05000247/LER-2001-005

LER-2001-005,

Docket Number
Event date:
Report date:
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
2472001005R00 - NRC Website

FACILITY NAME (1)

DOCKET

(1 SEQUENT REVISI IAL � ON LER NUMBER6)

PLANT AND SYSTEM IDENTIFICATION

Westinghouse 4-Loop Pressurized Water Reactor

EVENT IDENTIFICATION

Non-compliance with Overpressure Protection System Technical Specification

EVENT DATE

October 23, 2001

REFERENCES

Condition Reporting System Number(s): 200110152, 200105283, 200104833, 200004598

EVENT DESCRIPTION

While performing an engineering review of instrumentation setpoints associated with the Overpressure Protection System (OPS) [EIIS:JC], it was determined that there were past occasions during which Indian Point Unit 2 may have operated in a condition prohibited by the plant's Technical Specifications. At the time, plant personnel were unaware of these non-compliant conditions because it was believed that the OPS requirements were being met. The OPS is designed to relieve the Reactor Coolant System (RCS) [EIIS:AB] pressure for certain overpressure transients when RCS temperature is less than or equal to 305F to prevent these incidents from causing the peak RCS pressure to exceed 10 CFR 50, Appendix G limits. At the time of this discovery, the plant was operating at 100 percent power. The OPS is not required to be operable when RCS temperature is greater than 305F. Indian Point Unit 2 Technical Specification 3.1.A.4 specifies the requirements for the OPS. Furthermore Technical Specification Figures 3.1.A-2 and 3.1.A-3 define operational restrictions (pressurizer pressure, pressurizer level, and RCS temperature), which must be met if OPS is unavailable.

FACILITY NAME (1)

SEQUENT REVISI

IAL � ON Engineering review has concluded that on past occasions, OPS operational restrictions may not have been satisfied if allowance for instrument uncertainties are conservatively assumed. The root cause for this condition is human performance-related, and is attributed to inadequate implementation of procedural requirements associated with the OPS license amendment. A contributing factor was an inadequate review of this concern, as identified in NRC Information Notice 93-58, "Nonconservatism In Low-Temperature Overpressure Protection For Pressurized-Water Reactors." Subsequent procedural changes were implemented to account for the appropriate OPS instrument uncertainties.

EVENT ANALYSIS

The OPS is provided to relieve RCS pressure for certain overpressure transients when RCS temperature is less than or equal to 305F to prevent these incidents from causing the peak RCS pressure to exceed 10 CFR 50, Appendix G limits. The system uses the pressurizer power operated relief valves (PORVs) to accomplish the pressure reduction.

When the OPS is "armed," the PORVs will open upon receipt of the appropriate signal, and arming is accomplished either automatically by the OPS when the RCS is below a prescribed temperature or manually by the operator. The OPS is set to cause the PORVs to open at a pressure sufficiently low to prevent exceeding the Appendix G limits. OPS is not required to be operable at or below 305F if either, operating restrictions for pressurizer pressure, pressurizer level, and RCS temperature (Technical Specification Figures 3.1.A-2, and 3.1.A-3) are met, or an adequate vent path is provided. As noted on Figures 3.1.A-2 and 3.1.A-3, no allowance for instrument error is factored into the curves, which differentiate the acceptable and unacceptable areas of operation. Plant Operating Procedures (POP) 1.1, "Plant Restoration From Cold Shutdown To Hot Shutdown Conditions," and 3.3, "Plant Cooldown," specify the control room instrumentation to be used to determine RCS temperature, pressure, and pressurizer level. However, no information was previously identified in these procedures to enable operators to compensate for instrument uncertainties.

Summarized below are those periods (within the past three years) during which OPS had been declared inoperable, and RCS parameters maintained within the acceptable area of Figure 3.1.A-2. However, if allowance for instrument uncertainties is assumed, RCS parameters may have been marginally unacceptable.

11/30/00 - 12/1/00 During this period the plant was in cold shutdown for an extended outage with OPS declared inoperable. RCS parameters were being maintained in accordance with Figure 3.1.A-2.

FACILITY NAME (1)

DOCKET

(1 SEQUENT REVISI

IAL I ON

PAGE (3 ) LER NUMBER6) 8/3/00 - 8/4/00 Within this period the plant was in cold shutdown, and OPS had been declared inoperable to perform surveillance testing. RCS parameters were being maintained in accordance with Figure 3.1.A-2.

7/2/00 - 7/3/00 Within this period the plant was in cold shutdown, and OPS had been declared inoperable to perform surveillance testing. RCS parameters were being maintained in accordance with Figure 3.1.A-2.

2/16/00 - 2/17/00 OPS was declared inoperable due to plant conditions following recovery from a steam generator tube leak. RCS parameters were being maintained in accordance with Figure 3.1.A-2.

With the exception of the OPS, there were no structures, systems, or components that were inoperable and contributed to these past non- compliance conditions. The discovery of these conditions was not attributed to any personnel injury, radiation exposure, offsite dose release, or damage to equipment important to safety.

EVENT SAFETY SIGNIFICANCE

This report is being made pursuant to 10 CFR 50.73(a)(2)(i)(B), which requires that "Any operation or condition which was prohibited by the plant's Technical Specification except when 1) The Technical Specification is administrative in nature; 2) The event consisted solely of a case of a late surveillance test where the oversight was corrected, the test was performed, and the equipment was found to be capable of performing its specified safety functions; or 3) The Technical Specification was revised prior to discovery of the event such that the operation or condition was no longer prohibited at the time of discovery of the event.

All of the potential non-compliant conditions were discovered while performing an engineering review of instrumentation setpoints associated with the OPS. At the time of the potential non-compliances, plant personnel believed that the OPS requirements were being met. For those periods during which RCS parameters were determined to have been marginally unacceptable per Figure 3.1.A-2, the reactor coolant pumps, safety injection pumps, charging pumps, and pressurizer heaters were not operated, or decay heat removal was being accomplished by the Residual Heat Removal system. Since the RCS was never subjected to any overpressure transients that would have exceeded 10 CFR 50, Appendix G limits, this event has been determined to be of minimal safety significance.

FACILITY NAME (1)

DOCKET

IAL � ON

CORRECTIVE ACTION

The corrective action resulting from this event was to revise Plant Operating Procedures 1.1 and 3.3 to include the necessary allowances for instrument uncertainties. Technical Specification OPS operational restrictions will ultimately be controlled in the Pressure Temperature Limit Report (PTLR) when the conversion to the Improved Technical Specification (ITS) is completed. The ITS submittal is expected to be ready for the NRC's review during first quarter of 2002.

PREVIOUS OCCURRENCES

A review of previous occurrences that involved the same underlying concern or reason as this event was performed. One event associated with an OPS Technical Specification non-compliance was reported by LER 97-014-00. One of the corrective actions associated with this prior event was to, "Evaluate and revise other Technical Specification figures as required to provide clearer information to users." Our intent has been and remains to accomplish this in the ongoing Improved Technical Specification Project.