ML20039F198
| ML20039F198 | |
| Person / Time | |
|---|---|
| Site: | 05000561 |
| Issue date: | 01/24/1978 |
| From: | Cox T NRC |
| To: | Hodges W, Kelly G, Phillips L NRC |
| Shared Package | |
| ML111090060 | List:
|
| References | |
| FOIA-80-515, FOIA-80-555 NUDOCS 8201120159 | |
| Download: ML20039F198 (4) | |
Text
.
ROUTING AND TRANSMITTAL SLIP
> r O <n
.,a..,,,.,.....,
..... ~
.. ~ ~ ~
~L,syJ [Euy P//3 &
l<l4YAJG' e$
P/030 A
I. e.t.L.
, e LE N
- g.,,,,.
h'f h/ll/P.1 Pro 30 Y
" u".
... riau s..
kY
$f REMARKS ffMY MMMYCG W M7U) 0C W Me$7 gCML,Y /D&W77FMD oomu' I.55dE' od 85 M -1s$~,
YdV2. UMMW "
oA) 7Mer 4cuMety c5 7Nt1 S*therMMY
> < RhWoo Ow.
Do NOT use this form as a RECORD of approvals, concurrences, disapprovalg, clearances, and similar actions FROM tN.m..otoe. e,ms.o.es
.o.nr
..ssaihr/rs x
OPTIONAL FORM 48
+ie-eisoe-t nas-tas 3048-108
.usust le er esa PPedm(4tCFR8 10 0 19 20 e
$j59810403 R
MADDEN 80-515 PDR
Y 0t a*l.L J llf
SUMMARY
- STATUS OF ISSUE CONCERNING B&W MINIMUM FLOW DISTRIBUTION FACTOR 1.
"B&W has used a minimum core flow distribution factor of 0.99, based on a Topical Report (10025). This number is a key number in establishing DNBR as a function of core average power.
That is, a reduction in the flow factor could cause DNB at a lower core (average) power than DNB would occur with a 0.99 flow factor.
2.
In a letter dated 12/20/77, B&W reported that the flow factor was indeed 0.965 instead of 0.99, due to errors B&W identified in their Topical Report data.
3.
B&W has used a closed-channel Thermal-Hydraulic analysis code, CHATA, to design their cores, and this code incorporates the 0.99 flow distribution factor. This code was referenced in BSAR-205.
CHATA was submitted to NRC in February 1976 and is still "under review".
In the BSAR-205 Report to the ACRS (July 1977) we stated that, while CHATA was not yet approved, we had done some review and had reasonable assurance that (with a minimum flow factor of 0.99),
the proposed t-h design will account for departure from nucleate boiling in a satisfactory manner.
YC.
4.
B&W has also submitted a more sophisticated t-h code for rev'iew.
LYNX 1 & 2 (Topical Reports 10129 and 10130) were submitted in November 1976 and are currently "in hold due to higher priority items" (see NUREG 0390,10/15/77, page II-31).
B&W says that, using the LYNX calculations, the very recently reduced minimum flow factor, now 0.965, is OK and that no thermal design penalty will be incurred. The newer code accounts for cross-flow between fuel element channels.
5.
In B&W's 12/20/77 letter, they committed to (1) correct their Topical Reports 10025 and 10026 in the second quarter of 1978 and the second half of 1978, respectively, and (2) use the reduced flow factor reported in (1) in future analyses at the FSAR stage, on all affected applications, using methods "which will have been approved by the NRC staff". The rub is that we have not approved, even in a preliminary way, the analytical techniques B&W alludes toinitem(2)above,i.e.,theLYNXmethods.
6.
The Ross to Vassallo memo of 01/18/78 indicates that B&W will defend their claim of negligible effect on final calculations in the spring of 1978 (when they document the changes to T.R.10025).
This implied schedule is not; substantiated by the B&W letter of 12/20/77.
In Spring "78", B&W planned only to bring in the corrected topical, which will establish the minimum flow factor at 0.965.
d
D f'.
{ 7.
In a. telephone conference on 1/20/78, B&W made commitments to address the acceptability of the 0.965 flow factor within one to two weeks, in draft fo rm. This would be followed by a formal submittal shortly thereafter.
Wayne Hodges (AB) and Glenn Kelly (RSB) of our staff stated that what we must have for review is a comparison o' calculations done using both the more current CHATA/ TEMP method and the more sophisticated LYNX 1, 2 method. B&W said they would do:
(1) CHATA/ TEMP analyses at 112% power, calculating maximum velocity, DNBR, and other hot channel parameters, for both 0.99 and 0.95 flow factors, and (2) A similar analyses using the LYNX 1 & 2 method and the same input as (1) above.
i b