05000311/LER-2002-002
| Salem Generating Station Unit 2 | |
| Event date: | 04-20-2002 |
|---|---|
| Report date: | 06-19-2002 |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(i) |
| 3112002002R00 - NRC Website | |
FACILITY NAME (1)
DOCKET
LER NUMBER (6)
PLANT AND SYSTEM IDENTIFICATION
Westinghouse — Pressurized Water Reactor Containment Building Ventilation System {VA}* * Energy Industry Identification System {EDS} codes and component function identifier codes appear as {SS/CCC}
IDENTIFICATION OF OCCURRENCE
Event Date: April 20, 2002 Discovery Date: April 20, 2002
CONDITIONS PRIOR TO OCCURRENCE
The plant was in MODE 6 (REFUELING) at the time of discovery. No other structures, systems or components were inoperable at the start of this event that contributed to the event.
DESCRIPTION OF OCCURRENCE
On April 20, 2002, PSEG Nuclear discovered that the instrument loop for the containment differential pressure indicator contained additional 250 ohm resistors at the inputs to one of the containment differential pressure alarm modules. The effect of the additional resistors was to cause the indicated differential pressure to be one half of the actual differential pressure. Resistors were removed and all loop components were verified to operate properly.
TS 3.6.1.4 requires that primary containment internal pressure be maintained between -1.5 and +0.3 psig in MODES 1, 2, 3 and 4. Normal operating practice is to reduce containment pressure by manual operation of the Pressure-Vacuum Relief System when pressure exceeds the containment high pressure alarm setpoint (0.2 psig). The effect of the additional resistor was to cause the high pressure alarm module to actuate at 0.4 psig actual containment pressure (0.2 psig indicated).
If containment pressure exceeds 0.3 psig, TS 3.6.1.4 requires that the internal pressure be restored to within the limits within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or that the plant be in at least HOT STANDBY within the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br />.
PSEG Nuclear believes Salem Unit 2 operated with containment pressure greater than 0.3 psig for times greater than permitted by TS 3.6.1.4 during periods from May 1999 until April 2002.
Since this condition existed for longer than the time permitted by TS 3.6.1.4, it is reportable as a condition prohibited by plant Technical Specifications in accordance with 10 CFR 50.73(a)(2)(i)(B).
FACILITY NAME (1)
DOCKET
Salem Generating Station Unit 2 05000311 YEAR
CAUSE OF OCCURRENCE
This event resulted from the installation of an incorrect part as an equivalent replacement for an obsolete differential pressure alarm module {VA/PDA}. Configuration documents called for a 1-5 VDC alarm module with an external 250 ohm resistor to generate the required voltage from the 4-20 mADC current in the instrument loops for containment internal and external pressure. Instead, an alarm module with internal resistors that responded directly to the 4-20 mADC signals was installed. The net result was that the alarm module and the external resistors split the available loop current causing the alarm modules and control room indicator to read only one half of the signals.
The equivalency evaluation and procurement documentation called for a 1-5VDC input for the replacement module, but, as a result of discussion with the vendor (Rochester Instrument Systems), the procurement documentation also referenced a vendor part number for a module with a 4-20 mADC input. The vendor supplied a module with a 4-20 mADC input which was subsequently installed.
PREVIOUS OCCURRENCES
A review of reportable events identified no instances within the last two years involving conditions prohibited by Technical Specifications due to less than adequate procurement documentation.
SAFETY CONSEQUENCES AND IMPLICATIONS
There were no safety consequences associated with this event. The containment differential pressure indicator is non-safety related. It is separate from the protective and engineered safety feature instrumentation systems, and the OPERABILITY of these systems was unaffected. The small increase in containment pressure during normal operation would have negligible impact on the current containment pressure response results for the postulated large break LOCA or main steam line break.
The effect of this condition on release calculations would not have caused any limits in the Salem Offsite Dose Calculation Manual to be exceeded.
This event does not constitute a Safety System Functional Failure (SSFF) as defined in NEI 99-02.
CORRECTIVE ACTIONS
1. Resistors were removed and all loop components were verified to operate properly.
2. The Unit 1 containment differential pressure instrumentation loop was verified to be configured correctly.
3. Release calculations and the Annual Radioactive Effluent Release Report will be revised as required.
FACILITY NAME (1)
DOCKET
Salem Generating Station Unit 2 05000311 CORRECTIVE ACTIONS (continued) 4. The 4-20 mADC alarm module currently installed will be replaced and the Unit 2 instrument loop will be returned to the design configuration.
5. Procurement documentation will be revised to include a new part number corresponding to a 1- 5VDC alarm module.
6. Process failures associated with this event are being evaluated in accordance with PSEG Nuclear's corrective action program.
COMMITMENTS
Corrective action 3 is a regulatory commitment. There are no other NRC commitment items contained in this LER.