"Nuclear facility" means:

a. Any "nuclear reactor";

b. Any equipment or device designed or used for (1) separating the isotopes of uranium or plutonium, (2) processing or utilizing "spent fuel", or (3) handling, processing or packaging "waste";

c. Any equipment or device used for the processing, fabricating or alloying of "special nuclear material" if at any time the total amount of such material in the custody of the "insured" at the premises where such equipment or device is located consists of or contains more than 25 grams of plutonium or uranium 233 or any combination thereof, or more than 250 grams of uranium 235;

d. Any structure, basin, excavation, premises or place prepared or, used for the storage or disposal of "waste"; and includes the site on which any of the foregoing is located, all operations conducted on such site and all premises used for such operations;

"Nuclear reactor" means any apparatus designed or used to sustain nuclear fission in a self-supporting chain reaction or to contain a critical mass of fissionable material;

"Property damage" includes all forms of radioactive contamination of property.

This endorsement, issued by one of the below named companies, forms a part of the policy to which attached, effective on the inception date of the policy unless otherwise stated herein.

(The information below is required only when this endorsement is issued subsequent to preparation of policy.)

| Endorsement Effective | Policy No. | Endorsement No. |
|-----------------------|------------|-----------------|
| Insured                |            |                 |
| Additional Premium $   | Return Premium $ | In Advance $     | BI | PD |
|                        |            | 1st Anniv. $    | $  | $  |
|                        |            | 2nd Anniv. $    | $  | $  |

The Aetna Casualty and Surety Company

Hartford, Connecticut

Countersigned by _________Authorized Representative_______

XN13218 (11-91)

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