NRC NEWS U. S. NUCLEAR REGULATORY COMMISSION

 Office of Public Affairs Region IV 

 611 Ryan Plaza Drive - Suite 400

 Arlington, TX 76011-4005

No. IV-07-023 June 21, 2007

Contact: Victor Dricks E-Mail: opa4@nrc.gov

Phone: 817-860-8128

NRC ISSUES CONFIRMATORY ACTION LETTER 

 ON PALO VERDE NUCLEAR PLANT

The Nuclear Regulatory Commission staff has issued a Confirmatory Action Letter

(CAL) to Arizona Public Service Co. confirming the company’s commitments regarding actions

it will take to improve performance at the Palo Verde Nuclear Generating Station. APS operates

the plant located in Wintersburg, Ariz.

“Palo Verde is being operated safely, but performance improvements are needed,” NRC

Region IV Administrator Bruce S. Mallett said. “We intend to hold APS accountable to perform

a thorough evaluation of the causes of the performance problems at Palo Verde and to complete 

actions to correct them. The letter will serve as a roadmap for performance improvement.”

The letter confirms commitments the company has made to the NRC to:

1. Complete actions to address root and contributing causes identified in its evaluations

in response to performance problems associated with the voided containment sump suction

piping for all three units, and associated with the Unit 3 emergency diesel generator electrical

relay problems, including:

• Ineffective resolution of emerging technical issues, including thoroughness

of technical evaluations and troubleshooting

• Failure to routinely question the validity of engineering assumptions used

to support operability decisions for degraded equipment 

• Lack of consistently notifying operations personnel of immediate

operability concerns

• Inadequate performance monitoring measures necessary to fully assess the

effectiveness of the corrective actions.
2. Complete corrective actions that result in measurable improvement in the crosscutting

areas of human performance and problem identification and resolution. Specific areas to

address are:

• Palo Verde operability determination process; timeliness and thoroughness

for evaluations of conditions/significant conditions adverse to quality; and

engineering quality. 

3. Complete an independent (third party) safety culture assessment by September 15.

4. Incorporate the results of their in-depth evaluations and safety culture assessments

into a modified improvement plan. 

5. Submit to the NRC portions of the modified improvement plans that impact the

Reactor Safety strategic performance area, including safety culture improvement

initiatives by November 30.

Issuance of the CAL does not preclude subsequent issuance of an order formalizing the

commitments requiring other actions on the part of the company.

Palo Verde has been under increased NRC oversight since the fourth quarter of 2004

following a finding for a substantial safety issue. Inspectors found that APS had incorrectly left

air pockets in portions of the emergency core cooling system for each reactor that could have

hindered the system’s operation during certain types of accidents. The finding remains open

because APS has not effectively addressed performance problems. 

Those problems include a lack of questioning attitude, lack of technical rigor and poor

operability determinations by workers - factors which contributed to a more recent finding issued

by the NRC for problems with a emergency diesel generator at Unit 3, moving Palo Verde into a

higher level of NRC oversight.

Two substantive cross-cutting issues in the areas of human performance and problem

identification and resolution have also remained open since the NRC’s 2004 end-of-cycle

assessment. Palo Verde has also had numerous operational challenges since 2004, including

multiple reactor trips and unplanned shutdowns.

##

NRC news releases are available through a free list serve subscription at the following Web address: 

http://www.nrc.gov/public-involve/listserver.html . The NRC homepage at www.nrc.gov also offers a SUBSCRIBE

link. E-mail notifications are sent to subscribers when news releases are posted to NRC's Web site.