ML20033G785
| ML20033G785 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 03/30/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20033G782 | List: |
| References | |
| NUDOCS 9004120119 | |
| Download: ML20033G785 (7) | |
Text
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UNITED STATES
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ENCLOSURE 4 l
SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO.174 TO FACILITY OPERATING LICENSE NO. DPR-33 AMENDMENT NO. 177 TO FACILITY OPERATING LICENSE NO. DPR-52 l
AMENDMENT NO. 145 TO FACILITY OPERATING LICENSE NO. DPR-68 l
TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT, UNITS I. 2 AND 3 DOCKET NOS. 50-259, 50-260 AND 50-296 T
1.0 INTRODUCTION
By letter from the Tennessee Valley Authority (TVA), (the licensee), signed by M. J. Ray on March 6, 1990, the licensee requested an amendment to the Browns Ferry Technical Specifications- (TS).
The proposed TS changes would: (1) delete the remaining portion of temporary amendments 151,147, and 122 for Browns Ferry Units 1, 2 and 3 respectively; (2) clarify the actions to be taken in Limiting Condition for Operation (LCO) 3.7.B.4 (Standby Gas Treatment System) and revise the bases accordingly; (3) revise the requirements of LCO 3.7.C.2 (Secondary Containment); and (4) add a clarifying statment to LCO 3.7.C.4.b (Secondary Containment). TVA 's justification for this TS change involved benefits and savings in outage work efficiency without any reduction in safety.
In conjunction with their TS amendment request. TVA also requested a temporary waiver of compliance (in another letter dated March 6,1990) from the LCO requirement of 3.7.C.2.d while the staff completed its evaluation of the proposed amendnent.
The steff approved of TVA's request and issued a temporary waiver of TS compliance, on March 8,1990, based upon the insignificant impact j
upon safety and the potential for limiting further delays in restart.
l 2.0 EVALUATION The licensee proposed to change the Browns Ferry Units 1, 2 and 3 TS in order to c16rify the LC0 and associated bases pertaining to the interrelationships of primary containment, secondary containment and the standby gas treatment system (SGTS). The present TS are too restrictive since they prevent modifications to secondary containment components when primary containment integrity is not available, even when the reactor is defueled.
This change would result in the following TS modifications: (1) deletion of the remaining portion of the temporary TS amendments 151,147 and 122 for Units 1, 2 and 3 respectively (SGTS); (2) clarification of Section 3.7.B.4 (SGTS) and its associated bases; (3) revising requirements of Section 3.7.C.2 (secondary containment); and (4) addition of a clarifying statement to Section 3.7.C.4.b (SGTS and secondary containment).
9004120119 900330 P-PDR ADOCK 05000259 P
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The following is a description and evaluation of the proposed TS Change:
c (1) Deletion of Remaining Temporary TS Amendments (151, 147, and 122) 20, 1988, to allow fuel movement for the These amendments were issued July purpose of fuel reconstitution for Unit 2 when only two of the thre was inoperable. These amendments were justified based on the minimal gaseous fission product activity due to the age of the fuel. This change was a temporary change to be in effect until just prior to fuel load.
The portion of these temporary amendments dealing with the CREVS were subsquently removed by 156,152, and 127 that were issued October 3,1988 for Units 1, 2, amendments and 3, respectively. Fuel reconstitution has been completed; therefore, the Since these amendments are no remainder of these amendments are being deleted.
longer applicable due to the completion of the fuel reconstitution program, the staff concludes that deleting the remaining temporary TS changes is acceptable.
(2) Clarification of Section 3.7.B.4 and the Associated Bases The existing LCO 3.7.B.4 states the following:
"If these conditions cannot be met, the reactor shall be placed in a condition for which the standby gas treatment system is not required."
The proposed TS Change to LCO 3.7 B.4 would state the following:
"If these conditions cannot be met:
(a) Suspend all fuel handling operations, core alterations, and activities with the potential to drain any reactor vessel l
containing fuel.
Place all reactors in at least a HOT SHUTDOWN CONDITION within the (b) next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in a COLD SHUTDOWN CONDITION within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />."
The SGTS provides a means for minimizing the release of radioactive material by filtering and exhausting the air from any and all zones of the Units 1, 2 and 3 reactor buildings.
SGTS also maintains a negative pressure between the reactor building and the outside environment to preclude unfiltered leakage. Because of the SGTS safety function, when the seven day LCO is exceeded for one train of the SGTS being inoperative or more than one train becomes inoperative, all operations which have a potential for initiating J
a radioactive release are suspended for all three units.
The proposed change is being made to clarify what specific actions are to be taken if the seven day LCO for one train of SGTS inoperable (LCO 3.7.B.3) i cannot be met or if more than one train of the SGTS is inoperable. The current TS offers only general guidance if LCO 3.7.B.3 cannot be met and therefore creates the potentiel for varying interpretations by the operator as to what actions to take or what constitues a condition where the SGTS is not requirec.
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i This TS change will provide specific actions required to be taken if the LCO The cannot be met, thereby, minimizing the potenti61 for misinterpretation.
actions required by this LCO will provide for the safe and timely cessation of activities which have a potential for an accidental release of radioactive material, and provide for an orderly shutdown of all reactors with minimum This TS change is consistent with the General potential risk of fuel damage.
I Electric (GE) Boiling Water Reactor (BWR) Standard TSs (NUREG-0123) approved The bases of TS 3.7.B are also being revised to reflect this by the staff.
Based on the above, the staff concludes that the change to LCO 3.7.B.4 change.
is acceptable.
l (3) Revision of Requirements of Section 3.7.C.2 The existing LCO 3.7,0.2 states the following:
"If reactor zone secondary containment integrity cannot be maintained the following conditions shall be met:
The reactor shall be made suberitical and Specification 3.3.A shall a.
be met, b.
The reactor shell be cooled down below 212'F and the reactor coolant system vented.
Fuel movement shall not be permitted in the reactor zone, c.
d.
Primary containment integrity maintained."
The proposed TS Change to LCO 3.7.C.2 would state the following:
"If reactor zone secondary containment integrity cannot be maintained the l
following conditons shall be met:
Suspend fuel handling operations, core alterations, and activities a.
with the potential to drain any reactor vessel containing fuel.
b.
Restore reactor zone secondary containment integrity within four hours, or place all reactors in at least a HOT SHUTDOWN CONDITION within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and in a COLD SHUTD0tlN CONDITION within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />."
The secondary containment system is designed to minimize any ground level release of radioactive material which might result from a serious accident.
The reactor building provices secondary containment during reactor operation, when the drywell is sealed and in service.
The reactor building can also substitute for primary containment, if required, when the reactor is shutdown 4
and the drywell is open.
Because secondary containment is an integral part of the containment system, secondary containment is required any time primary containrient is required as well as during refueling operations.
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? t Proposed LCO 3.7.C.2.a is required for activities associated with the potential for imediate fuel damage or loss of reactor vessel water inventory. New or irradiated fuel handling operations and core alterations (i.e., movement of fuel, soerces, incore instrtments, or reactivity controls within the reactor pressure vessel with the head removed and fuel in the vessel) have the potential to cause a fuel handling accident.
This LCO provides for an orderly suspension of these agttvities and for movement of a component to a safe conservative position. Th. proposed LCO replaces existing LCO 3.7.C.2.c in its entirety with more explicit requirements.
Proposed LCO 3.7.C.2.b allows four hours to restore reactor building secondary containment operability before initiating shutdown of operating reactors.
This allows a re6sonable time to fix the problem before initiating shutdown.
The allowed time to reach a HOT SHUTDOWN CONDITION (12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />) and a COLD SHUTDOWN CONDITION (within the following 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />) is sufficient to allow an orderly shutdown and cooldwn of the reactor. A controlled evolution minimizes the potential risk for fuel damage.
This change and the specific allowable tirne frames are consistent with NUREG-0123, and fully scopes applicable portions of existing LCOs 3.7.C.2.a & b.
Since these requirements place the reactor in a safe condition and minimize the potential for occurrence of any design basis accident which could release radioactive material to the environment, the existing requirement 3.7 C.2.d (to maintain primary containment integrity), under these conditions, is unnecessary.
TS LCO 3.3.A defines the control rod shutdown margin and is applicable at all times during the fuel cycle. Untoupling this from secondary containment does i
not change the TS requirement for control rod operability under TS 3.3.A.
l A minor chenge to the beses is also being made to indicate that the reactor building provides primary containment, if required, when the reactor is shutdown and the drywell is open.
I Based on the above, the staff concludes that the change to LCO 3.7.C.2 is l
acceptable.
(4) Addition to Section 3.7.C.4.b I
The existing LCO 3.7.C.4.b states the following:
"The standby gas treatment system suction to the refueling zone will be blocked except for a controlled leakage area sized to assure the achieving of a vacuum of at least 1/4-inch of water and not over three inches of water in all three reactor zones."
The proposed TS change to LC0 3.7.C.4.b would add the following to the existing LCO:
"This is only applicable if reactor zone integrity is required."
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5-This change eliminates the requirement to block the SGTS suction to the refueling zone if reactor zone secondary containment is not required.
If reactor zone secondary containment was not required, the SGTS would not i
be required to be operable so the action of blocking its suction would be unneeded.
This clarification prevents inappropriate interpretations of operability requirements when SGTS is not operable, and is consistent with j
Each of the proposed TS changes described above seeks to clarify the BFN TS to limit the need for interpretation and to make them consistent with NUREG-0123.
The risk of design basis accidents without adequate containment or treatment are minimized by the actions requiring shutdown of BFN reactors in an orderly manner and suspension of fuel handling activities, core alterations, and activities with the potential to drain any reactor vessel.
Also, since the proposed TS changes improve the effect of operator responses to accident situations by clarifying required actions, we conclude that TVA's amendment request is acceptable.
3.0 FINDING OF EXIGENT CIRCUtiSTANCES TVA requested a revision of the secondary containment operability requirements in order to expedite performance of support modifications on common portions of the Emergency Equipment Cooling Water (EECW) system.
EECW is required for operability of the Emergency Diesel Generators that supply emergency power for the SGTS.
Since the SGTS is required to be operable whenever secondary cont 61nment is operable, this also requires EECW to be operable.
As such, modification work on the EECW system has been severely constrained by TS which require one train of EECW operable at all times.
By changing the operability requirements of secondary containment for certain plant conditions, TVA would be able to make both trains of EECW inoperable during the current outage.
This would allow TVA to potentially complete the required Unit 2 modifications nearly e month sooner than under the existing TS.
The staff finds that failure to grant the proposed changes could unnecessarily l
delay restart of Unit 2 by increasing the outage time for perfonr.ing required EECW modifications.
Furthermore, the staff finds that even had the licensee l
provided a more timely request, exigent circumstances would have still applied (i.e. TVA might have saved themselves even more outage time than one month with j
an earlier request). Accordingly, the staff concludes that TVA has satisfied the requirenents of 10 CFR 50.91(a)(6) for an exigent TS amendment.
4.0 FINAL h0 SIGNIFICANT HAZARDS CONSIDERATION DETERMINATION NRC staff reviewed the licensee's amendment application and determined, in accordance with the criteria of 50.92(c), that operation of Browns Ferry, Units 1, 2 and 3 according to the proposed amendment:
1)
Does not sienificantly affect the probability or consequences of any previously evaluated accident.
Secondary containment and SGTS are designed to function together to ninimize ground level releases of j
radioactive materials tht.t might result from an accident during reactor power or refueline operations.
The reactor building provides secondary containment during reactor operation, when the drywell is 1
.m.,
. p,
6-sealed and in service; the reactor building also provides, in effect, primary containment when the reactor is shutdown and the drywell is open, as during refueling.
Since the secondary containment is an l
integral part of the complete containment system, secondary contain-l ment is normally required at all times that primary containment is required as well as during refueling.
The proposed TS will eliminate l
the requirement to maintain primary and secondary containment integ-l rity together when the reactor is in cold shutdown, vented, and fuel When the reactor is undergoing refueling movements are precluded.
operations, the risk of inadvertent releases of radioactive material i
from potential accidents involving fuel handling, vessel draining, and/or core alterations are minimized while secondary containment and SGTS are operable.
However, when these systems are not operable, the i
risks of fuel handling and reactivity insertion accidents are i
minimized because fuel movement and core alterations are excluded whenever secondary containment is not operable or insufficient SGTS capacity is available.
The proposed amendment request provides specific actions to be j
taken if the LCOs cannot be met for the SGTS or secondary contain-ment system that are consistent with the STS for General Electric (GE)designedplants,asisBFN.
Both the current and proposed TS require an orderly reactor shutdown (if applicable) and controlled.
suspension of all activities that have the potential for leading to an accident, t
The Fuel Handling Accident and the reactivity insertion accidents are the previously evaluated accidents in Chapter 14 of the BFN Final Safety Analysis Report.
The proposed changes do not change the level l
of protection against these accidents and, therefore, do not afuct the probability or consequences of any accident previously evaluated.
I 2)
Does not create the possibility of a new or different kind of acci-I dent from any accident previously evaluated in the BFN Final Safety
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Analysis Report.
The changes clarify what to do when either the SGTS or secondary containment LCOs cannot be met.
The resulting actions to preclude accidents that may cause a radioactive material release are consistent with current industry practice and the Standard TS requirements for GE Boiling Water Reactors, i
Furthermore, the proposed changes do not add equipment to the plant l
l and do not allow any mode of plant operation which could initiate the possibility of a new or different kind of accident from any l
accident previously evaluated.
3)
Does not involve a significant reduction in a margin of safety. The i
changes are consistent with the existing BFN Safety Analysis and GE STS.
No adverse safety impact or reduction,in safety margins cccurs due to the proposed changes. The TS will continue to require an orderly shutdown of the operating reactor and cessation of all activities with the potential accident risk to release radioective material if secondary containment in SGTS LCOs cannot be met.
Therefore, the proposed changes do not involve a significant reduc-tion in a margin of safety, 1
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Accordingly, the Commission concludes that this amendment request does not involve significant hazards considerations.
5.0 ENVIRONMENTAL CONSIDERATION
These amendments involve changes to requirements with respect to the use of l
facility components located within the restricted area as defined in 10 CFR i
The staff has determined these amendments involve no significant Part 20.
increase in the amounts, and no significant change in the types, of any efflu-ents that may be released offsite, and there is no significant increase in individual or cumulative occupational radiation exposure. The Comission has previously issued a proposed finding that these amendments involve no signifi-l cant hazards consideration and there has been no public coment on such finding.
Accordingly, these amendments meet the eligibility criteria for categorical t
l exclusionsetforthin10CFR51.22(c)(9). Pursuant to 10 CFR 51.22(b), no environmental impact statement nor environmental assessment need be prepared in connection with the issuance of these amendments.
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6.0 STATE CONSULTATION
3 The Comission made a proposed determination that the amendment involved no significant hazards consideration which was published in the Federal Register (55 FR 9789) and consulted with the State of Alabama.
No public coments were received and the State of Alabama did not have any comments. The State of Alabama was also informed of the staff's final no significant hazards considerations determination and intent to issue a license amendment.
7.0 CONCLUSION
S The staff has concludec, based on the consideration discussed above, that:
(1) the amendments do not invcive significant hazards consideration, (2) there is reasonable assurance that the health and safety of the public will not be i
endangered by operation in the proposed manner, (3) such activities will be conducted in compliance with the Commission's regulations, and (4) the issuance of the amendments will not be inimical to the comon defense and security, nor to the health of the public.
Principal Contributor:
P. Hearn Dated: March 30, 1990 3
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