ML18025B751
| ML18025B751 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 04/01/1982 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18025B749 | List: |
| References | |
| NUDOCS 8204120097 | |
| Download: ML18025B751 (6) | |
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UNITEDSTATES c
NUCLEAR REGULATORY COMMISSION WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR" REACTOR REGULATION SUPPORTING AMENDMENT NO.
82 TO FACILITY OPERATING LICENSE HO. DPR-33 AMENDMENT NO.
79 TO FACILITY OPERATING LICENSE NO.
DPR-52 AMENDMENT NO.
53 TO FACILITY OPERATING LICENSE NO. DPR-68
, TENNESSEE 'ALL'EY'AUTHORITY BROWNS FERRY NUCLEAR PLANT UNIT NOS.
1 2 AND3 DOCKET HOS.
50-'259 50-260 AND 50-296 1.0 Introduction By 'letter dated April 24, 1981 (TVA BFHP TS 157),
and supplemented by letters dated April 29, 1981 and May 13, 1981, the Tennessee Valley Authority (the licensee or TVA) requested changes to the Technical Specifications (Appendix A) appended to Facility Operating License Nos.
DPR-33, DPR-52 and DPR-68 for the Browns Ferry Nuclear Plant, Unit Nos. 1, 2 and 3.
The proposed amendments ana revised Technical Specifications would clarify the definition of secondary con-tainment inte'grity.
2.0 Discussion The design of secondary containment at'the Browns Ferry Nuclear Plant is de-scribed in'Section 5.3 of the Final Safety Analyses Report '(FSAR).
Secondary
" containment consists of the one large reactor building that houses the primary containments for Units 1, 2 and 3, the control rooms for these three units, the spent fuel pools and associated refueling systems for the three units and much of the safety-related equipment and systems that serve the three units.
The reactor building is divided into four ventilation zones which may be is'olated independent of 'each other.
The refueling room which
. is common to the three units forms the refueling *zone.
The individual units below the refueling floor form the other three reactor zones.
The four zone ventilation control system provides increased capability for localizing the consequences of an accident or radioactive release such that the effect will be localized in one zone while maintaining the ability to isolate the entire'eactor building if necessary..
With one or more zones isolated the normal operations may be continued in the unaffected zones.
If the internal zone boundaries should fail, the entire reactor building would still meet the requirements of secondary containment by assuring filtered elevated release.
~ The zone system is not an engineered safeguard and the failure of the zone system would not in any way prevent isolation or reduce the capacity of the secondary containment system.
As noted in the FSAR, the reactor building is 820401
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P divided'nto four ventilation zones which may be isolated independent of each other.
The refueling areas
- which are common-to the three units - form the refueling zone.
The individual units located below the refueli'ng floor form the other three reactor zones.
As noted in the FSAR, the zone system is not.
an engineered safeguard.
As the FSAR also points out, a reactor zone is designed to be isolated upon isolation of the primary containment in that particular
- zone, by high radiation level.in the ventilation exhaust duct leaving that particular zone or by manual alignment.
The refueling zone is always isolated when any reactor zone is isolated.
The secondary containment system provides primary containment when any of the three primary containment systems are open such as during refueling and maintenance operations:
During normal operation - and when isolated - the secondary containment is maintained at a negative pressure relative to the building exterior.
Secondary
, containment integrity is required to be periodically verified by testing to be certain that the in-leakage rate is less than the standby gas treatment system (SGTS') capacity when the building is subjected to an internal negative press'ure of 0..25 inches of water.
The procedures for conducting this test are described in any of the summary technical reports on secondary containment leak.rat'e testing.
'Technicyl Specification 4.7.C.1.2,
.3, and.4 and associated surveillance require-ments specify the particular conditions for operation and testing requirements for the different zones.
It is noted that the secondary containment may be t'ested as a
whole or individual zones. "
On April 11, 1981; Unit 1 shutdown for refueling and major modifications to, the Mark I type torus.
As usual the primary (reactor) containment was opened to the Unit 1 reactor zone of secondary containment.
Since the reactor vessel head was left off, the primary system and the Unit 1 reactor zone were open to the refueling zone.
A large opening was cut into the torus to permit access
- for,
. personnel and equipment.
Also, equipment hatches between the reactor containment and reactor building were kept open to facilitate movement of. personnel and equipment.
Thus, the Unit 1 primary containment was open to-and could not be isolated from-two zones of secondary containment.
As discussed
- above, secondary containment at Browns Ferry consists of the single large reactor building. It is necessary to traverse the Unit 1 reactor zone of secondary containment to reach the Units.2 and 3 reactor zones.
This movement of personnel between zones raised a concern on the part of the NRC staff.
The doors between the zones had not been regularly maintained and some would not automatically close.
Also, the plant personnel occasionally propped open the doors between zones to facilitate movement of equipment.
In response t'o these
- concerns, TVA submitted the proposed changes to the Technical Specifi-'ations transmitted by their letter of April 24, 1981 to clarify the definition of secondary containment.
The'proposed
- changes, alone, did not alleviate these concerns.
These were discussed in conference calls with the TVA staff; and us (Region II, I'8E, and NRR) on April 23, 1981, April. 27, 1981 and May 8, 1981 and was the subject of TVA's supplemental letters of April 29, 1981 and.May 13, 1981.
In addition to the agreements discussed in these
- letters, TVA committed to include the doors between zones on a routine maintenance program to check that the door closures would automatically secure the doors.
E t
3.0 Evaluation The proposed changes to the Technical Specifications were prompted by NRC concerns.
The changes are bas.ically a clarification of the definition of secondary containment as defined in the FSAR.
The changes will add an entire new page-'page 4A-to the definition section of the Technical Specifications to define much more precisely what conditions must be met to maintain integrity in the individual reactor zones and the refuel zone within secondary containment and what conditions must be met in the overall reactor building to maintain secondary containment integrity.
As discussed in Section 2.0, above, during even normal operations, there is a need for very frequent traffic between the three reactor zones and between the reactor building, the. turbine building, the other adjoining buildings and the out-of-doors.
There are approximately 1000 operations type persorlnel and about 400 field.service personnel normally onsite;.the duties of'a'y of 'these personnel require that *they routinely move between zones and into and out;of secondary, containment.
During the Unit 1 outage,--'there were an additional N50 trades and labor personnel
- onsite, most of whom were frequently moving into or out of the reactor building; During the outages, it is necessary to bring large, heavy items of material into the reactor building on,.flat-bed trucks through the equipment air lock.
The only crane capable of handling heavy items
.is'n the refueling zone, which requires that the large hatch between the refueling zone and reactor zone be removed.
These proposed changes note specifically that such opening of inner doors or removal of hatches does not compromise overall secondary containment, provided that secondary containment to the environment is maintained.
This position is clearly confirmed by discussion in the FSAR.
To satisfy NRC concerns regarding tighter control between the individual zones, the licensee has made additional commitments as discussed in TVA's letters dated April 29, 1981 and t1ay 13, 1981.
These additional
~ommitments will, minimize the.
spread of contar'rination between the separate zones during accidents.
lie conclude that the proposed changes to the Technical. Specifications are desirable, will enhance safety at Bnowns.Ferry and are acceptable.
J'.0 Environmental Consideration Me have determined that these amen@gents..
do not authori.ze a change in effluent types or total amounts-nor an increase in power level 'and will not result in any signi'ficant environmental impact.
Having made this determination, we have further concluded that these amendments involve an action which is insignificant from the standpoint of envi'ronmental
- impact, and pursuant to 10 CFR Section 51.5(d)(4) that an. environmental impact statement, or negative declaration and environmental impact appraisal need not 5e 'pi epared io connection with the,i'ssuance of these amendments.
4 5.,0 'Conclusions.
.We have concluded based on the considerations discussed above that:
(1) because the amendments do not involve a s:ignificant increase in the probability or consequences of accidents: previously considered and do not involve a si'gnificant decrease in a safety margin, the amendments do not involve a significant hazards, consideration,'2) there is reasonable assurance that the health and safety of the public will not be endangered by operation'in the proposed
- manner, and (3) such activities will be conducted in compliance with the Commission's, regulations and the issuance of these amendments will not be inimical to the common defense and security or to the:health and safety of the public.
Dated:
April 1, 1982