Page 3 of 11 Parameter Performance Indicator Summary Overall Grade: White (Good)) System Trend: Stable Previous Report Overall Grade: White November 2006 Target Actual (based on SHMP This Report Green ) Actual Previous Report Functional Failures 0 0 0 Significant Component Failures 0 4 4 System Concerns and Risks Green Reportable Events 0 0 0 Outstanding Significant Orders 0 3 1 Deferred / Cycle Default PMS 0 0 0 Operator Workarounds 0 1 1 Outstanding Jumpers/PSCRs 0 0 0 TOEs 0 0 0 PICAs 0 4 4 RDSs 0 2 2 Predicted Future Unavailability (PFU) 1x10-3 yr/yr 6.48x10-4 yr/yr Boiler Low Level 6.29x10-4 yr/yr Boiler Low Level Actual Unavailability 0 0 0 Colour Grading Key: Excellent Good Marginal Poor
Page 4 of 11 Table of Contents 1.0 Purpose and Scope...5 1.1 Purpose...5 1.2 Scope...5 1.3 System Design Basis...5 2.0 System Health Summary...6 3.0 Detailed System Health Report...6 3.1 Performance Indicators...6 3.1.1 Functional Failures...6 3.1.2 Significant Component Failures...6 3.1.3 Reportable Events...7 3.1.4 Outstanding Significant Orders...7 3.1.5 Deferred / Cycle Default PMS...7 3.1.6 Operator Workarounds...7 3.1.7 Outstanding Jumper Records/PSCRs...7 3.1.8 Technical Operability Evaluation (TOEs)...8 3.1.9 PICAs...8 3.1.10 RDSs...9 3.1.11 Other Performance Indicators...9 3.2 Performance Trending...9 3.3 Maintenance Issues...9 3.4 Inspection Results...9 3.5 Testing Status...9 3.6 Operating Experience (OE)...9 3.7 SHM Walkdown Highlights...10 3.8 Chemistry Issues...10 3.9 Reliability Issues...10 3.10 Long Term System Health...10 3.11 Other Issues / Concerns...10 4.0 Recommendations...11
Page 5 of 11 1.1 Purpose 1.2 Scope 1.0 Purpose and Scope The purpose of this report is to document the health and performance of Shutdown System 2 (SDS2) and the Liquid Injection Shutdown System (LISS). The report documents the system performance, outstanding operability concerns, maintenance concerns, and new or outstanding design deficiencies based on the performance activities identified in the SHM Plan. The report also provides action items, in the form of recommendations, to improve system health. Monitoring Period: 2006-12-01 to 2007-04-30. This report covers the following SCIs: 68300 Shutdown System 2. 34700 Liquid Injection Shutdown System. 1.3 System Design Basis SDS2 shuts down the reactor when designated trip parameters exceed acceptable limits so as to prevent fuel failures during design-basis accidents. As such the system is designed to meet design requirements specified in the Safety System design guides and associated addenda. The system monitors for and trips under the following conditions: High neutron power. High logarithmic power rate. High or low heat transport pressure. Low heat transport differential pressure. Low heat transport pressurizer level. Low boiler (2 and 3) levels. Low boiler feedline pressure. High reactor building pressure. Critical SDS2 equipment failure (Programmable Digital Comparators - PDCs). Manual trip request. Upon detecting any trip condition (on two or more of its three channels), SDS2 must insert negative reactivity with sufficient depth and speed in order to mitigate the accident scenario. To accomplish this SDS2 triggers the LISS System. The LISS System injects a liquid neutron-absorbing poison (gadolinium nitrate greater than 300mK negative reactivity) into the moderator effectively shutting down the reactor.
Page 6 of 11 2.0 System Health Summary The overall grade for SDS2/LISS is White. The number of major component failures has not changed significantly since the last reporting period. However one of the failures involved the Programmable Digital Comparators (PDCs) as compared to no PDC failures over the previous reporting period. As such the system will not move to Green (Good) until PDC performance becomes more predictable. This is not expected to occur until the PDCs are replaced during the Refurbishment Outage. 3.0 Detailed System Health Report 3.1 Performance Indicators 3.1.1 Functional Failures 3.1.2 Significant Component Failures Four significant component failures occurred over the reporting period: On 2007-01-03, the signal for Regional Overpower (ROP) loop 6G momentarily dropped from 105 % F.P. to 89% F.P. during routine ROP calibrations. Channel G was subsequently rejected and ROP loop amplifier 68331-AF 16G replaced. Refer to Order 576091, PICA 07-0035. On 2007-01-20, the Boiler feed-line low pressure loop 68341-Loop 4H would not trip during testing. The problem was traced to a defective test circuit valve 68341-PV4H2. Channel H was rejected, the valve replaced and the loop successfully tested. Refer to Order 577977. On 2007-01-29, a watchdog trip was received on 68320-PDC-2H. The problem was traced to a failed I/O transceiver (nm629 chip) on the CPU board. The CPU board was replaced and the PDC returned to service. Refer to Order 578255, PICA 07-0539. On 2006-10-20, a spurious log rate trip was received on 68332-AF1H. The cause of the trip was not identified. However, the ion chamber loop cabling / connectors were checked and loop amplifier 68332-AF1H replaced on speculation. Refer to Order 582941, PICA 07-1771.
Page 7 of 11 3.1.3 Reportable Events 3.1.4 Outstanding Significant Orders There are three outstanding significant Orders: Order 585574 Procure replacement solenoid valves for the LISS System. There are no spare replacement solenoid valves in stock. Refer to Section 4, Item 1 Order 584762 Overhaul the actuator for LISS poison injection valve 3471-PV2J. The actuator and associated valve were removed from the 2007 Outage to due a parts shortage. The actuator will be refurbished during the 2008 Outage. Order 584763 Overhaul LISS poison injection valve 3471-PV2J. The valve was removed from the 2007 Outage to due a parts shortage. The valve is scheduled for overhaul during the 2008 Outage. 3.1.5 Deferred / Cycle Default PMS 3.1.6 Operator Workarounds Operator Workaround OWA 04-05 is outstanding regarding ineffective low flow trips on SDS2 for reactor power in the range of 53% - 80% F.P. This has resulted in the establishment of a No-Fly zone where operation in this range must be minimized due to the lack of trip coverage. During the previous reporting period Revision 4 PDC PROMs were replaced with Revision 3 PDC PROMs effectively establishing low flow trip coverage over the whole reactor power range. However the conditions for removal of the no fly zone have not been met and further work remains before the No-Fly zone can be removed. Refer to CNSC correspondence PLR: Update on Trip Coverage Design Analysis, TU File #06374. Refer to Section 4, Item 2. 3.1.7 Outstanding Jumper Records/PSCRs
Page 8 of 11 3.1.8 Technical Operability Evaluation (TOEs) No TOEs were raised for the reporting period however there is an outstanding action from one TOE previously raised on SDS2/LISS: TOE 01-21 3.1.9 PICAs The TOE was raised to evaluate the operability of 3471-V284 and V285 due to the valves not meeting code requirements. It was determined these valves were acceptable for use. However, replacement of the valves will be completed to meet code requirement. Refer to Order 503877. PICA 07-0035 The ROP signal for ROP loop 68331-Loop 6G dropped to 89% then returned to normal when the normal/calibrate handswitch was selected to calibrate. The loop amplifier was replaced, the loop tested and returned to service. Refer to Order 576091. PICA 07-0539 A watchdog trip occurred on 68320-PDC2H resulting in a Channel H trip. A defective CPU board was replaced and the PDC was returned to service. Refer to Order 578225. PICA 07-0825 The repair times for SDS2 ROP amplifiers is increasing due to ageing components. Supply of spare amplifier components is limited. The time between procurement of equivalent components and actual installation of components is long which leaves the system vulnerable due to the shortage of spare amplifiers. Refer to Section 4, Item 3. PICA 07-1771 A SDS2 Channel H trip occurred on Log rate. The log rate signal initially went irrational, then cleared 192 ms later. The loop amplifier was changed out and loop connections checked out. However the cause of the signal irrationality could not be identified. Refer to Order 582941.
Page 9 of 11 3.1.10 RDSs RDS #291 The RDS is to complete LISS piping modifications as per the LISS Water- Hammer study conducted by AECL. Work is nearly complete to document what changes have been completed to date. RDS 291 will then be closed out (projected completion date 2007-06-30) and remaining work regarding supports for small bore tubing runs will be dealt with under a new RDS. RDS status: Inactive (Priority 2.1). RDS #1953 The RDS is to review/revise design documentation to address operational requirements when the prompt fraction changes for SDS1/SDS2/RRS platinum detectors due to ageing. RDS status: Inactive (Priority 2.1). 3.1.11 Other Performance Indicators 3.2 Performance Trending 3.3 Maintenance Issues Maintaining a sufficient stock of spare ready to install ROP amplifiers continues to challenge electrical Maintenance. Some of the amplifier parts are difficult to procure due to obsolescence issues and this leads to delays in amplifier repairs. A strategy to repair or replace the amplifiers is under development. Refer to Section 4.0, Item 3. 3.4 Inspection Results 3.5 Testing Status 3.6 Operating Experience (OE)
Page 10 of 11 3.7 SHM Walkdown Highlights Percentage of required walkdowns completed during the period: 100%. 3.8 Chemistry Issues 3.9 Reliability Issues The Predicted Future Unavailability (PFU) for the reporting period is 6.48 x 10-4 yr/yr (boiler low level). 3.10 Long Term System Health The long term system health of SDS2 is contingent upon good PDC performance. There was one PDC failure over the reporting period. The failure was due to a faulty input/output transceiver on the CPU board. This type of failure is common and steps to eradicate the failure mode have included the replacement of the transceiver chips on CPU boards. However in the case of the latest CPU board failure the transceiver chip was replaced on the CPU board just last year, indicating an infantile failure of the chip. There are no plans to replace any more CPU transceiver chips. The amount of preventative maintenance on the boards is thought adequate to get the PDCs through to the Reburbishment Outage. There are enough PDC spares in stock to ensure adequate spares coverage leading to the replacement of the PDCs. The system is expected to trend green following the installation of new PDCs. Refer to Section 4.0, Item 4. 3.11 Other Issues / Concerns There are no in-stock spare LISS solenoid valves. There are four solenoid valves in service that were scheduled to be replaced over the past three annual plant outages. However, procurement of replacement LISS solenoid valves has lagged resulting in valve replacement delays. Refer to Order 585574 and Section 4.0, Item 1.
Page 11 of 11 4.0 Recommendations To address the deficiencies noted in the preceding pages, the following are the recommendations for the Shutdown System Two. Item No. 1 2 3 4 Description Expedite procurement of replacement LISS solenoid valves. Reference Section 3.1.4, 3.11. Action: Design Services - Procurement. Address any conditions preventing the removal of the No-Fly Zone and remove the No-Fly Zone. Reference Section 3.1.6. Action: Nuclear Safety / Design Services/System Performance Engineering. Identify critical spare components for Nucleonic instrumentation and procure spares. Maximize the number serviceable spare nucleonic amplifiers in the SDS2 Cold Rack. Reference Sections 3.1.9, 3.3. Action: Production Electrical / Systems Performance Engineering / Procurement Engineering. Install new PDCs during the plant Refurbishment Outage. Reference Section 3.10. Action: Systems Performance Engineering. Expected Completion Date 2007-12-31 TBD 2007-06-30 Path to Green 2008-12-31 Note: Recommendation carried over from the previous SHMR are identified by bold text.