ML20207U148
| ML20207U148 | |
| Person / Time | |
|---|---|
| Site: | Fort Saint Vrain  |
| Issue date: | 03/20/1987 |
| From: | Heitner K NRC |
| To: | NRC |
| References | |
| NUDOCS 8703240663 | |
| Download: ML20207U148 (3) | |
Text
FT 9
O h oc.h c + No.
so-u 7 1
e O
C. 'i 3 ~[O{$1 Po c k e. F Fiter can N ot e 40,
F om ',
K.
L. H t; & n ec F-z3t P,o ec b Plom<3e-Fu )+
st V<a,m bk bk b
'(, (.,
I Lk ),
Oc cu m a The a bad AaH Jc,cm 4
hur beem puJ,Jed to
% c-f u tA u e,
%, v t c 'e cu~,o u p c+
Col 0<<.<do, Jn C M. u d e n c_ e_t L c.4le c a cc..
- th H IE it re<p.1er+ thh Mo
+3)
. e.
y va go v1 a.e cop e r b h
H Rc cma Lumi P O W 's
% 1, 9 4 c. 1 %
8703240663 870320 PDR ADOCK 05000267 PDR
Enclosure REQUEST FOR ADDITIONAL INFORMATION 1.
The stress evaluation regions in the steam generator during the single cycle cooldown from power using firewater in the EES tube bundles did not consider the effects due to flow induced vibration or dynamic loading due to an SSE.
a.
Provide justification for not including the effects due to flow-induced vibration.
b.
Provide the basis, method and results of the stress evaluations which include the effects due to SSE loading for the Reheater tubes and their supports, the EES tubes and the EES tube support structure, the Superheater Helical Bundle and its supports structure, and the Superheater Down-comer.
2.
In Attachment 7 it is stated on pg. 3 that during the 90 minute period the tube metal temperature is less than 1300*F, while calculation No. 68-02 of Attachment 9 indicates that the maximum of all tube temperatures in this transient is 780*F. Provide a reconciliation and basis of these two values, indicating which is the correct value.
3.
Provide the. detailed methodology used for perfonaing the creep collapse analysis of the Reheater tube, and the User's Manual for the computer program " BUCKLE". Provide assurance that the time to reach yield stress in the maximum stressed point is shorter than the time at which the ovality becomes unbounded, i.e., show that collapse can not occur at a maximum stress which is lower than the yield stress.
4.
Provide a basis for the statement on p. 16 that "the structural integrity of the steam generator is not likely to be compromised due to excessive tube / plate interaction loads during the EES firewater cooldown event," in particular during simultaneous SSE loading.
S.
It is stated that Sanicro 31 reheater tube material is a European Alloy 800 - type material which met the required material specifications of Alloy 800 Grade 2 at the time when the steam generators were built.
Provide the chemical composition of this material and its strength levels (i.e, yield and ultimate strengths at appropriate temperatures).
In addition address the metallurgical treatment of Sanicro 31 in comparison with the treatment of the ASME Code Alloy 800 material. Further, explain why the Sanicro 31 will not degrade to below the minimum levels allowed for the Code material because of the temperature cycles which the steam generator tubes experience.
', 6.
It is implied that Sanicro 31 is equivalent to an Alloy 800 H material, e.g., S8-163 or SB-407.
If this is the case justify the value of 23,300 psi at 380"F for S. Current ASME Code values indicate S 16,700 psi for SG-T63 and 20,000 psi for S8-407 at 380*F.* values of 7.
Figure 4.4 is incomplete as submitted.
The temperature profile for the time in hours from 0 to 2 is missing.
Please supply this information.
8.
The possibility of accumulated creep-fatigue damage contributing to tube failure is not explicitly addressed in this submittal. Please provide an evaluation of this potential failure mecnanism in the context of the creep-collapse failure mode that was assumed.
9.
With regard to the Fort St. Vrain (FSV) Technical Specifications, 5.3.11 Steam Generator Bimetallic Welds Surveillance and SR 5.3.12 - Steam Generator Tube Leaks Surveillance, describe the results of the surveillance requirements including the number of times and the dates that they have been implemented.
Provide any other information that is available concerning degradation of the steam generator tubes.
l
/