ML19326B757
| ML19326B757 | |
| Person / Time | |
|---|---|
| Site: | Arkansas Nuclear  |
| Issue date: | 01/21/1974 |
| From: | ARKANSAS POWER & LIGHT CO. |
| To: | |
| Shared Package | |
| ML19326B722 | List: |
| References | |
| NUDOCS 8004170585 | |
| Download: ML19326B757 (1) | |
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Ltr. Phillips to Knuth
- V January 21, 1974 REACTOR BUILDING DUC'NORK DESIGN DEFICIENCY t
Description of Deficiency A review of the Reactor Building Ductwork design revealed that the plenum and supply ducts consisting of a portion of the Engineered Safeguard Reactor Building Cooling System may not be able to withstand the differen-tial pressures resulting from the rapid pressure buildup during a loss of coolant ace.ident. Generally, the prescac relief valve arrangement and relieving characteristics of these valves do not assure a properly low pressure differential compatible to the structural capacity of the ducts.
Analysis of the Safety Implications
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The deficiency described above may result in collapsing portions of the ducts during a loss of coolant accident. Damage to the ducts does not necessarily mean that a complete break-down in the operation of Engineered
( Safeguard Reactor Building Cooling System will occur.
The system may con-tinue to operate through the distorted ducts. However, efficiency of the system will be effected due to the decreased air supply.
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The cooling capacity of the system will be below the values given in the FSAR.
Corrective Action Taken The correction of this deficiency is either improving the relieving capac.ity of the system and thus decreasing the pressure differential or increasing the capacity of the ducts'by structural changes. Generally, it is more practical to reinforce the duct for the actual pressure differential and the design is progressing on this basis.
Information Detailed re-design is under way but has not yet been completed. The design is based on the LOCA pressure build-up rate, on the relieving capacity of the valves and volumes corresponding to the actual valve arrangement. These parameters establish the actual pressure differential on each location of the duct. The system is re-checked for this pressure and angle stiffness will be added where necessary. The checking and design of additional stiff-i ness will be completed by January 21, 1974. Construction schedule will be worked out based on the completed design and will be reported later.
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