ML100600914

E-mail Byron 1 & 2 - RAI for One -Time Extension of ESW Train Completion Time (ME2293-94)

ML100600914
Person / Time
Site:	Byron
Issue date:	02/26/2010
From:	David M Plant Licensing Branch III
To:	Schofield L, Simpson P Exelon Generation Co
M. J. David
References
TAC ME2293, TAC ME2294
Download: ML100600914 (3)

Text

From: David, Marshall Sent: Friday, February 26, 2010 8:57 AM To: 'patrick.simpson@exeloncorp.com'; 'Lisa.Schofield@exeloncorp.com' Cc: Howe, Andrew; Purciarello, Gerard; Harrison, Donnie; Campbell, Stephen

Subject:

BYRON 1 & 2 - RAI FOR ONE-TIME EXTENSION OF ESW TRAIN COMPLETION TIME (ME2293-94)

Importance: High Pat, Lisa, Below are additional questions on the subject license amendment request. I will be placing a copy of this e-mail in ADAMS.

Thanks, Marshall REQUEST FOR ADDITIONAL INFORMATION BYRON STATION, UNIT NOS. 1 AND 2 DOCKET NOS. STN 50-454 AND STN 50-455 The Nuclear Regulatory Commission (NRC) staff is reviewing Exelon Generation Company, LLCs (the licensees) license amendment request (LAR) dated September 24, 2009 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML092680090), as supplemented by letters dated November 13, 2009 (ADAMS Accession No. ML093200065), and January 19, 2010 (ADAMS Accession No. ML100200075). The LAR requests a one-time extension of the Completion Time (CT) to restore a unit-specific essential service water train to operable status for Technical Specification (TS) Limiting Condition for Operation 3.7.8, Essential Service Water (SX) System, from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 144 hours0.00167 days <br />0.04 hours <br />2.380952e-4 weeks <br />5.4792e-5 months <br />.

The NRC staff has determined that the following additional information is required to complete its review. Your staff has agreed to provide the requested information by March 5, 2010.

The NRC staff considers that timely responses to requests for additional information help ensure sufficient time is available for NRC staff review and contribute toward the NRCs goal of efficient and effective use of NRC staff resources. If circumstances result in the need to revise the requested response date, please contact me at (301) 415-1547.

1. Questions on the Commitments for Table 3 of Attachment 1 of the LAR:

(Ref: January 19, 2010, response to questions 3.c and 3.d) It is not clear what criteria was applied to identify the protected equipment or the fire zones to be subject to walkdowns, other than that risk insights were applied in some manner. A more specific definition of the criteria applied (e.g., top X cutsets, to Y% of risk, Fussel-Vessely or risk achievement worth values) needs to be identified for the NRC staff to conclude that the scope of the protected equipment and fire zones is adequate for tier 2 and for the compensatory measures.

(Ref: January 19, 2010, response to question 3.b) The response generally clarified the scope of the equipment which is protected, but this information needs to be included in a revised commitment reference. Specifically, the following items in Table 3 of Attachment 1 of the LAR are too vague and need to be formally clarified:

• Unit 1 SATs - this should specifically refer to transformer SAT 142 which is protected

• Unit 2 SATs - this should specifically refer to transformer SAT 242 which is protected

• Unit 1 120 VAC Inst Inverters - this should specifically refer to the four inverters protected In addition, the following aspects of Table 3 are confusing and should also be clarified as to exactly what the commitment entails:

• Comment entry on 4KV Bus 142 regarding "minimize or preclude" breaker switching operations - need to clarify three items: 1) why is this comment applied only to this bus (i.e., not bus 141, 241, 242), 2) is the commitment to preclude or to minimize, and what is the meaning of "minimize" with regards to a license commitment?, and 3) does the comment add additional requirements beyond "protected equipment", or does it supersede "protected equipment"?

• 1SX033/1SX034 and 2SX033/2SX034 - clarify why separate components are on a single line entry - does this mean one or the other is protected, or both?

• The entry for the fire zone walkdowns needs to clarify what is being committed with regards to "transient control" - it is assumed this means transient combustibles? Is the commitment that there will be no transient combustibles in the zone, or that they are simply stored properly, or something else? Does the commitment eliminate hot work in the zone (typical of licensees)?

2. Questions on the quality of the fire probabilistic risk assessment (Ref: January 19, 2010, response to question 1.b):

Item 5, regarding the lack of treatment of hot gas layers - the statement that, "A practical treatment of hot gas layer [HGL] formation is not yet available in industry" is not true, since there are simple Fire Dynamics Tools in NUREG-1805, Fire Dynamics Tools (FDTs) Quantitative Fire Hazard Analysis Methods for the U.S. Nuclear Regulatory Commission Fire Protection Inspection Program, for example, which provide simple correlations for HGL formation. The statement that "[HGL] formation is not expected to be a significant contributor to risk at a newer plant such as Byron with typically large volumes for dissipation " is too vague for the NRC staff to rely upon as a justification that neglecting HGL formation is not ignoring potentially risk-significant scenarios. The licensee should examine the fire areas of their plant using available tools to confirm that HGL formation will not occur or will not be significant and provide a more robust justification.

Item 11, regarding the choice of a motor fire to represent a typical transient fire - if the most likely type of transient combustible is temporary cabling (as stated in the RAI response), then selection of the electric motor fire source (i.e., 32/69 kw at the 75th/98th percentile heat release

rates in NUREG/CR-6850, EPRI TR-1011989, EPRI/NRC-RES Fire PRA Methodology for Nuclear Power Facilities) rather than electrical cabinet (i.e., 69/211 kw at the 75th/98th percentile heat release rates in NUREG/CR-6850) would seem more representative of the cited transient fire scenario. The basis for selecting a motor fire source instead needs to be justified.

E-mail Properties Mail Envelope Properties (0046140293E11F408991442DB4FE25CA066FF025FF)

Subject:

BYRON 1 & 2 - RAI FOR ONE-TIME EXTENSION OF ESW TRAIN COMPLETION TIME (ME2293-94)

Sent Date: 2/26/2010 8:59:34 AM Received Date: 2/26/2010 8:57:07 AM From: David, Marshall Created By: Marshall.David@nrc.gov Recipients:

patrick.simpson@exeloncorp.com ('patrick.simpson@exeloncorp.com')

Tracking Status: None Lisa.Schofield@exeloncorp.com ('Lisa.Schofield@exeloncorp.com')

Tracking Status: None Andrew.Howe@nrc.gov (Howe, Andrew)

Tracking Status: None Gerard.Purciarello@nrc.gov (Purciarello, Gerard)

Tracking Status: None Donnie.Harrison@nrc.gov (Harrison, Donnie)

Tracking Status: None Stephen.Campbell@nrc.gov (Campbell, Stephen)

Tracking Status: None Post Office:

HQCLSTR01.nrc.gov Files Size Date & Time MESSAGE 0 2/26/2010 Options Expiration Date:

Priority: olImportanceHigh ReplyRequested: False Return Notification: False Sensitivity: olNormal Recipients received: