ML20195J008
| ML20195J008 | |
| Person / Time | |
|---|---|
| Site: | McGuire, Mcguire  |
| Issue date: | 06/11/1999 |
| From: | NRC (Affiliation Not Assigned) |
| To: | |
| Shared Package | |
| ML20195J005 | List: |
| References | |
| NUDOCS 9906180057 | |
| Download: ML20195J008 (5) | |
Text
E Muou
. p' 4
UNITED STATFS g
[
NUCLEAR REGULATORY COMMISSION WASHINGTON, D.C. 20066-4001
- ...../
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NO.185 TO FACILITY OPERATING LICENSE NPF-9 ANQ AMENDMENT NO.167 TO FACILITY OPERATING LICENSE NPF-17 DUKE ENERGY CORPORATION MCGUIRE NUCLEAR STATION. UNITS 1 AND 2 DOCKET NOS 50-369 AND 50 370
1.0 INTRODUCTION
By letter dated June 10,1999, Duke Energy Corporation,'(DEC, the licensee), submitted a request for changes to the McGuire Nuclear Station, Units 1 and 2, Technical Specifications (TS). The requested changes would revise TS 3.7.9, " Control Room Area Ventilation System (CRAVS)," to establish actions to be taken for an inoperable control room ventilation system due to a degraded control room pressure boundary. This revision approves a one-time-only action for two CRAVS trains inoperable due to a degraded control room boundary in Modes 1,2,3, and 4, that is to be completed within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The applicable TS Bases have been revised to document the TS changes and to provide supporting information.
2.0 BACKGROUND
The existing Limiting Conditions of Operation (LCO) 3.7.9 surveillance requirements that test the integrity of the control room boundary require a positive pressure limit to be satisfied with one' ventilation train operating. 'While other surveillance requirements in the same specification test the operability and function of the ventilation train, the pressure test ensures that the control room pressure boundary leak tightness is adequate to meet design assumptions for post-accident operator doses.
Currently, there are no corresponding conditions, required actions, or completion times specified in LCO 3.7.9 should the control room pressure boundary surveillance not be met.
Under the existing specifications, LCO 3.0.3 must be entered (for two-train inoperability).
Requiring the plant to enter LCO 3.0.3 when the ventilation boundary is not intact does not
. provide time to effect required repairs or corrective maintenance activities.
The proposed change is similar in nature to LCO 3.6.16 for the Reactor Building. LCO 3.6.16 allows 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> to restore the reactor building envelope to operable status before requiring an orderly shutdown from operating conditions.
9906190057 990611 M
PDR ADOCK 05000369 P
PDR L
l 2-3.0 EVALUATION
)
The proposed changes are:
1.
A note has been added to LCO 3.7.9 for the Control Room Area Ventilation System to allow the control room boundary to be opened intermittently under j
administrative control. Corresponding Bases have been added which establish i
the administrative controls that are required to minimize the consenuences of the open boundary.
l 2.
Condition G is added to LCO 3.7.9 to specify that 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> are allowed to restore an inoperable control room boundary to operable status. Corresponding Bases are added to support this change.
3.
Condition E of LCO 3.7.9 for two inoperable CRAVS trains in Modes 1 - 4 is modified to exclude entry into this condition when the trains are inoperable because of the degraded control room pressure boundary. The associated Bases for Condition E are revised accordingly.
The LCO is modified by a Note allowing the control room boundary to be opened intermittently under administrative controls. For entry and exit through doors, the administrative control of the opening is performed by the person (s) entering or exiting the area. For other openings, these controls consist of stationing a dedicated individual at the opening who is in conGnuous communication with the control room. This individual will have a method to rapidly close the j
opening when a need for control room area isolation is indicated.
If the control room boundary is inoperable in MODES 1,2,3, or 4 such that the CRAVS trains can not establish or maintain the required pressure, action must be taken to restore an OPERABLE control room boundary within 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />. The 24-hour Completion Time is reasonable based on the low probability of a design basis accident occurring during this time period, the availability of the CRAVS to provide a filtered environment and compensatory measures available to the operator to minimize doses.
The proposed change would allow 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> (during Modes 1,2,3, or 4) to restore the capability to maintain control room boundary pressure before requiring the unit to perform an orderly shutdown and also allows intermittent opening of the control room boundary under i
adtninistrative control. The administrative controls establish appropriate compensatory j
measures to minimize the consequences of an event during this time. For example, when the I
control room boundary is opened for other than entry through doors, the proposed Bases require that a dedicated individual be stationed in the area in continuous contact with the control j
room to rapidly restore the boundary.
j i
Additionally, the proposed change is considered acceptable because of the low probability of an event requiring an intact control room boundary occurring during the 24-hour action completion time associated with Condition "G". On a per unit basis, the most severe condition, a j
core-damage accident, is estimated to occur with a probability of approximately 1.4E-07 during a 24-hour period. The probability of a LOCA, a less severe condition, is estimated to have a probability of occurrence of approximately 1E-05 during a 24-hour period. The probability of a 4
. steam generator tube rupture, which is the the least severe event, is estimated to occur with a probability of approximately 4E-05 during a 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> period.
Based on the low probability of an event occurring in this time and the availability of compensatory measures to minimize the consequences during an event, the proposed change l
is considered acceptable.
]
1 4.0 EMERGENCY CIRCUMSTANCE
)
The licensee's June 10,1999, letter states the following in rogard to the emergency circumstances related to the proposed action:
Note that the CRAVS equipment failure which precipitated the need for this LAR was a bearing failure on an air handling unit associated with CRAVS Train "B".
This failure occurred on June 9,1999 with no prior indication that the equipment was experiencing problems. As stated previously, failure to implement this LAR in a timely manner would result in the shutdown of McGuire Units 1 and 2.
Consequently, the criteria for submittal of an emergency TS change as stated in 10CFR50.91 is satisfied.
j The staff concludes that an emergency condition exists in that failure to act in a timely way would result in a shutdown of McGuire Nuclear Station, Units 1 and 2. In addition, the staff has assessed the licensee's reasons for failing to file an application sufficiently in advance to preclude an emergency, and concludes that the licensee promptly performed the inspection and identified the deficiency, promptly notified the staff of the deficiency, and proposed this amendment to remedy the situation. Thus, the staff concludes that the licensee has not abused the emergency provisions by failing to make timely application for the amendment. Thus, the conditions needed to satisfy 10 CFR 50.91(a)(5) exist, and the amendment is being processed on an emergency basis.
5.0 FINAL NO SIGNIFICANT HAZARDS CONSIDERATION
DETERMINATION in accordance with the criteria set forth in 10 CFR 50.91 and 50.92, McGuire Nuclear Station has evaluated this proposed Technical Specification change and determined it does not represent a significant hazards consideration. The following is provided by the licensee in support of this conclusion.
1.
Does the change involve a significant increase in the probability or consequences of an accident previously evaluated?
No. The Control Room Area Ventilation System and Control Room boundary are not assumed to be an initiator of any analyzed accident; they are provided to minimize doses to the control room operators during an accident. Therefore, these proposed changes have no impact on the probability of occurrence of any previously analyzed accident.
The proposed changes also have no impact on offsite dose consequences. The control room ventilation system and control room boundary provide protection for control room personnel only and do not mitigate radiological effluents released offsite. With the
. control room boundary inoperable and not pressurized, the accident analyses assume unfiltered air would enter the control room and operator doses would be significantly increased. Conservative accident analysis assumptions do not take credit for available compensatory measures to mitigate operator dose. These include the use of the alternate control room intake to select the intake with the lowest radioactivity level, filtration of outside air by an operable CRAVS train, and the availability of self contained 1
breathing apparatus.
Additionally, for cases where the control room boundary is opened under administrative control, compensatory measures would be required by the proposed TS to ensure the boundary can be rapidly restored. Based on the compensatory measures available to the control room operator to minimize dose, the compensatory measures required to rapidly restore an opened boundary, and considering the low probability of an event occurring in this short time period, the consequences are not considered to be significantly increased. Operators maintain the ability to mitigate a design basis event.
2.
Does the change create the possibility of a new or different kind of accident from any accident previously evaluated?
No. No changes are being made to actual plant hardware which will result in any new accident causal mechanisms. Also, no changes are being made to the way in which the plant is being operated. Therefore, no new accident causal mechanisms will be generated.
3.
Does this change involve a significant reduction in a margin of safety?
i No. Margin of safety is related to the ability of the fission product barriers to perform their design functions during and following accident conditions. These barriers include the fuel cladding, the reactor coolant system, and the containment system. The performance of these barriers will not be degraded by the proposed changes. The Control Room Ventilation System and control room boundary provide a protected environment for the control room operators during analyzed events. The proposed 1
change would allow the boundary to be degraded for a limited period of time. However, compensatory measures would be in place to rapidly restore an opened boundary and to utilize existing measures (breathing apparatus) to minimize operator dose. Therefore, it is expected that operators would maintain the ability to mitigate design basis events and none of the fission product barriers would be affected by this change. Therefore, the proposed change is not considered to result in a significant reduction in a margin of safety.
The NRC staff has reviewed the licensee's analysis and, based on this review, it appears that the three standards of 10 CFR 50.92(c) are satisfied. Therefore, the NRC staff determines that the amendment request involves no signficant hazards consideration.
6.0 STATE CONSULTATION
in accordance with the Commission's regulations, the North Carolina State official was notified of the proposed issuance of the amendments. The State official had no comments.
7.0 ENVIRONMENTAL CONSIDERATION
The amendments change requirements with respect to installation or use of a facility component located within the restricte-1 area as defined in 10 CFR Part 20 (and change surveillance requirements). The NRC sMff has determined that the amendments involve no significant increase in the amounts and no significant change in the types of any effluents that may be released offsite and that there is no significant increase in. individual or cumulative occupational radiation exposure. Accordingly, the amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments. The Commission has made a final no significant hazards finding with respect to this amendment.
8.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations, and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributors:
H. Walker J. Raval J. Segala F. Rinaldi Date: June 11, 1999