05000286/LER-2009-008, Technical Specification Prohibited Condition Due to Exceeding the Allowed Completion Time for an Inoperable Over Power Delta Temperature (Opdt) Bistable
| ML093440136 | |
| Person / Time | |
|---|---|
| Site: | Indian Point  |
| Issue date: | 12/02/2009 |
| From: | Joseph E Pollock Entergy Nuclear Operations |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-09-154 LER 09-008-00 | |
| Download: ML093440136 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(1), Submit an LER, Invalid Actuation 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 10 CFR 50.73(a)(2)(v), Loss of Safety Function |
| 2862009008R00 - NRC Website | |
text
-Entergy Indian Point Energy Center 450 Broadway, GSB P.O. Box 249 Buchanan, N.Y. 10511-0249 Tel (914) 734-6700 J. E. Pollock Site Vice President NL-09-154 December 2, 2009 U.S. Nuclear Regulatory Commission Attn: Document Control Desk Mail Stop O-P1-17 Washington, D.C. 20555-0001
SUBJECT:
Licensee Event Report # 2009-008-00, "Technical Specification Prohibited Condition Due to Exceeding the Allowed Completion Time for an Inoperable Over Power Delta Temperature (OPDT) Bistable" Indian Point Unit No. 3 Docket No. 50-286 DPR-64
Dear Sir or Madam:
Pursuant to 10 CFR 50.73(a)(1), Entergy Nuclear Operations Inc. (ENO) hereby provides Licensee Event Report (LER) 2009-008-00. The attached LER identifies an event where there was a Technical Specification prohibited condition for an inoperable Over Power delta Temperature (OPDT) bistable during past operation, which is reportable under 10 CFR 50.73(a)(2)(i)(B). This condition was recorded in the Entergy Corrective Action Program as Condition Report CR-IP3-2009-03817.
There are no new commitments identified in this letter. Should you have any questions regarding this submittal, please contact Mr. Robert Walpole, Manager, Licensing at (914) 734-6710.
Sincerely, JEP/cbr cc:
Mr. Samuel J Collins, Regional Administrator, NRC Region I NRC Resident Inspector's Office, Indian Point 3 Mr. Paul Eddy, New York State Public Service Commission LEREvents@lNPO.org I fLA
Abstract
On September 17, 2009, during performance of surveillance 3-PT-Q87D (Channel Functional Test of Reactor Coolant Temperature Channel 441) bistable 3TC-441C/D As-Found test readings were identified as out of specification for the Over Power Delta Temperature (OPDT) reactor trip function.
The bistable was adjusted in accordance with the procedure and all readings were left in specification.
Aný assessment of the condition determined that bistable 3TC-441C/D had been found out of specification on the previous quarterly surveillance on June 26, 2009.
Technical Specification 3.3.1 (Reactor Protection Instrumentation),
Table 3.3.1-1, Function 6 has an Allowable Value per Note 2 of 1.8% of delta Temperature span, which for bistable TC-441C/D correlates to a 0.144 Volts DC (Vdc) deviation from the nominal value.
The OPDT Trip test criteria is 6.60 (6.56 to 6.64)
Vdc.
The As-Found OPDT value was 6.86 Vdc which exceeded the TS allowed value.
On October 6, 2009, engineering concluded the second failure can not be assumed to have occurred at the time of discovery and represented an inoperable condition during past operation.
The apparent cause was a discrepancy between the maintenance and test equipment (M&TE) output and reference value seen by the bistable.
The discrepancy can be attributed to a deficiency with the test points used to input the reference value.
The failure mechanism was concluded to have been a faulty reference value that was sensed by the bistable.
The OPDT bistable (3TC-441C/D) was replaced.
Surveillance procedures 3-PT-Q87 A through D where revised to require recording voltages that are inputted into the instrument loop.
Troubleshooting will be performed on the bistable circuit for possible test point deficiencies.
The event had no effect on public health and safety.
(If more space is required, use additional copies of (If more space is required, use additional copies of NRC Form 366A) (17)
There was no safety system functional failure reportable under 10CFR50.73(a) (2) (v) as the OPDT function has four channels arranged in a two out of four logic configuration where the trip of two channels results in a OPDT trip.
Any of the remaining two operable channels would have generated the-trip signal to satisfy the safety function.
In accordance with reporting guidance in NUREG-1022, an additional random single failure need not be assumed in that system during the condition.
PAST SIMILAR EVENTS A review was performed of the past three years of Licensee Event Reports (LERs) for events that involved a TS violation due to a safeguards actuation device degrading and exceeding its TS limit.
LER-2009-005 reported a 480 volt bus undervoltage relay drifting and exceeding its TS value twice in addition to previous drifting outside its calibration limits.
The test results for this event provided evidence that the relay drifted outside its calibration acceptance criteria and therefore was inoperable during past operation.
The condition of inoperability exceeded the TS allowed completion time.
The cause of the condition reported in LER-2009-005 was personnel error due to inadequate knowledge of the drift monitoring program and component drift performance.
The CAs of the event reported in LER-2009-005 would not have prevented this event as the causes were different.
SAFETY SIGNIFICANCE
This event had no effect on the health and safety of the public.
There were no actual safety consequences for the event because there have been no conditions during past operation during the time the bistable exceed its TS limit requiring the actuation of OPDT or Rod Stop.
During this time period the unit had two RTs: one RT on August 10, 2009, due to a turbine generator trip as a result of a lightning induced generator lockout relay trip, and one RT on August 27,
- 2009, due to a turbine autostop oil trip.
The RPS monitors parameters related to safe operation and trips the reactor to protect the reactor core against fuel rod cladding damage caused by departure from nucleate boiling (DNB) and to protect against reactor coolant system (RCS) damage caused by high system pressure.
The RPS automatically trips the reactor under the following primary system conditions: 1) reactor power, as measured by neutron flux, reaches a pre-set limit, 2) temperature rise across the core, as determined from RCS loop differential temperature (DT),
reaches a limit either from OPDT set point or an overtemperature DT (OTDT) setpoint,
- 3) pressurizer pressure reaches an established minimum limit, 4) loss of reactor coolant flow as sensed by low flow, loss of pump power or pump breaker opening, 5) pressurizer pressure or level trip the reactor to protect the primary coolant boundary when pressurizer pressure or level reaches an established maximum limit.
The OPDT function is part of the RPS to initiate a RT.
The RPS is designed on a channelized basis to achieve separation between redundant protection channels.
The OPDT trip prevents power density, anywhere in the core, from exceeding 118% of design power density and prevents fuel pellet melting.
The OPDT function has four channels arranged in a two out of four logic configuration where the trip of two channels results in an OPDT trip.
Any of the remaining two operable channels would have generated the trip signal to satisfy the safety function.
The OPDT actuation logic is designed to withstand an input failure to the control system, which may require the protection function actuation, and a single failure in the remaining channels providing the protection function actuation.