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Russians use new tools to diagnose reactor problems

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May 24, 1996 Share This!

RICHLAND, Wash. — Symptom-based Emergency Operating Instructions, which were implemented to improve safety in U.S. nuclear power plants following the Three Mile Island accident, have been adopted recently by a facility in Russia.

The Novovoronezh Nuclear Power Plant, 480 kilometers (300 miles) south of Moscow, was the first plant to begin development of symptom-based EOIs in the former Soviet Union and is the first to implement them. "The EOIs are in use, with the operators trained and the procedures now in the control room," says Plant Manager Vyachealav Vikin.

The Department of Energy's International Nuclear Safety Program is supporting safety improvement projects -- including EOI development -- at Soviet-designed nuclear power plants in Russia, Ukraine, Bulgaria, the Czech Republic, Hungary, Lithuania, Slovakia and Armenia. In the United States, the technical lead for INSP is the Pacific Northwest National Laboratory in Richland, Wash.

Symptom-based EOIs, now in use at all U.S. nuclear power plants, focus on the "symptoms" of abnormal operations -- such as the loss of coolant and rupture of steam generator tubes -- and specify operator actions based on the symptoms. This approach, which improves the accuracy of decision making, enables operators to first stabilize the plant, then determine the cause of the problem. The procedures are more effective in cases where the specific cause is not apparent, or in the case of multiple causes.

At Novovoronezh, the implementation of 22 symptom-based EOIs at Unit 3 was completed on March 20 following approval by Rosenergoatom -- the operating organization for nuclear power plants in Russia. The development of the EOIs was led by Novovoronezh, with support from VNIIAES, the Russian technical institute for nuclear power plant operations. Ten additional EOIs are being developed for implementation later this year.

Prior to the adoption of symptom-based procedures, Unit 3 personnel relied on "event-based" instructions during abnormal or emergency operating situations. Event-based EOIs require plant operators first to identify the cause of the problem, then take specified corrective actions.

EOI development began at Novovoronezh in 1990, four years after the devastating accident at Chornobyl. Concerned about the safety of Soviet-designed reactors, the United States approached the then-Soviet Union with an offer to provide technical assistance for safety improvements. DOE asked the Institute of Nuclear Power Operations to lead the effort at Novovoronezh. INPO and U.S. utility experts described and demonstrated the U.S. methodology, which the plant experts adapted to develop their own EOIs.

In addition to the collaboration on EOIs, improvements have been made in management and operational controls procedures at Novovoronezh, including control room logkeeping and work control processes. Also, the staffing level of the control room was increased to include an additional person to serve as a shift technical assistant. This provides increased technical capability in the control room.

There are five pressurized water reactors at the Novovoronezh site, but only three -- Units 3, 4 and 5 -- are in operation. In the future, site officials plan to use the information gained from Unit 3 to develop new EOIs for Units 4 and 5.


Tags: Energy, Operations, Nuclear Power

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