Headquarters Daily report OCTOBER 06, 1994 *************************************************************************** REPORT NEGATIVE NO INPUT ATTACHED INPUT RECEIVED RECEIVED HEADQUARTERS X REGION I X REGION II X REGION III X REGION IV X *************************************************************************** PRIORITY ATTENTION REQUIRED MORNING REPORT - REGION OCTOBER 6, 1994 MR Number: H-94-0092 NRR DAILY REPORT ITEM SIGNIFICANT EVENTS EVENTS ASSESSMENT BRANCH DIVISION OF OPERATING REACTOR SUPPORT Subject: Common Mode Failure of Safety-Related Ventilation Systems The NRR/AEOD Events Assessment Panel on September 27, 1994, classified the inoperability of ESF ventilation systems at Waterford 3 as a Significant Event for the NRC Performance Indicator Program. The classification was based on programmatic deficiencies in design, post modification testing, and surveillance testing. Waterford has four different ESF ventilation systems that are used to filter radioactive material from the air during an accident. Each of the ventilation systems has two independent trains consisting of heaters, HEPA filters, charcoal, and an exhaust fan. The ventilation heaters are utilized to reduce humidity and ensure filter efficiency. To prevent spurious trips, the licensee installed new controllers in all the ESF ventilation systems between October 1992 and April 1993. Due to an engineering oversight, the new controller would fail high and trip the heaters on a loss of offsite power (LOOP). When power is restored, the high temperature heater trip with a 0.5 second time delay times out before the controller registers actual temperatures. Additionally, after the heaters trip, the ESF ventilation fans will operate for only 400 seconds before they trip unless the heaters are reset. The post modification tests did not identify this deficiency because the test did not introduce a LOOP condition. On March 16, 1994, the licensee performed an integrated Safety Injection Actuation Signal (SIAS) testing with a concurrent LOOP for the train B EDG. The train B Shield Building Ventilation System and Controlled Ventilation Area System were load shed and started as required, but tripped inappropriately after 400 seconds. On April 4, 1994, the same test was performed on the A EDG train with similar results. No followup action was taken. On May 3, 1994, the system engineer, after being informally informed about the test anomaly, discussed this issue with design engineering personnel and discovered the response time problem. The licensee increased the heater trip time delay to 2.0 seconds. This would allow enough time for the controller to reenergize and regain control. During the set point change, the licensee determined that the Control Room Air Conditioning System (CRACS) time delays were not in the preventive maintenance program. As found delay times for the A and B trains of CRACS were 4.67 and 3.21 seconds, respectively. The licensee concluded that these systems would have remained operable following a LOOP. Therefore, three of the four ESF ventilation systems were inoperable from the time the design change was installed until May 1994. The fourth system, CRACS, was operable only because timer relays had been inadvertently left out of the preventive maintenance program and had drifted out of specification. The licensee conservatively calculated that operator exposure to reset the heaters would be less than 7 rem under worst case conditions. An escalated enforcement action was taken and assessed a civil penalty of $112,500 to the licensee for violations of technical specifications and deficiencies in design and testing. Since these failures primarily affect post-accident doses, and do not contribute to a core damage, a PRA analysis of the increment to core damage frequency was not applicable. CONTACT: John R. Tappert, NRR/DOPS/OECB (301) 504-1167 PRIORITY ATTENTION REQUIRED MORNING REPORT - REGION II OCTOBER 6, 1994 Licensee/Facility: Notification: Carolina Power & Light Co. MR Number: 2-94-0084 Brunswick 1 2 Date: 10/06/94 Southport,North Carolina Dockets: 50-325,50-324 BWR/GE-4,BWR/GE-4 Subject: MEETING WITH LOCAL PUBLIC OFFICIALS Reportable Event Number: N/A Discussion: On October 5, 1994, a licensee meeting was held at the Brunswick Nuclear Plant Visitors Center with the local public officials in preparation for their November 1, 1994, Emergency Preparedness Drill. The new NRC Senior Resident Inspector and the Region II State Liaison Officer attended the meeting. Regional Action: None Contact: J. STAREFOS (404)331-5568