ML20237B554
| ML20237B554 | |
| Person / Time | |
|---|---|
| Site: | Catawba  |
| Issue date: | 08/12/1998 |
| From: | Gordon Peterson DUKE POWER CO. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20237B556 | List: |
| References | |
| TAC-MA3279, NUDOCS 9808190038 | |
| Download: ML20237B554 (9) | |
Text
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i Duka Energy C rpor'llon
[I Catawba Nuclear Station 4800 Concord Road York, SC 29745 (803) 831-4251 OFFICE
< Giry R. Peterson Vice President (803) 831-3426 fax August 12, 1998 l
U.S. Nuclear Regulatory Commission Attention:
Document Control Desk Washington, D.C.
20555 l
Subject:
Duke Energy Corporation Catawba Nuclear Station, Unit 2 Docket Number 50-414 Notice of Enforcement Discretion (NOED) Request Ice Condenser Technical Specification Surveillance L
Requirement 4.6.5.lb.2 TAC Number MA3279 l
Attached is the written documentation of the background and L
technical information supporting the Catawba Unit 2 Notice of Enforcement Discretion (NOED) request.
This information was discussed with the NRC staff in a telephone conference call on August 12, 1998.
l As discussed in detail in Attachment 1, Catawba is requesting l
discretion from enforcing Technical Specification Surveillance L
Requirement 4.6.5.lb.2.
This Surveillance Requirement governs verification of ice condenser system components with respect to the accumulation of frost or ice.
As shown in the attached justification, Duke Energy maintains that granting of
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discretionary enforcement in this case is in the best interests of nuclear safety.
Enforcement discretion is necessary for Unit 2 until the unit reaches Mode 5 of the End-of-Cycle 9 Refueling Outage.
The Unit 2 End-of-Cycle 9 Refueling Outage is currently scheduled to commence on September 5, 1998.
In addition, a a
license amendment request will be submitted for both units to change the Technical Specifications.
l This request for enforcement discretion was approved by the Catawba Plant Operations Review Committee (PORC) on August 12, 1998.
l 1,oo
,.o.a PDR ADOCK 05000414 P
POR
U.S.
Nuclear Regulatory Commission Page,2 August 12, 1998 Should you have any questions concerning this information, please
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call L.J.
Rudy at (803) 831-3084.
j Very truly yours, jr i
A g-i g
Gary / R. Peterson LJR/s
)
Attachment xc (with attachment):
I L.A.
Reyes U.S.
Nuclear Regulatory Commission Regional Administrator, Region II Atlanta Federal Center i
61 Forsyth St.,
SW, Suite 23T85 Atlanta, GA 30303
)
D.J.
Roberts i
Senior Resident Inspector (CNS)
U.S.
Nuclear Regulatory Commission Catawba Nuclear Station P.S.
Tam NRC Senior Project Manager (CNS) l U.S.
Nuclear Regulatory Commission Mail Stop O-14H25 i
Washington, D.C.
20555-0001 i
M.
Batavia, Chief Bureau of Radiological Health 2600 Bull St.
Columbia, SC 29207
Catawba Nuclear Station, Unit 2 Request for Enforcement Discretion Technical Specification 4.6.5.1b.2 Ice Condenser System Surveillance
' Duke Energy hereby requests that the NRC grant discretion in enforcing Technical Specification Surveillance Requirement 4.6.5.1b.2 and to allow the Catawba Unit 2 ice condenser to be considered operable,without having to completely perform this Surveillance Requirement.
Catawba cannot inspect the lower inlet plenum support structures and turning vanes while the unit is at
. power without incurring significant dose to personnel performing the inspection.
As demonstrated below, Catawba maintains that the lower inlet plenum support structures and turning vanes are capable of meeting the acceptance criteria of this Surveillance Requirement based on inspection data presently being obtained on Unit 1 and on the observed condition of accessible components on Unit 2.
1 a
l Upon determination that Surveillance Requirement 4.6.5.1b.2 was not being completely complied with, Catawba declared the Unit 2 ice condenser inoperable.
This declaration was made on August 3
12, 1998 at 1336 hours0.0155 days <br />0.371 hours <br />0.00221 weeks <br />5.08348e-4 months <br />.
l
.This request for enforcement discretion is only applicable to Catawba Unit 2.
Unit 1 is presently shut down and Surveillance l
Requirement 4.6.5.1b.2 will be performed in its entirety prior to resuming operation.
Enforcement discretion is being requested until Catawba Unit 2 enters Mode 5 of the End-of-Cycle 9 Refueling Outage, at which time the Surveillance Requirement will not be applicable.
This outage is currently scheduled to begin on September 5, 1998.
In addition, a license amendment request j
will be submitted for both Catawba Units 1 and 2 to modify the i
Technical Specifications.
r
- 1. Technical Specifications violated Catawba Unit 2 is requesting enforcement discretion from Surveillance Requirement 4.6.5.lb.2 which states, "The ice condenser shall be determined OPERABLE at least once per 9 months by verifying, by a visual inspection of at least two flow passages per ice condenser bay, that the accumulation of frost or ice on flow passages between ice baskets, past lattice frames, through the top deck floor grating, or past the lower inlet plenum support' structures and turning vanes is restricted
I to a thickness of less than or equal to 0.38 inch.
If one flow passage per bay is found to have an accumulation of frost or ice with'a thickness of greater than or equal to 0.38 inch, a representative sample of 20 additional flow passages from the same bay shall be visually inspected.
If these additional flow passages are found acceptable, the surveillance program may proceed considering the single deficiency as unique and acceptable.
More than one restricted flow passage per bay is evidence of abnormal degradation of the ice condenser. "
i Failure to meet this Surveillance Requirement would constitute inoperability of the ice condenser for Unit 2.
Catawba is therefore asking for NRC discretion in enforcing this particular Surveillance Requirement for those ice condenser components which are inaccessible during unit operation (the lower inlet plenum support structures and turning vanes) so that ice condenser operability is not dependent upon this portion of the surveillance being met.
2.
Circumstances surrounding the situation Ice condenser system description The ice condenser's primary function is the absorption of thermal energy released abruptly in the event of a loss of coolant accident, for the purpose of limiting the initial peak pressure in the containment.
A secondary function of the ice condenser is the further absorption of energy after the initial incident, causing the containment pressure to be reduced to and held at a lower level for a period of time.
The sodium tetraborate solution produced by a partial meltdown of the ice absorbs and i
retains iodine released during the. accident and serves as a heat transfer medium and neutron poison for cooling the reactor core following the postulated incident.
l The main part of the ice condenser is a mass of sodium tetraborate ice stored in an annular chamber inside the containment shell.
The ice is maintained in an array of vertical cylindrical columns.
The columns are formed by perforated metal baskets.
The baskets are assembled into a lattice framework to form a continuous column of ice.
The ice condenser is contained in the annulus formed by the containment vessel wall and the l
crane wall circumferentially over a 300 degree arc.
l Three sets of insulated doors are located, respectively, along the lower crane wall, in the intermediate deck, and in the top deck.
If lower containment compartment pressure exceeds upper containment compartment pressure by more than one pound per
square foot as the result of an accident, the lower inlet doors Will swing open and allow the evolved steam to flow into the ice condenser.
The direction of steam flow is changed 90 degrees by turning vanes.
The steam will condense on the ice and chilled structures, but air will pass through the ice bed and open the intermediate and top deck doors, venting to the upper compartment and compressing the containment atmosphere.
The lower inlet doors are spring loaded to assure flow uniformity, while the intermediate and upper doors are held closed by gravity only.
During the accident, borax solution mixed with condensed steam will leave the compartment via the doors and floor drains.
The l
solution will drain into the containment sump, where it will be available for residual core heat removal.
Iodine released during the accident will be dissolved and retained in the melted borax solution.
Description of circumstances During an evaluation of Technical Specification Surveillance Requirements associated with an inspection of the ice condenser system at Catawba, it was determined that all aspects of Surveillance Requirement 4.6.5.lb.2 are not being met.
In particular, the surveillance was not being performed for the lower inlet plenum support structures and the turning vanes.
A missed surveillance was declared and the Unit 2 ice condenser system (ice bed) was declared inoperable on August 12, 1998 at 1336 hours0.0155 days <br />0.371 hours <br />0.00221 weeks <br />5.08348e-4 months <br />.
The applicable ACTION requirement states, "Wi th the ice bed inoperable, restore the ice bed to OPERABLE status within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> or be in at least HOT STANDBY wi thin the next 6 hours6.944444e-5 days <br />0.00167 hours <br />9.920635e-6 weeks <br />2.283e-6 months <br /> and in COLD SHUTDOWN within the following 30 hours3.472222e-4 days <br />0.00833 hours <br />4.960317e-5 weeks <br />1.1415e-5 months <br />. "
The lower inlet plenum support structures and turning vanes are located in lower containment, and lower containment is not usually accessed during power operation as a result of dose considerations.
Dose rates in the lower ice condenser at power exceed 3.6 R/hr.
Catawba therefore elected to pursue this request for enforcement discretion to allow continued operation of Unit 2 until Mode 5 of the End-of-Cycle 9 Refueling Outage, which is currently scheduled to begin on September 5, 1998.
In addition, Catawba will submit, for both Units 1 and 2, a license amendment request to change the required frequency of Surveillance Requirement 4.6.5.lb.2 from 9 months to 18 months for the lower inlet plenum support structures and turning vanes.
l Changing the frequency to 18 months will allow this surveillance to be performed on the lower inlet plenum support structures and turning vanes during a refueling outage when lower containment is accessible.
Enforcement discretion is necessary until Unit 2 reaches Mode 5 of the End-of-Cycle 9 Refueling Outage.
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Therefore, this request is for the NRC to exercise discretion in pnfor,cing Surveillance Requirement 4.6.5.lb.2 with respect to the
'.ower inlet plenum support structures and turning vanes.
3.
The safety basis for the request, including the evaluation of l
the safety significance and potential consequences of the proposed action.
There are no safety consequences associated with this request.
Catawba believes, based on ice condenser surveillance data which is presently being taken on Unit 1 and on observable conditions associated with inspections of the accessible Unit 2 ice condenser components, that the Unit 2 ice condenser would be able to completely meet Surveillance Requirement 4.6.5.lb.2.
Catawba cannot perform all aspects of this surveillance with the unit at power.
In particular, the lower inlet plenum suppor t structures and turning vanes are inaccessible for inspection as a result of the high dose rates in lower containment.
Approval of this request is also preferable from a safety standpoint to the transient cycle that would be incurred on Unit 2 should it be required to be shut down to meet all aspects of this surveillance.
The surveillance will be performed in its entirety during the next Unit 2 refueling outage currently scheduled to commence on September 5, 1998.
Catawba believes that the Unit 2 ice condenser is currently fully capable of performing its design function in the event of an accident.
Currently, any ice buildup is removed from the lower inlet plenum support structures and turning vanes during refueling outages and cleanliness inspections of these components are performed.
NRC granting of this request for enforcement discretion will not result in any unavailability of the ice condenser.
It con therefore be concludod that no accident probabilities or consequences as delineated in the Catawba Probabilistic Risk Assessment will be adversely impacted.
- 4. The basis for the licensee's conclusion that noncompliance will not be of potential detriment to the public health and safety and that neither an unreviewed safety question nor a significant hazard consideration is involved.
NRC granting of this request for enforcement discretion will not have any adverse consequences from the standpoint of public health and safety.
As indicated above, Catawba believes that the Unit'2 ice condenser is capable of meeting all acceptance criteria of Surveillance Requirement 4.6.5.lb.2, were this surveillance able to be performed in its entirety.
The ice l
b condenser is therefore fully capable of meeting all technical requi,rements for operability and is capable of performing all design functions.
Granting of this request will allow continued operation of Catawba Unit 2 until the unit enters Mode 5 of the aforementioned refueling outage.
During the outage, Surveillance Requirement 4.6.5.lb.2 will be performed in its entirety.
Duke Energy has determined that no changes will be required to the Catawba Updated Final Safety Analysis Report in conjunction with this request for enforcement discretion.
There are no significant hazards considerations associated with this request for enforcement discretion.
This is demonstrated as follows:
This request for enforcement discretion does not involve a significant increase in the probability or consequences of an accident previously evaluated.
Granting of this request will have no significant effect on accident probabilities or consequences.
The ice condenser system is not an accident initiating system; therefore, there will be no impact on any accident probabilities by the granting of this request.
Catawba believes that the ice condenser is fully capable of meeting its design basis accident mitigating function.
Therefore, there will be no impact on any accident consequences.
This request for enforcement discretion does not create the possibility of a new or different kind of accident from any accident previously evaluated.
No new accident causal mechanisms are created as a result of the NRC granting of this request for enforcement discretion.
No changes are being made to the plant which will introduce any new accident causal mechanisms.
This request for enforcement discretion does not impact any plant systems that are accident initiators, since the ice condenser system is an accident mitigating system.
This request for enforcement discretion does not involve a significant reduction in a margin of safety.
Margin of safety is related to the confidence in the ability of the fission product barriers to perform their design functions during and following an accident situation.
These barriers include the fuel cladding, the reactor coolant system, and the containment system.
The performance of these fission product barriers will not be impacted by the NRC's granting of this request.
The ice condenser system is believed to be fully capable of performing as designed.
No safety margins will be impacted.
5.
The basis for the licensee's conclusion that the noncompliance will,not involve adverse consequences to the environment.
This request for enforcement discretion will not result in any changes in the types, or increase in the amounts, of any effluents that may be released offsite.
In addition. no increase in individual or cumulative occupational radiation exposures will be involved.
Therefore, it can be concluded that the NRC's granting of this request for enforcement discretion will not involve any adverse consequences to the environment.
6.
Proposed compensatory measures No compensatory measures are being proposed.
This issue does not create any safety concerns which warrant compensatory measures.
7.
Justification for the duration of the non-compliance The duration of the noncompliance is based on the time until Unit 2 enters Mode 5 of the next scheduled refueling outage.
Unit 2 is currently scheduled to begin the End-of-Cycle 9 Refueling Outage on September 5, 1998.
During this refueling outage, Catawba will perform Surveillance Requirement 4.6.5.lb.2 in its entirety, for all ice condenser components delineated in the surveillance.
Enforcement discretion will be necessary until the unit enters Mode 5 of the End-of-Cycle 9 Refueling Outage.
As stated in items 3 and 4, there is no safety significance or potential detriment to the health and safety of the public.
8.
Statement that the request has been approved by the facility organization that normally reviews safety issues.
This request was reviewed and approved by the Catawba Plant Operations Review Committee in a special meeting on August 12, 1998.
9.
How one of the NOED criteria for appropriate plant conditions specified in Section B is satisfied.
This request is intended to avoid an undesirable unit shutdown transient as a result of requiring compliance with the Technical Specifications and, thus, minimize potential safety consequences and operational risks.
NOED criterion B.1 is therefore satisfied.
- 10. If a follow-up license amendment is required, the NOED fequest must include marked-up TS pages showing the proposed TS changes.
The Catawba Units 1 and 2. marked-up Technical Specifications pages are included with this request for enforcement discretion.
The formal license amendment request will be submitted within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> of receipt of this request for enforcement discretion.
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- 11. A statement that prior adoption of approved line-item improvements to the TS or the ITS would not have obviated the need for the NOED request.
Catawba submitted its Improved Technical Specifications conversion license amendment to the NRC on May 27, 1997.
This amendment is presently undergoing NRC staff review.
The Improved Technical Specifications amendment relocates much of the detail concerning Surveillance' Requirement 4.6.5.1b.2 to the Bases of the Improved Technical Specifications, but its technical content is unchanged from that currently contained in Surveillance Requirement 4.6.5.lb.2.
Prior adoption of approved line-item improvements to the Technical Specifications or the Improved Technical Specifications'would therefore not have obviated'the need for this NOED request.
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