ML20198D823
| ML20198D823 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 12/17/1998 |
| From: | Ohanlon J VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| References | |
| 98-646, NUDOCS 9812230227 | |
| Download: ML20198D823 (10) | |
Text
-
Vinc;isi A EimcTRIC ANi) I'()WER C()\\1m NY RICilN1()N I), VilMilNI A 23261 December 17, 1998 U.S. Nuclear Regulatory Commission Serial No.98-646 Attention: Document Control Desk NL&OS/ETS R0 Washington, D.C. 20555 Docket Nos. 50-338 50-339 License Nos. NPF-4 NPF-7 Gentlemen:
VIRGINIA ELECTRIC AND POWER COMPANY NORTH ANNA POWER STATION UNITS 1 AND 2 REACTOR VESSEL SURVEILLANCE CAPSULE WITHDRAWAL SCHEDULES in accordance with 10 CFR 50 Appendix H, Section Ill.B.3, Virginia Electric and Power Company (Virginia Power) submits for NRC review and approval proposed reactor vessel materials surveillance capsule withdrawal schedules for North Anna Units 1 and 2 and the technical justifications supporting those schedules.
During the recent Unit 1 refueling outage, the surveillance capsule withdrawal tool became mechanically bound to Capsule W during its extraction. As a result, Virginia Power was unable to relocate Capsules Z and T.
Therefore, a proposed Unit 1 surveillance capsule withdrawal schedule was prepared to reschedule relocation of Capsules Z and T to occur during the next Unit 1 refueling outage. In addition, the proposed Unit 1 and 2 withdrawal schedules: a) add or modify requirements for relocating surveillance capsules to " lead factor" locations, b) reduce the number of required surveillance capsules in the North Anna Unit 2 surveillance program from five to four, and c) incorporate information, in the form of footnotes to the surveillance capsule withdrawal schedules, to indicate that additional capsules are available to satisfy neutron fluence monitoring requirements which may be established for a postulated 20-year license renewal period.
\\I i
f 9812230227 981217 PDR ADOCK 05000338-y P
PDR _
Dg o
, - s-1
., ~.
We request expeditious review and approval of the revised withdrawal schedules to support ' incorporating the activities into the upcoming North Anna Unit 2 refueling outage, which is currently scheduled for September 1999. If you have any further questions, please contact us.
Very truly yours, James P. O'Hanlon Senior Vice President - Nuclear Commitments made in this letter:
1.
There are no new commitments in this letter.
Attachments 1.
cc:
U.S. Nuclear Regulatory Commission Region II Atlanta Federal Center 61 Forsyth Street, SW Suite 23T85 Atlanta, Georgia 30303 Mr. M. J. Morgan NRC Senior Resident inspector North Anna Power Station
4 Technical Justification for the Proposed Reactor Vessel Materials Surveillance Capsule Withdrawal Schedules Virginia Electric and Power Company North Anna Power Station Units 1 and 2
Technical Justification for the Proposed North Anna Units 1 and 2 Reactor' Vessel Materials Surveillance Capsule Withdrawal Schedules INTRODUCTION During the recent Unit 1 refueling outage, the surveillance capsule withdrawal tool became mechanically bound to Capsule W during its extraction. As a result, Virginia Power was unable to relocate Capsules Z and T.
Therefore, a proposed Unit 1 surveillance capsule withdrawal schedule was prepared to reschedule relocation of Capsules Z and T to occur during the next Unit 1 refueling outage. In addition, the proposed Units 1 and 2 withdrawal schedules: a) add or modify requirements for relocating surveillance capsules to " lead factor" locations, b) reduce the number of required surveillance capsules in the North Anna Unit 2 surveillance program from five to four, and c) incorporate information, in the form of footnotes to the surveillance capsule withdrawal schedules, to indicate that additional capsules are available to satisfy neutron fluence monitoring requirements which may be established for a postulated 20-year license renewal period.
PROPOSED CHANGES Changes to the Unit 1 Reactor Vessel Materials Surveillance Capsule Withdrawal Schedule include:
(a) removal of references to Capsules Z and T relocation to higher neutron flux locations during the N1C13/14 refueling outage (14.7 EFPY), and (b) insertion of references to Capsules Z and T relocation to higher neutron flux locations during the N1014/15 refueling outage (16.1 EFPY).
Changes to the Unit 2 Reactor Vessel Materials Surveillance Capsule Withdrawal Schedule include:
(a) reduction in the number of required surveillance capsu!es from five to four in accordance with guidance in ASTM E-185-82 (1),
(b) designation of Capsule X as the capsule which satisfies the ASTM E-185-82 (1)
" fourth capsule requirement" (i.e., withdrawal at end-of-license (EOL)), and (c) insertion of references to Capsules Z and T relocation during the N2C13/14 refueling outage (15.3 EFPY).
Changes to both the Unit 1 and Unit 2 withdrawal schedules include:
(a) insertion of references to the availability of standby capsules to satisfy potential neutron fluence monitoring requirements during a postulated 20 year license renewal period, Page 1 of 7
.m 7
t (b). insertion of references to the availability of the capsules designated "X" to provide reactor vessel material properties data at a neutron fluence which exceeds the reactor vessel beltline neutron fluence at the end of a postulated 20 year license renewal period, and (c) updated surveillance capsule neutron fluence estimates at the time of capsule relocation or withdrawal, or at end-of-license if the capsule is a standby capsule.
TECHNICAL EVALUATION AND JUSTIFICATION Section Ill.B.3 of 10 CFR 50 Appendix H (2) requires a proposed surveillance capsule withdrawal schedule and its technical justification to be submitted to the NRC for review and approval prior to implementation.
The evaluation which follows provides the technical justification for the proposed surveillance capsule withdrawal schedules. The proposed capsule withdrawal schedules are attached as proposed UFSAR Tables 5.4-2 for Units 1 and 2.
North Anna Unit 1 Capsule Z and T Relocations The current surveillance capsule withdrawal schedule requires Unit 1 surveillance Capsules Z and,T to be relocated to locations of higher neutron flux during the North Anna Unit 1 Cycle 13/14 refueling outage (14.7 EFPY).
These relocations were instituted into the schedule to satisfy the ASTM E-185-82 Section 7.2.1 (1) requirement to maintain surveillance capsule lead factors in the range of one to three, and to provide for future contingencies. In addition, relocation of Capsule Z is required to ensure that it will accumulate sufficient neutron fluence at end-of-license (EOL) to meet the " fourth
- capsule neutron fluence requirement"in ASTM E-185-82 (1). Although Unit 1 Capsule X will achieve sufficient fluence at EOL to fulfill the ASTM E-185-82 (1) " fourth capsule neutron fluence requirement", previous attempts to remove Unit 1 Capsule X were unsuccessful, so it was reclassified as a " standby" capsule.
Following removal of the third Unit 1 surveillance capsule (i.e., Capsule W) during the N1C13/14 refueling outage in accordance with the Unit 1 withdrawal schedule, but prior to relocation of Unit 1 Capsules Z and T, the surveillance capsule withdrawal tool became mechanically bound to Capsule W. As a result, Virginia Power assessed the consequences of abandoning plans to relocate Capsules Z and T, and determined that the requirements of 10 CFR 50 Appendix H (2) and ASTM E-185-82 (1) could be met without relocation of these capsules during the N1C13/14 outage. Therefore, relocation
, of Unit 1 Capsules Z and.T is being rescheduled to occur during the N1C14/15 refueling outage (16.1 EFPY). The engineering analyses that support this change demonstrate that the proposed Unit 1 surveillance capsule withdrawal schedule meets the requirements of ASTM E-185-82.
Page 2 of 7
l Reduction in -Number of Required Capsules for the North Anna Unit 2 Surveillance Program According to Table 1 of ASTM E-185-82 (1), three surveillance capsules are required in a plant-specific surveillance program if the predicted shift in the Reference Temperature for the Nil Ductility Transition (RTnor) at the inside surface of the reactor vessel at EOL is less than 100 F. Four capsules are required if the predicted shift is between 100 F and 200 F. Five capsules are required if the predicted shift is greater than 200 F. The highest predicted transition temperature shift for North Anna Units 1 and 2 beltline materials is greater than 100 F, but substantially less than 200 F. Therefore, North Anna Units 1 and 2 both qualify for a four-capsule surveillance program in accordance
- with ASTM E-185-82 (1)..The proposed Unit 2 surveillance capsule withdrawal schedule includes only four " active" surveillance capsules; the remaining capsules are designated " standby."
Designation of Surveillance Capsule X as the Fourth North Anna Unit 2 Surveillance Program Capsule l
l According to the current North Anna Unit 2 surveillance capsule withdrawal schedule, Unit 2 has two surveillance capsules (X and Y) scheduled to be withdrawn prior to EOL.
As described above, the Unit 2 surveillance program requires only four capsules to be withdrawn and tested to fulfill the requirements of 10 CFR 50 Appendix H and ASTM E-185 (1). Therefore, Capsule X is being scheduled to be withdrawn at EOL to satisfy the requirements of ASTM E-185-82 (1). At EOL, Capsule X will have experienced a capsule fluence at least once but not greater than twice the peak EOL vessel fluence.
Withdrawal of Capsule X at EOL will also provide data at a fluence which bounds the expected end-of-license-renewal (EOLR) fluence (i.e., approximately 1.5 times the peak reactor vessel beltline EOL fluence).
- The engineering analyses which support the proposed surveillance capsule withdrawal schedule changes also demonstrates that Unit 2 Capsule Y will experience a neutron fluence at EOL which is at least once but not greater than twice the peak EOL vessel fluence. Thus, if for any reason Unit 2 Capsule X cannot be withdrawn, Capsule Y may be withdrawn to satisfy the ASTM E-185-82 (1) fourth capsule requirement for the l
current license period.
North Anna Unit 2 Capsule Z and T Relocations The Unit 2 reactor vessel materials surveillance capsule withdrawal schedule is being modified to include specific guidance for Unit 2 surveillance capsule relocations similar to those planned for Unit 1.
Specifically, the revised schedule incorporates the relocation of Unit 2 Capsules Z and T to higher neutron flux locations during the North Anna Unit 2 Cycle 13/14 refueling outage (15.3 EFPY). At present, there are four UnR 2 capsules (Z, T, Y, and S) designated " standby." Of these four, only one (Capsule Y) is presently installed in a vessel location which experiences a " lead factor" as defined in ASTM E-185-82.' Therefore, in order to satisfy the ASTM E-185-82 Section 7.2.1 (1)
Page 3 of 7
i requirement to maintain surveillance capsule lead factors in the range of one to three, and to ensure' that altornate surveillance capsules are available for contingencies, Capsules Z and T will be relocated to " lead factor locations" at approximately 15.3 EFPY.
Preparation for License Renewal Aging Management Programs for North Anna Units 1 and 2 Reactor Vessels As of this writing, there are no established requirements for reactor vessel neutron fluence monitoring or irradiated material properties data for a postulated license renewal period. However, by virtue of the presence of Unit 1 standby Capsules T, Y and S, and Unit 2 standby Capsules T, Z, and S, the North Anna Units 1 and 2 surveillance programs are capable of satisfying fluence monitoring requirements during an extended license period. The proposed surveillance capsule withdrawal schedules for Units 1 and 2 include footnotes indicating the availability of the standby capsules to satisfy license-renewal fluence monitoring requirements, but that these capsules are not required to satisfy the requirements of ASTM E-185-82 (1) during the current license period.
The North Anna Units 1 and 2 surveillance programs are capable of generating irradiated material properties data (i.e., from Charpy specimens) at a fluence which exceeds that of the reactor vessel beltline at end-of-license-renewal (EOLR). The reactor vessel beltline is expected to experience a fluence at EOLR of approximately 1.5 times the peak EOL reactor vessel beltline fluence. Because ASTM E-185-82 requires the fourth surveillance capsule (withdrawn at EOL) to have a fluence at least once but not greater than twice the peak EOL reactor vessel beltline fluence, the fourth surveillance capsule may have adequate fluence to bound the EOLR peak reactor 1
vessel beltline neutron fluence. The proposed North Anna Units 1 and 2 surveillance capsule withdrawal schedules indicate that the capsules designated "X", if withdrawn at EOL, is expected to provide material properties data at a fluence which meets or exceeds the peak reactor vessel beltline inner surface fluence at EOLR.
CONCLUSIONS Revised reactor vessel materials surveillance capsule withdrawal schedules have been developed for North Anna Units 1 and 2. These schedules meet the requirements of 10 CFR 50 Appendix H (2) and ASTM E-185-82 (1). The evaluatlon which demonstrates the adequacy of these schedules to meet applicable regulatory requirements during the current license period assumes relocation of Unit 1 Capsule Z to a higher neutron flux location during the N1C14/15 refueling outage. Additional Units 1 and 2 surveillance capsule relocations are specified in the surveillance capsule withdrawal schedules to ensure that standby capsules are maintained in " lead factor" locations.
Such relocations ensure that standby capsules are available for future contingencies.
Footnotes have been added to the surveillance capsule withdrawal schedules to indicate that the standby capsules are available to satisfy fluence monitoring Page 4 of 7
requirements that may be in effect during a license renewal period. A separate footnote indicates that the North Anna Units 1 and 2 capsules designated "X" are available to satisfy material properties data requirements which may be in effect during license renewal.
References:
(1) ASTM E-185-82, " Standard Practice for Conducting Surveillance Tests for Light-Water Cooled Nuclear Power Reactor Vessels," dated July 1,1982.
(2) 10 CFR 50 Appendix H, " Reactor Vessel Material Surveillance Program Requirements."
l Page 5 of 7
I 1
North Anna UFSAR Table 5.4-2 SURVEILLANCE CAPSULE WITHDRAWAL SCHEDULE' FOR NORTH ANNA UNIT 1 Capsule Capsule Lead Capsule Status' Estimated Insert Est. Capsule Ident. -
Location' Factor' Withdrawal EFPY/ Year Fluence (x10")'
EFPY/ Year V
165 1.6 Active 1.1/1979 NA 0.30 U
65*
1.0 Active 5.90/1987 NA 0.88-W 245 1.03 Active 14.7/1998 NA 2.04 Z
305*
0.69 Active' 16.1/2000 NA 1.48 Z
165*
1.6 NA 16.1/2000 1.48 Z
165 1.6 EOL/2018 NA 4.64 T
55' O.69 Standby' 16.1/2000 NA 1.48 T
245 1.03 NA 16.1/2000 1.48 T
245 1.03 NA NA 3.52 (EOL)
Y 295*
1.03 Standby' NA NA 4.24 (EOL)
S 45' O.55 Standby' NA NA 2.27 (EOL)
X 285*
1.6 Standby'
. EOU2018 NA 6.59 2 Withdrawal schedule meets requirements of ASTM E-185-82, " Standard Practice for Conducting Surveillance Tests for Light-Water Cooled Nuclear Power Reactor Vessels," dated July 1, 1982.
2 See North Anna UFSAR Figure 5.4-4 for original capsule installation locations.
3 Lead Factor is defined in ASTM E-185-82 as the ratio of the neutron flux density at the location of the specimens in a surveillance capsule to the neutron flux density at the reactor pressure vessel inside surface at the peak fluence locatJon.
- Capsules required to satisfy the requirements of ASTM E-185-82 during the current license period are designated Active.
Capsules not required by ASTM E-185-82, but which are maintained for contingencies, are designated Standby.
5 Surveillance capsule neutron fluence estimates based on fluence analysis presented in WCAP-ll777, ' Analysis of Capsulo U from the Virginia Electric and Power Company North Anna Unit 1 Reactor Vessel Radiation Surveillance Program," dated February 1988.
Capsule X may be withdrawn at EOL in lieu of Capsule Z to satisfy ASTM E-l 185-82 fourth capsule requirement for the current license period.
' Capsules T, Y, and S are available to satisfy potential fluence monitoring requirements during a postulated 20 year license renewal period.
' Capsule X may be withdrawn at EOL to provide material properties data at a fluence which exceeds that expected to be achieved at the end of a i
postulated 20 year license renewal period.
Page 6 of 7
._ ~_
North Anna UFSAR Table 5.4-3 SURVEILLANCE CAPSULE WITHDRAWAL SCHEDULE' l
FOR NORTH ANNA UNIT 2 l
Capsule Capsule Lead Capsule Status' Estimated Insert Est. Capsule ident.
Location' Factor' Withdrawal EFPYNear Fluence (x10")'
EFPYNear U
165*
1.66 Active 1.0/1982 NA 0.25 l
U 65*
1,19 Active 6.3/1989 NA 1.07 W
245*
1.19 Active 15.3/1999 NA 2.58 Z
305*
0.81 Standby
- 15.3/1999.
NA 1.76 Z
165a 1.66 NA 15.3/1999 1.76 Z
165 1.66 NA NA 5.82 (EOL)
T 55a 0.81 Standby' 15.3/1999 NA 1.76 T
65a 1.19 NA 15.3/1999 1.76 T
65o 1.19 NA NA 4.67 (EOL)
Y 295*
1.19 Standby' NA NA 5.50 (EOL)
~
S 45' O.65 Standby' NA NA 3.00 (EOL)
X 285*
1.72 Active' EOU2020 NA 7.95 2 Withdrawal schedule meets requirements of ASTM E-185-82, " Standard Practice for Conducting Surveillance Tests for Light-Water Cooled Nuclear Power Reactor Vessels," dated July 1,
- 1982, a See North Anna UFSAh Figure 5.4-4 for original capsule installation locations.
3 Lead Factor is defined in ASTM E-185-82 as the ratio of the neutron flux density at the location of' the specimens in a surveillance capsule to the neutron flux density at the reactor pressure vesuel inside surface at the peak fluence location.
- Capsules required to satisfy the requirements of ASTM E-185-82 during the current license period are designated Active. Capsules not required by ASTM E-185-82, but which are maintained for contingencies, are designated Standby.
5 Surveillance capsule neutron fluence estimates based on fluence analysis presented in WCAP-12497, " Analysis of Capsule U from the Virginia Electric
.and Power Company North Anna Unit 2 Reactor Vessel Radiation Surveillance Program," dated January 1990, 1
8. Capsules Z, T, Y, and S are available to satisfy potential fluence monitoring requirements during a postulated 20 year license renewal period.
Capsule Y may be withdrawn in lieu of capsule X to satisfy ASTM E-185-82 fourth capsule requirement for the current license period.
7 Withdrawal of Capsule X at EOL satisfies ASTM E-165-82 requirement for EOL capsule, and provide material properties data at a fluence which exceeds that expected to be achieved at the end of a postulated 20 year license renewal period.
Page 7 of 7
-