ML20086C021
| ML20086C021 | |
| Person / Time | |
|---|---|
| Site: | Fermi  |
| Issue date: | 11/19/1991 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20086C017 | List: |
| References | |
| NUDOCS 9111210321 | |
| Download: ML20086C021 (3) | |
Text
._-.. _ _ _ _ _. _ _ _., _ _ _.. _ _. _ _ _ _. _ _. _ _ _ _ _ _.. _ _ _ _.. _ _ _ _ _ _ _ _ - _ _ _ _.
- po ss eg*o UNITf D STATES NUCLE AR REGULATORY COMMISSION
{
.f WAsmN010N, D. C. 206%
% * * * * * /a SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR RECULATION RELATED TO AMEN 0 MENT NO. 76 TO FACILITY OPERATING LICENSE NO. NPF-43 DETROIT EDISON COMPANY FERMI-2 00,0KET NO. 50-341
1.0 INTRODUCTION
By letter dated December 22, 1988, the Detroit Edison Company (Deco or the licensee) requested an amendment to the Technical Specifications (TS) appended to facility Operating License Kn. Npf-43 for Termi-2. The proposed amendment would revise the TS by allowing routine TS surveillance testing of the reactor water cleanup system (RWCS) without necessitating renovel of the RWCS from service.
2.0 EVALUATION Currently, the TS indicates that there is one channel per trip system for the RWCS containment isolation instrumentation for the RWCS Differential Flow - High Trip Function. This does not accurately reflect that this_ trip function is accomplished by a combinatirn of redundant and non-redundant components.
The RWCS Differential flow - High Trip Function is accomslished by measuring flow into and out of-the RWCS at three locations where tae RWCS has an interface with other plant systems. These locations are:
RWCS inlet from tht ReactorCoolantSystem(RCS),
RWCS outlet to the RCS, and RWCS outlet to the Main Condenser and/or Radioactive Waste System.
The flow at each location is measured by a single flow transmitter which is input to a single flow summer circuit.
If the measured in-flow to the RWCS exceeds the peasured out-flow by the specified setpoint, a trip signal is generated for two. separate channels, each of which causes the closure of-a RWCS inlet primary containment isolation valve. One channel closes the inboard valve and--the other channel closes the outboard valve.
Inoperability of a flow transmittar or of the sumer circuit causes both channels to be
-inoperable. TS-Action 23 requires the RWCS to be isolated within cae hour-if both channels are inoperable.
93112J 0321 913j39 08 p
ADOCK 0500034 y von
_,_,_.__..._a,_,,._.._.,_._.,_._,.
O,,
Performance of a channel functional test is required by the TS for the RWCS Differential Flow - High Tria function on a quarterly basis. This testing requires both channels for tie trip function to be made inoperable since the testing affects tt.e non-redundant equipment coninon to both channels. The one hour time allowed oy Action 23 is insufficient to perform this testing, thus requiring the RWCS to be taken out of service each quarter.
This frequent requirement to remove the RWCS is detrimental in two ways.
First, the RWCS components are subject to more frequent cycling both in system temperature ano pressure.
This increases the rate of cyclic fatigue, which will increase the probability of a system component failure and a possibic radioactive release within the secondary containment.
Second, the frequent plant evolution increases the chance of plant transients.
1rproper operation of the system could adversely effect reactor water level and other parameters which are monitored for protective reasons and could lead to an undesirabit transient.
The provisions proposed in the December 22, 1988, application to alleviate this situation are contained in a new table notation (h) which is applied tc the itinimum Operable Channels per Trip System requirement for the RWCS Diffarential Flow - High trip function contained in TS Table 3.3.2-1, Isolation Actuation Instrunentation. The proposed ncte (h) reads:
(h) This trip function is derived from three non-redundant flow transmitters and 4. non redundant flow sunmr.
Inocerebtlity of the non-redundant circuitry causes the channeh in both trip systems to be inoperable. The remainder of the circuit is redundant and can be considered on a per trip system basis.
Both trip systems may be placed in an inoperable status for up to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> for required surveillance of the noa-redundant circsitry without taking the required ACTION provided that the cemainder of the Reactor Water Cleanup System Isolation channels (exceptSLCSInitiation)areOPERABLE.
The proposed footnote provioes additional information concerning the systen design as f ar as the combination, for this trip function, of non-redundant and redundant equipment. This information adds r,1arity to the requirements, in this manner, the change promotes safety by adding assurance that incorrect action is not taken, particularly in the event that a non-redundant component is determined to be inoperable.
The proposed footnote also gives provisions that allows surveillance testing of the non-redundant circuitry without necessitating removal of the RWCS from service. The time allowed without taking the required TS action to isolate the RWCS is two hours. This is consistent witt, the time period allowed in table notation (a) of the same table. Note (a) applies to a similar situation for channels made inoperable for testing where other channels in the same trip system renain operable for the same trip function.
~
3 The proposed note (h) also requires that the remainder of the RWCS isolation instrumentation channels, except the Standby Liquid Control System (SLCS) initiation signal, be operable during the differential flow surveillance testing. The channels aret i
Heat Exchanger / Pump /High Energy Piping Area Temperature - High, j
Heat Exchanger / Pump / Phase Separator Area Ventilation Differential Temperature - High, and Reactor Yessel Low Water Level - Level 2.
These signals provide both redundancy (in that-both trip systems must be operable) and diversity (in three signal sources) to assure that a RWCS breach is detected and automatically isolated should such a breach occur during the l
proposed two hour period.
The SLCS isolation signal is not associated with the containment isolation function and therefore it is not necessary to include it in this provision.
Based upon'the above, the proposed changes to the TS to allow for RWCS Differential Flow - High Surveillance Testing are acceptable.
3.0 STATE CONSULTATION
in accordance with the Commission's regulations, the Michigan State official was notified of the proposed issuance of the amendment. The State official had no comments.
4.0 ENVIRONMENTAL CONSIDERATION
Pursuant to 10 CFR 51.21, 51.32 and-51'.35, an environmental assessment and ~
-finding of no significant imp (act has been prepared published in the Federal Register on August 31, 1989 54 FR 36071).
Accordingly, based upon the environmental assessment, the Ocmission has
- determined that issuance of this. amendment will not have a significant effect _
on the quality of the human environment.
5.0 CONCLUSION
The staff has concluded, based on the considerations discussed above that: (1)
Lthere is reasonable assurance that the health and safety (2) such activiti not-be endangered by operation in the proposed manner,-
will be. conducted in. compliance with the Comission's regulations, and (3) the issuance of the amendment will not-be inimical to the connon defense and security er to the health and safety.of the.public.
Principal Contributor:- John Stang, PDlli-1/NRR Date:- November 19, 1991 d
,;., n n
,,..-..i.
~...c-
.