05000456/LER-2012-003, Fuel Handling Incident Area Radiation Monitors Inoperable Due to Incorrect Alarm Setpoint
| ML12215A350 | |
| Person / Time | |
|---|---|
| Site: | Braidwood  |
| Issue date: | 08/02/2012 |
| From: | Enright D Exelon Generation Co |
| To: | Office of Nuclear Reactor Regulation, Document Control Desk |
| References | |
| BW120078 LER 12-003-00 | |
| Download: ML12215A350 (5) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i) 10 CFR 50.73(a)(2)(vii), Common Cause Inoperability 10 CFR 50.73(a)(2)(ii)(A), Seriously Degraded 10 CFR 50.73(a)(2)(viii)(A) 10 CFR 50.73(a)(2)(ii)(B), Unanalyzed Condition 10 CFR 50.73(a)(2)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 10 CFR 50.73(a)(2)(iv)(A), System Actuation 10 CFR 50.73(a)(2)(x) 10 CFR 50.73(a)(2)(v)(A), Loss of Safety Function - Shutdown the Reactor 10 CFR 50.73(a)(2)(v)(B), Loss of Safety Function - Remove Residual Heat 10 CFR 50.73(a)(2)(i)(A), Completion of TS Shutdown 10 CFR 50.73(a)(2)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 4562012003R00 - NRC Website | |
text
Exelon Generation Company, LLC Braidwood Station 35100 South Route 53, Suite 84 Braceville,IL 60407-9619 August2,2012 BW120078 www.exeloncorp.com 10 CFR 50.73 U. S. Nuclear Regulatory Commission ATTN: Document Control Desk Washington, DC 20555-0001 Braidwood Station, Units 1 and 2 Facility Operating License Nos, NPF-72 and NPF-77 NRC Docket Nos. STN 50-456 and STN 50-457
Subject:
Licensee Event Report 2012-003 Fuel Handling Incident Area Radiation Monitors Inoperable Due to Incorrect Alarm Setpoints The enclosed Licensee Event Report (LER) is being submitted in accordance with 10 CFR 50.73, "Licensee Event Report System."
There are no regulatory commitments contained in this letter. Should you have any questions concerning this submittal, please contact Mr. Chris VanDenburgh, Regulatory Assurance Manager, at (815) 417-2800.
Respectfully, Daniel J. Enright Site Vice IJro,cirlont Braidwood Station
Enclosure:
LER 2012-003-00 cc: NRR Project Manager - Braidwood Station Illinois Emergency Management Agency - Division of Nuclear Safety US NRC Regional Administrator, Region III US NRC Senior Resident Inspector (Braidwood Station)
Illinois Emergency Management Agency - Braidwood Representative
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 10/31/2013 (10-2010)
, the NRC may digits/characters for each block) not conduct or sponsor, and a person is not reqUired to respond to, the information collection.
- 13. PAGE Braidwood Station, Unit 1 05000456 1 of 4
- 4. TITLE Fuel Handling Incident Area Radiation Monitors Inoperable Due to Incorrect Alarm Setpoints
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED YEAR ISEQUENTIALIREV FACILITY NAME DOCKET NUMBER MONTH DAY YEAR NUMBER NO.
MONTH DAY YEAR Braidwood Station, Unit 2 05000457 FACILITY NAME DOCKET NUMBER 06 03 2012 2012. 003.
00 08 02 2012 N/A N/A
- 19. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR §: (Check all that apply) 1 o 20.2201 (b) o 20.2203(a)(3)(i) o 50.73(a)(2)(i)(C) o 50.73(a)(2)(vii) o 20.2201 (d) o 20.2203(a)(3)(ii) o 50.73(a)(2)(ii)(A) o 50.73(a)(2)(viii)(A) o 20.2203(a)(1) o 20.2203(a)(4) o 50.73(a)(2)(ii)(B) o 50.73(a)(2)(viii)(B) o 20.2203(a)(2)(i) o 50.36(c)(1)(i)(A) o 50.73(a)(2)(iii) o 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL o 20.2203(a)(2)(ii) o 50.36(c)(1 )(ii)(A) o 50.73(a)(2)(iv)(A) o 50.73(a)(2)(x) o 20.2203(a)(2)(iii) o 50.36(c)(2) o 50.73(a)(2)(v)(A) o 73.71(a)(4) 099 o 20.2203(a)(2)(iv) o 50.46(a)(3)(ii) o 50.73(a)(2)(v)(B) o 73.71(a)(5) o 20.2203(a)(2)(v) o 50.73(a)(2)(i)(A) o 50.73(a)(2)(v)(C) o OTHER o 20.2203(a)(2)(vi) r8I 50.73(a)(2)(i)(B) o 50.73(a)(2)(v)(D)
Specify in Abstract below or in 2012 003 00 For the period of June 1 - 3, 2012, the setpoint for 1AR012J was incorrect for a time period greater than allowed by TS. A review of the previous three years was performed, which included a review of reactor power history, setpoint change documentation, and instrument reading for 1/2AR011J and 1/2AR012J. This review identified additional occurrences where the setpoints of one or both monitors were above required values. Additionally, operator logs were reviewed to determine whether a containment purge occurred (the purge valves were in service and open) during those time periods:
1.
Unit 1, June 1 - 3, 2012 (this event) -1AR012J monitor only. No containment purge occurred; 2.
Unit 1, December 15, 2011 - both monitors. Containment purge occurred during this time frame; 3.
Unit 1, September 3, 2011, during response to an unplanned power change - both monitors. No containment purge occurred; 4.
Unit 1, July 13 - 14, 2011, during response to an unplanned power change - both monitors. No containment purge occurred; and 5.
Unit 2, from October 24,2010, through January 24,2011 - both monitors. Containment purge occurred during this time frame.
No occurrences were identified during refueling activities in containment.
This event is reportable in accordance with 10 CFR 50.73(a)(2)(i)(B), any operation or condition which is prohibited by the plant's Technical Specifications.
B.
Cause of Event
The root causes of this event were determined to be:
1.
Contrary to procedure, Operations used the incorrect procedure attachment and did not validate the need to adjust 1AR012J setpoint.
The procedure for 1/2AR011J and 1/2AR012J setpoint changes contains a series of attachments for different plant operating modes. One attachment is for Mode 1-4 power changes. Another attachment is for setpoint changes once the unit has reached 100 percent reactor power. For this event, Unit 1 reached 100 percent reactor power on May 26, 2012.
On both May 30, 2012 and June 1, 2012, setpoint adjustments on 1AR011 J and 1AR012J were performed.
The attachment for Mode 1-4 power changes (the incorrect attachment) was used by Operations for the adjustment. The senior reactor operator did not review the procedure or validate that the attachment provided was the correct attachment for the current mode. In addition, on June 1, 2012, the operators did not validate the need to adjust 1AR012J, which had not demonstrated a trend increase similar to 1AR011J. The radiation monitors, 1/2AR011J and 1/2AR012J, normally track together, but because of a materiel condition deficiency associated with 1AR011J, 1AR012J was not alarming and had a much more linear track to the radiation levels.
Operations did not check the background radiation levels or the 1AR012J readings prior to performing the setpoint adjustment to both 1AR011 J and 1AR012J. Following completion of the setpoint adjustment, the new setpoint was outside the 10 mR/hr required per the TRM and was non-conservative.
2.
There is no procedural guidance or alarm response guidance that checks if the1/2AR011J or 1/2AR012J monitors have operable setpoints.
The existing design of the plant does not have an alarm when the containment radiation deviates from setpoint by greater than 10mR/hr. If procedure guidance existed that triggered monitoring the background radiation to check for operability limits, then there would be a higher probability of recognizing when 1/2AR011J and 1/2AR012J monitors are inoperable.
O.
Safety Consequences
2012 003 00 This condition had no actual safety consequences impacting plant or public safety. Braidwood did not experience an event where a containment ventilation isolation was required but would not have actuated due to an incorrect setpoint.
The fuel handling incident area radiation monitors 1/2AR011J and 1/2AR012J ensure containment isolation dependability by satisfying the requirements of NUREG-0800 and NUREG-0737.
TS 3.3.6 and TRM 3.3.p, provide insight to the allowable setpoints for the 1/2AR011J and 1/2AR012J monitors.
Specifically, TS Table 3.3.6-1, Note (b) states "...Trip setpoint shall be established such that actual submersion dose rate is <10 mR/hr in the Containment Building. The trip setpoint may be increased above this value in accordance with the methodology established in the Offsite Dose Calculation Manual." TRM Table T3.3.p-1, Note (b) states "...For containment purge or vent the setpoint value may be increased up to twice the maximum concentration activity in the containment determined by the sample analysis performed prior to each release in accordance with the Offsite Dose Calculation Manual (ODCM) provided the value is S 10% of the equivalent limits with the Noble gases to s 500 mrem/yr to the whole body and to S 3000 mrem/yr to the skin."
The containment atmosphere radioactivity, in order to contribute 10% of the ODCM limit for off-site dose, would indicate apprOXimately 640 mR/hr on the 1/2AR011J and 1/2AR012J monitors. This dose rate is higher than the 1/2AR011J and 1/2AR012J setpoints during the last three years (all setpoints were less than 200mRlhr, including refuel outage evolutions). Additionally, the effluent monitor setpoints for the low range noble gas detectors (1/2PR28J) are set at 1% of the ODCM limit for alert alarm and 10% of the ODCM limit for high alarm. These monitors would provide an indication to Operations that effluents are approaching the ODCM limits.
The maximum identified setpoints established for 1/2AR011J and 1/2AR012J during the period evaluated in this report was determined to be less than the 640 mrem/hr derived during the 10% ODCM calculation discussed above. Using the methods established in the ODCM, the 1/2AR011J and 1/2AR012J monitors would have provided a containment isolation signal prior to containment radiation levels reaching a level that challenged the established limits. Therefore, there was no loss of safety function from this event.
~.
Corrective Actions
Corrective actions to prevent recurrence:
Coach the personnel responsible for the setpoint adjustments of 1AR012J (this action is complete).
Revise procedures to include guidance to trigger implementing setpoint changes for 1/2AR011J and 1/2AR012J.
Previous Occurrences
No previous, similar Licensee Event Reports were identified at the Braidwood Station.
G. Component Failure Data
Manufacturer N/ANomenclature N/A Model N/A Mfg. Part Number N/A