ML20212F464
| ML20212F464 | |
| Person / Time | |
|---|---|
| Site: | Yankee Rowe |
| Issue date: | 12/24/1986 |
| From: | Mckenna E Office of Nuclear Reactor Regulation |
| To: | Papanic G YANKEE ATOMIC ELECTRIC CO. |
| References | |
| NUDOCS 8701120014 | |
| Download: ML20212F464 (5) | |
Text
r g
t, ~
DEC 2 41986 Docket No.50-029 Mr. George Papanic, Jr.
Senior Project Engineer-Licensing Yankee Atomic Electric Company 1671 Worcester Road Framingham, Massachusetts 01701
Dear Mr. Papanic:
SUBJECT:
YANKEE NUCLEAR POWER STATION - ADEQUACY OF STATION ELECTRIC DISTRIBUTION SYSTEM By letter dated August 29, 1986, you provided a revised report on the adequacy of station electric distribution system at Yankee. This report updates an earlier study, submitted on February 26, 1980 that was reviewed by the staff in a July 13, 1981 safety evaluation.
The revised study accounts for increases in plant loading on the buses and in the high pressure safety injection pump motor minimum starting, voltage.
In addition, other changes in the analysis assumptions and methodology were made.
In order for the staff to complete its review of this study, the additional
-information in the enclosure to this letter is required.
Your response is requested within 90 days of receipt of this letter.
The reporting and/or recordkeeping requirements contained in this letter affect fewer than ten respondents; therefore, OMB clearance is not required under P. L.96-511.
Sincerely,
/3/
Eileen M. McKenna, Project Manager Project Directorate #1 Division of PWR Licensing-A
Enclosure:
As Stated cc's:
See Next Page Pg PD/ PAD #1 Office:
Surname: EMcKe a g Glear Date:
12/3/86 12/>J/86 8701120014 861224 DR ADOCK 05000029 PDR
[
Mr. George Papanic, Jr.
Yankee Atomic Electric Company Yankee Nuclear Power Station cc:
Mr. James E. Tribble, President Yankee Atomic Electric Company 1671 Worcester Road Framingham, Massachusetts 01701 Thomas Dignan, Esquire Ropes and Gray 225 Franklin Street Boston, Massachusetts 02110 Mr. N. N. St. Laurent Plant Superintendent Yankee Atomic Electric Company Star Route Rowe, Massachusetts 01367 Chai rman
~ Board of Selectmen Town of Rowe Rowe, Massachusetts 01367 Resident Inspector Yankee Nuclear Power Station c/o U.S. NRC Post Office Box 28 Monroe Bridge, Massachusetts 01350 Regional Administrator, Region I U.S. Nuclear Regulatory Commission 631 Park Avenue King of Prucsia, Pennsylvania 19406 Robert M. Hallisey, Director Radiation Control Program Massachusetts Department of Public Health 150 Tremont Street, 7th Floor Boston, Massachusetts 02111
.-e
+
y--
w w
.m
- o. l, ;.
- 0E024 555 0
.jDistribution Copies:
49eetet1FWes?
~
NRC.PDR Local PDR-PAD #1-r/f
~
PAD #1 p/f.
TNovak, Actg. DD NThompson, DHFT OGC-Bethesda-
-EJordan-BGrimes-JPartlow Glear PShuttleworth EMcKenna ACRS (10)
LFMB 1
4
.,,.-~.-,,,-,,-.-,,.,=n-.-
n.
.n>
e e
e.,
4 s.
ENCLOSURE REQUEST FOR ADDITIONAL INFORMATION AUXILIARY POWER SYSTEM V0LTAGE STUDY YANKEE NUCLEAR POWER STATION
References:
1.
YAEC letter dated February 27, 1980 transmitting Report YAEC-1206, Auxiliary Power System Voltage Study.
2.
YAEC letter dated August 29, 1986 transmitting Report YAEC-1561 Auxiliary Power System Voltage Study.
1.
The previous Auxiliary Power System Voltage Study dated February 27, 1980, demonstrated the adequacy of the station electric distribution system by using an analytical model and computer program. To obtain further confidence, the results of the study were verified by an actual test to assure that the computer analysis was valid. Our review of the new study performed to resolve concerns related to the adequacy of the plant distribution system concludes that those issues should have been addressed and resolved in the previous study. The licensee should provide the basis that the new study assures the adequacy of the plant distribution system voltage this time.
2.
Our comparison of the previous study with the new study finds:
a.
There appears to be a significant load difference between the two studies (i.e., 5580 KVA - Table 3.1 of 1980 study vs. 6961 KVA -
Fig. 3.3.2-1 of 1986 study). Describe how the load estimates were made for each study and substantiate that the new study accurately represents the existing loads.
b.
From the plant configuration (Section 3.3.4) for the maximum load case, it appears that the new study) reduces the loading of the station service transformers (5 & 6 as intended.
However, it appears that this new configuration overloads either of the upstream station service transformers (2 & 3) which are rated 5000/6250 KVA each.
Is this in fact true and, if so, address why this is acceptable.
3.
The statement in the new study (page 8) "The analysis also assures that the grid voltage is at the minimum expected value, however, voltage regulators will maintain the described load voltage of 2400 volts" implies that the voltage regulator can maintain 2400 volts with a 15%
variation of the 115 KV sources. Thus, the voltage study was performed on the auxiliary power system at the 2400 volt buses and below.
If this is the case, we feel that the time delay associated with the voltage
2 regulators to correct the degraded grid voltage should be incorporated in the overall SI scenario time sequences. Otherwise, describe how the voltage regulators have been represented in the study during the transient and the steady state cases.
4.
With respect to the computer programs used to analyze the auxiliary power system, we noted that the old study used PTI program while the new study uses DAPPER (for the maximum load case) and the Stone / Webster (for the minimum load case) programs.
In view of the fact that there are changes in the computer programs, system configuration, and inasmuch as the original model and method did not predict the difficulties experienced with the electrical system voltages, we are not confident that the new methodology can accurately predict electrical distribution system voltages. Therefore, we conclude that Yankee Rowe should perform a new verification test to verify the analytical model's ability to accurately predict the electrical distribution system voltages for transient and steady state conditions. This test should be performed according to part B.4 of the Branch Technical Position PSB-1.
Please advise when this test will be performed and the results submitted for our review.
I e
r v
-