Decontamination of Distributed Control System at nuclear powerplant in China

CASE PROFILE / Cause of Incident
Fire was caused by an electric fault that took place in a batteries room inside the power plant. The DCS room, which was located next to a batteries room, was affected by the soot (smoke), that made its way into the cabinet through the ventilation gaps at the bottom of the cabinet.

Immediate Actions Taken:
The customer requested BELFOR to carry out an inspection and make appropriate loss mitigation recommendations.

ELECTRIC FAULT CAUSED FIRE

Preliminary Assessment:

• Quick test and laboratory analysis of the samples
  indicated a high level of contamination.
• The result are within IPC standard of 1.56 μg/cm² NaCl.
• Relative humidity is at 61% at the time of the inspection.
• Once the relative humidity is above 40%, the likelihood
  of onset of corrosion to metallic surfaces increases
  significantly.

Mitigation Recommendations:

• Decontamination work to be carried out immediately.

Loss Mitigation Measures:

• BELFOR technicians carried out the decontamination activities of 13 electrical server cabinets, 43 wiring cabinets, 66 TXS system cabinets and 5,000 PCBs and modules in the cabinets.
• Although the most effective method of decontamination was a two-step aqueous process, the customer opted for a one-step dry decontamination process. The twostep aqueous process required many levels of approval which would require more time to obtain.
• BELFOR mobilized manpower resources and equipment.
• Five air scrubbers, anti-static vacuum cleaners, dry ice blasting, ionized air gun and other anti-static tools were set up and used during decontamination work.
• All electronic modules were dismounted from the racks before decontamination work to avoid electrostatic damage.

Benefits of BELFOR Recovery Services

• Recovery Duration: 25 days | Replacement Timeframe (est.): 12 months
• Significant BI reduction of 11 months
• Recovery Price: USD$298,000 | Replacement Price (est.): USD$3,700,000
• Considerable cost savings of USD$3,400,000
• Customer quickly recovered operation with BELFOR’s recovery service. It effectively reduced the time to resume operation and the losses caused by the interruption to the operation.