ML20042G037
| ML20042G037 | |
| Person / Time | |
|---|---|
| Site: | Sequoyah  |
| Issue date: | 04/27/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20042G036 | List: |
| References | |
| NUDOCS 9005110018 | |
| Download: ML20042G037 (6) | |
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ENCLOSURE 3 SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION SUPPORTING AMENDMENT NO.137 TO FACILITY OPERATING LICENSE NO. DPR-77 AND AMENDMENT NO.123 TO FACILITY OPERATING LICENSE NO. DPR-79
,TJ.NNESSEEVALLEYAUTHORITY i
SEQUOYAH NUCLEAR PLANT, UNITS 1 AND 2 DOCKET NOS. 50-327 AND 50-328
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1.0 INTRODUCTION
By letter dated April 5, 1990, the Tennessee Valley Authority (TVA) proposed to revise Action Statement "a" of Limiting Condition for Operation (LCO) 3.8.1.1, minimum alternating current electrical power sources for the site, of the Sequoyah Nuclear Plant, Units 1 and 2 Technical Specifications (TSs).
These changes would add e footnote to the action statement for when one train of emergency diesel. generators (DGs) is inoperable to extend the allowable outage time for one train of DGs when the chemical cleaning of the DG fuel-oil storage tanks for a DG set is being performed.
The allowable outage time would be extended from 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br /> to 144 hours0.00167 days <br />0.04 hours <br />2.380952e-4 weeks <br />5.4792e-5 months <br />.
This is TVA TS Change Request 90-08.
The proposed revision to the action statement is to allow sufficient time for the cleaning of these tanks which is required by Surveillance Require-ment (SR)4.8.1.1.2.f.1.
The proposed revision would apply only to this SR and would extend the allowed outage time for a train of DGs to 144 hours0.00167 days <br />0.04 hours <br />2.380952e-4 weeks <br />5.4792e-5 months <br /> to clean the four tanks for one of the two DGs sets that constitute a train of DGs.
2.0 DISCUSSION A train of DGs at Sequoyah is two DG sets each set having four underground storage tanks.
A DG set is two diesel engines and one generator.
The four DG sets that comprise the two DG trains for the two Sequoyah units have a total of 16 storage tanks.
The 16 tanks are embedded inside the diesel generator building substructure below the DG sets.
The building houses the four DG sets.
Four of the 16 embedded DG tanks for one DG set will be cleaned at a time.
This will require the DG set for those four tanks to be considered inoperable because the DG' set would nct be able to receive fuel oil from its own tanks.
The affected DG set would be able to receive fuel oil from the tanks for the other DG set of the same train, from the tanks for the DG sets of the other train, from either of the two yard diesel fuel-oil storage tanks, or from tanker trucks brought onsite; but, by the TSs, this would not allow the affected DG set to be considered operable.
However, only one train of DGs would be affected at a time by the cleaning of the DG tanks.
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TVA evaluated the tasks required to clean the DG tanks for one DG set and pro-vided the following information on the time expected to perform the work and return the DG set and train to operable status.
TVA stated that the tasks to clean a set of four DG tanks include the following:
Connect temporary lines and verify operation.
Pump down embedded tanks and pull manways.
Pump out sludge and fuel residual and evacuate tank atmosphere.
Flush tanks with water and pump down.
Clean tanks of residue and rust.
Dry tanks.
Wipe tanks with sodium hypochlorite solution.
Quality control inspection of tanks Refill tanks with fuel-oil and replace manways, Remove temporary connections and make up permanent connections.
Perform surveillance tests of tanks to verify operability.
TVA has estimated that the planned duration, without allowance for contingen-cies, is approximately 100 hours0.00116 days <br />0.0278 hours <br />1.653439e-4 weeks <br />3.805e-5 months <br /> for each set of four embedded tanks. TVA has added an additional 44 hours5.092593e-4 days <br />0.0122 hours <br />7.275132e-5 weeks <br />1.6742e-5 months <br /> as a contingency allowance to resolve equipment problems, work in more severe environmental conditions than expected, and correct problems that may be found in a tank. Therefore, TVA has proposed 144 hours0.00167 days <br />0.04 hours <br />2.380952e-4 weeks <br />5.4792e-5 months <br /> that a DG set may be inoperable to clean its associated tanks.
L The total duration of 144 hours0.00167 days <br />0.04 hours <br />2.380952e-4 weeks <br />5.4792e-5 months <br /> exceeds the present 72-hour allowable outage time for one DG set or one train of DG sets.
This process would have to be repeated for each DG set.
As a results the present TSs require a two-unit shutdown for both units to perform de chemical cleaning required by SR l
4.8.1.1.2.f.1.
TVA states that su n a outage represents an unrealistic L
economic burden that was not considered when the TSs were first issued.
Although Unit 1 is currently shutdown for refueling at this time, Unit 2 is at l
L 100% power.
L 3.0 EVALUATION The DG fuel-oil tanks for the DG sets need to be cleaned.
The SR 4.8.1.1.2.f.1 requires these tanks to be cleaned once every 10 years, which is due now.
Cleaning these tanks will make the DG set associated with the tanks inoperable.
The Action Statement "a" for LC0 3.8.1.1 on the DG sets allows a DG set or a train of DG sets to be inoperable for 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />; however, TVA estimates that cleaning the tanks for one DG set may take up to 144 hours0.00167 days <br />0.04 hours <br />2.380952e-4 weeks <br />5.4792e-5 months <br />.
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The cleaning of these.DG tanks was discussed with TVA by the NRC project manager for Sequoyah during a visit to the site in the week of April 10 to April 13, 1990.
The project manager-toured the DG sets in the DG building.
The staff does not have a disagreement with the program to clean the tanks or
~ the estimate of 144 hours0.00167 days <br />0.04 hours <br />2.380952e-4 weeks <br />5.4792e-5 months <br /> to clean a set of four tanks for a DG set. The four tanks are piped togethey such that a tank or tanks can not be cleane6 sepa-rately from the other tanks, while the other tanks provide fuel-oil to the affected DG set.
The prudent plan is that once the program begins, it should continue until all four tanks for a DG set are cleaned.
To provide-fuel-oil.to the affected DG set, TVA will provide a temporary connection from the fuel tanks for the unaffected DG set of the same train as the af fected DG.
This will provide 3.5 days of fuel-oil for both DG sets of the affected train. The two DG sets of the other train will have their own DG tanks for a seven-day supply of fuel-oil.
The 3.5 days is sufficient to get more fuel-oil for the affected DG train from the yard tanks or tanker trucks brought onsite.
The tempurary connection is several industrial hoses joined together, each of which is circular woven fabric warp cords with heavy guage steel wire reinforcement around a diesel fuel-oil resistant rubber tube.
The hoses will have threaded couplings for connections and will be capabl+ of providing the required fuel flow to the affected DG set.
The hoses connect from one tank open to the atmosphere to a pump on the DG set which transfers oils to the day tanks or operating tanks for the DGs of the DG set.
The hoses will be at the suction pressure of the pump and are. rated for five inches Mercury vacuum.
The suction pressure of the pumps are at negligible inches Mercury vacuum.
The affected DG set will be able to get fuel-oil from the tanks for the other DG set of the same train, from the tanks for the DG sets of the other train, from either of the two yard diesel fuel-oil storage tanks, or from tanker trucks brought onsite. The only connection which is not hard piped is the temporary hoses being used to provide fuel-oil to the affected DG set. One of the two DG yard storage tanks will have a seven-day supply of fuel-oil available for a DG set and more can be brought onsite by tanker trucks.
The other DG yard tank will be used to store the fuel-oil pumped from the storage tanks until tanker trucks can remove it offsite.
Because the temporary hoses will breach the fire doors for both the DG sets of the affected DG train, TVA will have a continuous fire watch in the area while the firedoors are breached.
This fire watch will detect any fire, fuel-oil leaks, and damage to the hoses.
A fire watch as this one is a standard compensatory fire protection measure which is used when fire barriers are breached.
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One DG set and one DG train will be affected at a time.
If the non-affected DG train becomes inoperable for any reason and remains inoperable, the TSs require the operating units to shutdown in eight hours.
If the other DG set of the
'i affected train becomes inoperable and remains inoperable, the operating units must shutdown in 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />, as required by the TSs.
The proposed change to the maximum time allowed for a train of DG sets to be inoperable before the operat-ing units must shutdown applys only to cleaning the embedded fuel-oil tanks per SR 4.8.1.1.2.f.1 for one DG set at a. time.
Based on the above, the staff conclu' des that it is safe to have a single DG set temporarily connected to the embedded DG fuel-oil storage tanks of the other DG set of the same DG train by the proposed rugged, industrial hoses.
This is for when the Sequoyah units may be operating and for the 144 hours0.00167 days <br />0.04 hours <br />2.380952e-4 weeks <br />5.4792e-5 months <br /> estimated to be needed to clean the four embedded fuel-oil storage tanks for o DG set.
The temporary hoses to be used to provide fuel-oil to the affected DG set will be kept within the DG building, are of sufficient construction tu be acceptable for the time to clean the tanks, and will be observed during their use by the continuous fire watch.
4.0 EXIGENT CIRCUMSTANCES
TVA requested that this change be processed as an exigent change to support an expedited schedule to clean the embedded diesel generator fuel-oil storage tanks and replace the diesel fuel oil.
TVA stated that it had previously planned to pursue-this TS change as a regularly scheduled action item after the Unit 1 Cycle 4 refueling outage.
The request by TVA for.en exigent review by the staff of the proposed changes is based on the potential need to clean these tanks as soon as practical.
TVA has a fuel-oil sampling and analysis program intended to detect fuel deterior-ation.
Recently the results of diesel fuel-oil testing, while not out of compliance with TS acceptance criteria, identified an adverse trend with particulate levels in the fuel oil. TVA stated that the present particulate levels do not represent an operability concern but are indicative of fuel-oil deterioration.
As a result, it has expedited the chemical cleaning of the tanks which have not previously been cleaned since the plant was licensed and the replacement of the fuel-oil in the tanks.
This activity is planned for all four DG sets and would begin as soon as practical after receipt of the approval of this proposed TS change.
The staff is aware of this potential fuel-oil problem and agrees with TVA that the DG tanks should be cleaned as soon as practical because of the importance of the DGs during a loss of offsite power.
Therefore, the staff has concluded pursuant to 10 CFR 50.91(6) that exigent circumstances exist at Sequoyah in that (1) the licensee and the Commission need to act quickly and (2) time does j
not permit the Commission to publish this notice and allow 30 days for prior public coments.
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FINAL NO SIGNIFICANT HAZARDS CONSIDERATI the TSs and has determined that 5.0 d on criteria The staff has evaluated the proposed changes to a significant hazards consideration base The staff has concluced, based on Sect it does not repres:,4 established in 10 CFR 50.9 (c).above, that operation of Sequoy amendments wili:
bability or consequences of Not involve a significant increase in the pro an accioent previously evaluated.
tanks per SR 4.8.1.1.2.f.1 (1) l power The cleaning of the embedded DG fuel-oil storage The DGS are used to provide emergency e llowed time that a DG only effects the DGs.
to the site when offsite powerThe proposed change to increase the maximum The DG set train may be inoperable applys only to c for one DG set at a time.
ac ci <1e nt.
fuel-oil which is sufficient toof accide tanks per SR 4.8.1.1.2.f.a and only affected will be connected to a supply ofoperate th i
ll The other DG set in the affected DG tr TSs, if this DG set becomes unoperable If Final Safety Analysis Report.be operable but, as required by the ating units will be shutdown in 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
d remains inoperable, the dad remains inoperable, the oper A
hours, as required by the TSs.
non-affected DG train becomes inoperable an fire doors are breached toTherefore, the operating units will be shutdown in eight the h
continuoas fire watch will be posted where t edetec h temporary hose.
proposed action does not significantlyconsequen l
ted.
Not create the possibility of a new or di (2) previously analyzed.
nnected to the storage The DG day tanks of the affected DG set will be coin with temporar The temporary hoses will be tanks of the other DG set of the same traDuring this industrial hoses with threaded fittings.
detect potential fires, hose leaks, i
inside the DG building.affected DG rooms will be breached ano a c Therefore, the proposed action does not posted while the doors are breached to and damage to the hoses.the possibility of a new or different analyzed.
in of safety.
Not involve a significant reduction in a marg ffected by the cleaning of (3)
Only DGs and only one DG set at a time will be aThe temporary rugged, industrial hosesThe hoses are the embedded fuel-oil storage tanks.
fuel-oil to the affected DG set is severdiconnecte h DG building.
l from the rated above their intended use and wilThe affected DG set w other unaffected DG fuel-oil storage tanks, the tanks.
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5.0 FINAL NO SIGNIFICANT HAZARDS CONSIDERATION
S The staff has evaluated the proposed changes to the TSs and has determined that it does not represent a significant hazards consideration based on criteria established in 10 CFR 50.92(c).
The staff has concluded, based on Section 3.0 above, that operation of Sequoyah units 1 and 2 in accordance with the proposed amendments wili:
(1)
Not involve a significant increase in the probability or consequences of an accioent previously evaluated.
The cleaning of the embedded DG fuel-oil storage tanks per SR 4.8.1.1.2.f.1 only affects the DGs.
The DGS are used to provide emergency electrical power to the site when offsite power is not available and are not an initiator of an accitient.
The proposed change to increase the maximum allowed time that a DG train may be inoperable applys only to cleaning tne embedded fuel-oil storage tanks per SR 4.8.1.1.2.f.a and only for one DG set at a time.
The DG set affected will be connected to a supply of fuel-oil which is sufficient to operate the DG set as assumed in the analysis of accidents in the Sequoyah Final Safety Analysis Report.
The other DG set in the affected DG train will be operable but, as required by the TSs, if this DG set becomes unoperable and remains inoperable, the operating units will be shutdown in 72 hours8.333333e-4 days <br />0.02 hours <br />1.190476e-4 weeks <br />2.7396e-5 months <br />.
If the non-affected DG train becomes inoperable and remains inoperable, the operating units will be shutdown in eight hours, as required by the TSs.
A continuous fire watch will be posted where the fire doors are breached to detect fires, fuel-oil leaks, and damage to the temporary hose.
Therefore, the proposed action does not significantly increase the probability or consequences of an accident previously evaluated.
(2) Not create the possibility of a new or different kind of accident from any previously analyzed.
The DG day tanks of the affected DG set will be connected to the storage tanks of the other DG Set of the same train with temporary, but rugged, industrial hoses with threaded fittings. The temporary hoses will be inside the DG building.
During this period, the fire doors to the affected DG rooms will be breached and a continuous fire watch will'be posted while the doors are breached to detect potential fires, hose leaks, and damage to the hoses.
Therefore, the proposed action does not create the possibility of a new or different kind of accident from any previously I
analyzed.
(3) Not involve a significant reduction in a margin of safety.
l-Only DGs and only one DG set at a time will be affected by the cleaning of
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the embedded fuel-oil storage tanks.
The temporary connection to provide l
fuel-oil to the affected DG set is several rugged, industrial hoses connected together and are entirely within the DG building.
The hoses are l
rated above their intended use and will be used only for the time to clean I
the tanks.
The affected DG set will be able to get fuel-oil from the l
other unaffected DG fuel-oil storage tanks, a yard DG fuel-oil storage I
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.j 4. tank, and tanker trucks brought onsite if needed. The continuous fire watch while the temporary hoses are being used and the fire doors are open.
, are.a standard compensatory fire protection measure when fire barriers are breached.
The fire watch can detect any fuel-oil leaks or damage 'to the hoses.
Therefore, the proposed action does not involve a significant reduction in a margin of safety.
Based on this, the. staff concluded'that no significant hazards considerations exist for the proposed amendments.
6.0 CONSULTATION WITH THE STATE AND THE PUBLIC The staff consulted with the State of Tennessee on April 20, 1990.
The staff discussed the basis for its conclusion that the proposed amendments involved
'.with the cleaning of the DG fuel-oil storage tanks were acceptable.
The State of Tennessee had no comments on the proposed action.
A notice in the Federal Register (55 FR 13868) for this proposed action was
. published on April 12, 1990.
The notice requested public comments within 15 days by April 27, 1990, because exigent circumstances existed.
These cir-cumstances are discussed in Section 4.0 above.
There were no comments from the public.
7.0 ENVIRONMENTAL CONSIDERATION
These amendments involve a change to a requirement with respect to the installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20.
The staff has determined that the amendments involve no significant-increase in the amounts, and no significant change in the types, of any effluents that may be released offsite, and that there is no significant increase in individual or cumulative occupational radiation expo-sure.
The Commission has previously issued a proposed finding that these
-amendments involve no significant hazards consideration and there has been no public comment on such finding.
Accordingly, the amendments meet the eligibil-ity criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant.to 10 CFR.51.22(b), no environmental impact statement nor environmen-tal assessment need be prepared in connection with the issuance of these amendments.
7.0 CONCLUSION
Tno Commission made a proposed determination that the amendment involves no significant hazards consideration which was published in the Federal _ Register (55 FR 13868) on April 12, 1990, and consulted with the State of Tennessee.
No public comments were received and the State of Tennessee did not have any comments.
The stcff has concluded, based on the considerations discussed above, that: (1) there is reasonable assurance that the health and safety of the public will not be endangerad by operation in the proposed manner, and (2) such activities will be condv:ted in compliance with the Commission's regulations, and the issuance of the amendments will not be inimical to the common defense and security nor to the health and safety of the public.
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1 Principal Contributor:
J. Donohew Dated: April 27, 1990
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