ML20040F415
| ML20040F415 | |
| Person / Time | |
|---|---|
| Site: | LaSalle  |
| Issue date: | 02/04/1982 |
| From: | Sargent C COMMONWEALTH EDISON CO. |
| To: | Schwencer A Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8202090173 | |
| Download: ML20040F415 (2) | |
Text
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[D) ona First Natiorn.t Plata. Chicago, I'linois Commonwealth Edloon 7'
kC '
Address Reply to: Post Office Box 767 N
- Chicago, Illinois 60690 February 4, 1982 to is S
/q Mr. A. Schwencer, Chief b
AECSQg Licensing Branch #2 2
9 O
Division of Licensing 8 Jggy C U. S. Nuclear Regulatory Commission "ge:raturg h Washington, DC 20555 pg
//
Subject:
LaSalle County Station Unit 2 f6 Response to Questions on Reactor Pressure Vessel Pressure / Temperature-Curves NRC Docket No. 50-374-
Dear Mr. Schwencer:
The purpose of this letter is to, provide a response to questions asked by Mr. B.
Elliott of your staf f during a telephone conversation in early December, 1981.
The Commonwealth Edison Company response to the four ques-tions concerning the reactor' pressure vessel pressure / temperature curves and transition temperature is provided in Enclosure 1 attached.
If there are any further questions in this regard, please contact this office.
Very truly yours, G
C. E. Sa rgent Nuclear Licensing. Administrator 1m Enclosure cc:
NRC Resident Inspector - LSCS 3401N p
hI l
8202090173 820204 PDR ADOCK 05000374 A
o-ENCLOSURE 1 Ql. Is the PT curve (FSAR Figure 5.2-9) corrected for instrument errors?
Response
No.
There is no need for temperature instrument corrections with BWR PT cur'/es because they are establish via very conservative methods that provide wide margins from any threshold of concern.
This question was addressed for Unit 1 as item IIIB.5 where references 1 and 2 appear (Table 5.2.lla of-FSAR).
The second reference indicates NRC acceptance of the GE methodology with respect to conservatisms used to establish PT curves for BWR's.
Such methodology was used in the generation of the Unit 2 PT curves as reported in NEDO-21778 generically and FSAR Section 5.2.3 and Q121 series responses for LaSalle specifically.
Q2. What is the transition temperature for Unit 2 RPV7
Response
RT(NDT) for Unit 2 vessel is 52 F as shown in FSAR 0
Figure 5.2-9.
It was determined by the estimation method explained in paragraph 5.2.3.3.1.4 and used in CECO response to Question 121.17 as recorded in the FSAR.
That estimate starts with the +400F temperature at which the Charpy-V test data on centerline plate (Heat C9404-2) shows a minimum test value.
It then adds 420F per GE procedure Y1006A006 to translate to the 50 ft'. Ib. reference value, adds 300F to translate longitudinal test data to the transverse convention, and substracts 600F per Subsection NB o f ASME III Code.
This results in the 52 F 0
initial transition temperature estimate.
Cross-correlation with the copper content curve o f Figure 5.2-11 gives (52+40) 1000F, hence acceptable estimate.
Q3. What method was used to estimate the' transition temperature for forgings?
Response
The forging transition temperatures were estabi'ished via the same method used for Unit 1 vessel as outlined on FSAR page Q121.17-2 under paragraph B. Forgings.
t Q.4 Was the pre-service test curve'used for Unit 2 in error by 18
- F l
due to non-allowance for instrument error based on uncertainty?
Response
No.
Instrument calibration allowances are not needed cue to the conservatism in methodology as outlined in the response to Q.1 above.
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