05000261/LER-2011-001

LER-2011-001, Condition Prohibited by Technical Specifications When Non-Seismic System was Aligned to Refueling Water Storage Tank due to Regulatory Requirements not Adequately Incorporated in Plant Documentation

H. B. Robinson Steam Electric Plant, Unit No. 2
Event date:	05-04-2011
Report date:	07-05-2011
Reporting criterion:	10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications
2612011001R00 - NRC Website

10. POWER LEVEL

100%

FACILITY NAME

Rich Rogalski TELEPHONE NUMBER (Include Area Code) 843-857-1626

CAUSE SYSTEM COMPONENT

MAN U-

TO EPIX CAUSE SYSTEM COMPONENT

MANU-

14. SUPPLEMENTAL REPORT EXPECTED

• YES (If yes, complete 15. EXPECTED SUBMISSION DATE) I NO

MONTH DAY YEAR

ABSTRACT (Limit to 1400 spaces. i.e.. aooroximatelv 15 sinale-soaced typewritten lines) On May 4, 2011, with H. B. Robinson Steam Electric Plant (HBRSEP), Unit No. 2, in Mode 1 at 100% power, it was determined that over the last 40 years, HBRSEP, Unit No. 2, periodically performed cleanup of the Refueling Water Storage Tank (RWST) by aligning the non-seismically qualified refueling water purification system to the safety related and seismically qualified RWST without recognizing that the action rendered the RWST inoperable. As a result, on multiple occasions, the RWST was inoperable for a period longer than allowed by Technical Specification (TS) Limiting Condition for Operation 3.5.4, Emergency Core Cooling Systems - Refueling Water Storage Tank.

The cause of this event was that regulatory requirements for the separation of seismically qualified and non-qualified systems, structures, and components were not adequately incorporated into the Design Basis Document (DBD) and Updated Final Safety Analysis Report (UFSAR).

Administrative controls have been put in place on the alignment restrictions for piping that could affect the operability of the RWST. Additional corrective actions planned include DBD and UFSAR changes and modifications of applicable plant procedures.

The condition described in this Licensee Event Report is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B), any operation or condition which was prohibited by the plant's Technical Specifications.

I. DESCRIPTION OF EVENT

On May 4, 2011, with H. B. Robinson Steam Electric Plant (HBRSEP), Unit No. 2, in Mode 1 at 100% power, it was determined that over the last 40 years HBRSEP, Unit No. 2, periodically performed cleanup of the Refueling Water Storage Tank (RWST) [TK] by aligning the non-seismically qualified refueling water purification system [KH] to the safety related and seismically qualified RWST without recognizing that the action rendered the RWST inoperable. As a result, on multiple occasions, the RWST was inoperable for a period longer than allowed by Technical Specification (TS) Limiting Condition for Operation (LCO) 3.5.4, Emergency Core Cooling Systems — Refueling Water Storage Tank, Condition B.

TS LCO 3.5.4, Action B, requires that, with the RWST inoperable for reasons other than Condition A, restore the RWST to Operable status within 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> or be in Mode 3 within 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and Mode 5 within 36 hours4.166667e-4 days <br />0.01 hours <br />5.952381e-5 weeks <br />1.3698e-5 months <br />, in accordance with Condition C. (Condition A pertains to inoperability associated with RWST boron concentration and temperature limits.)

II. CAUSE OF EVENT

This event was investigated using the HBRSEP, Unit No. 2, Corrective Action Program (CAP) and is documented in NCR 463557.

The NCR 463557 investigation concluded that the regulatory requirements for the separation of seismically qualified and non-qualified systems, structures, and components were not adequately incorporated into the Design Basis Document and Updated Final Safety Analysis Report (UFSAR).

This is a historical condition that has existed for the life of the plant.

III. ANALYSIS OF EVENT

The HBRSEP, Unit No. 2, original plant design included a refueling water purification loop, consisting of a refueling water purification pump, filter, and demineralizer. The loop can be aligned to filter and demineralize either the spent fuel pool or the RWST. The refueling water purification loop is non- seismically qualified. It is normally isolated from the RWST by manual isolation valves which are within the seismically qualified boundary of the RWST.

As stated in the NCR 463557 investigation, for the first forty years of plant operation, HBRSEP, Unit No. 2, periodically aligned the refueling water purification loop to the RWST and operated the system to maintain the water quality of the RWST. This had been done in both on-line and outage conditions.

During the last three years, the purification loop was in service aligned to the RWST while HBRSEP, Unit No. 2, was on-line for periods of less than 1 day to as many as 161 days.

NCR 463557 was initiated in May 2011. The investigation concluded that the regulatory requirements for the separation of seismically qualified and non-qualified systems, structures, and components were not adequately incorporated into the Design Basis Document and Updated Final Safety Analysis Report (UFSAR).

IV. SAFETY SIGNIFICANCE

The risk impact of having the RWST aligned for purification has been evaluated and determined to be of low risk impact ( to a pipe break, as well as the increase in risk due to a seismic event. The result of the analysis was based on having the non-seismic refueling water purification loop in service aligned to the RWST with the plant on-line for a conservative estimate of approximately 5000 hours0.0579 days <br />1.389 hours <br />0.00827 weeks <br />0.0019 months <br /> per year. The analysis conservatively assumed that the refueling water purification path will fail and drain the RWST under a range of seismic events. Also, operator actions are conservatively not credited after a break in the purification flowpath. Even with these conservative assumptions, having the RWST in recirculation mode while the plant is at power results in a very small increase in risk due to seismic events.

The condition described in this Licensee Event Report is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B), any operation or condition which was prohibited by the plant's Technical Specifications.

V. CORRECTIVE ACTIONS

Completed Corrective Actions:

• Administrative controls have been put in place to provide guidance for Operations on alignment restrictions for piping that could affect the operability of the RWST.

Planned Corrective Actions:

• Applicable Operations procedures will be revised to restrict alignment of the refueling water purification loop to periods when RWST operability is not required.

• Applicable sections of the UFSAR and Design Basis Documentation will be revised to include restrictions on the operating modes when the purification loop is allowed to be used to purify the RWST.

VI. PREVIOUS SIMILAR EVENTS:

Licensee Event Reports (LERs) for HBRSEP, Unit No. 2, were reviewed from the past 5 years. No similar events were identified.