ANTECEDENTS
The Hungarian Atomic Energy Authority ordered CBF corrective actions to be taken. The decision prescribes that ‘Appropriate, independently operated (e.g. from the other water and power supply systems of the nuclear power plant) emergency diesel generators provided with protection against external hazards (earthquake, extreme weather conditions and flooding) have to be installed at the Paks Nuclear Power Plant.’

INITIAL CONDITION
The design area is located at the junction of road T and road V-2 on the power plant site. Currently, it is covered by grass and ornamental trees are planted in it. On its west side, it is delimited by an asphalt paved road leading to building No. 1003.

There are underground operational utilities in the area:

• DN 500 supply cooling water pipe: (01VD90)
• A pair of heating pipes in an underground reinforced concrete duct: 01UB1902 (73UN36Z100), 01UB2002 (73UN37Z100)
• Drinking water pipes: 00UK108 (00UK132Z100), 00UK022133 (00UK33Z102), 00UJ303 (73UJ161)
• Sanitary sewers: 00UL10503 (00Ul227100)
• Storm sewers: CSUL163 (00UU79Z144), CSUL164561 (00UU80Z107)
• Communications substructures
• 0.4 kV underground cable
• 6 kV underground cable
• Area light poles and underground cable
• Dosimetry pipe

REASON FOR, AND JUSTIFIABILITY AND PURPOSE OF, MODIFICATION
On the basis of the CBF corrective actions, the design basis of the diesel generator had to be specified in such a way that:

• it should be able to supply power to all necessary consumers in every accident situation where the total loss of power supply to the site has to be reckoned with;
• the simultaneous involvement of more than one unit (even all units) in the accident has to be assumed;
• the cooling demand of the reactor and the spent fuel pool has to be taken into account;
• they have to be available even in the case of loads exceeding the design basis of the currently installed emergency diesel generators;
• the accident diesel generator is able to perform its task in the long run (e.g. beyond the operating period of the installed emergency diesel generators).
• In addition to implementing the CBF corrective actions, establishment of the replaceability of the existing emergency diesel generators for maintenance purposes.

Taking into account the foregoing, MVM Paksi Atomerőmű Zrt. plans to carry out the following tasks:

• procurement, installation and placing into service of one accident diesel generator with a power output of minimum 4 MW;
• establishment of a new diesel engine room;
• installation and placing into service of a new accident diesel generating station and electrical connections between Units 1 to 4.

We continued the development of the concepts outlined in the Feasibility Study serving as a basis for the design work, and used the parts found to be suitable for technical design.

BASIC DESIGN DATA
Surveying
The area was surveyed and a design base map was prepared by FTV Zrt.

Az base map is prepared in the system of MVM Paksi Atomerőmű Zrt. The elevation data relate to the base elevation set at the Baltic Sea level.

Basic utility data

The Principal, MVM ERBE Zrt., supplied the utility data obtained from the register of MVM Paksi Atomerőmű Zrt. with the consolidated utility plan serving as a basis for design and the layout of the installation site.

DESCRIPTION OF THE PROPOSED TECHNICAL SOLUTION
Connection of utilities relating to the building of the proposed accident diesel generator with a replacement function.

• Storm sewer (00UU79, 00UU80)
• Sanitary sewer (00UL22)
• Drinking water pipe (00UK32)
• Communications substructures
• Protection systems
• Irrigation water branch
• A pair of underground district heating pipes (73UN36, 73UN37)
• Demineralised water pipe (00RV50)

Stormwater drainage
Storm water runoff from the proposed building and the proposed oil unloading station (any possible oily storm water is passed through a Bárczy oil filter) may be connected to a closed gravity storm sewer located near the site.

Sewerage
Sewage from the proposed building is drained via a new gravity branch to an existing gravity sewer on the north side of the building (00UL22Z100).

Drinking water pipe
The proposed drinking water pipe (00UK32) is connected, as a new branch, to an existing pipe on the north side of the building (00UK32Z100).

Fire water pipe
It is not necessary to establish a new fire hydrant and a fire water pipe in the yard area because of the fire protection of the proposed building. The firewater hydrants existing in the yard area around the new building are satisfactory, water to the wall-mounted fire hydrant network within the building will be supplied from the drinking water system.

Irrigation water
One branch is constructed from the new water main for the purposes of an underground irrigation tap on the north side of the building.

District heating
New district heating pipelines (73UN37, 73UN36) will run parallel to road No. V-2, within the inner protection fence (yellow), branching off from the district heating pipelines located 12.5 m from the fence. The proposed pair of pipelines crosses road No. V-2 perpendicularly and is connected to the building after running underground parallel to the ramp.

Demineralised water
The proposed demineralised water pipeline is an existing pipeline (01WP08) within the inner protection fence (yellow) 16 m from the fence. After running underground under road No. V-2, it will be connected to the proposed building in its existing manhole, with a branch-off point provided with a gate valve.