ML17313A870
| ML17313A870 | |
| Person / Time | |
|---|---|
| Site: | Palo Verde  |
| Issue date: | 03/31/1999 |
| From: | Zwolinski J NRC (Affiliation Not Assigned) |
| To: | James M. Levine ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR |
| Shared Package | |
| ML17313A871 | List: |
| References | |
| REF-GTECI-***, REF-GTECI-NI, TASK-***, TASK-OR NUDOCS 9904050051 | |
| Download: ML17313A870 (5) | |
Text
gp.tt slobby
~o
+)t*w+
UNITED STATES NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 2055$ 4001 w-5 A8'arch 31, 1999 Mr. James M. Levine Senior Vice President, Nuclear Arizona Public Service Company Post Office Box 53999 Phoenix, Arizona 85072-3999
SUBJECT:
DEGRADED SWITCHYARDVOLTAGEISSUES ATTHE PALO VERDE NUCLEAR GENERATING STATION
Dear Mr. Levine:
Your February 16, 1999, letter to Dr. William D. Travers, Executive Director for Operations, NRC, was in response to a letter dated November 23, 1998, from Dr. R. Scale, ACRS, to Dr. Travers regarding the reprioritization and proposed resolution of Generic Safety Issue (GSI)-171, "Engineered Safety Features Failure from Loss of Offsite Power Subsequent to a Loss-of-Coolant Accident." Specifically, your letter commented on the following statement contained in the ACRS letter:
"In addition, NRR has raised concerns that degraded switchyard voltage events at Salem and Palo Verde nuclear plants indicate it is possible that plants have either not implemented undervoltage protection properly or conditions have changed that invalidate original design basis capability."
In your February 16 letter, you state that analysis and operating experience have shown that
. the Palo Verde site has a low vulnerability to a LOCAfgrid collapse/loss-of-offsite-power (LOOP) scenario.
Your letter also indicates that a second mechanism could cause a LOOP during a LOCA, due to a reduction of voltage at the buses monitored by the degraded voltage relays.
You conclude that the effects of this degraded voltage scenario are due to the limited capability of the degraded voltage protection systems, not improper implementation of the protection nor a changing design basis capability. Your letter identifies the actions that have been taken to ensure that this'potential scenario willnot affect the Palo Verde units.
(
In a memorandum to Dr. Travers dated March 22, 1999, the ACRS Executive Director pointed out that the statement was quoted from the background information provided by the staff during the Committee's review of the proposed resolution of GSI-171. This memorandum further noted that the November 23 ACRS letter did not imply that Arizona Public Service Company had not properly implemented undervoltage protection at the Palo Verde site. The ACRS does not plan to pursue this issue at this time, and does not require additional information from or a meeting with Arizona Public Service Company.
The background information used by the ACRS included an internal staff document that reported on'a meeting held on July 30, 1998. While proper implementation of undervoltage protection and design basis capability at Salem and Palo Verde were discussed during this 990405005i 99033K PDR ADOCK 05000528 P
Mr. James M. Levine March 31, 1999 meeting, it was not the primary concern of the staff relative to degraded voltage within the context of GSI-171. The primary issue relative to degraded voltage was, similar to that expressed in your letter, the limited capability of the existing automatic undervoltage protection systems at nuclear power plants given a LOCA. In addition, while we recognize that the reliability of the U.S. power grid has been excellent and has improved over the past 10 to 15 years (see NUREG/CR 5496), there is still a concern that future deregulation may result in unexpected degradation of grid stability,with the potential for degraded voltage conditions.
We agree that existing undervoltage protection systems at plants are, in general, not capable of providing protection for all scenarios.
The staff is currently reviewing your December 16, 1998, submittal that proposes to make permanent those measures that have been taken to ensure that degraded voltage scenarios willnot affect the Palo Verde site. We expect to provide our findings on this proposal by August 31, 1999.
Docket Nos. STN 50-528, STN 50-529 and STN 50-530 cc: See next page Sincerely, Original Signed By S. Black for John A. Zwolinski, Director Division of Licensing Project Management Office of Nuclear Reactor Regulation DISTRIBUTION:
(Docket. File (w/incoming)
CNorsworthy PUBLIC (w/incoming) EPeyton EDO ¹ 990099 PHarrell, RIV WTravers EMerschoff, RIV FMiraglia MKnapp AThadani FCongel PNorry JMitchell, EDO JBlaha OGC S Burns OPA SCollins/RZimmerman OCA BS heron JCalvo
'kane ACRS JZwolinski/S Black SRichards PDIV-2 Reading (w/incoming)
MFields (w/incoming)
DOCUMENT NAME: GT990099.WPD
- See previous concurrence OFC PDIV/PM PDIV/LA EICB PDIV/D ~
D:DLP NAME M
ds EPeeyt n
JCatvo*
SRichar s
JZwoli ski DATE 3/
/99 3WI/99 3/22 /99 3/ >I /99 OFFICIAL RECORD COPY 3/
/99
~
g 0
P J
v l
1 l[
Palo Verde Generating Station, Units 1, 2, and 3 CC:
Mr. Steve Olea Arizona Corporation Commission 1200 W. Washington Street Phoenix, Arizona 85007 Mr. David Summers Public Service Company of New Mexico 414 Silver SW, ¹1 206 Albuquerque, New Mexico 87102 Douglas Kent Porter Senior Counsel Southern California Edison Company Law Department, Generation Resources P.O. Box 800
- Rosemead, California 91770 Senior Resident Inspector USNRC P. O. Box 40 Buckeye, Arizona 85326 Regional Administrator, Region IV U. S. Nuclear Regulatory Commission Harris Tower 8 Pavillion 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064 Chairman, Board of Supervisors ATTN: Chairman 301 W. Jefferson, 10th Floor Phoenix, Arizona 85003 Mr. Jarlath Curran Southern California Edison Company 5000 Pacific Coast Hwy Bldg DIN San Clemente, California 92672 Mr. Robert Henry Salt River Project 6504 East Thomas Road Scottsdale, Arizona 85251 Terry Bassham, Esq.
General Counsel El Paso Electric Company 123 W. Mills El Paso, Texas 79901 Mr. John Schumann Los Angeles Department of Water 8 Power Southern California Public Power Authority P.O. Box 51111, Room 1255-C Los Angeles, California 90051 Mr. Aubrey V. Godwin, Director Arizona Radiation Regulatory Agency 4814 South 40 Street Phoenix, Arizona 85040 Ms. Angela K. Krainik, Manager Nuclear Licensing Arizona Public Service Company P.O. Box 52034 Phoenix, Arizona 85072-2034, Mr. John C. Horne, Vice President Power Generation El Paso Electric Company P.O. Box 982 El Paso, Texas 79960
/ ~
C P
j