ML090390026
| ML090390026 | |
| Person / Time | |
|---|---|
| Site: | Prairie Island  |
| Issue date: | 02/06/2009 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| References | |
| Download: ML090390026 (4) | |
Text
1 PrairieIslandNPEm Resource From:
Richard Plasse Sent:
Friday, February 06, 2009 2:40 PM To:
Eckholt, Gene F.; Vincent, Robert
Subject:
FW: Some more RAI for Prairie Island Attachments:
PINGP RAI response follow-up and new items (Yang on Metal fatig).doc draft followup RAIs,can we discuss Tues 2/10?
Hearing Identifier:
Prairie_Island_NonPublic Email Number:
596 Mail Envelope Properties (Richard.Plasse@nrc.gov20090206143900)
Subject:
FW: Some more RAI for Prairie Island Sent Date:
2/6/2009 2:39:54 PM Received Date:
2/6/2009 2:39:00 PM From:
Richard Plasse Created By:
Richard.Plasse@nrc.gov Recipients:
"Eckholt, Gene F." <Gene.Eckholt@xenuclear.com>
Tracking Status: None "Vincent, Robert" <Robert.Vincent@xenuclear.com>
Tracking Status: None Post Office:
Files Size Date & Time MESSAGE 53 2/6/2009 2:39:00 PM PINGP RAI response follow-up and new items (Yang on Metal fatig).doc 65530 Options Priority:
Standard Return Notification:
No Reply Requested:
No Sensitivity:
Normal Expiration Date:
Recipients Received:
Part I - Seeking clarification on some of the PINGP responses to previous RAIs in metal fatigue area Near the end of NSPM response to RAI 4.3.1.4-1, second last paragraph, it appears as follows:
The calculation of the primary nozzle CUFs performed in 1969 for Unit 2 is based on photoelastic and thermal transient analyses considering the worst case normal and upset loading conditions. The maximum peak stress intensity considering worst case normal and upset conditions was conservatively applied for the total number of design cyclic applications (i.e.,
24,000 cyclic applications for all transients the unit must undergo, which bounds the applicable design transients in Table 4.3-1 of the PINGP LRA). This resulted in a very conservative cumulative usage factor of 0.88 for the inside surface of the primary inlet nozzle base metal.
(a) Please explain exactly what worst case normal and upset loading conditions means and identify it from the transients listed in LRA Table 4.3-1. If the worst loading condition is not one of the transients listed in LRA Table 4.3-1, explain why. In either case, provide basis to show it is the worst loading condition.
(b) Please explain how you came up with 24000 cycles. The staff tried different ways of adding cycles for the transients listed in Table 4.3-1 of the PING LRA without a match.
Side question:
OBE is not included in LRA Table 4.3-1. Why not? Did you include OBE in fatigue calculations?
Part II - additional RAI RAI 4.3.1-1 The PINGP metal fatigue of reactor coolant pressure boundary management program relies on transient cycle monitoring to evaluate the fatigue usage described in the license renewal application. This approach tracks the number of occurrences of significant thermal and pressure transients (significant events) and compares the cumulative cycles, projected to cover the renewal period, against the number of design cycles specified in the design specifications. The projected cycles are then used to evaluate the total cumulative usage factor (CUF) which covers the period of extended operation. For this approach to work, none of the significant events tracked should produce stresses greater than those that would be produced by the design transients. That is, the P-T (Temperature and Pressure) characteristics, including their values, ranges, and rates, all must be bounded within those defined in the design specifications. Please provide (a) Additional information so the staff can confirm that the program will ensure that P-T characteristics, including their values, ranges, and rates remain bounded within the range defined in the design specifications during the renewed license term.
(b) Histogram (cycle accumulating charts) of heatup transient tracking history, and the histogram for the cooldown transient as well.
RAI 4.3.3-1 The last row of LRA Table 4.3-8 shows that the Fen for RHR Class 1 Piping Tee is 2.55 for stainless steels. Text of the LRA, the 1st line on Page 4.3-24, indicates that this is the bounding Fen. Please explain why this value is bounding when the true bounding Fen for stainless steels is 15.35. The value Fen=2.55 will arrive under two conditions, as indicated on Page 4.3-23 of LRA (a) T<200 oC, any, any DO (b) T 200°C, 0.4%/sec, any DO If you used condition (a) for your Fen calculation, specify the T value used. If you used condition (b),
specify the values with basis. Clarify these questions and revise the LRA appropriately. If you used the true bounding value15.35 for the Class 1 Piping Tee, reflect it on the last row of LRA Table 4.3-8 and make any necessary adjustments.