ML20006D625
| ML20006D625 | |
| Person / Time | |
|---|---|
| Site: | North Anna  |
| Issue date: | 02/02/1990 |
| From: | Office of Nuclear Reactor Regulation |
| To: | |
| Shared Package | |
| ML20006D623 | List: |
| References | |
| NUDOCS 9002140136 | |
| Download: ML20006D625 (4) | |
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- NUCLE AR REGULATORY COMMISSION 7
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SAFETY-EVALUATION EY THE OFFICE OF NUCLEAR F,EACTOR REGULAT10t(
4 RELATED TO AMENDMENT NOS.' 125 ' AND 109 TO -
FACILITY OPERATitlG LICENSE N05. NPF-4 AtlD NPF-7 VIRGINI A ELECTRIC AND POWER COMPANY OLD DOMINION ELECTRIC COOPERATIVE NORTH ANNA POWER STATION, UNITS h0.1 AND NO. 2 DOCKET NOS. ~ 50-338 AND 59-339 1.0 INTROCUCT10N J 0n: Oc tober 19, 1988, the NRC issued Infortration Notice No.= 88-83, " Inadequate Testing of Relay Contacts in Safety-Related Logic Systems." This information notice described an hRC inspection at the Duane Arnold Energy Center that discovered apparent deficiencies with the logic system functional test procedures for the reactor core isolation cooling'and high pressure coolant injection systems.
After a review of the information notice, the Virginia Electric and Power
-(NA-1&2)(determined that the NA-182 Technical Specifications:(TS) are not
' Company the licensee) of the North Anna Power Station Units No.1 and No. 2 explicit when describing the extent of the functional testing required during l
reactor operation. 'They consequently.. submitted licensee event report (LER)88-027 on Decernber 15, 1988 to document the difference between the.TS inter-1 t pretation.and'the NA-1&2. Updated Final Safety Analysis Report (UFSAR)..
By letter dated May 8,1989, the licensee proposed the removal, from the NA-1&2 UFSAR, of on-line testing of safety system slave relays.,In that letter the licensee proposed changing the-UFSAR to reflect their interpretation of the TS 'requirenents for testing which would require only master relay-activation coupled with a' slave relay continuity test.
The slave relay coil is:not.
energized and the sl6ve relay contacts are not exercised with that interpre-
.tation. NA-182 has not performeo on-line slave relay testing as described in i
- the UFSAR since initial startsp in 1978 (NA-1) and 1980 (NA-2).
In the'May 8,1989 letter end in a June 51989 meeting, the licensee described the testing which has been done, technical difficulties with certain aspects of the tests and the possible risks associated with a failure of the testing
.i equipment.
The licensee's proposal to remove the testing description from.the UFSAR was not acceptable and the staff reiterated that the information' notice-
- accurately described the NRC position that the logic system functional test should be a test of all relays and contacts and that any exceptions should be justified on a case-by-case basis.
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j On June 9',1989, a conference call was held between NRC Region II, NRR, the NA-1&2'NRC Senior Resident Inspector and licensee staff to discuss engineered j
safety features (ESF) slave relay on-line testing.
Cased on the meeting and
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conference call, the licensee agreed to revise their interpretation oflthe testing requirements to be consistent with NUREG-0452, Rev. 4. " Standard Technical Specifications for Westinghouse Pressurized Water Reactors." By l
letter dated June 9,1989, the licensee requested discretionary enforcement for -
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h the monthly ESF slave relay testing to allow them tire to develop the necessary_
testing procedures and determine any relays that cannot be tested on-line p
without excessive risk and provide justification.
The NRC Region !! granted L
i the discretionary enforcement, by letter dated July 12, 1989, the licensee submitted their ESF slave relay
' test plan, basis > for off-line testing, ch6nges to IS and safety analysis. By.
L, Amendment Hos.123 and 107 dated Septenter 7 '1989, the NRC issued -TS changes which accepted one aspect of the licensee's July 12, 1989 letter in that the-E quarterly testing of slave relays (instead cf monthly) was consistent with
. Standard Technical Specifications and was therefore acceptable.
This Safety Evaulation addresses the remaining technical aspects of the July 12, 1989 submittal.
2.0 DISCUSSION AND EVALUATIOM In Attachment I to the July 12, 1989 letter, the licensee listed the 28 ESF
, sieve relays (per unit).. the f requency of testing and the criteria for on/off L-line testing.
Twenty-two relays will be tested only during refueling while y
the remainin six will be tested quarterly and during refueling.
The. testing during refue ing-requirement existed previously.
This requirement is part of the system functional testing and will remain unchanged. -Three criteria are provided by the licensee for justifying off-line only testing.--
1.
A single failure in the Safeguards Test Cabinet circuitry would cause an
' inadvertent RPS or ESF actuation.
2.
The test will adversely affect two or more components in one ESF system or two or nore ESF systems.
3.
The test will create a transient (reactivity, thermal or hydraulic) condition on the RCS.
' Attachment 2 of the July 12, 1989 letter provided a relay-by-relay basis for
-off-line testing.
It described the design function,' equipment actuated, operational irrpact and safety significance of testing.
Several.of the descriptions of the safety significance of testing state that there is no safety significance if the test circuit performs properly. The.
described impact on saf ety assumes a worst case scenario of the safeguards test cabinet, a failure of the blocking circuit to actually block actuation of the final equipment.
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Af ter review of _the attachnents, the staff concluces that the relay ano subse.
quent testing evaluations appear to be complete and that the assignment of the slave relays to the three criteria is acequately justified.
Attachneht 3 provided an analysis of the test equipnent, safeguards testing cabinet, ano f ailure of the blocking circuit.
This test equipment provides two basic types of tests, "Go" and " Block". The "Go" circuits actuate the ESF equipment while the " Block" tircuits prevent actuation of the ESF equipment with circuit integrity verified by electrical continuity testing.
The attach-nent provices details of the blocking schemes and possible failure modes. is the proposed changes to the TS. The proposed change states that only slave. relays which do not satisfy the three criteria will be functionally tested on-line. provided the licensee's safety analysis for the proposed TS c hange s.
In this analysis the licensee notes that since construction, nodifi-cations have been niece which noded equipment that would be actuateu curing testing ano therefore an adequate oesign for testing all of the slave relays on-line-.coes not exist.
In addition to inadequate testing design, the licensee does not have a high confidence level in the reliability of their test equipnent.
The analysis confirms' that the testing will still include coil continuity tests of the. slave relays on a quarterly basis and full testing at refueling, w-To date, there has not been a failure of a slave relay to perform its safety f unction at NA-182. To cetermine a potential f ailure rate, the licensee used cverall failure rates for slave and auxiliary relays at NA-1&2 and diviced them by the number of ESF slave relays only.
The staff agrees with the licenste's conclusion that this appears to be a conservative estimate of ESF slave relay f ailure-rates.
The licensee concluded that (1) the probability of inadvertent RPS or ESF actuation, (2) the length of time to perform the test which otsables one channel, and (3) performing tests with test equipment which may be unreliable and abnormal operation nodes, present a greater risk to overall plant safety than not testing ESF slave relays on-line. The reliability of-the ESF slave relays h'es been shown to remain high. The staff agrees with the-licensee's
. conclu sion.
3.0 SUMMARJ The staff has concluded that, baseo on the reasons described above, the TS changes which allow certain ESF slave relays to be exempt from quarterly testing are acceptable.
Also, the revised TS definition of the ESF slave relay test is acceptable.
Finally, the licensee should continue to improve the test eouipment eno consider otsign modifications which would allow complete testing of all ESF slave relay coils anc contacts without undue risk to plant safety.
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4.0 ENVIRONMENTAL C0flSIDERATION
' l These amendments involve a change to a recuirenent with respect to installation or use of a f acility component located within the restricted area as defined in 10- CFR Part 20. We have determined that the amendrents involve no significant
. i increase in the amounts, and no significant change in the types, of any ef fluents 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 amendaents involve no significant lazards consideration and there has been no public comment on such finding.
Accordingly, these amendments meet the eligibility criteria for catecorical.
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 these amendments.
5.0 CONCLUSION
We have concluded, based on the considerations discussed above, that (1) there is reasonable assurance that the health and safety of the public will not be endangered by operetion in the proposed manner, and (2) such activities will-be conducted in conpliance with the Commission's regulations, and the issuance a
of the amendnents will nct be inimical to the common defense and security or to the health and safety of the public.
Date: - February 2,1990 Principal Contributor:
J 5tewart
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