ML20248D449
| ML20248D449 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 08/03/1989 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20248D443 | List: |
| References | |
| NUDOCS 8908110043 | |
| Download: ML20248D449 (5) | |
Text
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UNITED STATES NUCLEAR REGULATORY COMMISSION
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ENCLOSURE 3 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO.122 TO FACILITY OPERATING LICENSE NO. DP AND AMENDMENT NO.111 TO FACILITY OPERATING LICENSE NO. DPR-79 TENNESSEE VALLEY AUTHORITY SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2 DOCKET N05. 50-327 AND 50-328
1.0 INTRODUCTION
the Tennessee Valley Athority (the licensee)
By letter dated December 22, 1988, proposed to modify the Sequoyah Nuclear Plant (SQN), Units I and 2, Technical The proposed changes are to delete inappropriate surveillance Specifications (TS).
testing requirements associated with tne auxiliary building gas treatment system (ABGTS). Surveillance requirements (SR's) for ABGTS actuation exist in These are Section_7, " Plant Systems," and Section 9, "Refjeling Operations."
SR 4.7.8.d.2 and 4.9.12.d.2, respectively, The ABGTS SR's from Section 7 are applicable during Modes 1, 2, 3, and 4; and the ABGTS SR's from Section 9 are applicable whenever irradiated fuel is in the storage pool.
The ABGTS test requirement associated with the auxiliary building ventilation The ABGTS test munitoring system (ABVMS) would be deleted from Sections 7 and 9.
requirements associated with a phase A containment isolation signal would The high radiation
'be deleted from Section 9 but would remain in Section 7.
signal from the spent fuel pool monitors would be deleted from Section 7 but A new requirement would be added to Table 4.3.-9 of remain in Section 9.
Specification 3.3.3.10. " Radioactive Gaseous Effluent Monitoring," to demonstrate automatic isolation of the auxiliary building ventilation exhaust any time the ABVMS (radiation monitor) indicates measured radiation levels above the alarm / trip setpoint. Also, two typographical errors in the Unit 1 Specification 3.3.3.10 would be corrected.
2.0 EVALUATION
2.1 System Description
The ABGTS is a fully redundant air cleanup system provided to reduce gaseous radioactive nuclide releases from the auxiliary building secondary containment enclosure (ABSCE) during < d dents.
It does this by drawing air from the fuel handling arei,s, weste packaging areas, and emergency core cooling system (ECCS) pump areas, through ducting normally used for ventilation purposes to air cleanup equipment, and then directing this air to the shield building In doing so, this system draws air from all parts of the auxiliary exhaust vent.
building to establish a negative pressure region in which virtually no unprocessed air passes from this secondary containment enclosure to the atmosphere.
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I The auxiliary building ventilation system (ABVS) is described in Sections 9.4.2 I
This system and 6.2.3 of the Sequoyah Final Safety Analysis Report (FsAR).
serves all areas of the auxiliary building including the radwaste areas and the It is designed to maintain acceptable environmental conditions for personnel access, for protection of mechanical and electrical fuel handling areas.
equipment and controls, and to limit the release of radioactivity to the environment.
The ABVS supply air is ducted to various clean or accessible areas of the auxiliary building and fuel. handling areas where it flows to areas of progres-sively greater contamination potential before being exhausted through a du system by the building exhaust fans.
building is provided by four exhaust fans, each rated at 50 percent of the These fans discharge into the auxiliary building exhaust system capacity.
vent.
Air utilized to ventilate the fuel handling, waste packaging, and cask shipping The discharge from areas is exhausted by the fuel handling area exhaust fans.
these fans is also directed into the auxiliary building exhaust vent.
During periods of high radiation in the auxiliary building exhaust or upon a containment isolation signal, the auxiliary building supply and exhaust fans The radiation in the auxiliary building ventilation are automatically stopped.
exhaust is monitored by the ABVMS. Low-leakage dampers located in the ducts, An isolation barrier is which penetrate the auxiliary building, are closed.
thus formed between the building and the outdoor civironment, and the ABGTS is automatically placed in service.
2.2 Plant Syste,m During Modes 1, 2, 3 and 4, surveillance of the ABGTS filter trains is required "ABGTS filter trains shall be demonstrated OPER-in SR 4.7.8.d.2 as follows:
ABLE by verifying, at least once per 18 months, that the filter trains start on a Containment Phase A Isolation test signal; or a high radiation signal from the fuel pool radiation monitoring system or the auxiliary building ventilation The licensee proposes to retain the SR on Containment monitoring system."
Phase A Isolation test signal only and delete the SR's on a high radiation signal from the fuel pool radiation monitoring system and the auxiliary building ventilation monitoring system.
In the current TS, both Section 3.7.8 (SR 4.7.8.d.2) and Section 3.9.12 (SR 4.9.12.d.2) address SR's from the spent fuel pool radiation signal (SFPRS).
The basis for Section 3.7.8 states that the operability of ABGTS is to ensure that radioactive materials leaking from the emergency core cooling system equipment following a loss-of-coolant accident are filtered prior to reaching the environ-Deletion of SR's on the SFPRS from Section 3.7.8 continues to satisfy this basis because the SR on the SFPRS in Section 3.9.12 remains and wou ment.
The 18 month test maintain a high degree of reliability of ABGTS actuation.
Under the frequency in Section 3.7.8 would be maintained in Section 3.9.12.
current TS, an inoperable fuel pool radiation monitor, while in Modes 1, 2, 3 and 4, would require that ABGTS be declared inoperable and could possibly 2
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. result in a plant shutdown which is considered by the staff to be inappro-priate. The NRC standard technical specifications (STS) for Westinghouse PW do not require a plant shutdown for an inoperable ABGTS.Therefore, t house PWR.
The proposed deletion of the auxiliary building ventilation monitoring system from SR 4.7.8.d.2 and 4.9.12.d.2 was justified for the following reasons. The (1) Phase A containment ABGTS is automatically initiated by four signals:
isolation (2) high radiation in the fuel handling area, (3) high radiation in the auxiliary building exhaust vent and (4) high temperature in the auxi-Even though the high radiai.icn signal in the 11ary building air intakes.
auxiliary building vent is one of the signals, it is not assu to the environment is isolated once the vent exhaust radiation mo the trip setpoint.
Upon in unrestricted areas are maintained in accordance with 10 CFR 20.
receipt of their respective signals, the supply and exhaust fans and fuel handling area exhaust fans stop; and dampers in the normal ABVS pa the auxiliary building vent.Thus, the auxiliary bLilding vent is not a post-acci-building exhaust vent. dent release path, and the radiation monitor provides no furt following an isolation.
The cur _ rent ABGTS SR's 4.7.8.d.2 and 4.9.12.d.2 impose inappropriate actions Should the single auxiliary building vent radiation for an-inoperable ABVMS.
monitor become inoperable, the ABGTS must be declared inoperable and conse-Since simi quently a plant shutdown is required by Specifications 3.0.3.
effluent monitoring technical specifications allow continued reactor operation with vent path sampling, shutdown of the plant due to an inoperable auxiliary building vent radiation monitor is inappropriate.
The staff agrees with the licensee that ABGTS activation upon a high radiation signal from the auxiliary building ventilation monitoring system is in any accident analysis.
to an inoperable auxiliary building vent radiation monitor would this release pathway isolation every 18 months (See Section 2.4) which is priate.
Thus, assur-consistent with the 18 months in SR's 4.7.8.d.2 and 4.9.12.d.2.
ance of the capability to prevent radioactive release in excess of 10 CFR Part This is consistent with the bases 20' limits to the environment is maintained.The staff finds the licen;ee's propos for TS 3.3.3.10.
2.3 Refueling
" ABGTS filter train In TS Section 4.9.12.d.2, the following SR's are required:
shall be demonstrated OPERABLE by verifying that the filte fuel pool radiation monitoring system or the auxiliary building ven monitoring system." Phase A Isolation test signal and the signal from the auxiliary b ventilation monitoring system.
m_
. The reasons for not requiring ABGTS for the radiation signal from the auxiliary Principally, the high building vent were provided above (see Section 2.2). radiation path.
The reason for deleting the signal response from the Containment Phase A Isolation test signal is as follows:
limitations on the ABGTS ensure that all the radioactive Deletion of the Containment adsorbers prior to discharge to the atmosphere.
Phase A Isolation test signal from SR 4.9.12.d.2 continues to satisfy the bases because TS Section 4.9.12.d.2 retains the SR for a high radiation signal fr the fuel pool radiation monitoring system.
ment Phase A Isolation test signal is retained in SR 4.7.8.d.2 for Modes 1, 2, Since the TS Bases are 3 and 4 primarily to mitigate LOCA's (see Section 2.2).
met with the proposed changes, the staff finds the proposed changes accept Instrumentation; Radioactive Gaseous Effluent Monitoring 2.4 The licensee proposed to add a new requirement to Specification 3.3.3.10
" Radioactive Gaseous Effluent Monitoring," to demonstrate automatic isolation of the auxiliary b'ufiding ventilation exhaust cny time the exhaust radiation This require-monitor indicates measured levels above the alarm / trip setpoint.
ment is currently performed as part of the ABGTS actuation test from a high radiatton signal from the ABVS in SR's 4.7.8.d.2 and 4.9.12.d.2 but wouldTh be del ~eted by the proposed changes to the TS.
2.2.
"For the auxiliary The proposed addition to Table 4.3.-9, is as follnws:
building ventilation system, at least once every 18 months, the CHANNEL FUNCTIONAL TEST shall also demonstrate automatic isolation of this if the following condition exists:The proposed TS change is equivalent to the current the alarm / trip setpoint."
requirements in SR's 4.7.8.d.2 and 4.9.12.d.2 for requiring a test ABGTS using the ABVMS.
tion for the ABVMS are listed as item "5" of Table 4.3-9. Not meeting the proposed TS (inoperable channels) would lead to grab sample analyses The effluent whereas not meeting the current TS would result in cold shutdown.
justification for not requiring plant shutdown was presented in Section 2.2.
Therefore, the addition of the new requirement is acceptable to the staff.
2.5 Other Proposed Changes The Two typographical errors in the Unit 1 TS 3.3.3.10 would be corrected.
typographical corrections in the TS (Page 3/4 3-80) are strictly administra and do not alter any intent of the specification. The first correction is made The second correction adds partial sentences inadver-The added words are consistent with the to a misspelled word.
tently onitted from a table notation.
The staff finds the Unit 2 TS 3.3.3.10 and the wording used by the STS.
proposed changes acceptable.
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. ENVIRONMENTAL CONSIDERATION t to the instal-3.0
'These amendments involve a change to a requirement with respec lation or use of a facility component located within the restricted are defined in 10 CFR Part 20 and changes to the surveillance requirem increase in The staff has determined that the amendments involve no significant ffluents that may the amounts, and no significant change in the types, o individual or hazards cumulative occupational radiation exposure.
issued a proposed finding that these amendments involve no signifi ding.
consideration and there has been no public comme l
exclusion set forth in 10 CFR 51.22(c)(9). environmental im be prepared in connection with the issuance of these amendments.
CONCLUSION 4.0 _
l o
The Commission made a proposed determination that the amendme l Register significant hazards consideration which was published in the Fede No public comments were received and the Sta have any comments.
h The staff has concluded, based on the considerations discussed a (1) there is reasonable assurance that the health and safety (2)such will not be endangered by operation in the proposed manner, and i
gulations, activities will be conducted in compliance with the C defense and security nor to the health and safety of the public.
S. B. Kim 1
Principal Contributor:
Dated: August 3, 1989 I
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