05000413/LER-2003-006, Regarding 1B Containment Spray System Inoperable for Longer than Technical Specifications Allow Due to Heat Exchanger Baffle Plate Degradation
| ML033500337 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 12/08/2003 |
| From: | Jamil D Duke Power Co |
| To: | Document Control Desk, Office of Nuclear Reactor Regulation |
| References | |
| LER 03-006-00 | |
| Download: ML033500337 (14) | |
| Event date: | |
|---|---|
| Report date: | |
| 4132003006R00 - NRC Website | |
text
P Duke c Powere A Duke Energy Company D.M. JAMIL Vice President Duke Power Catawba Nuclear Station 4800 Concord Rd. / CNOI VP York, SC 29745-9635 803 831 4251 803 831 3221 fax December 8, 2003 U. S. Nuclear Regulatory Commission ATTENTION:
Document Control Desk Washington, DC 20555-0001
SUBJECT:
Duke Energy Corporation Catawba Nuclear Station Unit 1 Docket Nos. 50-413 Licensee Event Report 413/03-006 Revision 0 1B Containment Spray System Inoperable for Longer than Technical Specifications Allow Due to Heat Exchanger Baffle Plate Degradation Attached please find Licensee Event Report 413/03-006 Revision 0, entitled "lB Containment Spray System Inoperable for Longer than Technical Specifications Allow Due to Heat Exchanger Baffle Plate Degradation."
This Licensee Event Report does not contain any regulatory
commitments
This event is considered to be of no significance with respect to the health and safety of the public.
Questions regarding this Licensee Event Report should be directed to R. D. Hart at (803) 831-3622.
Sincerely, D. M. Jamil Attachment 1 ea12 2-www. duke-energy. corn
I U.S. Nuclear Regulatory Commission December 8, 2003 Page 2 xc:
L.
A. Reyes U. S. Nuclear Regulatory Commission Regional Administrator, Region II Atlanta Federal Center 61 Forsyth St.,
SW, Suite 23T85 Atlanta, GA 30303 S.
E. Peters (addressee only)
NRC Project Manager (CNS)
U.
S. Nuclear Regulatory Commission Mail Stop 0-8 G9 Washington, DC 20555-0001 E.
F. Guthrie Senior Resident Inspector (CNS)
U. S. Nuclear Regulatory Commission Catawba Nuclear Site INPO Records Center 700 Galleria Place Atlanta, GA 30339-5957
Abstract
The lB containment spray system (CSS) was declared inoperable on October 6, 2003 at 0400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br /> to allow the installation of inspection ports to support upcoming Unit 1 refueling activities.
Inspections of the lB CSS heat exchanger revealed degradation of the baffle plates.
Engineering review of the B CSS heat exchanger determined that the heat exchanger could not be returned to service within the time limits required by Technical Specifications (TS).
A notice of enforcement discretion (NOED) was requested from the NRC to allow time to prepare and approve an exigent TS change to support continued operation.
The NRC granted the NOED on October 9, 2003 at 2125.
Subsequent evaluations by engineering with support from a vendor determined that the lB CSS heat exchanger could be determined to be operable with some limitations on shell side flows.
This evaluation was reviewed and approved by station management and the B CSS heat exchanger was declared operable on October 21, 2003 at 2106.
The exigent TS change was determined to not be required and was withdrawn.
The B CSS heat exchanger is being replaced during the current Unit 1 refueling outage.
The health and safety of the public was not affected.
NRC FORM 366 (7-2001)
(If more space Is required, use additionalcopies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, use additional copies of NRC Forn 366A) (17) calculated large early release frequency (LERF).
At Catawba, LERF is dominated by sequences,involving inter-system loss-of-coolant-accidents (ISLOCAs) or pressure spikes due to hydrogen burns.
It is unlikely that the CSS could mitigate the pressure spikes due to a hydrogen burn.
The CSS system may have some impact on Large Late Releases.
However, the impact of one CSS train unavailable is small.
Generally, accidents that lead to core damage involve loss of support systems and the independent failures are not large contributors.
These systems support both the core damage mitigation systems as well as CSS.
The increase in the Large Late Release Frequency can be approximated by multiplying the frequency of the Intact Containment release categories with sprays available by the failure probability of CSS with only one train (2.3E-02).
Note that this approximation is conservative since it assumes that a CSS train failure will move a sequence from the Intact Containment category to the Late Containment Failure category.
The increase in the Large Late Release Frequency is approximately 2.2E-08 for a 14 day CSS extension.
This increase is approximately 0.08 percent of the total late containment failure probability for a year.
A qualitative assessment of the risks that were not considered in the quantitative analysis resulted in the development of several compensatory measures.
These were implemented during the period of non-compliance with the Technical Specifications.
At Catawba, the residual heat removal (RHR) system has been designed to include a provision for diversion of a portion of the RHR pump flow from the low head injection path to auxiliary spray headers in the upper containment volume.
For this mode, the RHR pumps continue to supply recirculation flow from the containment sump to the core via the safety injection and centrifugal charging pumps.
The diversion of the RHR flow from the low head injection path to the auxiliary spray headers occurs only after the switchover to the recirculation mode and no earlier than 50 minutes after initiation of the LOCA.
The inspection of the B CSS heat exchanger identified that the divider plate between the 2 passes appeared to be intact.
Since the segmental baffles function both to support the heat exchanger tubes and to promote heat transfer by diverting flow back and forth across the tube bundle, tube integrity, heat transfer effectiveness and overall structural integrity were evaluated.
Existing (If more space is required, use additional copies of (If more space is required, use additional copies of (If more space is required, useadditionalcopies of (If more space is required, use additional copies of NRC Form 366A) (17) corrective actions that may have assisted in detecting the B CSS heat exchanger condition sooner.
Energy Industry Identification System (EIIS) codes are identified in the text as [EIIS: XX].
This event did involve an equipment failure and is reportable to the Equipment Performance and Information Exchange (EPIX) program.
This event did not include a Safety System Functional Failure.
There were no releases of radioactive materials, radiation exposures or personnel injuries associated with this event.