ML20083M939
| ML20083M939 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 05/12/1995 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20083M937 | List: |
| References | |
| NUDOCS 9505220136 | |
| Download: ML20083M939 (5) | |
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.A UNITED STATES j~
j NUCLEAR REGULATORY COMMISSION -
2 WASHINGTON, D.C. 20666-0001
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,o SAFETY EVALUATION BY THE OFFICE OF NUCLEAR REACTOR REGULATION RELATED TO AMENDMENT NOS.192 AND 173 TO FACILITY OPERATING LICENSE NOS. NPF-4 AND NPF-7 I
VIRGINIA ELECTRIC AND POWER COMPANY' OLD DOMINION ELECTRIC COOPERATIVE NORTH ANNA POWER STATION. UNITS NO. 1 AND NO. 2 DQCKET NOS. 50-338 AND 50-339
1.0 INTRODUCTION
By letter dated October 25, 1994, the Virginia Electric and Power Company (the licensee) proposed changes to the Technical Specifications (TS) for the North Anna Power Station, Units No. I and No. 2 (NA-1&2). The proposed changes would extend the functional surveillance testing frequency for the hydrogen recombiners from once per 6 months to once per 18 months. The extension of the surveillance requirement is consistent with Generic Letter (GL) 93-05, "Line-Item Technical Specifications Improvements to Reduce Surveillance Requirements for Testing During Power Operation." The proposed changes would also delete the surveillance requirement to operate the containment purge blowers. This change would clarify that the TS surveillance requirement applies only to the hydrogen recombiner purge blowers.
Finally, minor editorial changes would be made to provide consistency between the NA-1&2 TS.
2.0 BACKGROURD The Hydrogen Recombiner System (HRS) removes the hydrogen gasses that accumulate in the containment atmosphere following a design-basis loss-of-coolant accident (LOCA). The HRS consists of two electric hydrogen recombiners each of which may be powered from either unit's emergency busses and each hydrogen recombiner is capable of being aligned to either unit's containment atmosphere.
The NA-l&2 units are equipped with two different types of " purge blowers."
One type of purge blowers are an integral part of the HRS.
These hydrogen recombiner purge blowers are capable of exhausting containment gasses directly to the atmosphere even with the recombiner incapable of removing hydrogen gas.
The second type of purge blowers are the containment purge blowers which exhaust directly from the containment to atmosphere and are not associated with the hydrogen recombiners. The containment purge blowers are not part of the HRS since they cannot provide a suction source for the hydrogen recombiners.
In addition, testing of the containment purge blowers does not contribute to establishing the operability of the hydrogen recombiners and no 9505220136 950512 PDR ADOCK 05000338 P
. credit for their operation is assumed in the Updated Final Safety Analysis Report (UFSAR) accident analysis.
The NA-l&2 UFSAR describes the HRS.
Each hydrogen recombiner consists of a blower, an electric preheater, a reaction 4
chamber and cooler, instrumentation, and piping, all of which are mounted on a skid.
The piping associated with the hydrogen recombiner blowers is seismically qualified.
Each of the skid-mounted hydrogen recombiner blowers is also designed to provide containment purge if necessary to maintain the hydrogen concentration at safe levels in the unlikely event that it is required.
The NA-l&2 UFSAR also provides a description of the containment purge blowers as a permanently installed, 50 standard cubic foot per minute, positive-displacement, purge blower in parallel with the containment vacuum pumps for each unit. This purge blower can draw air from the containment after a LOCA and discharge it to the Gaseous Waste Disposal System.
It can be operated in parallel with the HRS blowers when the containment is to be purged, ensuring that a failure of both recombiner systems will not leave the containment without purge capability.
4 The piping for the containment purge blowers is not totally. seismically qualified. Therefore, these purge blowers are not used to take suction from the containment and discharge to the process vents when operating. Therefore, it is not appropriate to apply a surveillance requirement to test this system while in Modes 1 or 2.
The licensee described the redundant external HRS in its response to NUREG-0737, Item II.E.4.1.
It also described the Containment Purge System, also referred to as the backup Hydrogen Purge System.
The response states "The backup Hydrogen Purge System is presently isolated from the hydrogen analyzers l
and recombiners by an administratively locked closed valve.
This system is not operated during normal plant operations.
Its use would only be contemplated if both hydrogen recombiners fail and after a radiation survey had been made to determine personnel accessibility to the manual isolation valves."
NRC Inspection Report 50-338/339 82-04 dated March 5, 1982, closed NUREG-0737, Item II.E.4.1 from a design modification aspect and NRC Inspection Report 50-338/339 83-05 dated April 1, 1983, closed NUREG-0737, Item II.E.4.1 from a procedure and testing aspect.
The NA-l&2 design and experience with the HRS is consistent with the findings in GL 93-05. The proposed TS changes would require that the hydrogen recombiners be tested once per 18 months which is the normal refueling cycle for NA-l&2.
A statement would be added to the NA-1 TS 3.6.4.2 Action that the provisions of Specification 3.0.4 are not applicable. This allows operational flexibility to change modes prior to completion of surveillance requirements
j to prove operability. The addition of this statement is in accordance with NUREG-1431. " Standard Technical Specifications - Westinghouse Plants." This exemption from Specification 3.0.4 is already contained in the NA-2 TS 3.6.4.2.
NA-l&2 TS Surveillance Requirement 4.6.4.2.a states in part that "... each purge blower operates for 15 minutes." The NA units are equipped with two different types of " purge blowers." One type of purge blowers are an integral part of the HRS. These hydrogen recombiner purge blowers are capable of exhausting containment gasses directly to atmosphere even with the recombiner incapable of removing hydrogen gas. The second type of purge blowers are the containment purge blowers which exhaust directly from the containment to -
atmosphere and are not associated with the hydrogen recombiners. Surveillance Requirement 4.6.4.2.a would be modified to state that the purge blowers being referred to in this surveillance requirement are the hydrogen recombiner purge blowers.
NA-1 Surveillance Requirement 4.6.4.2.a.4 requires that the integrity of all heater circuits be verified by performance of a continuity and resistance to ground test following a functional test. The requirement for a continuity test is not required in NA-2 TS nor in NUREG-1431, " Standard Technical Specifications - Westinghouse Plants." The performance of a continuity test of the heaters following the recombiner functional test is unnecessary. The functional test verifies the ability of the recombiner heaters to increase the recombiner temperature to the required value. The satisfactory completion of the functional test verifies proper heater continuity. Therefore, the requirement for continuity testing of recombiner heaters would be deleted from the NA-1 TS.
3.0 TS SPECIFIC CHANGES TS 3.6.4.2 - NA-1 The existing Action will be designated as "a."
Action "b" will be added stating "The provisions of Specification 3.0.4 are not applicable."
Surveillance Reauirement (SR) 4.6.4.2 - NA-182 Add the words "once per 18 months by" following OPERABLE.
SR 4.6.4.2 - NA-1 All "2" symbols will be replaced with " greater than or equal to" in order to maintain consistency between both units' TS.
SR 4.6.4.2.a - NA-1&2 The words "At least once per 6 months by" are deleted and the words " hydrogen recombiner" will be inserted in front of " purge blower."
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, SR 4.6.4.2.a - NA-1 The words "at least" have been added before "15 minutes" for consistency between units.
'SR 4.6.4.2.b - NA-l&2 The existing heading for SR items 1 through 4 will be deleted.
SR 4.6.4.2.b.2 - M-1 The word " enclosure' has been added after "recombiner" for consistency between units.
SR 4.6.4.2.b.4 - NA-1 The words " continuity siW will be deleted, This SR will read " Verifying the integrity of all heater slactrical circuth by performing a resistance ;to ground test following the above required functional test. The resistance to ground for any heater phase shall be greater than or equal to 10,000 ohms."
SR 4.6.4.2.b.1 throuah 4.6.4.2.b.4 - NA-l&2 These items will be designated alphabetically and rearranged.
In addition, minor editorial char.ges have been made to these TS sections to improve the readability and consistency between units.
4.0 EVALUATION Testing the hydrogen recombiners once per 18 months is consistent with GL 93-05 and is therefore acceptable. Also, the proposed changes regarding the surveillance frequency continuity test for heater circuits, and operational flexibility for mode changes are consistent with NUREG-1431,
" Standard Technical Specifications" and therefore acceptable.
Finally, the containment purge blowers are not part of the HRS and no credit is assumed for their operation in the NA-l&2 UFSAR accident analyses. Therefore, modifying the NA-1&2 TS surveillance requiremert 4.6.4.2.a to state the purge blowers referred to in the surveillance requirements are the hydrogen recombiner purge blowers is acceptable. Therefore, based on all of the above, the staff finds the proposed caanges to be acceptable.
5.0 STATE CONSULTATION
In accordance with the Commission's regulations, the Virginia State official was notified of the proposed issuance of the amendment. The State official had no comment.
6.0 ENVIRONMENTAL CONSIDERATION
These amendments change a requirement with respect to installation or use of a facility component located within the restricted area as defined in 10 CFR Part 20. The NRC 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 exposure. 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 (59 FR 60388). Accordingly, these amendments meet the eligibility criteria for categorical exclusion set forth in 10 CFR 51.22(c)(9).
Pursuant to 10 CFR 51.22(b) no environmental impact statement or environmental assessment need be prepared in connection with the issuance of the amendments.
7.0 CONCLUSION
The Commission has concluded, based on the considerations discussed above, [
5 that:
(1) there is reasonable assurance that the health and safety of the public will not be endangered by operation in the proposed manner, (2) such activities will be conducted in compliance with the Commission's regulations; and (3) the issuance of the amendments will not be inimical to the common defense and security or to the health and safety of the public.
Principal Contributor:
Leon B. Engle Date: May 12,1995