cracking of Alloy 600/82/182 welds in the June 12, 2009, letter. The staff reviewed the PBNP RCS piping materials and concluded that there is a low probability of rapidly propagating fractures in the large-and medium-bore piping as discussed in various staff safety evaluations of the licensee's leak-before-break analyses, referenced on page 10 of Enclosure 1 in licensee's June 12, 2009, letter. The plant also has adequate RCS leakage detection systems to allow the plant to be

-4 shut down before a rupture occurs. For the smaller piping (2-inch to 8-inch lines), the licensee stated that the smaller lines were constructed with compatible materials and have design pressures, temperatures, and nondestructive examination requirements similar to the larger piping. Based on operating experience for similar lines at this and other PWRs, the staff 'finds that the smaller lines should have a low probability of pipe rupture during the extension period.

On the basis of its evaluation of the licensee's submittal in light of the extension criteria in SECY-06-0078, the staff finds that:

It is acceptable for the licensee to provide a plan for GSI-191 resolution after the Commission has made its final decision on an acceptable resolution plan for open GSI-191 issues.

The licensee has put in place mitigative measures and adequately described how these mitigative measures will minimize the risk of degraded ECCS and CSS functions during the extension period.

• The proposed mitigative measures include improvements to the ECCS sump or materials inside containment to better ensure a high level of ECCS sump performance.

In addition, the staff agrees with the licensee's statement that the combination of acceptable lSI test results, minimal primary water stress corrosion cracking susceptibility, upgraded sump strainers, reduced quantities of debris that can be credibly generated from medium and small bore piping, and leak-before-break piping analyses provide reasonable assurance that a postulated LOCA which results in a challenge to the proper functioning of the sump strainers is not likely during the proposed extension period.

Based on the licensee having satisfactorily addressed the NRC GL 2004-02 due date extension criteria as discussed above, the NRC staff finds that extending the completion date for GL 2004-02 corrective actions until 90 days beyond receipt of the above noted Commission direction is acceptable for PBNP Unit 1. The staff considers the granted extension period to be of low safety concern given the mitigation measures and plant improvements already in place, and expects the licensee to provide the corrective action plan as described in the licensee's letter dated June 11,2010.

The extension to complete actions for GL 2004-02 that was approved by the NRC by the letter dated June 30, 2009, for PBNP Unit 2 to June 30, 2011, remains unchanged.

Principal Contributor: Roberto L. Torres, NRR Date:

J1U1e 30, 2010

ML091800430).

The NRC has determined that for PBNP Unit 1, it is acceptable to extend the due date for completion of Generic Letter 2004-02 "Potential Impact of Debris Blockage on Emergency Recirculation During Design Basis Accidents at Pressurized-Water Reactors," corrective actions as described in the enclosed NRC staff evaluation of the extension request, until 90 days following Commission direction to the NRC staff based on their review of the information submitted by the NRC staff to address the NRC Staff Requirements Memorandum (M100415) dated May 17, 2010. The licensee committed to submit to the NRC an updated resolution plan, including milestones, within 60 days beyond receipt of the above noted Commission direction.

The NRC will then review the licensee's submittal and determine whether an additional extension is appropriate. Enclosed is the NRC staff evaluation.

If you have any questions, please contact me at (301) 415-3049.

Sincerely, IRAJ Terry A. Beltz, Senior Project Manager Plant Licensing Branch 111-1 Division of Operating Reactor Licensing Office of Nuclear Reactor Regulation Docket Nos. 50-266 and 50-301

Enclosure:

As stated cc w/encl: Distribution via ListServ DISTRIBUTION:

PUBLIC LPL3-1 R/F RidsNrrDorILp/3-1 Resource RidsNrrPMPointBeach RidsNrrLABTully RidsNrrDorlDpr Resource RidsAcrsAcnw_MailCenter RidsOgcRp Resource RidsRgn3MailCenter Resource RTorres, NRR MScott, NRR RidsNrrDssSsib ADAMS Accession No.: ML101800052

• via memo dated June 25 2010 OFFICE LPL3-1/PM LPL3-1/LA DSS/SSIB/BC LPL3-1/BC NAME TBeltz BTuily MScott * (JLehning for)

RPascarelli DATE 06/30/10 06/30/10 06/25/10 06/30/10