ML17304B326

Special Rept 2-SR-89-005:on 890712,load Shed Signal of 13.8 Kv Bus 2E-NAN-S02 Resulted in Deenergizing Reactor Coolant Pumps 1B & 2B & Reactor Trip.Caused by Less than Nominal Decay Heat.Unusual Event Declared.Ler Will Be Submitted

ML17304B326
Person / Time
Site:	Palo Verde
Issue date:	07/14/1989
From:	Haynes J ARIZONA PUBLIC SERVICE CO. (FORMERLY ARIZONA NUCLEAR
To:	NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM)
References
192-00498-JGH-T, 192-498-JGH-T, 2-SR-89-005, 2-SR-89-5, NUDOCS 8907200409
Download: ML17304B326 (6)

Text

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ACCESSION NBR:8907200409 DOC.DATE: 89/07/14 NOTARIZED: NO DOCKET FACIL:STN-50-529 Palo Verde Nuclear Station, Unit 2, Arizona Publi 05000529 AUTH. NAME AUTHOR AFFILIATION HAYNES,,J.G. Arizona Public Service Co. (formerly Arizona. Nuclear Power RECIP.NAME RECIPIENT AFFILIATION Document Control Branch (Document Control Desk) R

SUBJECT:

Special R 2-SR-89-005:on 890712,notification of unusual I event declared on low pressurizer pressure.

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il Arizona Public Service Company PALO VERDE NUCLEAR GENERATING STATION P.O, BOX 52034 ~ PHOENIX, ARIZONA85072-2034 192-00498-JGH/TDS/JJN July 14, 1989 U. S. Nuclear Regulatory Commission NRC Document Control Desk Washington, D.C. 20555

Subject:

Palo Verde Nuclear Generating Station (PVNGS)

Unit 2 Docket No. STN 50-529 (License No. NPF-51)

Special Report 2-SR-89-005 File: 89-020-404 Attached please find Special Report 2-SR-89-005 prepare'd and submitted pursuant to,Emergency Plan Implementing Procedure -03. This report discusses a NOTIFICATION OF UNUSUAL EVENT due to a Safety Injection System Actuation.

If you have any questions, please contact T. D. Shriver, Compliance Hanager at (602) 393-2521.

Very tr ly yours, J. G. Ha nes Vice President.

Nuclear Production JGH/TDS/JJN/kj Attachment cc: W. F. Conway (all w/a)

D. B. Karner J. B. Hartin T. J. Polich H. J. Davis A. C. Gehr INPO Records Center R. T. Hilstead C. F. Tedford F. L. Russo T. J. Agnos R. Colson swy07 )0I )409 PDR ADOCK 8907 1 4 05000529 PDC

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4k Palo Verde Nuclear Generating Station Unit 2 Notification of Unusual Event Docket No. 50-529 License No. NPF-51 Special Report No. 2-SR-89-005 This Special Report is being provided pursuant to Emergency Plan Implementing Procedure (EPIP)-03, "Notification of Unusual Event Implementing Actions" to report the declaration of a Notification of Unusual Event (NUE) for Palo Verde Unit 2. The NUE was declared pursuant to EPIP-02, "Emergency Classification" as. a result of the initiation of a Safety Injection Actuation Signal (SIAS) on low pressurizer pressure.

On July 12, 1989 Palo Verde Unit 2 was operating at 100 percent power in Hode 1 (POMER OPERATION) when a load shed signal on 13.8 KV Bus, 2E-NAN-S02, resulted in Reactor Coolant Pumps (RCPs) 1B and 2B being deenergized. As a result of the partial loss of forced circulation, at approximately 2212 HST the reactor tripped on low DNBR which resulted in a turbine trip. Following the reactor and turbine trip, the Reactor Coolant System (RCS),pressure decreased as expected. However, additional depresurization occurred due to less than nominal decay heat and RCP heat generation, greater than nominal pressurizer spray valve leakage, and three pressurizer heaters being out of service. At approximately 2213 HST the RCS pressure decreased to the Safety Injection and Containment Isolation setpoint. The Safety Injection and, Containment Isolation Actuation resulted in the actuation of the "A" and "B" Diesel Generator Start Sequencer. All Engineered Safety Features actuated as designed.

At approximately 2223 HST on July 12, 1989, a Notification of Unusual Event (NUE) was declared. At approximately 2237 HST on July 12, 1989, the appropriate state and local agencies were notified via the Notification and Alert Network (NAN). The Nuclear Regulatory Commission (NRC) Operations Center was notified at approximately 2308 HST on July 12, 1989.

Stable conditions were achieved and the NUE was terminated at approximately 2322 HST on July 12, 1989. The event did not result in any challenges to fission product barriers or result in any releases of radioactive materials.

A Licensee Event Report will be submitted within 30 days of the event in accordance with 10CFR50.73 which will provide further details concerning the load shed from 2E-NAN-S02, the decrease of RCS pressure below the safety injection and containment isolation actuation setpoint, and the greater than nominal pressurizer spray valve leakage.