ML20040B701
| ML20040B701 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 01/20/1982 |
| From: | Leasburg R VIRGINIA POWER (VIRGINIA ELECTRIC & POWER CO.) |
| To: | Clark R, Harold Denton Office of Nuclear Reactor Regulation |
| References | |
| NUDOCS 8201260331 | |
| Download: ML20040B701 (4) | |
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VittutNEA ELi>cTurc A.;o Pows:st Cost ANY HICIIMONIb VIHUINIA 20261 H. Il 1.nannn un vu. rumn...r Na.c s. man oa a mas summ 7--^
x Serial No. 017 Mr. Harold R.
Denton, Director Of fice of Nuclear Reactor Pegulation
/
PSE&C/slw/KSB Attn:
Mr. Pnbert A. Clark, Chief
/
Operating Reactors Branch No.,$
z Docket Nos. 50-338 Division of Licensing 50-339 U.S.
Nuclear Regulatory Commission Wanhington, DC 20555 1 License Nos. NPF-4 NPF-7 Gentlemen:
GENERAL DESIGN CRITERI A 17 ANALYSIS NORTH ANNA UNIT NOS. 1 AND 2 Thin letter is in response to your letter of December 28, 1981.
In view of our Februa ry 28, 1982 GDC-17 analysis submittal date, we want to clarify several points presented in your letter.
We stated in a letter to you dated July 24, 1981, Serial No. 908A, that, "our analyses to determine the adequa cy of the installed generator breaker are being conducted in reference to our interpretation of item 2 of the ' Guidelines for Voltage Drop Calculations' which was attached to the NRC letter dated August 8, 1979, entitled ' Adequacy of Station Electrical Distribution System Voltages'.
Our interpretation is based on a May 20, 1981 telephone conference with your Mr. L.
B.
Engle and is as follows:
In the analyses of voltage conditions available from the Reserve Station Service System, we are assuming that the worst case would be for Unit 2 to have all of its loads on the reserve, while Unit 1 has its SI activated safety loads and intake structure loads only on the reserve. We are able to make this assumption on the basis that Unit 1 now has a generator breaker which provides the capability of tripping the unit without transferring loads to the reserve system.
We feel that the ' accident' or the ' anticipated transient in the unit being analyzed' discussed in item 2 of the reference, does not include the occurrences that would cause Unit 1 to transfer loads to reserve at the same time that Unit 2 is fully loaded from the reserves."
Vepco is continuing the GDC-17 analysis effort based on the above interpretation of your August 8,
1979 letter regarding the adequacy of the North Anna electrical distribution system.
In order that our February 28, of 1982 CDC-17 analysis submittal schedule be maintained, immediate final y '
agreement on the analysis basis is necessary.
j
//I 8201260331 820120 PDR ADOCK 05000338 P
PDR I
Vint,ista Ftrciusc avu Ibwru Coersy to Mr.
H.
R.
Denton while this is not a complete response to your December 28, 1981 letter, we tw?lieve clarification of your points concerning installation of a Unit 2 generator breaker and transfer of Unit I normal station service buses to the RSST's is necessary to support our February 28, 1982 GDC-17 analysis submittal date.
Please contact us if you require further information prior to our final submittal.
In order to expedite a resolution of this, we are prepared to meet you at your earliest convenience.
/
f///
/$" ' k ' /.
R.
H.
Leasburg cc: Mr.
J.
P. O'Reilly, Regional Administrator Office of Inspection and Enforcement Region II
.)
Vivomia larcTwie awn Ibwra Cowrawy To Mr.
H.
R. Denton I
NRC Request "1.
Confirm if generator breaker will be utilized for the Unit 2 guNrator."
Vepco Responso A generator breaker will not be installed on Unit 2 unless our analysis indicates the installation is required to ensure compliance with the GDC-17 guidelines.
NRC Request "2.
Submit amended technical specifications to cover the modifications made in the electrical distribution system.
The amendment should cover the electrical line-up and equipment required to be operational in both units to assure that two sources of offsite power are made available to the 4160V buses of both units.
This includes the AC
- buses, D.C.
systems and auxi i lary supporting equipment."
Vepco Response l
Our July 24, 1981 letter contained a preliminary copy of our proposed changes to the Unit 1 Technical Specifications.
The Unit 2 Technical Specifications will be similarly modified and submitted in " draft" form for your review by February 28, 1982.
NRC Request "3.
Provide detailed information to support the assumption in your December 1,
1991 submittal which stated that Unit 1 normal station service busen will not be fed from the reserve transformers during the worst case voltage conditions.
If this is achieved by design features provide a description of such design features that assure such an operation.
If design features are not included to prevent this condition, provide a voltage analysis to cover operation under the loading condition."
Vepco Response The basis for our assumption that Unit I normal station service buses will not be fed from the reserve station service transformers (RSST's) during worst case voltage conditions (which include Unit 2 loading on the RSST's) is that the Unit 1 generator breaker greatly reduces the probability of loading the RSST's with the Unit 1 normal station service buses.
Therefore, the probability that Unit 1 normal station service buses transfer to the RSST's during worst case voltage conditions is extremely small.
We believe this assumption forms the basis for acceptable GDC-17 analysis.
As such, we previously submitted this assumption for your review in our July 24, 1981 letter to you, Serial No. 908A, and in a May 20, 1981 telephone conference with your Mr. L. B. Engle.
l
VNo NIA E LPM NIC A M D POh t h COM PN TO Mr. II.
R.
Denton NRC Request "4.
Provide the following information on the generator breaker currently installed in Unit 1.
a.
Source (s) of operating power; b.
The bases used for generator breaker sizing (maximum system fault current that breaker could experience); and c.
A table showing generator breaker design specifications, testing required by VEPCO, testing performed and test results.
The table should conta'.n as a minimum the following:
(1) voltage rating (KV rms);
(2) load current (continuous KA);
(3) insulation levels (4) interrupting capacity (KA-rms) symmetrical, asymmetrical; (S) close and latch (KA-peak);
(6) short time rating (KA)
(7) maximum rate of rise recovery voltage: and (8) out-of-phase switching.
d.
Detailed information on out-of-phase switching and protective equipment (sync-check-relays, etc.) installed at North Anna that would preclude out of phase operation of the generator breaker.
c.
What onsite testing will be or has been performed on the generator breaker regarding:
(1) preoperational tests; (2) periodic tests; and (3) maintenance frequency."
Vepco Response Our September 23, 1981 letter to you, Serial No. 908B, transmitted most of the generator breaker technical data you requested. We will summarize all the data you requested and submit it by February 28, 1982.
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