ML111780424

June 22, 2011, Meeting Handout #1 - NRC Meeting Diesel Fuel Oil LAR for Prairie Island Ngp

ML111780424
Person / Time
Site:	Prairie Island
Issue date:	06/22/2011
From:	Thomas Wengert Xcel Energy
To:	Plant Licensing Branch III
Wengert, Thomas
References
Download: ML111780424 (40)

Text

NRC Meeting Diesel Fuel Oil LAR June 22, 2011

Xcel Energy Participants Christopher Lethgo - Engineering Supervisor Dale Vincent - Licensing Engineer 2

Agenda Introductions - Vincent Meeting purpose - Vincent Background - Lethgo Unit 1 DFO System - Lethgo Unit 2 DFO System - Lethgo Current TS and Bases - Vincent Proposed TS and Bases - Vincent Proposed LAR Scope - Vincent Summary - Vincent 3

Meeting Goals Discuss diesel fuel oil issues Provide scope of proposed LAR and basis 4

Background

Issues Review of DFO storage system License basis Single failure design requirements Compensatory measures 5

Background

Issues continued CDBI (2007) identified EDG frequency issue Higher frequency - more DFO consumption Compensatory measures Limit frequency range Increase DFO storage requirement 6

Background

Issues continued 2010 identified single failure issue Each FOST has only one transfer pump Multiple transfer pumps have the same power supply A single failure could prevent access to fuel oil in multiple FOSTs until repairs were made.

Compensatory measures 7 days of fuel oil supply in each train 7

Background

DFO System Unit 1 Operation - 1973 Unit 2 Operation - 1974 Two emergency diesel generators (D1, D2)

Plant only had the safeguards DFO system now associated with Unit 1 8

Background

DFO System continued Unit 2 safeguard buses reconfigured - 1992 Unit 2 EDGs installed (D5, D6)

Address SBO requirements Unit 2 safeguards buses separated from Unit 1 EDGs Unit 2 DFO system installed Safeguards power to 121 MDCLP from Unit 2 EDGs 9

Unit 1 DFO System D1 - Fairbanks Morse EDG Train A Safeguards Bus D2 - Fairbanks Morse EDG Train B Safeguards Bus 12 DDCLP CL Train A header 22 DDCLP CL Train B header 10

Unit 1 DFO System Contributes to Cooling Water (CL) System Equivalent to service water and emergency service water systems at other plants System is shared between the units Five CL pumps Two safeguards DD pumps Separate TS DFO requirement One safeguards MD pump Powered by either Unit 2 EDG 11

Unit 1 DFO System Six Class I tanks All tanks interconnected Any tank can supply any Unit 1 or CL diesel Available volume - 17,500 gallons/tank Maximum volume - 19,500 gallons/tank 2 non-Class I tanks for heating boiler Volume - 35,000 gallons/tank 12

Unit 1 DFO System 13 Drawing For Information Only

Unit 1 DFO System Design features All tanks interconnected Seismic Designed for Probable Maximum Flood Buried Anchored Elevated vent 14

Unit 1 DFO System Transfer pumps One transfer pump per tank Pumps are safety-related 121 and 122 EDG FO storage tank pumps Train A safeguards bus 121 DDCLP tank pump Train A safeguards bus May also be powered from Unit 2 123 and 124 EDG FO storage tank pumps Train B safeguards bus 122 DDCLP tank pump Train B safeguards bus May also be powered from Unit 2 15

Unit 1 DFO System Transfer pumps continued Any tank can supply any Unit 1 or CL diesel 121 and 122 EDG FO storage tank pumps Provide automatic makeup for D1 121 DDCLP tank pump Provide automatic makeup for 12 DDCLP 123 and 124 EDG FO storage tank pumps Provide automatic makeup for D2 122 DDCLP tank pump Provide automatic makeup for 22 DDCLP 16

Unit 1 DFO System License basis 14 day supply for one EDG and one DDCLP Probable Maximum Flood duration 13 days Replenish supply after 14 days Single failure not a consideration for external flood event EDG loading Original license basis: FSAR Table 8.4-1 loads (one unit DBA, other unit hot shutdown)

Current license basis: USAR Table 8.4-1 loads (Unit 1 DBA) 17

Unit 1 DFO System Current volume requirements Approximately 42,000 gallons for one EDG Approximately 19,500 gallons for one DDCLP These volumes require minimum of 4 tanks 18

Unit 2 DFO System D5 - SACM* EDG Train A safeguards bus D6 - SACM EDG Train B safeguards bus

• Societe Alsacienne de Constructions Mecaniques de Mulhouse (SACM) 19

Unit 2 DFO System Four Class I tanks 21, 22, 23, and 24 Available volume - 30,800 gallons/tank Maximum volume - 32,800 gallons/tank One Non-Class 1 receiving tank Approximately 15,000 gallons 20

Unit 2 DFO System 21 Drawing For Information Only

Unit 2 DFO System Design features All tanks interconnected Seismic Designed for Probable Maximum Flood Underground concrete vault Anchored Elevated vent Emergency fill connection above flood level 22

Unit 2 DFO System Transfer pumps One transfer pump per tank Pumps are safety-related 21 and 23 tank pumps Train A safeguards bus 22 and 24 tank pumps Train B safeguards bus 23

Unit 2 DFO System License basis 14 day supply for one EDG Probable Maximum Flood duration 13 days Replenish supply after 14 days Single failure not a consideration for external flood event USAR Table 8.4-2 loads (Unit 2 DBA) 24

Unit 2 DFO System Current volume requirements Maintain 75,000 gallons for one EDG This volume requires a minimum of 3 tanks 25

Current TS and Bases Technical Specification Total supply within limits Total supply applicable - one or both EDGs operable Limits based on operation of one EDG for 14 days Basis: maximum probable flood 26

Current TS and Bases Bases Background discussion Mixed NUREG-1431 and old TS Bases Basis for requirements not clear ASA discussion Discusses DBA - confusing Good discussion of DFO system 27

Current TS and Bases Regulatory requirement - 10CFR 50.36(2)

(ii) A technical specification limiting condition for operation of a nuclear reactor must be established for each item meeting one or more of the following criteria:

(C) Criterion 3. A structure, system, or component that is part of the primary success path and which functions or actuates to mitigate a design basis accident or transient that either assumes the failure of or presents a challenge to the integrity of a fission product barrier.

28

Proposed TS and Bases High level changes Replace current TS More alignment with standard TS 29

Proposed LAR Scope Add new license basis Supply to mitigate DBA+LOOP Assume single failure 7-day supply Make license basis same for both units 30

Proposed LAR Scope TS changes Implement proposed new license basis 7-day supply for each EDG Replace current TS Administrative changes 31

Proposed LAR Scope Basis for TS change Current TS Cope with external flood Does not meet 10CFR 50.36(2)(ii)(C)

Proposed TS Mitigate DBA with assumed single failure Meets 10CFR 50.36(2)(ii)(C) 32

Proposed LAR Scope Proposed TS consistent with regulatory guidance Regulatory Guide 1.137 NUREG-0800 NUREG-1431 33

Proposed LAR Scope Proposed TS improves safety 7-day supply available for each EDG More DFO required DFO supply can be replenished in 7 days System design supports proposed TS No modifications required 34

Proposed LAR Scope Relocate DFO volumes to Bases Resolve non-conservative TS issue Flexibility for future volume changes Per TSTF-501 Calculate volumes per RG 1.137 - both units 35

Proposed LAR Scope Improve TS alignment with NUREG-1431 New license basis Uniform interpretation and compliance Improve clarity for operator use Administrative changes 36

Proposed LAR Scope Bases Make consistent Reflect new license basis Include DFO volumes per TSTF-501 37

Questions / Comments Discussion 38

Summary Propose to add new license basis Propose new TS Relocate DFO volumes to Bases Current DFO system designs support the proposed license basis and TS Meets regulations for required TS Consistent with regulatory guidance Plant safety is improved 39