Subject: Surry Nuclear Power plant on Natural Circulation Cooldown

From: Chris in Delaware

Date: Mon, 18 Apr 2011 16:01:00 -0400

Due to tornadic activity disrupting normal off-site power, Surry Units 1 and 2 needed to rely on their Emergency Diesel Generators (EDG) to provide all emergency and normal shutdown and cool-down power requirements.

Right now

v Surry Units 1 and 2 are in the Lowest Declared Emergency, known as Unusual Event. IF the conditions degrade, THEN the next level declared is, Alert. Then, Site Emergency, then General Emergency.

v Please look at the NRC Website to see an actual Status Report. See Event Number 46761 about 2/3rd's of the way down the page. These Status Reports are REQUIRED:

http://www.nrc.gov/reading-rm/doc-collections/event-status/event/2011/20110418en.html

Power Reactor	Event Number: 46761
Facility: SURRY Region: 2 State: VA Unit: [1] [2] [ ] RX Type: [1] W-3-LP,[2] W-3-LP NRC Notified By: GEOFFREY HILL HQ OPS Officer: JOHN KNOKE	Notification Date: 04/16/2011 Notification Time: 19:24 [ET] Event Date: 04/16/2011 Event Time: 18:55 [EDT] Last Update Date: 04/16/2011
Emergency Class: UNUSUAL EVENT 10 CFR Section: 50.72(a) (1) (i) - EMERGENCY DECLARED 50.72(b)(2)(iv)(B) - RPS ACTUATION - CRITICAL 50.72(b)(3)(iv)(A) - VALID SPECIF SYS ACTUATION 50.72(b)(2)(xi) - OFFSITE NOTIFICATION	Person (Organization): VICTOR MCCREE (RA) ERIC LEEDS (NRR) KATHLEEN O'DONOHUE (R2DO) WILLIAM GOTT (IRD) ALLEN HOWE (NRR)

Unit	SCRAM Code	RX CRIT	Initial PWR	Initial RX Mode	Current PWR	Current RX Mode
1	A/R	Y	100	Power Operation	0	Hot Standby
2	A/R	Y	98	Power Operation	0	Hot Standby

Event Text

UNUSUAL EVENT DECLARED DUE TO LOSS OF ALL OFFSITE POWER FROM TORNADO DAMAGE

"At 1849 hrs, Surry Power Station (SPS) Unit 1 and Unit 2 experienced an automatic Reactor Trip from a Loss of Offsite Power, as a result of a tornado touching down in the station's switchyard. Unit 1 reactor tripped as a result of a Loss of Coolant Flow > P-8 (35% power), and the Unit 2 reactor tripped as a result of a 500 kV Leads Differential Turbine-Generator trip. Both units responded as designed.

"Unit 1 electrical power is being provided by Number 1 Emergency Diesel Generator (EDG) to the 1H emergency bus, with the Station Blackout (SBO) diesel loaded on to the 1J emergency bus. Unit 2 electrical power is being supplied by the number 2 EDG to the 2H emergency bus, with the number 3 EDG loaded on to the 2J emergency bus.

"All Unit 1 control rods inserted on the reactor trip, and all Unit 2 control rods inserted on its respective reactor trip. The Low Level Intake Structure (LLIS) is without power. All three Emergency Service Water Pumps are running to supply the intake canal. Efforts are underway to restore Bus 7, which will give each unit an emergency bus powered by offsite power (Unit 1 1J, Unit 2 2H) and restore power to the LLIS.

"Decay heat is being removed by auxiliary feedwater on both units and atmospheric steam release via the steam generator Power Operated Relief Valves (PORVs). Both units are currently on natural circulation. All other system parameters are normal and stable.

"At 1855 hrs a Notification of Unusual Event (NOUE) was declared due to a loss of offsite power (applicable to U1 and U2). Additionally, due to an estimated 100 gallon fuel oil spill from an above ground storage tank near the station's garage, the Virginia State Department of Environmental Quality was notified at 2041 and the Surry County Local Emergency Planning Coordinator was notified at 2114. At 2334, the Virginia State Department of Environmental Quality was notified and the Surry County Local Emergency Planning Coordinator was notified at 2336, due to an estimated 200 gallon oil leak to the ground from a station switchyard transformer damaged during the tornado.

"The NRC Resident Inspector has been notified and is on-site."

Notified DHS (Rickerson), FEMA (Boscoe), DOE (Turner), HHS (Hoskins), and USDA (Russell).

. See related EN #46762. To top of page !!!!! THIS EVENT HAS BEEN RETRACTED. THIS EVENT HAS BEEN RETRACTED !!!!! ..

v Fortunately the Emergency Diesel Generators started and loaded as designed. With the unusual numbers of tornados, there is a possibility that Surry can be subject to a Station Blackout (SBO), where ALL electrical power would be lost. Batteries, are only good for 8 hours in this condition, then damage will occur. This could have happened sooner:

IF a *SBO were to occur then:

* No Spent Fuel Pool Cooling would lead to Fuel Damage dependent on how Fresh the fuel is from a recent refueling outage

* No Spent Fuel Pool Ventilation would lead to hydrogen (H₂) buildup and subsequent explosion with release of fission products

* Steam Generators being Fed with the Steam Driven Auxiliary Feedwater. Pumps would have to be manually operated, by a local operator - This is feasible if there are no radiation fields present as there are in Fukushima. Turbine Driven Auxiliary Feedwater (AFW) pumps have a history of being unreliable after a period of time.

* Heat Removal without Reactor Coolant Pumps (RCPs), is by Natural Circulation, which works, but is not rapid. Further, this method requires significant amount of Makeup Water to the Steam Generators.

To do Now:

* Bring in additional Electrical Sources of power and ready the crew to hook them up to Vital Loads.

* Bring in/or Assess the Steam Generator Water Inventory and bring in replenishments if required.