ML20154F832
| ML20154F832 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 09/12/1988 |
| From: | Cartwright W VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | NRC OFFICE OF ADMINISTRATION & RESOURCES MANAGEMENT (ARM) |
| References | |
| 88-511, NUDOCS 8809200145 | |
| Download: ML20154F832 (4) | |
Text
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YINGIN*A ELucinic Ann Powan CoxPurY Hrcnxoxn,Vamoixtr 2020:
September 12, 1988 United States Nuclear Regulatory Commission Serial No.
88 511 Attention: Document Control Desk NL/DJV:Jmj Washington, D.C.
20555 Docket Nos.
50 338 50 339 License Nos. NPF-4 NPF-7 Gentlemen:
VIRGINIA uifJRILMID POWER CGiPANY NORTH ANNA POWER STATION UNITS 1 AE _2 REFUELING OUTAGE PLANS i
The purpose of this letter is to inform the NRC of our current plans regarding the upcoming refueling outages for North Anna Power Station Units 1 and 2.
The North Anna 1 and 2 refueling outages were originally scheduled to commence in February, 1989 and November, 1988, respectively. However, we have recently conducted a review of the North Anna outage schtdules, and this review has resulted in a revision to outage plans for both units.
Several unanticipated outages of units in the Virginia Power system, particularly the three month outage following the Unit I steam generator tube rupture event, have made it i
desirable to extend the operating cycles of both units so as to fully utilize the energy in the reactor cores and defer operating and maintenance costs associated with the refueling outages.
Since the Unit 2 reactor core has sufficient fuel to permit full power operation for approximately one and one-half months after November 1,1988, the Unit 2 cycle can be extended past the peak winter load period and into early February,1989.
Given this Unit 2 outage schedule, the Unit I cycle needs to be extended to April, 1989 in order j
to avoid both units being out of service simultar,eously.
Consequently, the Unit I and 2 refueling outages have been rescheduled to commence in April, 1989 and February, 1989, respectively.
Because of this change in outage plans, several licensing issues have de-veloped which will require your review and approval. These issues are as follows:
1.
NRC approval will be required to permit a one-time extension of the Technical Specifications surveillance interval for the containment integrated leak rate tests for Units 1 sr.d 2.
2.
NRC approval will also be required to permit a one-time extension of certain other Unit 1 surveillances that are required by the Techni-cai Specifications to be performed on an 18-month frequency.
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t 3.
NRC approval will be required to permit a one-time extension to the NRC approved fuel rod burnup limit for a number of fuel rods in four fuel assemblies which are part of a program that we have undertaken with Westinghouse and EPRI.
This program is intended to obtain data on fuel rod corrosion at high burnups.
In addition, there are a number of refueling outage activities involving licensing issues which will require your review and approval. These issues are as follows:
1.
Certain Unit 1 and 2 steam generator and reactor coolant pump large bore snubbers will be removed and replaced with rigid restraints as described in our lettar of November 11, 1986.
2.
Our letter dated June 17, 1987 proposed changes to the Technical Specifications to implement Virginia Power's statistical DNBR methodology, and to impose a less restrictive negative moderator temperature coefficient limit.
The less restrictive moderator temperature coefficient limit may be required for operation near the end of the current operating cycles, and the statistical DNBR methodology may be required in the design of the Unit I and 2 core reloads.
Therefore, your approval of these proposed changes is requested by November 30, 1988.
3.
The integrated leak rate tests for both units will be performed using the "mass point method" as recommended by the NRC and proposed in our Technical Specifications change request which was submitted on May 26, 1988.
4.
We are evaluating our test procedures for the upcoming containment integrated leak rate tests for both units. As part of this eval-uation we have identified that certain containment penetrations should not be considered as leakage paths in the test.
Therefore, we plan to submit, for your review and approval, appropriate engi-neering evaluations to support excluding these penetrations from the overall containment leakage rate.
5.
We anticipate having to plug additional steam generator tubes, and therefore, have performed analyses to permit an increase in the number of plugged steam generator tubes.
These analyses will be submitted along with proposed changes to the Technical Specifica-tions for both units to increase the allowable heat flux hot channel factor.
6.
North Anna Unit 2 is in the third period of its first inspection interval and plans to conduct those hydrostatic tests which are required by ASME Section XI during the next two refueling outages for the unit. Because of the plant's design and component geometry, it is not practical to meet certain hydrostatic test requirements of Section XI.
Therefore, we will be submitting requests for relief from these requirements.
1 1
i 7.
As part of our efforts to reduce the number of automatic reactor trips, we are planning to modify the reactor protection system to l
increase the power level below which the reactor trip on turbine trip is blocked. Accordingly, changes to the both units' Technical Specifications will be proposed.
8.
We are investigating means of improving the reliability of the l
residual heat removal system (RHR) during operation with the reactor coolant system partially filled (NRC Generic Letter 87-12).
We t
intend to propose changes to both units' Technical Specifications to eliminate the automatic RHR suction valve closure interlock and to reduce the required RHR flow rate under certain conditions in order to reduce the potential for pump cavitation due to fluid vortexing i
in the suction piping.
9.
Following the Unit 1 steam generator tube rupture event a number of t
i tubes were plugged as a preventive measure in oMer to preclude a j
similar tube failure.
Based on further evaluat.on and testing by i
Westinghouse, it has been concluded that a number of tebes that were i
plugged are, in fact, not susceptible to the same failure mechanism l
j that caused the tube rupture.
Therefore, we intend to submit for I
your review and approval appropriate engineering evaluations in
)
support of removal of these plugs during this and future retueling j
outages.
I
- 10. We are continuing, in concert with Westinghouse, to evaluate im-f proved fuel rod cladding materials.
This program was initiated i
during the current Unit 1 fuel cycle when two deraonstration fuel i
i assemblies with a number of fuel rods clad with an advanced, zir-conium based alloy cladding material were approved for use by the NRC. We intend to extend this program during the next fuel cycle by j
j inserting into these same demonstration fuel assemblies a number of 9
additional fuel rods with a similar, but slightly different, clad-l ding material.
A proposed license amendment and exemption from 10 l
J CFR 50.46 will be submitted for your approval in support of this 1
extension of th: advanced fuel cladding material demonstration
[
j program.
l We request your timely consideration of each of the above licensing issues.
l For eacii of the above issues for which a licensing package has not already l
l been submitted, we expect to submit the licensing package by the end of i
j September 1988, with the exception of itemi 8 and 9 above, which should be i
j submitted by October 31, 1988 and November 30, 1988, respectively.
l i
Very truly your,
i f/
i W. R. Cartwri t
I j
Vice President - Nuclear
s cc:
U. S. Nuclear Regulatory Comission 101 Marietta Street, N.W.
Suite 2900 Atlanta, GA 30323 Mr. J. L. Caldwell NRC Senior Resident Inspector North Anna Power Station