ML20028H413
| ML20028H413 | |
| Person / Time | |
|---|---|
| Site: | Grand Gulf  |
| Issue date: | 12/26/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20028H414 | List: |
| References | |
| NUDOCS 9101020397 | |
| Download: ML20028H413 (7) | |
Text
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Mr. William T. Cottle.
TS 3.6.1.9 - Replace the limitation on usage of the purge system to not more than 1000 hours0.0116 days <br />0.278 hours <br />0.00165 weeks <br />3.805e-4 months <br /> per year with a general statement that the purge systems will be used "only to maintain the primary containment atmosphere within established guidelines or for purge system maintenance, modifications or retests which require a purge system operating." Also ACTION b would be deleted.
TS 4.6.1.9.1 - Delete this surveillance requirement which requires a determination of the cumulative time that the purge system has been used during the past year at least once per 7 days.
The proposed administrative procedures would preclude usage of the containment purge systems in Operational Conditions 1, 2, or 3; except for the following reasons:
(1) Relative humidity greater than 90 percent, (2) Average containment temperature greater than 90 degrees F, (3) Explosive gas greater than the lower explosive limit, (4) Oxygen concentration less than 19.5 percent, (5) Airborne particulate radioactivity greater than 25 percent of the maximum permissible concentration (MPC) in 10 CFR Part 20, (6) Gaseous radioactivity greater than 25 percent of the MPC, (7) Containment pressure less than -2 inches water guage or greater than +5 inches water guage, and (8) Purge system operation required for surveillance or post maintenance tests The above eight reasons are the " established guideli'25" referred to in the proposed TS.
la Operational Conditions 4 and 5, operation of purge systems would not be restricted.
Based on its review of the licensees submittals, the staff agrees that the licensees proposed purge criteria (3) through (8) above are safety related and therefore, justifiable reasons for operating the purge system.
However, the containment purge system is not needed to control containment air quality and temperature, as demonstrated in a special test during which the purge systems were isolated.
Therefore, criteria (1) and (2) should not be used as purge criteria.
The parameters used in criteria (3) through (7) were r.onitored from February 17 to November 6,1987, during Fuel Cycle 2. Air samples taken during that period showed that oxygen concentrations remained near normal and explosive gases treained below the lower limit of detection.
Because of the relatively clean condition in the containment, airborne particulate radioactivity did not reach the criterion of 25 percent MPC.
The purge system was used once for 14 hours1.62037e-4 days <br />0.00389 hours <br />2.314815e-5 weeks <br />5.327e-6 months <br /> for containment pressure relief when a low pressure weather system caused a drop in atmospheric pressure.
The purge system was also used once for about
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Mr. William T. Cottle
- 4-11 hours to reduce gaseous radioactivity locally to perform maintenance on a leaking seal in the reactor water cleanup heat exchanger.
Although criteria (3), (4), and ($) were not needed during the monitoring period, they are safety-related reasons for purging and should be retained as purge criteria.
Criteria (6) and (7) were demonstrated as necessary purge criteria during the monitoring period.
With respect to criterion (8), the data taken during the monitoring period demonstrated that the purge systems were used primarily for surveillance tests (about 53 hours6.134259e-4 days <br />0.0147 hours <br />8.763227e-5 weeks <br />2.01665e-5 months <br />) and maintenance tests (about 7 hours8.101852e-5 days <br />0.00194 hours <br />1.157407e-5 weeks <br />2.6635e-6 months <br />).
Therefore, criterion (8) is needed.
Containment access monitoring during the period February 17 to November 6. 1987, showed that a total of 6910 manhours were spent in contain-ment for routine surveillance and maintenance.
This is equivalent to about 26 manhours per day.
However, only once was the purge system needed for about 11 hours1.273148e-4 days <br />0.00306 hours <br />1.818783e-5 weeks <br />4.1855e-6 months <br /> to reduce gaseous radioactivity for maintenance purposes.
As the plant ages and more maintenance is required on radioactive components, it may be n
necessary to increase the use of the purge systems.
Criteria ($) and (6) will permit such use for safety-related reasons.
In summary, the staf f concludes that criteria (3) through (8) above are safety-related and should be used to determine when the purge systems may be used during Operational Conditions 1, 2, and 3..
The total time that the low volume purgo and the high volume purge were used during the 225 day monitoring period was about 85 hours9.837963e-4 days <br />0.0236 hours <br />1.405423e-4 weeks <br />3.23425e-5 months <br />.
This is equivalent to 138 hours0.0016 days <br />0.0383 hours <br />2.281746e-4 weeks <br />5.2509e-5 months <br /> per year.
In consideration of the expected increased radioactivity of the plant as it. ages and conseqent need for more frequent purging, the staff concludes that aa upper i
limit of 400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br /> per year on. containment purging by the high volume purge and the low volume-purge is acceptable.
With respect to the proposed TS 3.6.1.9 changes, the staff concludes that:
(1) -The present limitation of 1000 hours0.0116 days <br />0.278 hours <br />0.00165 weeks <br />3.805e-4 months <br /> per year should be changed to 400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br /> per year, and (2) The purge criteria should be a part of the TS or Bases.
An acceptable TS would be to state that the purge systems shall be " opened only for safety-related reasons" and then list the six safety-related reasons.
Alternatively, the six safety-related reasons could be listed in the TS Bases.
The specification of the-safety-related uses in the TS is necessary to p_reclude use of the purge systems for nonsafety reasons.
l With respect to the proposed deletion of TS 4.6.1.9.1, the staff concludes that the requirement to determine the accumulated time the purge system has been used should be retained. However, the frequer.cy of the determination could be decreased _from once per 7 days to once per 31 days, i
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Mr. William T. Cottle 5-
3.0 CONCLUSION
The staff concludes that:
(1) The drywell purge limitations in TS 3.6.2.7 are acceptable and should remain the same; (2) The containment purge limitations in TS 3.6.1.9 should be changed to limit purging to 400 hours0.00463 days <br />0.111 hours <br />6.613757e-4 weeks <br />1.522e-4 months <br /> per year and only for safety-related reasons as defined in the proposed criteria (3) through (8) listed in 2.0 above. The proposed criteria (3) through (8) should be included either in the TS or the Bases; and (3) TS 4.6.1.9.1 should be retained; but the frequency of the surveillance may be reduced.
Dated:
Principal Contributors:
Angela Chu J. Kudrick
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W" GG LTR/66883 December 26,1990 DISTRIBU110N
M. Virgili-: -
!E4 T. Quay L. Derry L. Kintner C. McCracken H5801 000 MS15818 E. Jordan HNBB 3701 ACRS (10) MS P-315 PD4-1 Plant File R. Mullikin, Region IV
Mr. William T. Cottle December 26, 1990 The reporting and/or recordkeeping requirements contained in this letter affect fewer than ten respondents; therefore, OMB clearance is not required under P.L.96-511.
Sincerely, ORIGINAL SIGNED BY:
Lester L. Kintner, Senior Project Manager Project Directorate IV-1 Division of Reactor Projects III, IV, and V Office of Nuclear Reactor Regulation
Enclosure:
As stated cc w/ enclosure:
See next page DISTRIBUTION Docket File NRC PDR Local PDR' PD4-1-Reading
- 8. Boger MS14A1 H. Virgilio MS 13E4 T. Quay L. Berry L.'Kintner C.'McCracken MS801 OGC MS15B18 E. Jordan FNBB 3701 ACRS (10) liS P-315 PD4-1 Plant File R.'Mullikin, Region IV
- See Previous Concurrence
-OFC
- PD4-1/LA*
- PD4-1/PM*
- SPLB/BC*
- PD4-1/D
......:...................................................gye...................................
NAME :LBerry
- LKintner: 1h
- CMcCracken
- TQuay
' DATE :12/05/90
- 12/14/90
- 12/18/90
- \\*/1b/90 OFFICIAL RECORD COPY Document Name:
GG LTR/66883 i
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DEC 2 01990 MEMORANDUM FOR:
C. Ernie Rossi, Director Division of Operational Events Assessment Office of Nuclear Reactor Regulation FROM:
Thomas M. Novak, Director Division of Safety Programs Office for Analysis and Evaluation of Operational Data SUBJE(.T :
BWR MODE SWITCH EXPERIENCE Enclosed is an AEOD Engineering Evaluation concerning BWR reactor mode switch experience.
Events found in the evaluation represent unnecessary challenges to the reactor protection system and potential loss of the main condenser as a heat sink.
Type SB-1 reactor mode switches are still in use.
It is suggested that the Office of Nuclear Reactor Regulation consider issuing an information notice to alert BWR operators who still usc type SB 1 reactor mode switches to events involving this type reactor mode switch and provide BWR operators in general with information about these events, ff 81nn! Dicned byr ahomasM,so m Thomas M. Novak, Director Division of Safety Program:,
Office for Analysis and Evaluation of Operational Data
Enclosure:
As stated Distribution:
PDR JRosenthal GZech KRaglin, TTC Central File EJordan SRubin AChaffee, NRR ROAB R/F Dross MWilliams DSP R/F TNovak KBlack WJones VBenaroya RSavio, ACRS Glanik LSpessard MTaylor, ED0
'See previous concurrence:
/
ROAB:DSP:AE00 ROAD:DSP:AE0D C:ROAB:DSP:AE00 DSP:AE00 p.;,DperAE00 WJones:mmk' Glanik' JRosenthal' VBenaroya TWyak 6/13/90 6/14/90 6/15/90 12/l1/90 12/g/90 L
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ItEMORANDUM FOR:
Charles E. Rossi, Director Division of Operational Events Assessment Office of Nuclear Reactor Regulation FROM:
Thomas M. Novak, Director Division of Safety Programs Office for Analysis and Evaluation of Operational Data
$UBJECT:
BWR MODE SWITCH EXPERIENCE Enclo;ed is an AEOD Engineering Evaluation concerning BW reactor mode switch experience. Events found in the eveluation represent u ~necessary challenges to the reactor protection system and potential loss of t main condenser as a heat sink. Type SB-1 reactor mode switches are sti in use.
It is suggested that the Office of Nuclear Reactor Regulation cons)42).
er issuing a supplement to a previously issued information notice (NRC IN 8}c This supplement would serve to alert BWR operators who still use ty peB-1 reactor mode switches to events involving this type reactor mode switty and provide BWR operators with
/
the information about these events.
Thomas H. Novak, Director Division of Safety Programs Office for Analysis and Evaluetion of Operational Data
Enclosure:
As stated
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Distribution:
PDR JRosenthal HWillicms Central File EJordan KBlad ROAB R/F Dross RSay'.E. ACRS DSP R/F TNovak HTay Wr, EDO AE00 R/F LSpessard KRag11n, TTC WJones GZech PBaranowsky, NRR Glanik SRubin
/
- See previous concurrence:
ROAB:DSP:AEOD ROAB:DSP:AE0D C:ROAB:DSP:pE0D D:DSP:AF0D WJones:mk*
GLaniL*
JRosenthal,,4/d TNovak 6/13/90 6/14/90 6//(/90 6/ /90
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