LER
Remember there are so called calibration problems in other "new" 3 stage plants. I don't think they can control the manufacturing characteristics of the components and the 3 stage are just too complex for the duty of the valves. I anticipate as theses valves aged into a plant, maybe two or three cycles...they will magically become too erratic to keep in the plant. Then they will got back to the 2 stage in an expedited manner just like Pilgrim.
The 3 stage is prone to opening according to the NRC
I going hunting for calibrated issues in other new 3 stage SRVs!!!
ABSTRACT (Limit to 7400 spaces, i.e., approximately 15 single-spaced typewritten lines) The As-Found test results for the eleven Safety/Relief Valve (S/RV) pilot assemblies removed and replaced during the 2017 Refueling Outage at James A. FitzPatrick Nuclear Power Plant (JAF) identified ten (10) S/RV pilot assemblies that lifted outside of the allowable tolerance required by Technical Specification Surveillance Requirement 3.4.3.1. Nine (9) two-stage S/RV’s were found out of tolerance high, and one three-stage was found out of tolerance low. The ten S/RV pilot assemblies are assumed to have been inoperable at some point in the operating cycle that preceded the 2017 Refueling Outage resulting in a condition reportable pursuant to 10 CFR 50.73(a)(2)(i)(B).
The S/RV design features an electric actuation capability that provides a diversified means of opening the S/RV’s despite the out of tolerance condition. However, the electric lift function is considered a backup to the mechanical S/RV’s and is not credited in the accident analysis. Therefore, the TS inoperability of the ten (10) S/RV’s also resulted in a condition reportable pursuant to 10 CFR5O.73(a)(2)(v)(D).
The cause of the two-stage failures has been identified as corrosion bonding; the cause of the three-stage failure is attributed to calibration and subsequent setpoint drift. The safety consequences associated with this event are considered low due to the electric actuation capability.
Background The ASME Boiler and Pressure Vessel Code requires the reactor pressure vessel be protected from overpressure during upset conditions by self-actuated safety valves. As part of the nuclear pressure relief system, the size and number of SIRVs are selected such that peak pressure in the Reactor Coolant Pressure Boundary (RCPB) will not exceed the ASME Code limits.
The James A. FitzPatrick Nuclear Power Plant (JAF) used ten (10) two-stage and one (1) three-stage Target Rock Safety/Relief Valves (S/RV) [EIIS Identifier: SB] for emergency pressure relief during operating Cycle 22. These valves are located on the main steam lines between the reactor vessel, and the first isolation valve within the drywell. Each S/RV discharges steam through a discharge line to a point below the minimum water level in the suppression pool.
The S/RVs can actuate by either of two modes: the safety mode or the relief mode. In safety mode (or spring mode of operation), the spring-loaded pilot valve opens when steam pressure at the valve inlet overcomes the spring force holding the pilot valve closed. Opening the pilot valve allows a pressure differential to develop across the main valve piston and opens the main valve. This satisfies the code requirement.
Each S/RV can be opened manually in the relief mode from the control room by its associated two-position switch. If one of these switches is placed in the open position the logic output will energize the associated S/RV solenoid control valve directing the pneumatic supply to open the valve. Seven of the installed S/RV solenoid control valves can also be energized by the relay logic associated with the Automatic Depressurization System (ADS).
During each refueling outage all eleven of the pilot assemblies are removed and replaced with vendor tested and certified components. The pilots that are removed are sent to a vendor facility for testing, refurbishment, and certification. The test results for pilot assemblies removed in 2017, during Refueling Outage 22, identified ten (10) S/RV pilot assemblies that were out of allowable tolerance. Nine (9) of the pilots (all two-stage) lifted at greater than the allowable setpoint range, and one (three-stage) lifted at less than the allowable setpoint range.
In order to address the concerns with corrosion bonding, JAF will commence replacement of two-stage with three-stage Target Rock S/RVs in the next Refueling Outage (RO). Industry experience has shown that the three stage S/RVs are less susceptible to corrosion bonding. The design of the three-stage S/RVs produces a greater mechanical force on opening, resulting in a greater likelihood of overcoming any potential effects of corrosion bonding that might occur.
Event Description As-Found testing was performed on all eleven main S/RV pilot assemblies removed in 2017, during R022. The testing was conducted by NWS Technologies. The TS setpoint for each S/RV is 1145 +1- 34.3. During the initial lift test, ten of the eleven pilot assemblies failed to open within the allowable range (1110.7 to 1179.3). Nine of the ten two-stage and the three-stage S/RV pilot failed high and low outside the allowable range, respectively. As-Found failed test results are tabulated below.
NRC FORM 366A (06-201 6) Page 2 of 4
NRC FORM 366A U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY 0MB: NO. 3150-0104 EXPIRES: 03131/2020 (04-2017) Estimated burden per response to comply with this mandatory collection request: 80 hours. Reported ,“ “., LICENSEE EVENT REPORT (LER) lessons learned are incorporated into the licensing process and fed back to industry. Sendcomments ‘‘‘ CONTINUATION SHEET regarding burden estimate to the FOIA, Privacy and Information Collections Branch (1-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to / lnfocoIlects.Resourcenrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means
. . .
used to impose an information collection does not display a currently valid 0MB control number, the (See NUREG-1 022, R.3 for instruction and guidance for completing this form NRC may not conduct or sponsor, and a person is not required to respond to, the informahon collechon. http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/srl 022Ir3I)
1. FACILITY NAME 2. DOCKET NUMBER 3. LER NUMBER YEAR SEQUENTIAL REV James A. FitzPatrick Nuclear Power Plant 05000 — 333 NUMBER NO. 2017 —004 —01
Table 1 — As-Found Test Results
In-service Pilot Serial First Test Acceptance Range Location Number (psig) (1110.7— 1179.3 psig)
O2RV-71A 1088 1184 Unsat—High
O2RV-71B 1080 1254 Unsat—High 02RV71C(a) 51 1103 Unsat—Low
O2RV-71E 1235 1245 Unsat—High
O2RV-71F 1195 1183 Unsat—High
O2RV-71G 1194 1202 Unsat—High
O2RV-71H 1111 1228 Unsat—High
O2RV-71J 1192 1242 Unsat—High
O2RV-71K 1193 1239 Unsat—High
O2RV-71L 1056 1214 Unsat-High (a)Three.Stage
Cause JAF has extensive internal Operating Experience with the S/RVs failing higher than the allowable setpoint. Causal evaluations identified corrosion bonding as the cause for the upward setpoint drift on the two-stage S/RVs. The As-Found test results shown above in conjunction with the successful second lift of all two-stage valves support this conclusion. Corrosion bonding is a crevice corrosion phenomenon that occurs between highly polished metals in a wetted solution in close proximity to each other. This close proximity (usually a gap of between 0.1 and 100 iJm) creates a crevice-like condition between the two wetted surfaces setting up the conditions for crevice corrosion to occur. An oxygen rich environment is created by the accumulation of oxygen in the area of the pilot disc due to the breakdown of water into hydrogen and oxygen. Susceptible material in the tight geometry with exposure to oxygen and high temperatures are the conditions which cause corrosion bonding in JAF S/RVs. There is extensive industry experience with corrosion bonding in the Target Rock two-stage S/RVs pilot assemblies.
As stated above, the three-stage S/RV pilot valve failed the As-Found testing low. Disassembly and testing was performed by NWS Technologies to determine cause. NWS concluded that the three-stage S/RV pilot was originally calibrated within the lower half of the acceptance range in the OEM specification. Calibration within the lower half of the acceptance range resulted in a greater setpoint drift, which ultimately resulted in the S/RV pilot being outside the allowable range.
“
“i., LICENSEE EVENT REPORT (LER) lessons learned are incorporated into the licensing process and fed back to industry. Sendcomments ‘*, CONTINUATION SHEET regarding burden estimate to the FOIA, Privacy and Information Collections Branch (T-5 F53), U.S. Nuclear Regulatory Commission, Washington, DC 20555-0001, or by e-mail to lnfocolIects.Resourcenrc.gov, and to the Desk Officer, Office of Information and Regulatory Affairs, ** NEOB-10202, (3150-0104), Office of Management and Budget, Washington, DC 20503. If a means
. .
used to impose an information collection does not display a currently valid 0MB control number, the (See NUREG-1 022, R.3 for instruction and guidance for completing this form NRC may not conduct or sponsor, and a person is not required to respond to, the information collection. http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1022/r3/)
1. FACILITY NAME 2. DOCKET NUMBER 3. LER NUMBER YEAR SEQUENTIAL REV James A. FitzPatrick Nuclear Power Plant 05000 — 333 NUMBER NO. 2017 —004 —01
External
• Edwin I. Hatch Nuclear Plant, Unit 1: LER-16-004 “Safety Relief Valves As Found Not Meeting Tech Spec Surveillance Criteria,” May 26, 2016 • Edwin I. Hatch Nuclear Plant, Unit 2: LER-08-004 “Safety Relief Valves Allowable Exceeded Due to Setpoint Drift,” August 12, 2008
Corrective Actions Future Corrective Actions • Commence replacement of S/RVs with redesigned three-stage (R023) Previous Corrective Actions • Installed Stellite 21 discs in all eleven S/RV pilot assemblies during refurbishment at the vendor facility • Installed the S/RV Electric Lift System recommended by the Boiling Water Reactor Owner’s Group • Installed enhanced insulation on the S/RVs
Safety Significance Nuclear Safety Actual Consequences There were no actual consequences to the general safety of the public, nuclear safety, industrial safety, or radiological safety associated with this event.
Potential Consequences The potential consequences of this event are associated with the over-pressurization of the Reactor Coolant Pressure Boundary. The S/RVs provide overpressure protection for the Reactor Coolant Pressure Boundary as required by the ASME Boiler and Pressure Vessel Code. Events similar to the one reported herein may be significant if design limits are challenged. The potential consequences of this event are considered low based on the operation and availability of the Electric Lift System.
Radiological Safety There was no radiological safety impact associated with this event.
Industrial Safety There was no industrial safety impact associated with this event.
References • Issue Report No. 04077124, R22 SRV As-Found Testing Failures • Issue Report No. 04082823, R22 3-Stage SRV As-Found Testing Failure • JAF Technical Specifications
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