05000499/LER-2005-002, Regarding Essential Chiller 22C Inoperable Longer than Allowed by Technical Specifications
| ML051230363 | |
| Person / Time | |
|---|---|
| Site: | South Texas  |
| Issue date: | 04/27/2005 |
| From: | Parkey G South Texas |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| NOC-AE-05001868 LER 05-002-00 | |
| Download: ML051230363 (6) | |
| Event date: | |
|---|---|
| Report date: | |
| Reporting criterion: | 10 CFR 50.73(a)(2)(i)(B), Prohibited by Technical Specifications 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)(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 |
| 4992005002R00 - NRC Website | |
text
Nuclear Operating Company South Teas Pirvle Ekltric Generating Station 00. Bar 282 fsdilrrnnh r7as 77483 April 27, 2005 NOC-AE-05001868 1 OCFR50.73 U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 South Texas Project Unit 2 Docket No. STN 50-499 Licensee Event Report 2005-02 Essential Chiller 22C Inoperable Longer Than Allowed By Technical Specifications Pursuant to 1 OCFR50.73(a)(2)(i)(B), the STP Nuclear Operating Company submits the attached Licensee Event Report 2005-02 regarding the inoperability of Essential Chiller 22C for a time period longer than allowed by Technical Specifications.
This event did not have an adverse effect on the health and safety of the public.
There are no commitments contained in this event report. Resulting corrective actions will be implemented in accordance with the Corrective Action Program.
If there are any questions regarding this submittal, please contact S. M. Head at (361) 972-7136 or me at (361) 972-7800.
G. L. Parkey Vice President, Generation and Plant General Manager wem/
Attachment: LER 2005-02 STI: 31872604
NOC-AE-05001 868 Page 2 of 2 cc:
(paper copy)
(electronic copy)
Bruce S. Mallett Regional Administrator, Region IV U. S. Nuclear Regulatory Commission 611 Ryan Plaza Drive, Suite 400 Arlington, Texas 76011-8064 U. S. Nuclear Regulatory Commission Attention: Document Control Desk One White Flint North 11555 Rockville Pike Rockville, MD 20852 Richard A. Ratliff Bureau of Radiation Control Texas Department of State Health Services 1100 West 49th Street Austin, TX 78756-3189 Jeffrey Cruz U. S. Nuclear Regulatory Commission P. O.'Box 289, Mail Code: MN116 Wadsworth, TX 77483 A. H. Gutterman, Esquire Morgan, Lewis & Bockius LLP David H. Jaffe U. S. Nuclear Regulatory Commission Jack A. Fusco Michael A. Reed Texas Genco, LP C. A. Johnson AEP Texas Central Company C. Kirksey City of Austin Jon C. Wood Cox Smith Matthews J. J. Nesrsta R. K. Temple E. Alarcon City Public Service C. M. Canady City of Austin Electric Utility Department 721 Barton Springs Road Austin, TX 78704
NRC FORM 366 U.S. NUCLEAR REGULATORY COMMISSION APPROVED BY OMB: NO. 3150-0104 EXPIRES: 06/3012007
,6-2004)
, the NRC may digits/characters for each block) not conduct or sponsor, and a person Is not required to respond to, the Information collection.
- 73. PAGE South Texas Project Unit 2 05000 499 1 OF 4
- 4. TITLE Essential Chiller 22C Inoperable Longer Than Allowed By Technical Specifications
- 5. EVENT DATE
- 6. LER NUMBER
- 7. REPORT DATE
- 8. OTHER FACILITIES INVOLVED
_ FACILITY NAME DOCKET NUMBER MONTH DAY YEAR YEAR SEQUENTIAL REV MONTH DAY YEAR NUMBER NO.I________________________
_FACILITY NAME DOCKET NUMBER 2
28 2005 2005 -
02 -
00 4
27 2005
- 9. OPERATING MODE 1 1. THIS REPORT IS SUBMITTED PURSUANT TO THE REQUIREMENTS OF 10 CFR§: (Check all that apply)
O 20.2201(b)
El 20.2203(a)(3)(i)
El 50.73(a)(2)(i)(C) al 50.73(a)(2)(vii)
Cl 20.2201(d) 0 20.2203(a)(3)(ii) 0 50.73(a)(2)(ii)(A)
[I 50.73(a)(2)(viii)(A)
El 20.2203(a)(1)
El 20.2203(a)(4)
El 50.. 73(a)(2)(ii)(B)
El 50.73(a)(2)(viii)(B)
[__ 20.2203(a)(2)(i)
El 50.36(c)(1)(i)(A)
El 50.73(a)(2)(iii) l0 50.73(a)(2)(ix)(A)
- 10. POWER LEVEL E
20.2203(a)(2)(ii)
El 50.36(c)(1)(ii)(A)
El 50.73(a)(2)(iv)(A)
El 50.73(a)(2)(x)
El 20.2203(a)(2)(iii)
El 50.36(c)(2)
El 50.73(a)(2)(v)(A)
El 73.71(a)(4)
El 20.2203(a)(2)(iv)
El 50.46(a)(3)(ii) al 50.73(a)(2)(v)(B)
El 73.71(a)(5) 100 El 20.2203(a)(2)(v)
El 50.73(a)(2)(i)(A)
El 50.73(a)(2)(v)(C)
[I OTHER El 20.2203(a)(2)(vi) 0 50.73(a)(2)(i)(B)
El 50.73(a)(2)(v)(D)
Specify in Abstract below or in SUMMARY OF THE EVENT, INCLUDING DATES AND APPROXIMATE TIMES When an Essential Chilled Water loop is secured, a corresponding temperature increase and consequent volume expansion results. This will raise the level in the expansion tank, causing alarms.
Draining the tank back into the normal band below the alarm set point is the usual action taken. This resets the alarm and allows future level alarms to remain valid. Draining to restore normal level and clear the alarm is not directed by procedure. It is considered good operating practice to keep alarms cleared so that system status can be properly monitored.
The Essential Chilled Water expansion tanks are not located at the highest point in the system.
Nitrogen is used to maintain a minimum system pressure to keep the piping system normally full and to prevent air in-leakage. In the case of "C" train, the highest point in the system is at elevation 78' and the normal level of the expansion tank is at approximately 30' elevation. A difference of 48' of head or approximately 21 psig must be maintained on the expansion tank to prevent a vacuum from forming at the 78' elevation when the pump is secured.
Following the securing of Essential Chiller 22C at 1318 on 2/16/05, three "Chilled Water Expansion Tank HI/LO" alarms were received in the control room. The alarms prompted at least three draining evolutions of the Essential Chilled Water Expansion tank "C" to clear the "Hi Level" alarm. These draining evolutions occurred over a three-day period and were performed by three different shift crews.
The nitrogen supply to Essential Chilled Water was isolated on 2/19/05 at 1451 to repair a nitrogen leak in the system. The maintenance activity on the nitrogen system was completed and nitrogen was restored at approximately 0136 on 2/20/05. This resulted in the chilled water expansion tanks going without a nitrogen supply for approximately 11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br />. Unknown to the Operations staff, the relief valve on the "C' train Essential Chilled Water expansion tank was leaking by the seat, resulting in a loss of the overpressure on the tank.
During the period of the nitrogen outage, a "Chilled Water Expansion Tank "HI/LO" alarm was received in the control room several times. In all cases, a Plant Operator was dispatched to check the level in the Essential Chilled Water "C" expansion tank. The Plant Operator was then instructed to "restore level to the normal band".
The Plant Operator drained the tank to restore level to the normal band in the usual manner. The Plant Operator construed the directions to mean, "maintain level in the normal band" and continued to monitor the tank level for some time after that. The Plant Operator subsequently drained water from the tank
.3 (If more space is required, use additional copies of (If more space is required, use additional copies of log and the individual watchstation log.
- 4.
Cover this event (associated LER) in Licensed Operator Requalification (LOR & POR) Training.
- 5. Include this event (associated LER) in the Essential Chilled Water lesson plan for initial Licensed and Non-Licensed Operator training programs.
- 6. Verify the repair of the leaking safety valve.
VI.
PREVIOUS SIMILAR EVENTS
There have been no similar events at STP within the last 3 years.
VII.
ADDITIONAL INFORMATION
Engineering will determine proper tank operating level to prevent "normal alarms" from occurring during periods of idle train conditions. Normal expansion should not routinely result in alarms prompting operator action.