ML063320478

E-mail, Miller, NRR, to Distel, Exelon, Draft Request for Additional Information, Oyster Creek AST LAR

ML063320478
Person / Time
Site:	Oyster Creek
Issue date:	11/28/2006
From:	Geoffrey Miller NRC/NRR/ADRO/DORL/LPLI-2
To:	Distel D Exelon Corp
References
TAC MC6519
Download: ML063320478 (5)

Text

From: Ed Miller To: david.distel@exeloncorp.com Date: 11/28/2006 3:10:57 PM

Subject:

Draft Request for Additional Information, Oyster Creek AST LAR

Dave, Attached are draft questions pertaining to the Oyster Creek Alternative Source Term License Amendment Request. I am providing these questions in draft form to verify that the requested information and regulatory basis for the questions is understood. Additionally, the information is being provided to allow you to identify any information that is currently on the Oyster Creek docket that may be responsive to the draft questions. If you need any clarification, please contact me.

G. Edward Miller Project Manager Division of Operating Reactor Licensing U.S. Nuclear Regulatory Commission (301) 415-2481

Mail Envelope Properties (456C97D1.2C1 : 9 : 35080)

Subject:

Draft Request for Additional Information, Oyster Creek AST LAR Creation Date 11/28/2006 3:10:57 PM From: Ed Miller Created By: GXM@nrc.gov Recipients Action Date & Time exeloncorp.com Transferred 11/28/2006 3:11:09 PM david.distel (david.distel@exeloncorp.com)

Post Office Delivered Route exeloncorp.com Files Size Date & Time MESSAGE 1140 11/28/2006 3:10:57 PM TEXT.htm 944 AST RAI Draft for E-mail.wpd 17381 11/28/2006 3:02:22 PM Options Auto Delete: No Expiration Date: None Notify Recipients: Yes Priority: Standard ReplyRequested: No Return Notification: None Concealed

Subject:

No Security: Standard To Be Delivered: Immediate Status Tracking: Delivered & Opened

DRAFT REQUEST FOR ADDITIONAL INFORMATION OYSTER CREEK GENERATING STATION (TAC NO. MC6519)

By letter dated March 28. 2005, AmerGen Energy Company, LLC requested changes to the Facility Operating License for the Oyster Creek Nuclear Generating Station (Oyster Creek).

The LAR requested to revise the Oyster Creek licensing basis in the area of radiological dose analyses for design-basis accidents using the alternative source terms depicted in Regulatory Guide 1.183, Alternative Radiological Source Terms for Evaluating Design Basis Accidents at Nuclear Power Reactors. The Nuclear Regulatory Commission (NRC) staff has been reviewing the submittal and has developed the following draft questions during its review. The following questions do not represent a formal NRC staff position.

1. Justify the use of MAAP4 for the containment accident thermal-hydraulics. Describe the phenomena occurring in containment as the accident progresses and show that MAAP4 can adequately model these phenomena in terms of any benchmarking to data or other computer codes for each phenomena. Since MAAP4 is being used for design basis calculations, show that the MAAP4 calculations bound the expected response.

2. RG 1.183 Position 4.5 states that technical specification values should be used.

Position 6.2 states a similar position for the MSIVs. Given that secondary bypass leakage rate is calculated as a function of pressure:

a. Provide justification that leakage through narrow, ill-defined clearances that may change with pressure, like the stem and seat areas of valves, can be modeled as isentropic nozzles.

b. Provide a reference to an NRC approval supporting page 36/45 of Attachment 1, which states that this modeling approach is consistent with the current licensing basis.

c. Provide the results of a sensitivity study to show the difference between the time dependent leakage assumption and the results using the technical specification leakage.

3. On page 33 of Attachment 1 to the March 28, 2005 submittal, you state that the current licensing basis for Oyster Creek includes an assumption of full mixing credit for dilution/mixing in the secondary containment. Please provide the reference where the NRC staff found this assumption acceptable.

4. With regard to the assumptions for drywell iodine removal:

a. What are the separate removal coefficients for spray and for sedimentation?

b. How do the STARNAUA removal models compare to the models referred to in RG 1.183 as acceptable spray removal and natural deposition models?

c. On page 8 of Attachment 3 you give justification for assuming that the aerosol and elemental iodine removal rates are the same in the drywell, stating that it is believed that the elemental iodine will adhere to the aerosol, and if that is not so that the elemental iodine would be removed from the containment at a rate greater than the particulate. What is the basis for the statement that elemental iodine would be removed from the containment at a rate greater than particulate?

5. Credit is proposed for control of the pH in the suppression pool following a LOCA by means of injecting sodium pentaborate into the reactor core with the standby liquid control (SLC) system. The SLC system design was not previously reviewed for this safety function (pH control post-LOCA). Licensees proposing such credit need to demonstrate that the SLC system is capable of performing the pH control safety function assumed in the AST LOCA dose analysis.

a. Identify whether the SLC system is classified as a safety related system as defined in 10 CFR 50.2, and whether the system satisfies the regulatory requirements for such systems. If the SLC system is not classified as safety related, please provide the information requested in Items A.1 to A.5 below to show that the SLC system is comparable to a system classified as safety related.

If any item is answered in the negative, please explain why the SLC system should be found acceptable for pH control agent injection.

(i) Is the SLC system provided with standby AC power supplemented by the emergency diesel generators?

(ii) Is the SLC system seismically qualified in accordance with Regulatory Guide 1.29 and Appendix A to 10 CFR Part 100 (or equivalent used for original licensing)?

(iii) Is the SLC system incorporated into the plants ASME Code ISI and IST programs based upon the plants code of record in accordance with 10 CFR 50.55a?

(iv) Is the SLC system incorporated into the plants Maintenance Rule program consistent with 10 CFR 50.65?

(v) Does the SLC system meet the requirements of 10 CFR 50.49 and Appendix A to 10 CFR 50 (GDC 4, or equivalent used for original licensing)?

b. Describe proposed changes to plant procedures that implement SLC sodium pentaborate injection as a pH control additive and associated operator training.

c. How is transport of the sodium pentaborate to the suppression pool assured to occur? Is a LPSI pump injecting at the time of SLC injection?

d. Show that the SLC system has suitable redundancy in components and features to assure that, for onsite or offsite electric power operation, its safety function of injecting sodium pentaborate for the purpose of suppression pool pH control can be accomplished assuming a single failure. For this purpose, the check value is considered an active device since the check valve must open to inject sodium pentaborate. If the SLC system can not be considered redundant with respect to its active components, the licensee should implement one of the three options described below, providing the information specified for that option for staff review.

Option 1 Show acceptable quality and reliability of the non-redundant active components and/or compensatory actions in the event of failure of the non-redundant active components. If you choose this option, please provide the following information to justify the lack of redundancy of active components in the SLC system:

Identify the non-redundant active components in the SLC system and provide their make, manufacturer, and model number.

Provide the design-basis conditions for the component and the environmental and seismic conditions under which the component may be required to operate during a design-basis accident. Environmental conditions include design-basis pressure, temperature, relative humidity and radiation fields.

Indicate whether the component was purchased in accordance with Appendix B to 10 CFR Part 50. If the component was not purchased in accordance with Appendix B, provide information on the quality standards under which it was purchased.

Provide the performance history of the component both at the licensees facility and in industry databases such as EPIX and NPRDS.

Provide a description of the components inspection and testing program, including standards, frequency, and acceptance criteria.

Indicate potential compensating actions that could be taken within an acceptable time period to address the failure of the component. An example of a compensating action might be the ability to jumper a switch in the control room to overcome its failure. In your response please consider the availability of compensating actions and the likelihood of successful injection of the sodium pentaborate when non-redundant active components fail to perform their intended functions.

Option 2 Provide for an alternative success path for injecting chemicals into the suppression pool. Provide a description of the alternative injection path, its capabilities for performing the pH control function, and its quality characteristics.

Does the alternate injection path require actions to be taken in areas outside the control room? How accessible will these areas be? What additional personnel would be required?

Option 3 Show that 10 CFR 50.67 dose criteria are met even if pH is not controlled. If you chose this option, demonstrate through analyses that the projected accident doses will continue to meet the criteria of 10 CFR 50.67 assuming that the suppression pool pH is not controlled. The dissolution of CsI and its re-evolution from the suppression pool as elemental iodine must be evaluated by a suitably conservative methodology. The analysis of iodine speciation should be provided for staff review. The resulting iodine speciation should be incorporated into the dose analyses. A description of the dose analysis assumptions, inputs, methods, and results should be provided. It should be noted that using option will incur longer staff review times.