ML18029A238
| ML18029A238 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry, Oconee  |
| Issue date: | 10/16/1984 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML18029A237 | List: |
| References | |
| NUDOCS 8411060313 | |
| Download: ML18029A238 (9) | |
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UNITED STATES NUCLEAR REGULATORY COMMlsslON WASHINGTON, D. C. 20555 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO. 114 TO FACILITY OPERATING LICENSE NO.
DPR-33 AMENDMENT NO. 108 TO FACILITY OPERATING LICENSE NO.
DPR-52 AMENDMENT NO.
82 TO FACILITY OPERATING LICENSE NO.
DPR-68 TENNESSEE VALLEY AUTHORITY BROWNS FERRY NUCLEAR PLANT UNITS 1, 2
AND 3 DOCKET NOS. 50-259, 50-260 AND 50-296 1.0 Introduction By letter dated April 30, 1982 (TVA BFNP TS 173) and supplemented by letter dated June 10, 1982, the Tennessee Valley Authority (the licensee or TVA) requested amendments to Facility Operating License Nos.
DPR-33, DPR-52 and DPR-68 for the Browns Ferry Nuclear@lant, Units 1, 2 and 3.
The proposed amendments would revise the Technical. Specifications appended to the above Facility Operating Licenses to:
- 1) revise the operability requirements for the reactor water cleanup (RWCU) system isolation instrumentation,
- 2) revise the operability requirements for the residual heat removal service water (RHRSW) pumps,
- 3) revise the suppression chamber water level datum for HPCI suction switchover,'4) delete surveillance requirements for RWCU system compartment temperature detectors,
- 5) clarify operability and surveillance requirements on the residual heat removal (RHR) pumps,
- 6) revise the bases for drywall-to-torus leak rate testing,
- 7) correct a typographical error, 8) revise the requirements on control rod drive maintenance when fuel is present around the rods,
- 9) for Unit 2 only, revise the surveillance requirements on standby coolant supply pump operability, and 10) revise raw milk sampling requirements.
2.0 Evaluation 2.1 RWCU S stem Hi h
Tem erature Sensor (Units 1,2,3)
Technical Specification Table 3.2.A requires that the reactor water cleanup system floor drain high temperature instrumentation be operable with two channels per trip system.
A proposed change would expand this requirement to specify that each trip system requires two independent channels from each of the two floor drain locations.
(This change is consistent with the as-built facility and is not the result of a modification).
This change provides clarification only and is acceptable.
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2.2 RHRSW Pum Timers Units 1,2,3 The licensee has requested changes to the residual heat removal service water
{RHRSM) pump timer assignements to each Unit.
Pump timers Al, 83, Cl, and D3 would be assigned to Units 1 and 2 replacing timers A1, 83, Cl, and Dl.
Timers A3, Bl, C3, and Dl would be assigned to Unit 3, replacing Al, 83, Cl, and D3.
The revised assignments are consistent with FSAR figMre 10.9.3 control logic requirements and are acceptable.
2.3 HPCI Suction Switchover Set oint (Units 1,2 3
Table 3.2.8 of the Technical Specifications specifies the high pressure cooTant injection (HPCI) suction trip level setting as "7" above normal water level".
A change proposed by the licensee would revise the trip level setting to "7" above instrument zero".
This would provide a fixed datum, making the Trip level independent of future changes to the normal water level.
This change in itself would not result in a change to the setpoint and is therefore acceptable.
2.4 Editorial Correction Units 1,2 3
Note 9 to Table 3.2.8 of the Technical Specifications'efers to paragraph "3.5. I" for a list of pressures to be maintained by the head tank.
The licensee has requested that Note 9 be changed to reference "3.5.H"; this change would correct an editorial error and is therefore acceptable.
2.5 RWCU Instrumentation Surveillasae (Units 1,2,3 The licensee has requested changes to Technical Specification Table 4.2.A to delete surveillance requirements for the reactor water cleanup space temperature detectors (RTDs).
The RWCU space temperature RTD channels are not part of the primary containment isolation system and have no related safety limit or limiting condition for operation.
(Separate channels using temperature switches are provided for RWCU floor drain/space high temperature isolation).
Based on consistency with 10 CFR 50.36(c),
and NUREG-0123 BWR Standard Technical Specifications this change is acceptable.
2.6 RHR S stem 0 erabilit (Units 1,2,3 The RHR system for each unit consists of four loops (A,B,C, 5 D).
Each loop consists of a pump, heat exchanger, piping path; and associated diesel generator.
If two RHR pumps or associated heat exchangers are inoperable, Specification 3.5.8.6 permits operation for seven days if the remaining two loops are operable.
Specification 3.5.8.6 does not specifically include a
requirement for operability of the diesel generators associated with the
remaining trains.
- However, such a requirement is intended as evidenced by the associated surveillance specification which includes the diesel generators in the surveillance tests.
A change proposed by TVA would revise 3.5.B.6 to specifically include a requirement for operability of the associated diesel generators serving the operable redundant RHR trains.
This change would revise the limiting condition for operation, to be consistent with its associated surveillance requirement and with Specification 1.0.E (definition of "operability").
This change is therefore acceptable.
2.7 Dr ell to Su ression Chamber Leaka e
Units 1,2 3
Technical Specification 4.7.A.4.d requires a periodic test to determine if drywell to suppression chamber leakage is within a limit of 0.14 pounds per second of air when the pressure differential is 1 psi.
The bases for 4.7.A.4.d states that 0.14 pps-'f air corresponds to a 0.25 inches of water per minute rate-of-change of suppression chamber pressure.
Based on a
suppression chamber air volume of 119,000 cubic feet, the correct value or the rate-of-change is 0.38 inches of water per minute.
TVA has proposed that the bases for 4.7.A.4.d be revised accordingly.
This change would correct the error and is acceptable'.8 Standb Coolant Su l
(Unit 2 Standby coolant supply connection and RHR crossties are provided to maintain a, long-term reactor core and primary containment cooling capability independent of primary centainment integrity or operability of the Residual Heat Removal System associated with a given unit.
The standby coolant supply connection and RHR crossties provide added long-term redundancy to the other emergency core and containment cooling systems, and are designed to accommodate certain situations which could jeopardize the functioning of these systems.
By proper valve alignment, the network created by the standby coolant supply connection and RHR crossties permits the D2 (or Dl) RHR service water pump and header to supply raw water directly to the reactor core of Units 1 or 2 as the reactor pressure approaches 50 psig.
The service water pump and header can also be valved to supply raw water to the drywell or suppression chamber of either unit.
In a similar fashion, the B2 (or Bl)
RHR service water pump and header can supply raw water to the reactor core of Units 2 or 3 or into the respective suppression chambers.
Technical Specification 4.5.C.4 for each Browns Ferry unit specifies:
"lrihen it is determined that one of the RHRSll pumps supplying standby coolant is inoperable at a time when operability is required, the
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operable RHRSW pump on the same header and its associated diesel generator and the RHR heat exchanger header and associated essential control valves shall be demonstrated to be operable immediately and every 15 days thereafter."
Because Unit 2 has four pumps available,
{by virtue of crossties to both the BED headers) whereas Units 1 and 3 only have two, this requirement sometimes requires unnecessary diesel testing when Unit 2 is operating and Unit 1-or 3 is in an outage.
(The Technical Specifications for Unit 2 require additional testing upon loss of one of four pumps, whereas the Technical Specifications for Units 1 and 3 require additional testing upon loss of one of two pumps).
The licensee has requested a change to the Unit 2 Technical Specification to require testing of the operable RHRSW pump heat exchanger, control valves, and associated diesel generator when it is determined that three pumps are inoperable.
This will provide compatibility with Units 1 and' in that for each unit additional testing will be required when only one pump is available for supplying standby coolant.
This change is therefore acceptable based on consistency'ith Units 1 and 3.
2.9 Control Rod Drive Maintenance nits 1,2,3 Tennessee Valley Authority has requested changes to the Technical Specifications that would alter the ':requirements for performing maintenance on control rods without removing the fuel assemblies surrounding them.
The staff has reviewed the proposed changes and prepared the following evaluation.
The current Technical Specification 3.10.A permits-maintenance on a
control rod without removal of fuel from around the rod if analysis has demonstrated that the core will be subcritical by at least 0.38 percent delta k/k with that rod and the strongest additional rod completely withdrawn.
Alternatively, if all other control rods are fully inserted and have their directional control valves electrically disarmed, it is not necessary to assume the second rod to be withdrawn.
For two rods to be withdrawn similar conditions prevail except that the margin to subcriticality is not
-specified.
Any number of rods may be withdrawn if the fuel surrounding each rod is first removed from the core.
In each circumstance described above the mode switch must be locked in the refuel position and be operable.
Withdrawn rods may be bypassed in order to satisfy the "one-rod-out" interlock.
No fuel may be loaded into the core unless all rods are fully inserted.
Two factors motivate the request for a change in the Technical Specification.
Except for specific times in the cycle {beginning of cycle,
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VL e.g.) the identity of the strongest rod and the shutdown margin are not known.
Extensive calculation are required to obtain this knowledge.
In addition, the requirement for disarming all remaining directional control valves during single rod maintenance (the most often encountered situation) requires a time consuming procedure which results in added personnel exposure and wear on the directional control valve electrical connectors.
The revised Technical Specification deletes the requirement to obtain the "strongest-rod-out" shutdown margin and replaces it with a requirement to demonstrate margin to criticality for the situation in which maintenance is to be performed on two rods.
For performing maintenance on a single control rod only the immediately surrounding rods are required to have their directional control valves disarmed.
Surveillance on the refueling interlocks must also be performed prior to withdrawing the rod for maintenance.
For maintenance on two non-adjacent control rods without removing fuel from the cells all other control rods must have their directional control valves disarmed electrically.
The two maintenance cells must be'separated by more than two control cells in any direction.
As before, any number of control rods may be removed for maintenance if the fuel is removed from each cell prior to the removal of the rod.
Withdrawal of a single control rod from the core will not result in criticality since sufficient shutdown margin is required to preclude its occurrence.
The single rod withdraw'n interlock prevents the withdrawal of a second rod.
Performance of surveillance on the interlock prior to withdrawing the rod assures that the interlock is operable.
Additional assurance against withdrawal of a ~h worth adjacent rod is provided by electrically disarming three directional control valves on these rods.
We conclude that sufficient control exists to preclude inadvertent criticality when maintenance is being performed on a single rod.
When maintenance is being done on two rods without fuel removal additional precautions are required.
Prior to withdrawal of the second rod a
determination is made that criticality will not occur when the rod is withdrawn.
l.ow worth of the second rod is assured by the requirement that it be separated from the first by more than two control cells in each direction.
Additional assurance that a third rod cannot be withdrawn is provided by the requirement that all remaining rods have their directional control valves electrically disarmed.
An additional requirement that the source range monitor be operable provide assurance that the subcriticality of the core may be monitored at all times.
We conclude that sufficient controls exist to preclude inadvertent criticality when maintenance is being performed on two rods simultaneously.
Based on our review, which is described
- above, we conclude that the
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I fl proposed revisions to Technical Specification,3.10.A of Browns Ferry Nuclear Plant, Units 1, 2, and 3 are acceptable.
2.10 Raw Milk Sam lin (Units 1,2,3 Environmental Technical Specifications (Appendix B) Paragraph 4.2.3.b requires that "milk shall be collected monthly when animals are off
- pasture, from at least four farms in the vicinity of the plant and analyzed as indicated in Table 4.2-1 and figure 4.2-1."
Figure 4.2-1 depicts five dairy farms.
The licensee has requested a change to the figure deleting two of the dairy farms and adding a
new one, stating that the two deleted sampling points no longer have milk producing animals.
This change is acceptable based on the need to have four locations with milk producing animals.
3.0 Environmental Considerations The amendments involve changes in the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20 and in surveillance requirements.
%e staff has determined that the amendments involve no significant in'crease in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no signii'icant increase in individual or cumulative occupational radiation eXposure.
The Commission has previously issued a proposed finding that the amendments involve no significant hazards consideration and there has been no public comment, on such finding.
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.
4.0 Conclusion We have 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, and (2) 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'efense and security or to the health and safety of the public.
Principal Contributor:
W. Brooks, W. Long, R. Clark October l6, l984
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