ML20202F158
| ML20202F158 | |
| Person / Time | |
|---|---|
| Site: | Byron, Braidwood  |
| Issue date: | 11/26/1997 |
| From: | Hosmer J COMMONWEALTH EDISON CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| NUDOCS 9712090027 | |
| Download: ML20202F158 (3) | |
Text
y Common % collllt t dN10 CufMP.InY IUK) Opus Plact-Ikw ners Gros e, ll,605145'*01 November 26,1997 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, D.C 20555 0001
Subject:
Clarification of Response to Request for AdditionalInformation Associated with Revised Steam Generator Tube Rupture Analysis Byron Nuclear Power Station, Units 1 and 2 Facility Operating Licenses NPF-37 and NPF-66 NPC Docket Numbers: 50-454 and 50-455 Braidwood Nuclear Power Station, Units 1 and 2 Facility Operating Licenses NPF-72 and NPF-77 NRC Docket Numbers: 50-456 and 50-457
References:
1.
Telecon with M. Lesniak (Comed) and G. Dick (NRR),
dated November 20,1997, 2.
Response to Request for AdditionalInformation for the Steam Generator Tube Rupture Analysis, letter from J. Hosmer to NRC, dated March 20,1997.
3.
J. Hosmer letter to NRC transmitting the Revised Steam Generttor Tube Rupture Topical Report for Byron and Braidwood Stations, dated November 13, 1996.
4.
" Acceptance for Referencing of Licensing Topical Report WCAP 11397 Revised Thermal Design Procedure," letter from Ashos C. Thadani (NRC) to W. J. Johnson (Westinghouse), dated January 17, 1989.
5.
'4 inghouse Reload Safety Evaluation mthcdology,"
WCAP-9272-P-A, dated July 1985.
6.
" Increased SGTP/ Reduced TDF/PMTC Analysis Program, h
Engineering / Licensing Report, "WCAP-13964, dated January 1994.
i I
The following response is provided to clarify the information discussed in Reference I and I
y submitted in response to question A.1 from Reference 2 concerning T,, values used at Byron and.
l Braidwood. The nominal design T.,, window for Byron ano Braidwood is 569.1 "F to 588.4 *F ljE1EMEMERM 9712090027 V71126 PDR ADOCK OSCOO454 P
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A Unicom Company
U.S. NRC Ncvember 26,1997 The calculated temperature uncertainty (including rod controller deadband) for Byron /Braidwood is
+/-7.6 'F. A +1.14 F bias is added as a penalty for steam generator (SG) tube fouling. This is consistent with the previously reported uncertainty of 8.74 *F (Reference 6). The manner in which uncertainties and penaltics are applied in the safety analyses is discussed below. In all cases, the values assumed in the safety analyses bound the calculated uncertainties.
=
For DNB-limited safety anal)ses, a T,.,, of 589.9 *F (upper nominal T,,, limit + SG tube fouling penalty) is used as the initial temperature. An uncertainty equivalent to 7.6 'F is included in the DNB limit. Therefore, the DNB events are effectively analyzed for a T,,of 597.5 F (see Table 1). This is consistent with the NRC approved methodology of Reference 4 For the safety anal)ses which are not DNB limited, a T.,, of 597.9 'F (see Table 1) is used as the initial tensperature for events which are more limaing at high initial temperatures. A T.,, of 561,1 "F (see Table 1) is used for the eve.nts which are analyzed at low T,yg.
This is consistent with the NRC approved methodology of Reference 5.
As discussed in References 2 and 3, the revised steam gene ator tube rupture analysis assumes a T.,, of 567 *F (see Table 1). The corresponding low T,,. sign limit of 575 F is controlled via the reload design process. This is consistent with the NkJ approved methodology of Reference 5.
The Byron and Braidwood Technical Specification temperature limit for DNB e an indicated T.,,
less than or equal to 591.2 *F. The indicated value is determined as the upper nominal T,y, limit +
control system operatiag allowance + SG tube fouling - instrument uncertainty (588.4"F + 4.0 F
+ 0.8'F - 2.0"F = 591.2 F). As shown in Table 1, the high temperature inputs to the various safety analyses bound this indicated Technical Specification value.
Please address any questions or comments to this office.
Sincerely,
'rd,f/ L
(
John B. Hosmer Engineering Vice President Attachment cc:
Regional Administrator - RIII Byron /Braidwood Project Manager - NRR Senior Resident Inspector - Braidwood Senior Resident Inspector - Byron 3ffice of Nuclear Safety - IDNS Unla'byrbwdagtstavgdoc
K Table 1 Calculated DNB-Limited Analyses NOT Analyses NOT Revised SGTR Uncertainty Analyses DNB-Limited -
DNB-Limited -
Analysis high low temperature
)
temperature limiting limiting
}
Nominal T,,
N/A 588.4 F 588.4 F l
569.l'F 575 F Uncertainty *
+ /- 7.6*F
+ 7.6 F"
+ 8.0 F
- 8.0 F
- 8.0 F SO Fouling
+ 1.14 F
+ 1.5 F
+ 1.5"F N/A N/A Penalty / Bias Analysis N/A 597.5 F**
597.9 F 561. I'F 567 F
}
T,,, Value l
" Uncertainty" may include rod con: roller deadband tolerance, measurement uncertainty, or other random uncertainties.
The uncertainty for DNB-limited analyses is not applied directly to the nominal T.,,,
The value
_)
given in the table is the equivalent temperature corresponding to the statist: cal uncertainty specific to the DNB r.nalysis that is applied to the DNB limit. Therefore, the Analysis T.,, value is an effective temperature versus an actual input temperature.
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