05000321/LER-2009-005, Licensee Event Report Inadequate Procedure Results in a Group 1 Isolation and Reactor Scram
| ML091940537 | |
| Person / Time | |
|---|---|
| Site: | Hatch  |
| Issue date: | 07/13/2009 |
| From: | Madison D Southern Nuclear Operating Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NL-09-0994 LER 09-005-00 | |
| Download: ML091940537 (4) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(iv)(A), System Actuation 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)(viii)(B) 10 CFR 50.73(a)(2)(iii) 10 CFR 50.73(a)(2)(ix)(A) 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)(v), Loss of Safety Function 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications |
| 3212009005R00 - NRC Website | |
text
Dennis R. Madison Vice President - Hatcil Southern Nuclear Operating Company, Inc.
Plant Edwin I. Hatch 11028 Hatch Parkway North Baxley, Georgia 31513 Tel 912.537.5859 Fax 912.366.2077 SOUIHERN'\\
COMPANY July 13, 2009 Docket No.:
50-321 NL-09-0994 U. S. Nuclear Regulator AnN: Document Cont Washington, D. C. 205 y Commission rol Desk 55-0001 G
Edwin I. Hatch Nuclear Plant Licensee Event Report Inadequate Procedure results in a roup 1 Isolation and Reactor Scram Ladies and Gentlemen:
In accordance with the requirements of 10 CFR 50.73(a)(2)(iv)(A), Southern Nuclear Operating Company is submitting the enclosed Licensee Event Report (LER) concerning a Group 1 isolation and reactor scram resulting from an inadequate procedure.
This letter contains no NRC commitments. If you have any questions, please advise.
Sincerely,
~~'7?)~~~
D, R. Madison Vice President - Hatch DRM/MJK/
Enclosure: LER 1-2009-005 cc:
Southern Nuclear Operatinq Company Mr. J. T. Gasser, Executive Vice President Ms. P. M. Marino, Vice President - Engineering RTYPE: CHA02.004 U. S. Nuclear Requlatorv Commission Mr. L. A. Reyes, Regional Administrator Mr. R. E. Martin, NRR Project Manager - Hatch Mr. J. A. Hickey, Senior Resident Inspector - Hatch
INRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 0813112010 9-2007)
, the NRC may not conduct or sponsor, and a person is not required to respond to, the information collection.
- 13. PAGE Edwin I. Hatch Nuclear Plant Unit 1 05000321 1 OF 3
- 4. TITLE Inadequate Procedure results in a Group 1 Isolation and Reactor Scram
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILIT1ES INVOLVED FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SEOUENTIAL REV MONTH DAY YEAR 05000 NUMBER NO.
FACILITY NAME DOCKET NUMBER 05 15 2009 2009 - 005 -
0 07 13 2009 05000
- 9. OPERATING MODE
- 11. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check aI/ that apply) o 20.2201(b) o 2O.2203(a)(3)(i) o 50.73(a)(2)(i)(C) o 50.73(a)(2)(vii) 4 o 20.2201 (d) o 2O.2203(a)(3)(ii) o 50.73(a)(2)(ii)(A) o 50.73(a)(2)(viii)(A) o 20.2203(a)(l) o 2O.2203(a)(4) o 5O.73(a)(2)(ii)(B) o 50.73(a)(2)(viii)(B) o 20.2203(a)(2)(i) o 5O.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 5O.36(c)(1 )(ii)(A) 18I 5O.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) 000 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) o 50.73(a)(2)(i)(B) o 50.73(a)(2)(v)(D)
Specify in Abstract below or in =
(If more space is required, use additional copies of NRC Form 366A)
PLANT AND SYSTEM IDENTIFICATION
General Electric - Boiling Water Reactor Energy Industry Identification System codes appear in the text as (EIIS Code XX).
DESCRIPTION OF EVENT
On May 15,2009 at 05:19 EDT. Unit I was in the cold shutdown mode to investigate problems in the nuclear instrumentation system (EIIS Code TG) that had been previously identified. At that time, a Group I isolation signal on actual low condenser vacuum (EIIS Code SG) was generated when Operations personnel moved the reactor mode switch to the run position per subsection 7.1 of special pUIpose procedure 42SP-05-] 2-09-PT-I-I. "Test of Nuclear Instrumentation Response to Diverse Logic System Actuations." Because the Main Steam Isolation Valves (EIIS Code SB). (MSIVs) were open at the time the Group I isolation signal was generated; they closed per design resulting in a reactor scram trip signal on MSIVs less than 90 percent open with the mode switch in the run position. Since the unit was in the cold shutdown condition at the time of the event, all controls rods (EIIS Code AA) were already inserted fully and therefore no rod motion occurred. However, the Main Steam Line Drain (EllS Code SB) and Reactor Water Sample Line (EllS Code CE) isolation valves also closed per design on the Group I isolation signal. Operations personnel returned the reactor mode switch to the shutdown position and reset the isolation and scram signals. Operations personnel left the MSIVs in the closed position.
CAUSE OF EVENT
The direct cause of this event was personnel error resulting in the development of an inadequate test procedure. Specifically, procedure 42SP-05-12-09-PT-I-I did not contain the necessary steps to defeat the low condenser vacuum isolation logic that is armed when the reactor mode switch is in the run position. Consequently. the MSIVs. and the Main Steam Line Drain and Reactor Water Sample Line isolation valves, closed as designed on an actual low condenser vacuum signal when the reactor mode switch was moved to the run position as directed by the test procedure. The procedure was inadequate because the engineer who drafted the procedure overlooked the low condenser vacuum Group 1 isolation logic on the plant elementary diagrams and misinterpreted the procedure review process thus not requiring a technical review of the procedure prior to issuance.
REPORTABILITY ANALYSIS AND SAFETY ASSESSMENT This event is reportable per 10 CFR 50.73(a)(2)(iv)(A) because unplanned actuations of safety feature systems listed in 10 CFR 50.73 occurred. In this instance. a Group I isolation along with a reactor protection system (Ens Code IG), (RPS) actuation resulting in a reactor scram.
The Condenser Vacuum - Low Function is provided to prevent over pressurization of the main condenser in the event of a loss of the main condenser vacuum. Since the integrity of the condenser is an assumption in offsite dose calculations, the Condenser Vacuum - Low Function is assumed to be operable and capable of initiating closure of the MSIVs. The closure of the MSIVs is initiated to PRINTED ON RECVCLED PAPER NRC FORlA 366A (!HOO7) (9-2007)
LICENSEE EVENT REPORT (LER)
CONTINUArlON SHEET U.S. NUCLEAR REGULATORY COMMISSION
- 1. FACILITY NAME 2.00CKET
- 6. LER NUMBER
- 3. PAGE Edwin 1. Hatch Nuclear Plant Unit 1 05000321 YEAR I
SEQUENTIAL IREVISION NUMBER NUMBER 3
OF 3
2009 005 a
prevent the addition of steam that would lead to additional condenser pressurization and possible rupture of the diaphragm installed to protect the turbine exhaust hood, (EllS Code TA) thereby preventing a potential radiation leakage path following an accident. Condenser vacuum pressure signals are derived from four pressure switches that sense the pressure in the condenser. Four channels of Condenser Vacuum - Low Function are available and are required to be operable to ensure that no single instrument failure can preclude the isolation function. The Allowable Value is chosen to prevent damage to the condenser due to pressurization, thereby ensuring its integrity for offsite dose analysis. As noted in the technical specifications, the channels are not required to be operable in Modes 2 and 3 when all turbine stop valves (TSVs); (EllS Code TA) are closed, since the potential for condenser over pressurization is minimized. Switches are provided to manually bypass the channels when aU TSVs are closed. This provides an isolation function for the Group I valves.
In this event, a Group 1 isolation signal was generated per design when the mode switch was moved to run with the low condenser vacuum isolation logic armed. Although an actual low condenser vacuum condition existed, the Group 1 isolation was not necessary to protect the condenser integrity. With the unit in Cold Shutdown, no steam was present to create the potential for over pressurization and thus condenser integrity could not have been challenged. However, the Group 1 isolation logic functioned as designed and would have prevented over pressurization of the condenser had it been required to do so.
Based on this analysis, it is concluded that this event had no adverse impact on nuclear safety.
CORRECTIVE ACTIONS
Engineering Support personnel reviewed and revised procedure 42SP-05-l2-09-PI-I-l to correct the error. Personnel successfully performed the corrected procedure on May 20, 2009.
The procedure drafter was coached on the importance of a thorough technical review, the proper application of human performance tools, and correct interpretation of the procedure review matrix.
ADDITIONAL INFORMATION
Other Systems Affected: None
Failed Components Information
None Commitment Information: This report does not create any new permanent licensing commitments.
Previous Similar Events
There are no similar events within the past two years in which an inadequate procedure resulted in a Group I isolation and reactor scram.
PRINTED ON RECYCLED PAPER NRC FORM 36M (~2007)