ML20150F648
| ML20150F648 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 03/29/1988 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20150F646 | List: |
| References | |
| NUDOCS 8804050302 | |
| Download: ML20150F648 (4) | |
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EFFTYEVALUATIONBYTHEOFFICEOFNUCLFARREACT00 REGULATION RELATED TO AMENDMENT NOS. 98 AND 85 TO FACILITY OPEDATING LICENSE NO. NPF-4 AND NPF 7 VIRGINIA ELECTRIC AND POWER COMPANY OLD DOMINTON ELECTRIC COOPERATIVE NORTH ANNA POWER STATION, UNITS NO. 1 AND NO. 2 DOCKET NOS. 50-338 ann 50-339 INTRODUCTION By letter dated May ?7, 1987, the Virginia Electric and Power Company (the licensee) reouested a change to the North Anna Power Station. (Inits No. I and No. 2 (NA-1A2) Technical Specifications (TS).
Specifically, the proposed change would modify TS 3/4.6.3, Table 3.6.1 to:
(11 correct an inconsistency between the licensee's response to NUREG-0737 and the NA-2 TS with regard to the isolation signal for the containment instrument air system.
At the time of the requested change, instrument air isolated on a Phase B signal in NA-1 and a Phase A signal in NA-2.
This reouest would change the containment isolation signal in NA-2 from Phase A to Phase B in compliance with NUREG-0737; and (?) place the hydrogen recombiner containment isolation valves for NA-182 under administrative control in order to permit functional testing in Modes 1 through 4.
Item (1) above was addressed in Amendment No. 82 to Facility Operating License No. NPF-7 for NA-2, which was issued on October 22, 1987 This Safety Evaluation (SE) addresses Item (2), as noted above. Our discussion l
and evaluation of item (2) of the licensee's change request dated May 27, 1987 is provided below.
DISCUSSION Technical Specification surveillance requirements as listed in TS 4.6.4.?.a for NA-182 require a functional test of the hydrogen recembiners every 6 months. TS 3.6.1.1, however, requires that containment integrity be naintained in Modes 1-4 and specifies that the valves listed in Table 3.6-1, which do not receive automatic closure signals, be maintained closed unless otherwise noted in Table 3.6-1.
At present, the valves not receiving automatic closure signals include the hydrogen recorbiner renote-manual isolation valves (NA TV-HC-104A and B,10FA and B,106A and B, and 107A and B; NA ? - TV-HC-204A and B, 205A and B, ?O6A and B, and 207A and B). The licensee proposed that Table 3.6-1 be changed by adding asterisks to these valves to provide for takinq administrative control in order to pemit surveil-lance testing at power.
During.these periods (approximately a hours every 6 months 1 the operation of the affected valves would be administrative 1y j
controlled by a Periodic Test (PT) procedure.
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. General Design Criterion (GDC) 56 (Primary Containment Isolation) requires that lines which connect directly to the containment atmosphere and penetrate reactor containment should consist of one isolation valve inside containment and one isolation valve outside containment.
If it is not practical to locate a valve inside containment. the design should conform to Standard Review Plan (SRP) Section 6.2.4.11.6.d.
The design of the NA-182 hydrogen recombiner has two remote-manual isolation valves outside containment, which are designed to withstand the effects of postulated accidents. This design is consistent with SRP Section 6.2.4.11.6.d. which states that if it is not practical to locate an isolation valve inside containment, both isolation valves may be located outside containment provided the dasign of the valve nearest containment can withstand the effects of postulated accidents.
GDC 56 also provides that the isolation valves be' automatic or lecked closes, unless the isolation provisions for a specific class cf lines are acccptable on another cefined basis. The valves involved in th;s amendment are remote manual valves.
SRP Section 6.2.4 accepts use of remote manual valves for lines associated with essential systems. The system involved is an essential system and thus remote manual valves are acceptable for this class of lines on the basis defined in SRP 6.2.4.
In a letter from the NRC dated January 12, 1984, an NRC SE was provided which accepted NA-1&2's action taken in response to NUREG-0737. Item II.E.4.1 (Ded-icated Hydrogen Penetrations).
The NRC SE found the licensee's request to add the remotely operated (HC Series) valves to Table 3.6-1 acceptable and that "opening of these valves will take place only under specific administrative control as specified in post-accident procedures." During the testing period, the recombiner would be connected directly to the containment atnosphere and the recombiner and associated piping could possibly be pressurized to 45 psig if an accident were to occur.
For normal operation, the recombiner is designed for an operating pressure limit of 10 psig.
A review by the licensee of the hydrogen recombiner system design was performed to evaluate conducting the test at power.
The hydrogen recombiners and their associated piping systems are seismically designed and missile protected. The piping and components are designed to ASME III, Class 2 through Sumer 1973 Aadendum.
The recombiner system piping is 150 lb. carbon steel. The recombiner pressure-retaining boundary is 304 stainless steel, is designed to withstand 50 psig and was originally tested to 75 psig.
The recombiner technical manual specifies a 10 psig rating for cperating conditions (1300-1400'F) and 50 psig for non-operating conditions.
Rockwell l
International was contacted and stated that the 10 psig operating pressure limit is imposed to limit the mass flow through the recombiner in order to provide assurance that effluent hydrogen concentration meets specifications.
l and that there is no overstress concern with a pressure excursion to 45 psig at operating temperatures.
I Further analysis and evaluation has concluded that the recombiner could withstand a design basis accident (DBA) since sufficient design margin exists to preclude a breech of the hydrogen recombiner components and associated piping. This conclusion was based upon a review of the Reckwell Stress Report (TI-019-120-003) and application of design inforination through calculations to show that sufficient design margin existed for the postulateo test configura-
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tion with a temperature of 1250 F and a pressure excursion to 50 psig.
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The alignment of the recombiner to the containnert during functional testing provides verification of design flow capability for the actual flow path used during accident conditions.
Alternstive testing schenes to keep the recombiner separated from containment atmosphere would require some degree of pipine i
reconfiguration which could potentially affect the integrity of the piping system t
following restoration after testing.
In addition, the capability exists to isolate the containmert from the recombiner by taking operator action from the l
control room in the event containment isolation is required while surveillance I
testing is in progress.
Prior to implementation of this TS change, which wculd allow functional testing at power, precautions will be added to the two affected pts (68.1.1 ard 68.1.2) to instruct the control room operator to secure the recombiner and shut any open HC valves if a containment isolation signal is generated while the test is in progress.
EVALUATION The proposed change will add the renotely operated (HC Series) hydrogen recombiner isolation valves to TS Table 3.6-1 to allow administrative control for limited periods of time in order to permit surveillance testing at power.
The proposed change has previously been found to be acceptable in the NRC SE dated January 12, 1984 which accepted the licensee's actions in response to l
NUREG-0737, Iten II.E.4.1 (Dedicated Hydrogen Penetrations).
In addition, the i
opening of these valves unc'er administrative control (by procedure) for j
testing will not affect containment conditions or the operation of any other i
eouipment which directly communicates with containment. Moreover, the design conditions used for the construction of the recombiner system ensure that i
containnent conditions will not be degraded and integrity will be maintained j
for existing accident analysis.
Also, upon receipt of a containment isolation J
1 signal, the affected valves can be shut remotely from the control room.
Prior to implementation of the proposed TS, as discussed above, the licensee has 3
I committed to modify the NA-182 pts (68.1.1 and 68.1.2) to instruct control roon operators to secure the recombiner and shut any open HC valves should a containment isolation signal be generated when the hydrogen recombiner functional test is in progress. Based on all of the above, we find this change to be acceptable.
t ENVIRONMENTAL CONSIDERATION l
These amendments involve a change in the installation or use of a facility f
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component located within the restricted area as defined in 10 CFR Part 20.
l 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 f
may be released offsite, and that there is no sionificant increase in individual or cumulative occupational radiation exposure.
The Cemission has previously published a proposed finding that there amendments involve no sionificant hazards consideration and there has been no public coment on such finding. Accordinoly, these amendments meet the eligibility criteria for categorical exclusion set forth l
in10CF9651.22(c)(9). Pursuant to 10 CFR 651.22(b), no environnental impact statement or environmental assessment need be prepared in connection with the issuance oi these amendments.
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CONCLUSION We have concluded, based on the consideratiers discussed above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the preposed manner, and (2) such activities will be conducted in conpliance with the Comission's reculations, and the issuance of the amendments will not be inimical to the comon defense and security or to the health and safety of the public.
Date:
March 29, 1988 Principal Contributor:
Leon Engle
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