ML19339A441
| ML19339A441 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 12/29/1976 |
| From: | Johnson W YANKEE ATOMIC ELECTRIC CO. |
| To: | Office of Nuclear Reactor Regulation |
| References | |
| WYR-76-132, NUDOCS 8011030821 | |
| Download: ML19339A441 (5) | |
Text
i Tel: phons 617 366-9011 7 tO - 3 9 0-0 7 3 9 YANKEE ATOMIC ELECTRIC COMPANY
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United States Nuclear Regulatory Commission Kashington, D. C.
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Yankee Rowe Core 12 ECCS Performance Analysis /RNB Lockout and Elevated Upper Head Temperature Concerns
Reference:
(1)
License No. DPR-3 (Docket No. 50-29)
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Letter, A. Schwencer, USNRC to R. H. Groce, YAEC, December 10, 1976.
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(3)
" Exxon Nuclear Company, Revised Nucleate Boil r4 i Q
f7 Lockout for WREM-based ECCS Evaluation Models 7,
XN-76-44, September 1976.
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u (4) Yankee Nuclear Power Station, Proposed Change f5 lQ*' pec g
j No. 142, October 8, 1976.
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Dear Sir:
A re-analysis of the limiting break si:e (0.6 DECLG) for Yankee Rowe Core 12 at 180 EFPD and 10.15 kw/ft (Exxon Fuel) has been completed in accordance with Reference (2). The post-CHF return-to-nucleate boiling heat transfer correlation lockout model used is described in Reference (3).
The previous analysis of the 0.6 DECLG break size at 180 EFFD and 10.15 I"
kw/ft (Exxon Fuel) was submitted in Reference (4) which addressed T ho the upper hemispherical head volume. Table 1comparesthekeyparamefers of interest for the two analyses. As can be seen in Table 1, the retur..-to-nucleate boiling lockout has a negligible affect (2.4*F) on peak clad temperature for this case.
In response to informal NRC questions regarding Reference (4),
additional analyses addressing T in the upper hemispherical head and the DNB lockout have been conduckOb up to End-of-Bypass (E0BY) for the 0.8, 0.6, and 0.4 DECLG break sizes at beginning-of-cycle conditions.
Table 2 lists the clad and fuel temperatures at E0BY for the above break sizes. Also, the previous results of che 0.6 DECLG (Reference 4) are shown for comparison.
The extrapolated clad temperature at BOCREC for the 0.6 DECLG break size is 74*F higher than the 0.8 DECLG break size and 59'F higher than the 0.4 DECLG break si:c.
This further justifies YAEC's previous contention in Reference (4) that the 0.6 DECLG break remains the most liniting break size.
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U,nited, States Nudnar Regulatory Commission December 29, 1976 Attn: Office of Ntclear Reactor Regulation Page Two Any further questions regarding this matter should be directed to Mr. W. J. S:yme:ak at our Engineering Office, 20 Turnpike Road, Westborough, Massachusetts, telephone (617) 366-9011, Extension 2844.
Very truly yours, YANKEE ATOMIC ELECTRIC COMPANY a
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W. P.'l Johnson Vice President WJS/kg I
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Table 1 Yankee Rowe Core 12 LOCA Analysis Post-CIIF Return-to-Nucleate Boiling Lockout (RNBLO) Sensitivity Study Break Size:
0.6 DECLG Maximum Total LIICR:
10.15 kw/ft Fuel Exposure:
180 EFPD Fuel Type:
Exxon Parameter Without RNBLO With RNBL End-of-Bypass, seconds 39.54 39.54 PCT Rod Clad Temperature O E0BY, "F 1282.1 1280.7 Bottom of Core Recovery, seconds 101.6 101.6 PCT Rod Clad Temperature @ BOCREC, OF 1875.3 1872.0 Time of Peak Clad Temperature, seconds 112.1 111.7 Peak Clad Temperature, "F 1987.5 1985.1
i Table 2 Yankee Rowe Core 12 LOCA Analysis Results of Additional LCCA Analysis with Elevated Upper-IIcad Temperature (UllT) and Post-CilF Return to Nucicate Boiling Lockout (RNBLO)
Analysis with Elevated UHT Analysis with Elevated and RNBLO UIIT Only Break Size:
0.8 0.6 0.4 0.6 Break Type:
DECLG DECLG DECLG DECLG Cycle Conditions:
BOC BOC BOC BOC Total Max. LilGR, kw/ft:
8.7 8.7 8.7 8.7 E0BY, seconds:
33.30 39.54 43.54 39.54 PCT I?od Clad Temperature at E0BY, F
1243.1 1317:1~
1262.1 1314.90 150Cl EC, seconds 100.46 101.64 105.14 101.64 PCT ltod Clad Temperature at BOCREC, OF 1751. 0 1824.5 1765.4 1823.0 o
NRC renu 195 U,$. NUCLEAR GECULATORY C US$10N DOCKER NUM E A g
50-29
<>M8 NRC DISTRIBUTION ros PART 50 DOCKET MA.TERIAL 10:
FROM:
DATE oF DOCUMENT Yankee Atomic Electric Company 12/29/76 N. R. C.
Westborough, Mass *,
DATE RECEtVED
~ 1/3/77 W. P. Johnson
&E TTE a ONoTORIZED PROP INPUT FORM NUMBER oF COPIES RECEIVED XoRtc8NAL 5CUNCLAss FIED Thrgp signed Osp'.v 40 copies. encl reevd.
DESCRIPTeoN ENCLoSU RE Ltr. w/ attached....re our 12/10/76 ltr. &
Exxon Nuclear Co.'s September 1976 ltr. &
Yankee Nuclear Power Station's 10/8/76 ltr.
...regarding Yankee Rowe Core 12 ECCS Performance Analysis /RNB Lockout & Elevated Upper Head Tem,peraturc Concerns.
ACKNOWLEDGED PLANT !MME:
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SAFETY FOR ACTION /INFORMATION EWTpn 1/4/77 RJL lASSIGNED AD:
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