Under management of ...

Management (or managing) is the administration of an organization, whether it be a business, a not-for-profit organization, or government body. Management includes the activities of setting the strategy of an organization and coordinating the efforts of its employees or volunteers to accomplish its objectives through the application of available resources, such as financial, natural, technological, and human resources. The term "management" may also refer to the people who manage an organization.

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Note added at 1 hr (2017-07-31 06:48:43 GMT)
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The implementaion of which has been/is managed by Atomic ...

outsourced by Atomic Energy Organization

Or

... project implemented with Atomic Energy Organization as the employer.

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Note added at 1 hr (2017-07-31 06:51:54 GMT)
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The best I offer is:

.... was outsourced by the Atomic Energy Organization as the employer.