ML090780909

RAI from the Containment and Ventilation Branch the Proposed Extended Power Uprate Amendment

ML090780909
Person / Time
Site:	Monticello
Issue date:	03/19/2009
From:	Tam P Division of Operating Reactor Licensing
To:	Exelon Nuclear
Tam P
Shared Package
ML090780914	List: ML090780909
References
TAC MD9990
Download: ML090780909 (5)

Text

Accession No. ML090780909 DRAFT REQUEST FOR ADDITIONAL INFORMATION CONTAINMENT AND VENTILATION BRANCH MONTICELLO NUCLEAR GENERATING PLANT TECHNICAL SPECIFICATION CHANGES FOR EXTENDED POWER UPRATE DOCKET NO. 50-263

1.

Refer to Enclosure 5, Safety Analysis Report for Monticello Constant Pressure Power Uprate of letter dated November 5, 2008, (PUSAR). Information regarding decay heat model, 2 uncertainty, guidance of GE SIL 636 Rev 1, and crediting of passive heat sinks in drywell (DW), wetwell (WW) airspace and suppression pool (SP) is not stated for various analysis except for long-term suppression pool temperature response as indicated below.

Please provide the information as per the following table for the current and extended power uprate (EPU) conditions. Provide justification if uncertainty and guidance of SIL 636 Revision 1 was not included.

Analysis Decay Heat Model 2

Uncertainty Included (Yes or No)

Guidance of SIL 636 Rev 1 included (Yes or No)

Passive heat sinks in DW, WW airspace

& SP credited (Yes or No)

Short term drywell pressure response Current EPU Long term recirculation line break suppression pool temperature response Current ANSI/ANS 5.1-1979 Yes No EPU ANSI/ANS 5.1-1979 Yes Yes Long term 0.5 sq ft steam line break drywell temperature response Current EPU DBA LOCA for Net Positive Suction Head Current EPU Appendix R Fire Current EPU Station Blackout Current EPU Anticapated Transient without Scram Current EPU Small Steam Current

Line Break Accident EPU

2.

Refer to PUSAR, for the short term LOCA analysis which resulted in drywell peak pressure and temperature listed in Table 2.6-1, please confirm that the assumption for FW coastdown was the same as in current analysis or more conservative. If FW coastdown used in analysis was less conservative, please justify.

3.

Refer to PUSAR, for the short term LOCA analysis which resulted in drywell peak pressure and temperature listed in Table 2.6-1, please confirm that the assumption for MSIV closure time was the same as in current analysis or more conservative. If MSIV closure time used in analysis was less conservative, please justify.

4.

PUSAR, Sections 2.6.3.1.1 does not describe the type of LOCA break (for example steam line break) that resulted in the peak drywell gas temperature of 338o F. As per the USAR Revision 24, Table 5.2-8, the peak drywell gas temperature 335o F is based on a small steam line break LOCA. Please provide the break area in the EPU and the current analysis of record. Please describe the analysis method, inputs, assumptions, and differences with the current analysis in the USAR. In the EPU analysis, for how much transient time does the drywell gas temperature exceed the EPU drywell wall temperature of 278 oF given in Table 2.6-1.

5.

PUSAR, Sections 2.6.3.1.1, third sentence, please explain the basis of 35 psig drywell pressure?

6.

PUSAR, Section 2.6.1.1.1 a) Bulk Pool Temperature describes a different approach for calculating long term suppression pool temperature response using the RHR heat exchanger K value. In this approach the minimum K-value is 147 Btu/sec oF and is assumed to increase with increase in suppression pool temperature. This approach is less conservative than the method used in USAR which assumes a constant value of K. Please explain why a different approach is used for EPU analysis and how is assurance provided that the heat exchangers will not have a K value less than 147 Btu/sec oF or less than values in the table in Section 2.6.1.1.1 of the PUSAR?

7.

PUSAR Sections 2.6.1.1.1 and 2.6.5, why is K-value for the RHR heat exchanger assumed to be constant at 147 Btu/sec oF in the DBA LOCA NPSH analysis (Section 2.6.5) as compared to K as varying with hot side inlet temperature in the long term suppression pool temperature response analysis (Section 2.6.1.1.1)? Please verify if constant K-value of 147 Btu/sec oF was used in the Appendix R Fire, SBO, ATWS and SBA analysis for NPSH and is consistent with the current analysis in USAR.

8.

PUSAR, Section 2.6.1.1.1, fourth paragraph, states the EPU analysis assumes thermal equilibrium for the first 30 second and subsequently heat and mass transfer between the wetwell airspace and the suppression is mechanistically modeled. Please justify why is it conservative for suppression pool long term temperature response analysis as opposed to assuming thermal equilibrium between the wetwell airspace and the suppression pool as assumed in the current licensing basis per USAR Revision 24, Table 5.2-7 item number 6.

9.

PUSAR, Section 2.6.1.1.1, third paragraph states Confirmation of the ability of the RHR heat exchanger to support the K value used is verified by performance of a heat exchanger efficiency test. Please verify if the testing is performed as per NRC Generic Letter (GL) 89-13.

10.

PUSAR Section 2.6.5, under the heading DBA LOCA, third paragraph states The pump flow rates for the long-term case are 4000 gpm total RHR flow and 3035 gpm for CS pump A and 3029 gpm for CS pump B. Please verify if one or two CS loops (one pump per loop) are used for the DBA LOCA NPSH analysis and which pump is used?

11.

Refer to PUSAR Section 2.6.5, under the heading Small Steam Line Break Accident (SBA). Please verify that the input parameters used were biased to maximize the suppression pool temperature and minimize the wetwell pressure or that their nominal values were used. Provide justification if nominal values of the input parameters were used in the analysis and the analysis is conservative.

12.

PUSAR Section 2.6.5, please define the various pump flows for RHR and CS pumps used in the DBA LOCA, Appendix R, SBO, ATWS, SBA analysis, i.e whether these are pump runout flow, rated flow or design flow. Please verify if these flows are consistent with the current analysis in the USAR and with operating procedures. If these are not the same, provide a tabulation of the EPU values, the current analysis values used for analyzing these events, and the operating procedure values and provide justification for the differences. How do these pump flows compare with flows used in the DBA LOCA analysis for long term suppression pool temperature response in PUSAR Section 2.6.1.1.1.

13.

PUSAR Section 2.6.1.2.2, besides SRV opening set point, the SRV load in the suppression pool would depend on the SRV discharge line air and water volumes, and configuration of the submerged structures in the suppression pool. Please verify these parameters will not change under EPU conditions.

14.

PUSAR Section 2.6.1.5, EPU has resulted in changes in temperature response both in the drywell and wetwell. Refer to GL 96-06, please explain why pipe penetration integrity of water filled isolated piping that is susceptible to thermally induced over-pressurization is unaffected by the EPU. Please explain why the higher temperatures of EPU conditions will not affect the calculated leakage pressure through the valve bonnet gaskets and discs for each of the penetrations.

15.

PUSAR Section 2.6.2: Please explain why a feedwater line break and main steam line break under EPU conditions are not considered for subcompartment analysis?

16.

PUSAR Section 2.6.2: Please explain why drywell head subcompartment pressurization analysis is not done at EPU conditions.

17.

PUSAR Section 2.6.2, last sentence under Technical Evaluation states To increase margins, these shield bricks will be removed by modification. Please describe the proposed modification and explain how margins between the energy required for containment liner penetration and brick missile energy will be increased.

18.

PUSAR Section 2.6.6: The drawdown time is the time period following the start of the accident during which loss of offsite power causes loss of secondary containment vacuum (relative to atmospheric pressure) which is assumed to result in releases from the primary containment directly to the environment without filtering. What is the affect of EPU on the reactor building drawdown time and dose evaluation?

19.

PUSAR Table 2.6-1 provides the drywell wall temperature of 273 oF for the current analysis and 278 oF for the EPU analysis for a 0.5 sq ft steam line break. Please verify that the 278 oF wall temperature analysis is based on the EPU maximum drywell gas temperature of 338 oF. For this analysis, please provide a comparison table listing the analysis method used, assumptions, and inputs for the current analysis and EPU analysis and provide justification for differences. Please verify that the EPU analysis for a 0.5 sqft steam line break is limiting.

20.

PUSAR Section 2.6.1.2.1, second paragraph, last sentence, please explain why the vent thrust loads at EPU conditions are less than the Monticello plant specific values calculated for the Mark I containment long term program.

21.

PUSAR Table 2.6-1, identifies the new limit for peak bulk suppression pool temperature as 208 oF. Please verify that all equipment that requires qualification is still acceptable at the increased EQ temperature.

22.

PUSAR Table 2.6-1, Note 3 states maximum internal pressure for drywell and wetwell is 62 psig. What is meant by maximum internal pressure?

23.

PUSAR Table 2.6-1, Note 5, why is 0.5 sq ft steam break into the drywell assumed for this analysis? Please explain why a multiplier greater than 1 (e.g the value of 1.2 is recommended in NUREG 0800 BTP 6-2 Revision 3) was not used with the Uchida condensing heat transfer coefficient for determining the containment liner temperature of 278 oF? Is the assumption of initiation of sprays at 10 minutes from LOCA consistent with emergency operating procedures?

24.

PUSAR Section 2.6.3.1.1, please provide justification for increasing the drywell airspace temperature limit from 335 oF to 340 oF.

25.

PUSAR Section 2.6.5, under heading Technical Evaluation, second paragraph, first sentence, please define what is meant by realistic decay heat model.

26.

PUSAR Section 2.6.5, under heading Suction Strainer Debris Loading, please specify the type of strainer installed in Monticello and included in the EPU analysis?

27.

PUSAR Section 2.6.5, under heading Appendix R Fire, please describe the Appendix R fire scenario on which the analysis is based (e.g. fire zone, equipment affected, assumed operator actions etc), and indicate if it is the limiting case for NPSH margin.

28.

PUSAR Section 2.6.5, under heading Small Steam Line Break Analysis, third paragraph, last sentence states The CS pump is expected to maintain water level during this event, and actual flow rate is expected to be significantly less (approximately 200 gpm). Please verify if the CS pump is designed to operate at such low flow conditions without any problems.

29.

PUSAR Section 2.6.5, for the NPSH cases analyzed, DBA LOCA, Appendix R Fire, ATWS and SBA, it is stated that containment overpressure (COP) is required to meet the required pump NPSH. Please clarify whether the COP required is necessitated due to conservatism in the analysis, and whether it can be (or has been) shown that with a realistic analysis, COP is not needed.

30.

PUSAR Section 2.7.6, under heading Technical Evaluation, last sentence of first paragraph states EPU may affect the HVAC serving these areas as a result of slightly higher process temperature. Please explain what heat load causes the process temperature slightly higher.

31.

PUSAR Section 2.7.6, under heading Technical Evaluation, last sentence of second paragraph last sentence, please explain why HPCI room temperature is expected to remain within its design limit without taking credit for HVAC operation.

32.

PUSAR Section 2.7.6, under heading Technical Evaluation, fourth paragraph, what is the EPU impact on reactor building HVAC system, which is described in USAR Revision 24, Section 5.3.4, that performs cooling under normal conditions. What are the results of evaluation of the EPU impact due to additional heat load in the fuel pool on the reactor building HVAC system.

33.

PUSAR Section 2.7.5, under heading Conclusion states the proposed EPU with respect to HVAC operation in drywell is acceptable. However there is no evaluation of drywell HVAC under the heading Technical Evaluation.

34.

PUSAR Section 2.7.5, under heading Technical Evaluation, please describe how the increase in the area temperature of 1.8 °F or less is calculated. Is this based on the EPU revised design heat load in that area while the currently designed HVAC system serving that area is operating?

35.

PUSAR Section 2.7.5, under heading Technical Evaluation and Conclusion, please provide the result and conclusion of the detail evaluation of the feedwater and condensate pump area heat load.

36.

PUSAR Section 2.7.1.1, fourth paragraph discusses the EPU effects on the CREF due to increase in the radiological source term during LOCA, and use of RG 1.3 for evaluation of loading of CREF charcoal filters. USAR Revision 24 Table 14.7-13 provides assumptions used in the current LOCA dose analysis. USAR Section 14.7.2.4.3, Control Room Dose Evaluations" lists the parameters applied in the control room dose evaluations for the current analysis. Please list and justify the differences (if any) in assumptions or parameters used in EPU control room dose evaluation, and LOCA dose analysis as per RG 1.3, from the current analysis assumptions and parameters listed in USAR Table 14.7-13 and Section 14.7.2.4.3.