ML090700308
| ML090700308 | |
| Person / Time | |
|---|---|
| Site: | Calvert Cliffs  |
| Issue date: | 03/10/2009 |
| From: | Constellation Energy Group, Nuclear Generation Group |
| To: | Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML090700305 | List: |
| References | |
| Download: ML090700308 (3) | |
Text
Calvert Cliffs Nuclear Power Plant, Inc.
March 10, 2009 ATTACHMENT (1)
ADDITIONAL INFORMATION - LICENSE AMENDMENT FOR MEASUREMENT UNCERTAINTY RECAPTURE POWER UPRATE
ATTACHMENT (1)
ADDITIONAL INFORMATION - LICENSE AMENDMENT FOR MEASUREMENT UNCERTAINTY RECAPTURE POWER UPRATE 1
During a phone call between Calvert Cliffs Nuclear Power Plant (Calvert Cliffs) and the Nuclear Regulatory Commission (NRC) on February 24, 2009, the NRC requested the following information concerning the Unit 1 and 2 fluence values:
NRC Question 1:
What is the difference between the cross-section data advocated by Regulatory Guide 1.190 (Reference 1) and that utilized in the Units 1 and 2 surveillance capsule reports (References 2 and 3)?
CCNPP Response:
The latest Calvert Cliffs Units 1 and 2 surveillance capsule analyses (References 2 and 3) were performed using the ENDF/B-V cross-section data base. Regulatory Guide 1.190 (Reference 1) recommends using the latest version ENDF/B-VI. Per footnote 2 of Regulatory Guide 1.190, "It should be noted that in many applications the ENDF/B-IV and the first three MODs of the ENDF/B-V iron cross-sections result in as much as ~20% under prediction of the vessel inner-wall fluence..." Thus, a conservative 20% bias is applied to the Calvert Cliffs fluence results.
NRC Question (2):
What is the difference in the end-of-extended-life (EOEL) vessel-clad interface fluence values using ENDF/B-V and ENDF/B-VI?
CCNPP Response:
For Unit 1, the fluence at EOEL [48 effective full power year (EFPY)] as calculated with ENDF/B-V cross-sections is 5.11E+19 n/cm2, while the fluence at EOEL (48 EFPY) as calculated with ENDF/B-VI cross-sections is 6.13E+19 n/cm2. The difference is 1.02E+19 n/cm2. For Unit 2, the fluence at EOEL (48 EFPY) as calculated with ENDF/B-V cross-sections is 5.79E+19 n/cm2, while the fluence at EOEL (48 EFPY) as calculated with ENDF/B-VI cross-sections is 6.95E+19 n/cm2. The difference is 1.16E+19 n/cm2.
NRC Question (3):
What is the difference between the projected fluence at the vessel-clad interface at the next surveillance capsule withdrawal and the EOEL fluence using ENDF/B-V cross-sections?
CCNPP Response:
For Unit 1, the fluence at EOEL (48 EFPY) as calculated with ENDF/B-V cross-sections is 5.11E+19 n/cm2, while the fluence at EOC19 in 2010 (26.53 EFPY) as calculated with ENDF/B-V cross-sections is 3.25E+19 n/cm2. The difference is 1.86E+19 n/cm2. For Unit 2, the fluence at EOEL (48 EFPY) as calculated with ENDF/B-V cross-sections is 5.79E+19 n/cm2, while the fluence at EOC18 in 2011 (27.20 EFPY) as calculated with ENDF/B-V cross-sections is 3.33E+19 n/cm2. The difference is 2.46E+19 n/cm2.
NRC Question (4):
Compare the margin terms from responses 2 and 3.
ATTACHMENT (1)
ADDITIONAL INFORMATION - LICENSE AMENDMENT FOR MEASUREMENT UNCERTAINTY RECAPTURE POWER UPRATE 2
CCNPP Response:
For Unit 1, the difference in EOEL fluence using ENDF/B-V and ENDF/B-VI cross-sections is 1.02E+19 n/cm2, while the difference in fluence at EOEL (48 EFPY) and at EOC19 in 2010 (26.53 EFPY) as calculated with ENDF/B-V cross-sections is 1.86E+19 n/cm2. For Unit 2, the difference in EOEL fluence using ENDF/B-V and ENDF/B-VI cross-sections is 1.16E+19 n/cm2, while the difference in fluence at EOEL (48 EFPY) and at EOC18 in 2011 (27.20 EFPY) as calculated with ENDF/B-V cross-sections is 2.46E+19 n/cm2. Thus, the fluence margin between the next capsule withdrawal and EOEL exceeds the inverse margin from a change in cross section data base for both Units 1 and 2.
References:
- 1.
Regulatory Guide 1.190, March 2001, Calculational and Dosimetry Methods for Determining Pressure Vessel Neutron Fluence
- 2.
Babcock & Wilcox (B&W) Report BAW-2160, June 1993, Analysis of Capsule 97° BG&E CCNPP Unit No. 1
- 3.
Babcock & Wilcox (B&W) Report BAW-2199, February 1994, Analysis of Capsule 97° BG&E CCNPP Unit No. 2