NLS2009073, Response to Nuclear Regulatory Commission Request for Additional Information Alternative Source Term

Response to Nuclear Regulatory Commission Request for Additional Information Alternative Source Term

ML092510169
Person / Time
Site:	Cooper
Issue date:	09/01/2009
From:	Minahan S Nebraska Public Power District (NPPD)
To:	Document Control Desk, Office of Nuclear Reactor Regulation
References
NLS2009073, TAC MD9921
Download: ML092510169 (10)

Text

N Nebraska Public Power District "Always there when you need us" 50.90 NLS2009073 September 1, 2009 U.S. Nuclear Regulatory Commission Attention: Document Control Desk Washington, D.C. 20555-0001

Subject:

Response to Nuclear Regulatory Commission Request for Additional Information Re: Alternative Source Term (TAC No. MD9921)

Cooper Nuclear Station, Docket No. 50-298, DPR-46

References:

1.

Letter from Carl F. Lyon, U. S. Nuclear Regulatory Commission, to Stewart B. Minahan, Nebraska Public Power District, dated August 19, 2009, "Cooper Nuclear Station - Request for Additional Information Re:

Alternative Source Term (TAC No. MD992 1)"

2.

Letter from Stewart B. Minahan, Nebraska Public Power District, to the U.S. Nuclear Regulatory Commission, dated October 13, 2008, "License Amendment Request for Application of the Alternative Source Term for Calculating Loss-of-Coolant Accident Dose Consequences"

Dear Sir or Madam:

The purpose of this letter is for Nebraska Public Power District to submit a response to requests for additional information (RAI) from the Nuclear Regulatory Commission (NRC) (Reference 1). The RAI requested information in support of NRC's review of a license amendment request for the Cooper Nuclear Station (CNS) facility operating license and technical specifications to adopt the Alternative Source Term for use in calculating the Loss-of-Coolant Accident dose consequences (Reference 2).

Responses to the specific RAI questions are provided in the Attachment to this letter. No regulatory commitments are made in this submittal.

Information submitted by this response to the RAI does not change the conclusions or the basis of the no significant hazards consideration evaluation provided with Reference 2.

If you have any questions concerning this matter, please contact David Van Der Kamp, Licensing Manager, at (402) 825-2904.

COOPER NUCLEAR STATION P.O. Box 98 / Brownville, NE 68321-0098 Telephone: (402) 825-3811 / Fax: (402) 825-5211 wwvwvnppd.com

NLS2009073 Page 2 of 2 I declare under penalty of perjury that the foregoing is true and correct.

Executed on 9/

9 (d te)

Sincerely, Stewart B. Minahan Vice President and Chief Nuclear Officer

/em Attachment cc:

Regional Administrator w/ attachment USNRC - Region IV Cooper Project Manager w/ attachment USNRC - NRR Project Directorate IV-1 Senior Resident Inspector w/ attachment USNRC - CNS Nebraska Health and Human Services w/ attachment Department of Regulation and Licensure NPG Distribution w/ attachment CNS Records w/ attachment

NLS2009073 Attachment Page 1 of 7 Attachment Response to Nuclear Regulatory Commission Request for Additional Information Re: Alternative Source Term (TAC No. MD9921)

Cooper Nuclear Station, Docket No. 50-298, DPR-46 QUESTION #1 Provide the loading sequence for each emergency diesel generator (EDG) at Cooper Nuclear Station (CNS). In your response, describe the changes that have been made to the EDG loading sequence to support the license amendment request (LAR) for CNS dated October 13, 2008 (Agencywide Documents Access and Management System (ADAMS) Accession No. ML082910760).

RESPONSE

No new electrical loads were added to support this Cooper Nuclear Station (CNS) license amendment request (LAR). Thus, it is not necessary to provide the loading sequence for Diesel Generators (DGs). The Standby Liquid Control (SLC) system has always been connected to the emergency busses. (A description of the electrical supply for the SLC system is included in the response to Question No. 1.1 of Attachment 2 to the LAR).

QUESTION #2 Describe how the loads being added to the CNS EDGs (i.e., standby liquid control system (SLC) components) affect the capability and capacity of the EDGs (e.g., describe the impact of the proposed change on the EDG ratings).

RESPONSE

No new electrical loads are being added to the DGs to support this LAR. As noted above, SLC system has always been connected to emergency busses. A description of the electrical supply for SLC system is included in response to Question 1.1 of Attachment 2 of the LAR.

SLC is not considered in the load calculation because it does not automatically initiate. It is manually initiated, if needed, and can be initiated up to six hours after the Design Basis Accident (DBA) Loss of Coolant Accident (LOCA).

Operators may add additional load to the DGs during the post-accident time period provided DGs do not exceed design load limitations. This will ensure DGs will not exceed their peak loading capabilities and will have adequate fuel reserves. Fuel consumption for DGs is based on these load constraints. Therefore, running SLC is acceptable post-LOCA.

NLS2009073 Attachment Page 2 of 7 QUESTION #3 In response to question 1 in attachment 2 of the LAR, the licensee stated that SLC is a non-safety-related system. Given that the SLC is a non-safety-related system, describe how this system will be electrically separated from the safety-related system (i.e., provide a detailed discussion on how a fault on the non-Class iE electrical circuit will not propagate to the Class iE electrical circuit). Also, describe the independence (e.g., electrical and physical separation) and redundancy of these systems.

RESPONSE

As stated in response to Question 1.1 in the LAR, power and control for each of the two SLC system pumps are fed from separate essential Motor Control Centers (MCCs) which are in turn fed from divisionally separate essential busses with standby power supplied by the DGs.

The SLC squib valves and their associated continuity meters are powered by these same essential MCCs, providing divisionally separate essential power to these valves. SLC system pressure and level indication is powered by a non-essential power panel that is powered via a switchable power source to either of the two essential busses, each of which can be supplied by a DG.

This is original configuration of the electrical supply for the SLC system, and no. changes were made in support of this LAR. Based on design of the power and control for SLC, there is no potential for a fault on a non-Class 1 E electrical circuit to propagate to a Class 1 E electrical circuit. Thus, if SLC tank heaters fail, essential power to the pumps and Squib valves would not be affected.

QUESTION #4 Describe how the SLC meets the single failure criterion.

RESPONSE

CNS design was developed concurrently with development of the earliest regulations and standards regarding single failure. Because of this timing, CNS design was only compared to the developing regulations and standards and not necessarily required to meet them. As a result, the applicability of single failure to CNS is limited to those items which CNS has committed to. Although SLC is not required to meet single failure criterion, the system is designed with two independent pumps and two explosively actuated injection valves, each powered from separate emergency busses. These are the only active components in the system. A detailed discussion of the suitability of SLC system redundancy in components and features is included in response to Question No. 3 in Attachment 2 of the LAR.

NLS2009073 Attachment Page 3 of 7 QUESTION #5 Describe how the operators will be notified in the event that the SLC would become inoperable (e.g., control room annunciators).

RESPONSE

Alarms are provided to notify Control Room operators for SLC Tank Hi/Low Level, SLC Tank Hi/Low Temperature, loss of continuity to the squib valves, and SLC Tank Heater Ground to Solution. When SLC is initiated, the operator turns a key locked switch in the Control Room to the "ON" position and then verifies the pump starts from observing pump discharge pressure and red indicating lights for running (green indicates off). The operator also checks to see that the continuity light for the associated squib valve goes out indicating the squib has fired.

QUESTION #6 Provide a list and description of components being added to your Title 10 of the Code of Federal Regulations Section 50.49 (10 CFR 50.49) program due to this LAR. Confirm that these components are qualified for the environmental conditions they are expected to be exposed to.

RESPONSE

No new components are added to the Environmental Qualification (EQ) program in support of this LAR. The proposed amendment does not change the operating environment for any components located outside the drywell. EQ profiles are, however, being revised to address the chemical spray that would be introduced into the containment if SLC injection is required.

The radiological analysis for Alternate Source Term (AST) credits SLC system injection to maintain the suppression pool pH levels above 7.0 following a DBA-LOCA to limit the evolution of elemental (gaseous) iodine being released into the containment atmosphere. The new function is to control the pH of the water in the suppression pool, reactor vessel, and core cooling systems following a DBA LOCA. The radiological analysis for AST is not used in the EQ profiles.

Under DBA-LOCA conditions, significant quantities of acid are generated. Injection of sodium pentaborate decahydrate (Na 2B10016-1011H20) solution from SLC is credited with buffering the acidity and maintaining pH of the suppression pool inventory above 7.0 for the duration of the DBA-LOCA. Chemical composition of the suppression pool is representative of containment spray conditions after the spray system is manually initiated 10 minutes into the DBA LOCA. Figure 1 reflects the pH profile of the suppression pool following a DBA-LOCA with SLC injection.

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CNS Buffered Pool pH Transient Figure 1 Suppression Pool pH with SLC Injection following DBA-LOCA Implementation of AST impacts the EQ Program since it effectively changes chemical composition and pH of the drywell spray under DBA-LOCA conditions. Spray conditions for small break LOCAs that do not result in fuel failure will remain as a demineralized water spray. Except for chemical composition of the containment spray, AST implementation does not change any other environmental parameter or profile used to establish environmental qualification of electrical equipment important to safety. Implementation of AST will change the spray condition for EQ Program equipment located in the following EQ Zones:

AST Impact on Environmental Conditions EQ Zone Description Remarks WCPLT Worst Case Plant (All EQ Zones)

Used for Commodity Items WCIPC Worst Case Inside Primary Containment PC2 Primary Containment (Drywell) between El. 931' and Outside of Shield Wall El. 958' PC4 Primary Containment (Drywell) outside of shield wall below El. 931' near Reactor Recirculation Pumps PC5 Primary Containment (Drywell) (>15 ft. from Recirculation Pumps)

PC6 Primary Containment (Torus Air Space)

NLS2009073 Attachment Page 5 of 7 When dissolved in an aqueous solution, each mole of sodium pentaborate dissociates into two (2) equivalents of sodium (Na), two (2) equivalents of borate (B(OH)4), and eight (8) equivalents of boric acid (H 3B0 3) as shown in the following equation.

Na2B1 00 16 + 16H 20 + 2Na+ + 2B(OH)4-+ 8B(OH) 3 The following concentrations are being used as a basis for evaluating EQ equipment for containment spray under DBA-LOCA conditions.

Compound Molarity (mol/L)

Ppm Hydriodic Acid, HI 9.72xl0-0.12 Cesium Hydroxide, CsOH 9.44 x 10-'

14.15 Nitric Acid, HNO3 7.37x1O-'

4.64 Hydrochloric Acid, HCl 4.9 7xlO-4 18.12 Borate, B(OH)4 2.32x 10-3 182.91 Boric Acid, H3B0 3 9.27x10-3 574.14 The pH range used to demonstrate qualification following a DBA-LOCA with SLC injection is 7.0 - 8.4. The following table provides a summary of the affected equipment types, listed by EQ Data Package (EQDP), and how the equipment will be qualified for the new chemical spray conditions.

Listing of EQ Equipment Affected by AST Implementation EQDP #

Description Make /

Qualification Method Remarks Model for Chemical Spray EQDP.2.105 GE/PCI Pressure A171P Existing SRV Position Indication is Switch Qualification to not required for DBA-Demineralized LOCA.

Spray remains valid EQDP.2.116 Namco EA-180 Limit EA180 Series Test and Analysis Evaluated for EQ Zone Switches WCIPC.

EQDP.2.118 Target Rock SRV 1/2 SMS-S-Test and Analysis SRVs are not required for Solenoid 02-1 DBA-LOCA.

Conservatively evaluated for chemical spray.

Analysis credits sealing of enclosures.

EQDP.2.171 Limitorque Actuator SMB Series Test and Analysis Evaluated for EQ Zone Components (B0212)

WCPLT.

EQDP.2.172 R.A. Hiller MSIV SA-A 111 Test and Analysis Evaluated for EQ Zone Pilot Control Valve SA-A085 PC5. Analysis credits Manifold Assembly sealing of enclosures.

EQDP.2.178 Limitorque SMB with SMB Series Test and Analysis Evaluated for EQ Zones Reliance Class RH PC4 and PC5.

Motors EQDP.2.179 Limitorque SMB/SB SB and SMB Test and Analysis Evaluated for EQ Zone DOR with Peerless Series PC4.

125/25OVDC Motors

NLS2009073 Attachment Page 6 of 7 Listing of EQ Equipment Affected by AST Implementation EQDP #

Description Make /

Qualification Method Remarks Model for Chemical Spray EQDP.3.114 CONAX 7H04-10001-Test and Analysis Evaluated for worst case of Temperature 01 EQ Zones PC I, PC4, and Elements (RTD &

PC5.

T/C)

EQDP.3.115 Victoreen HRRM 875 Test and Analysis Evaluated for EQ Zone PC5.

EQDP.4.122 Raychem Flamtrol Flamtrol Test and Analysis Evaluated for EQ Zone Cable WCPLT.

EQDP.4.123 Kerite HTK/FR Cable HTK/FR Test and Analysis Evaluated for EQ Zone DOR 1000V WCIPC.

EQDP.4.125 Cerro Firewall SR Firewall SR Test and Analysis Evaluated for EQ Zone (KS-500)

WCPLT.

EQDP.4.126 GE EPAs 238X600NSG Test and Analysis Evaluated for EQ Zone DOR 001 PC5 and PC6.

EQDP.4.136 CONAX ECSA N-11027-01 Test and Analysis Generic Qualification.

and N-11136-Conax ECSAs inside the 01 drywell are currently qualified by EQDP.3.114.

EQDP.4.138 Rockbestos Firewall Firewall III Test and Analysis Evaluated for EQ Zone III and Firewall SIS WCPLT.

EQDP.4.139 Brand-Rex Ultrol Ultrol Test and Analysis Evaluated for EQ Zone Cable WCPLT.

EQDP.4.147 Raychem WCSF-N WCSN-N Test and Analysis Evaluated for EQ Zone Bolted WCPLT.

EQDP.4.148 CONAX Coaxial 7T26-10000-Test and Analysis Evaluated for EQ Zone EPAs 01 WCPLT.

EQDP.4.158 GE Low Voltage SI-57275 Test and Analysis Evaluated for EQ Zone.

DOR Control Cable (Type WCPLT.

SI-57275)

EQDP.4.163 IST Low Voltage Serial No.

Test and Analysis Evaluated for EQ Zone EPA 913501 PC5.

EQDP.4.164 EGS Grayboot GB-1, -2, -3 Test and Analysis Evaluated for EQ Zone Connectors Series PC5.

EQDP.4.166 Namco EC-210 EC-210 Test and Analysis Evaluated for EQ Zone Connectors Series PC5.

EQDP.4.175 EGS QDC Connector 880701 Test and Analysis Evaluated for EQ Zone Series and WCPLT.

Namco EC-290 EQDP.4.183 BIW Bostrad 7 Bostrad 7 Test and Analysis Evaluated for worst case of DOR Instrumentation EQ Zones PC I and PC5.

Cable EQDP.4.184 Raychem NPKP and NPKP and Test and Analysis Evaluated for EQ Zone NMCK Y-Splice Kits NMCK WCPLT.

EQDP.4.185 Raychem WCSF-N WCSF-N Test and Analysis Evaluated for EQ Zone Inline Crimped Crimped WCPLT.

Connection EQDP.4.186 Raychem NPKV Stub NPKV Test and Analysis Evaluated for EQ Zone Connection WCPLT.

NLS2009073 Attachment Page 7 of 7

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Listing of EQ Equipment Affected by AST Implementation EQDP #

Description Make /

Qualification Method Remarks Model for Chemical Spray EQDP.4.189 Cerro Pyrotrol III Pyrotrol III Test and Analysis Evaluated for EQ Zone DOR Cable WCPLT.

EQDP.4.192 Rockbestos Firewall Firewall SR Test and Analysis Evaluated for EQ Zone SR (KS-550)

PC4.

EQDP.4.197 Raychem NMCK NMCK Test and Analysis Evaluated for EQ Zone Splice Kits WCPLT.

EQDP.4.205 EGS Patel P-1 Thread P-1 Test and Analysis Evaluated for EQ Zone Sealant WCPLT.

QUESTION #7 In response to question 1.5 in attachment 2 of the LAR, the licensee stated that the components exposed to a harsh environment have been evaluated as either qualified or identical to qualified equipment. The licensee should confirm that the identical components added to environmental qualification (EQ) list due to this LAR were maintained as EQ components or provide the attributes, the detailed evaluation, and the documentation to upgrade these components to meet the requirements of 10 CFR 50.49.

RESPONSE

No new components are added to the EQ program in support of this LAR. The appropriate SLC components are already included in the EQ program and remain qualified. The proposed amendment does not change the operating environment for any components located outside the drywell. EQ profiles are, however, being revised to address the chemical spray that would be introduced into the containment if SLC injection is required.

EQ equipment inside containment will remain qualified for the spray conditions that will exist if SLC is initiated following a DBA-LOCA. A review of the EQDP's has revealed no problems, and the EQDPs have been updated to reflect the new chemical spray conditions using at least one of the following technical approaches:

1) Credit the chemical spray composition in existing IEEE qualification test program(s).

2) Use separate effects testing or analysis to demonstrate material compatibility with Sodium Pentaborate.

3) Device is hermetically sealed or otherwise protected from chemical spray.

4) Component is located in EQ Zone PC 1, which is above the highest spray header elevation.

5) Demonstration that the component has performed its function prior to manual spray initiation.

ATTACHMENT 3 LIST OF REGULATORY COMMITMENTS© 4 ATTACHMENT 3 LIST OF REGULATORY COMMITMENTS© 4

Correspondence Number: NLS20090073 The following table identifies those actions committed to by Nebraska Public Power District

,(NPPD) in this document. Any other actions discussed in the submittal represent intended or planned actions by NPPD. They are described for information only and are not regulatory commitments. Please notify the Licensing Manager at Cooper Nuclear Station of any questions regarding this document or any associated regulatory commitments.

COMMITMENT COMMITTED DATE COMMITMENT NUMBER OR OUTAGE None 1*

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PROCEDURE 0.42 REVISION 24 PAGE 18 OF 25