NRC NEWS

U.S. NUCLEAR REGULATORY COMMISSION

Office of Public Affairs Region III

2443 Warrenville Road

Lisle IL 60532

Site: www.nrc.gov

Blog: http://public-blog.nrc-gateway.gov

No. III-11-036

Contact: Viktoria Mitlyng (630) 829-9662

 Prema Chandrathil (630) 829-9663

December, 2 2011

E-Mail: OPA3.RegionIII@nrc.gov 

NRC CONCLUDES DAVIS-BESSE NUCLEAR PLANT SAFE TO RESTART AND 

ISSUES CONFIRMATORY ACTION LETTER

The U.S. Nuclear Regulatory Commission has determined that the operators of the DavisBesse nuclear power plant, FirstEnergy Nuclear Operating Corp. (FENOC) have provided 

reasonable assurance that the shield building is capable of performing its safety functions and 

that the utility can proceed with restarting the plant. The NRC’s independent assessment 

evaluated a wide range of information such as technical details ranging from the size of the 

cracks, the utility’s sampling and testing of the concrete in the building to determine the extent of 

the cracks, and its structural analysis. The plant is located in Oak Harbor, Ohio about 40 miles 

southeast of Toledo.

The NRC will hold a public meeting in which FENOC will discuss their technical 

analysis and explain why the plant is safe to continue to operate with the cracks in the shield 

building. The meeting will take place in the near future with details to be issued once finalized.

However, the NRC has issued a Confirmatory Action Letter (CAL-attached) to the 

operator of the plant, FENOC. The CAL details and confirms FENOC’s agreement to take 

certain actions to monitor and ensure the cracks in the shield building continue to not adversely 

impact safety going forward. The NRC will review and evaluate FENOC’s actions in response 

to the CAL in order to make sure they are thorough and complete. 

The FENOC commitments to the NRC include:

- Determine and provide the root cause of the cracks in the shield building, corrective 

actions, and develop a long-term monitoring program.

- Select multiple areas in the shield building that have no cracks but are adjacent to 

known cracks to determine whether the area of the cracks has spread.

- Perform additional analysis in known cracked areas to determine whether the width of 

the cracks has increased.
Even though the NRC has concluded the shield building can perform its safety functions, 

the NRC will continue to inspect whether the shield building in its current condition meets all 

design requirements in the plant’s license. 

Failure to meet the commitments in the CAL may result in additional regulatory action if 

the utility does not provide reasonable assurance that the NRC can rely on the FENOC to meet 

the NRC’s requirements and protect public health and safety.

On Oct. 10 the NRC was informed by FENOC that while conducting work to replace the 

Davis-Besse reactor vessel head its workers identified cracks in the shield building. The shield 

building is a 2.5 foot thick reinforced concrete building that surrounds a 1.5 inch thick steel 

containment vessel that encloses the reactor. The two buildings are separated by a 4.5 foot 

space. 

The NRC will issue an inspection report documenting its review of this issue and the 

agency’s conclusions 45 days after the inspection is complete.

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UNITED STATES

NUCLEAR REGULATORY COMMISSION

REGION III

2443 WARRENVILLE ROAD, SUITE 210

LISLE, IL 60532-4352

December 2, 2011

CAL No. 3-11-001

Mr. Barry Allen

Site Vice President

FirstEnergy Nuclear Operating Company

Davis-Besse Nuclear Power Station

5501 North State Route 2, Mail Stop A-DB-3080

Oak Harbor, OH 43449-9760

SUBJECT: CONFIRMATORY ACTION LETTER - DAVIS-BESSE NUCLEAR

POWER STATION

Dear Mr. Allen:

This letter confirms commitments by FirstEnergy Nuclear Operating Company (FENOC) 

regarding the identification of cracks in the reinforced concrete shield building at the 

Davis-Besse Nuclear Power Station. During the recent mid-cycle outage to replace the reactor 

vessel closure head, which began on October 1, 2011, FENOC discovered laminar cracking in 

the safety-related shield building of the containment system while performing hydrodemolition 

operations. Based on an evaluation of FENOC’s extent of condition and technical analysis of 

the Davis-Besse shield building laminar cracking, the NRC staff concluded that FENOC

provided reasonable assurance that the shield building is capable of performing its safety 

functions. In order to provide continued long-term confidence, FENOC has agreed in telephone 

conversations between you, Steven West, and Steven Reynolds, on November 21, 2011; a 

followup telephone conversation between you and Jamnes Cameron on November 22, 2011; in 

a FENOC commitment letter dated November 23, 2011 (ML11329A033); and a telephone 

conversation between you and Steven Reynolds on December 2, 2011, to the following actions

(both completed and planned):

1. FENOC will provide the results of the root cause evaluation and corrective actions to the 

NRC, including any long-term monitoring requirements, by February 28, 2012.

2. FENOC will identify four shield building locations, which were core bored during this 

evaluation, for examination. These uncracked locations will be directly adjacent to 

locations that have been confirmed to be cracked. The four uncracked locations, as 

designated on FENOC drawing C-111A, are: 

a. adjacent to a flute shoulder [S9-666.0-12];

b. in a flute area [F4-1-666.0-3];

c. adjacent to Main Steam Line penetration 39 [S7-652.0-6.5]; and

d. adjacent to Main Steam Line penetration 40 [S9-650.0-9].
B. Allen -2-

3. FENOC will examine the four core bore locations from Commitment 2 above with a 

borescope to verify cracking has not migrated to these core bores located in solid 

(i.e., uncracked) concrete, within 90 days following plant restart (Mode 2) from the 

2011 mid-cycle outage.

4. FENOC will examine the crack interface to identify any changes by performing a core 

bore in a known crack area within the Main Steam Line Room, within 90 days following 

plant restart (Mode 2) from the October 2011 mid-cycle outage.

5. FENOC will identify two additional shield building locations, which were core bored 

during this evaluation, for examination. These uncracked locations will be directly 

adjacent to locations that have been confirmed to be cracked. The two uncracked 

locations, as designated on FENOC drawing C-111A, are: 

a. in a flute area [F5-777.0-4]; and

b. adjacent to a flute shoulder [S2-783.5-4.0].

6. FENOC will examine the four core bore locations from Commitment 2 along with the 

two core bore locations from Commitment 5 with a borescope to verify cracking has 

not migrated to these core bores located in solid (i.e., uncracked) concrete, during the 

seventeenth refueling outage currently scheduled to commence in 2012.

7. FENOC will examine the crack interface to identify any changes by examining either 

existing core bore locations with known cracks, or by performing a core bore in a similar 

area:

a. adjacent to a flute shoulder [S9-666.0-11];

b. near the top of the shield building [S9-785-22.5]; and

c. adjacent to Main Steam Line penetration [core bore from Commitment 4].

during the seventeenth refueling outage currently scheduled to commence in 2012.

Pursuant to Section 182 of the Atomic Energy Act, 42 U.S.C. 2232, you are required to:

1) Notify me immediately if your understanding differs from that set forth above;

2) Notify me if for any reason you cannot complete the actions and commitments within the 

specified schedule and advise me in writing of your modified schedule in advance of the 

change; and 

3) Notify me in writing when you have completed the actions and commitments addressed 

in this Confirmatory Action Letter.

Issuance of this Confirmatory Action Letter does not preclude issuance of an Order formalizing 

the above commitments or requiring other actions on the part of FENOC, nor does it