ML20206T364
| ML20206T364 | |
| Person / Time | |
|---|---|
| Site: | Oconee  |
| Issue date: | 05/22/1989 |
| From: | Hodges M Office of Nuclear Reactor Regulation |
| To: | Matthews D Office of Nuclear Reactor Regulation |
| Shared Package | |
| ML20206S598 | List: |
| References | |
| FOIA-99-28 TAC-M68080, TAC-M68081, TAC-M68082, NUDOCS 9902110336 | |
| Download: ML20206T364 (4) | |
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NAY ! ! 1989 MEMORANDUM FOR:
D. B. Matthews, Project Director Project Directorate II-3 Division of Reactor Projects I/II FROM:
M. Wayne Hodges, Chief Reactor Systems Branch Division of Engineering & Systems Technology
SUBJECT:
OCONEEINADEQUATECORECOOLING(ICC)
TECHNICAL SPECIFICATI0f15 Plant Name:
Oconee 1, 2, 3 TAC No.:
68080, 6808I, 68082 Docket No.:
50-269, 50-270, 50-287 Project Directorate:
Project Directorate II-3 Project Manager:
D. Hood
)
Revew Branch:
SRXB Review Status:
Complete The Reactor Systems Branch has reviewed Oconee's Technical Specifications for ICC instrumentation and we find them acceptable. However, we believe that their technical justification section on RVLIS is misleading and we have reiterated our strong belief for the need for RYLIS.
4".a!F.mdby M. Wayne Hodges, Chief 9902110336 990203 Reactor Systems Branch QfQS Division of Engineering & Systems Technology PDR
Enclosure:
DISTRIBUTION As stated pocket tile SRXB R/F MWHodges cc:
A. Thadani
' LPhillips G. Lainas GSchwenk D. Hood GSchwenk R/F SRXB Members Oconee P/F
Contact:
G. Schwenk, SRXB x10878 ST SRXB. DEST SRXB: DES GSCHWEP:j5 PHILLIPS MWHODGES f,
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If two channels are inoperable, at least one channel shall be restored to operable status within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br />, or the unit shall be in hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
For Wide Range Hot Leg Level and Reactor Vessel Head Level:
If one channel is inoperable, the channel shall be restored to operable status within 7 days, or a report shall be submitted to the Comission within the next 30 days outlining the cause of the inoperability and the plans and schedule for restoring the channel to operable status.
If two channels are inoperable, at least one channel shall be restored to operable status within 7 days, or the unit shall be in hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br />.
For Subcooling Monitors:
If one of the required channels is inoperable, at least one channel shall i
be restored to operable status within 30 days or the unit shall be in hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and below 300*F within the next 24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
If two of the required channels are inoperable, at least one channel shall be restored to operable status within 48 hours5.555556e-4 days <br />0.0133 hours <br />7.936508e-5 weeks <br />1.8264e-5 months <br /> or the unit shall be in hot shutdown within the next 12 hours1.388889e-4 days <br />0.00333 hours <br />1.984127e-5 weeks <br />4.566e-6 months <br /> and below 300'F within the next f
24 hours2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br />.
We have reviewed these Specifications and find them more consistent with the GL'b8-37 guidance than are the existing Technical Specification, even though the action statements are isss restrictive than recomended in the generic j
letter. We conclude that they provide adequate assurance that these instruments will be operable when their use is required. Therefore, we find the proposed Specifications acceptable. However, we disagree with the
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1 licensee's technical justification section which discusses the Reactor Vessel LevelIndicationSystem(RVLIS). We believe that this justification could be interpreted to mean that RVLIS is not useful for any risk-significant ever.t.
The staff must reiterate our strong belief that RVLIS is a necessary instrument. The addition of a reactor coolant inventory system will improve the reliability of plant operators to diagnose the approach of ICC and to i
assess the adequacy of responses taken to restore core cooling. The benefit will be preventive in nature in that the instrumentation will assist the operator in avoidance of a degraded or melted core when voids in the reactor coolant system and saturation conditions result from over cooling, steam generator tube rupture, and small break loss of coolant events. The addition of a reactor coolant inventory system, coupled with upgraded in-core thermocouple instruments and a subcooling margin monitor, provides an ICC instrumentation package which could reduce significantly the likelihood of incorrect operator diagnosis and errors for events such as steam generator tube ruptures, loss of instrument bus or control system upsets, pump seal failures, or overcooling events originating from disturbances in the secondary coolant side of the plant. For low probability events, involving coincidental multiple faults or more rapidly developing small break LOCA conditions, the ICC instrunentation could also reduce the probability of incorrect operator diagnosis and subsequent errors leading to a degraded core.
The staff also cautions the licensee about the difficulty in using the probabilistic risk assessment of a loss of inventory event to show the benefits of RVLIS.
It is very important that such an assessment be properly.
adjusted to include the incremental improvement which might result from the inclusion of RVLIS. For example, if it is assumed that RVLIS does not provide any new information but only redundant to existing information or if RVLIS is not fully utilized in procedure for a given scenario, such a scenario would be virtually unaffected by the addition of RVLIS. Such an assumption gives no
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credit for early detection of ICC with vessel water level indication and the corresponding potential for corrective operator action or for benefits for j
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using RYLIS when the other instruments give failed or incorrect readings.
Lastly, it is important to recognize that staff believes that being able to l
ascertain reactor water level is of fundamental importance as a safeguard in dealing with beyond design bases events and potential sequence which have not been previously considered or analyzed. The staff also believes that'it is important that RVLIS be fully utilized in the plant procedures and will review j
this area in depth during our review of the Babcock & Wilcox Owenrs Group i
Abnornal Transient Operating Guidelines.
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