ML070750116
| ML070750116 | |
| Person / Time | |
|---|---|
| Site: | Harris  |
| Issue date: | 02/23/2007 |
| From: | Chandu Patel NRC/NRR/ADRO/DORL/LPLII-2 |
| To: | Yadusky J Progress Energy Carolinas |
| Patel C, NRR/DORL/LPL2-2, 415-3025 | |
| References | |
| TAC MD2723 | |
| Download: ML070750116 (3) | |
Text
From:
Chandu Patel To:
internet: john.yaduski@pgnmail.com Date:
02/23/2007 2:37:19 PM
Subject:
RAI for steam generator water level setpoint review
- John, Please respond to this RAI within reasonable time frame.
Reference 1: Letter from C. S. Kamilaris (Progress Energy Carolina) to NRC, Shearon Harris Nuclear Power Plant, Unit No. 1, Docket No. 50-400/License No. NP-63, Request for License Amendment to Revise Values Associated with the Steam Generator water Level (SGWL) Trip Setpoint, dated August 2, 2006.
1.
Mid-Deck Plate P Determination (Page A1-8 of 13 of Reference 1)
Westinghouses Nuclear Safety Advisory Letter (NSAL)-02-3 and its revision indicated that the uncertainty in the steam generator water level (SGWL) measurement caused by the placement of mid-deck plate between the upper and lower pressure taps may adversely affect the SGWL low-low trip with an uncertainty bias in a non-conservative direction. In addressing the NSAL-02-3 concerns, the licensee indicated that a bounding value of 119.6% steam flow was used to determine the mid-deck plate P that was considered in the SGWL low-low trip setpoint uncertainty analysis.
Provide information to explain how the steam flow rate of 119.6% was determined as the upper limiting steam flow. The information should include a discussion of the non-LOCA transients (such as a feedwater water break, turbine trip, loss of normal feedwater, and steam line break etc..) that were analyzed to determine the upper bounding steam flow during transients. Also, discuss how the calculated process measurement accuracy (PMA midPlateP) of 2.3% in Tables 3-10A, 3-10B and 3-10C of Reference 1 was calculated.
2.
Process Measurement Accuracy (PMA) under Transient Conditions (page A1-9 of 13 of Reference 1)
The licensee indicated that new PMA values, which account for the process pressure under transient conditions, were used in determining the impact of SGWL reactor trip system (RTS) and engineered safety feature actuation system (ESFAS) setpoint uncertainty analysis of calculation HNP-1/INST-1010 (Attachment 5 to Reference 1) for the following SGWL trip setpoints: SGWL low-low (feedwater line break and loss of normal feedwater), SGWL low coincident with steam/feedwater flow mismatch, and SGWL high-high.
Tables 3-10A, 3-10B, 3-10C and 3-18 of Reference 1 discussed the applicable setpoint uncertainty analysis to support the TS changes. The analysis considered the following PMAs:
PMARefLegTemp (reference leg temperature variation), PMApressure (process pressure variation), PMAsubcool (downcomer subcooling effect), PMAFluidvelocity (fluid velocity effect) and PMA MidPlate P (mid-deck plate P). Discuss the specific transients used to determine the values of PMAs in Tables 3-10A, 3-10B, 3-10C and 3-18 of Reference 1. The reviewer also identified that many PMAs discussed in NSAL-03-09 were not considered in the analysis. The PMAs not considered were the intermediate-deck plate P, feedwater ring and feedwater ring support P, lower-deck plate support P, non-recoverable conditions due to carryunder, decrease in subcooling due to carryunder.
Explain why the identified PMAs were not considered in the setpoint uncertainty analysis.
3.
ERef Leg and EHELB used in the SGWL Setppint Uncertainty Analysis The values of ERef Leg and EHELB in Table 3-10A of Reference 1 were 1.5% and of 10% for
the SGWL low-low setppint (feedwater line break) uncertainty analysis, while ERef Leg and EHELB discussed in Tables 3-10B, 3-10C and 3-18 were zero for the uncertainty analysis for the SGWL low-low (loss of normal feedwater), SGWL low coincident with steam/feedwater flow mismatch, and SGWL high-high trips, respectively.
Provide a definition of the ERef Leg and EHELB,and discuss the methods and applicable transients used to determine the respective values of ERef Leg and EHELB used in Tables 3-10A, -10B, 10C and -18 of Reference 1. If the values of E represent the environmental effects, discuss any other environmental effects, such as the cable insulation resistance effect, which should be, but not already considered in the uncertainty analysis.
4.
Safety Analysis Value Used in Determining the SGWL High-High Trip Setpoint The SGWL high-high trip was used in the design basis analysis to terminate a feedwater malfunction or excessive feedwater flow event. Following the trip signal, the turbine will trip and auxiliary feedwater will isolate. Westinghouse NSAL-02-4 indicated that neglecting the effects of the void content of two-phase mixture above the mid-deck plate may adversely affect the SGWL high-high trip with an uncertainty bias in a non-conservative direction. Table 3-18 of Reference 1 indicated that the safety analysis limit (SAL) of the SGWL high-high trip setpoint used in the design basis event (DBE), a feedwater malfunction or excessive feedwater flow event, was 100% level.
Address the effects of void content, as discussed in NSAL-02-4, on the SAL for the SGWL high-high trip setpint used in the DBE analysis, and show that the SAL of 100% level adequately included the void content effects.
5.
Initial SG Water Inventory Assumed in Safety Analysis Westinghouses NSAL-02-5 discussed potential inaccuracies in the initial conditions assumed in safety analyses affected by the SGWL.
Provide a discussion of the initial SG water inventory assumed in the safety analyses, and justify that applicable SGWL measurement uncertainties, as discussed in NSAL-02-5, were appropriately considered.
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RAI for steam generator water level setpoint review Creation Date 02/23/2007 2:37:19 PM From:
Chandu Patel Created By:
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