ML17157A276
| ML17157A276 | |
| Person / Time | |
|---|---|
| Site: | Susquehanna  |
| Issue date: | 08/13/1990 |
| From: | Russell W Office of Nuclear Reactor Regulation |
| To: | Martin T NRC OFFICE OF INSPECTION & ENFORCEMENT (IE REGION I) |
| References | |
| NUDOCS 9008150133 | |
| Download: ML17157A276 (9) | |
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August 13i l990 Q~A-J Pj'Imp MEMORANDUM FOR:
Thomas T. Hartin, Regional Administrator Region I FROM:
SUBJECT William T. Russell, Associate Director for Inspection and Technical Assessment Office of Nuclear Reactor Regulation ALLEGATION (RI-89-A-0072)
ADJUSTMENT OF MOLDED CASE CIRCUIT BREAKERS (HCCB) AT SUSQUEHANNA We have reviewed your memorandum of July 3, 1990, regarding the adjustments of molded-case circuit breakers (HCCB) at Susquehanna.
We agree that this activity is not prohibited by any NRC requirement.
- However, we also conclude that the reuse of a circuit breaker which has been unsealed and adjusted without the manufacturer's approval and outside NEHA guidelines, and which has lost its UL approval in the process, constitutes a modification to the facility subject to the provisions of 10 CFR 50.59.
The unsealing and adjustment of a molded-case circuit breaker cannot be treated as a normal maintenance activity by licensees.
Additional discussion on the basis for concluding that such activities constitute modifications is included in Enclosure 1.
Since the unreviewed safety question tests included in 10 CFR 50.59 appear to be adequate and appropriate for control of this type of activity, we do not intend to issue any additional guidance suggesting that such adjustments are either endorsed or prohibited.
We would, of course, be available to assist the Region in dealing with any specific technical issues where you chose to inspect a licensee's 10 CFR 50.59 evaluation.
Based on my staff's discussions with you and your staff on August 9, 1990, I
understand that you are in agreement with this approach.
In addition, I understand that your staff will review the circumstances surrounding the molded-case circuit breaker adjustments at Susquehanna to assure that they were, or will be, handled as facility modifications subject to 10 CFR 50.59.
I believe that this approach and the factual information included in your memorandum will form the basis for our resolution of the related allegation (RI-89-A0072).
ORlGWALSI8%O ~~
y T MUSSEL" William T. Russell, Associate Director for Inspection and Technical Assessment
Enclosure:
As Stated cc:
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Thomas T. Hartin August 13I 1990 cc:
B. Grimes, NRR U. Potapovs, NRR W. Brach, NRR S. Varga, NRR J.
B. Ebneter, RII A. B. Davis, RIII R. D. Hartin, RIV J.
B. Hartin, RV Distribution:
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MEMORANDUM FOR:
Thomas T. Martin, Regional Administrator Region I FRO;
SUBJECT:
William T. Russell, Associate Director for Inspection and Technical Assessment Office of Nuclear Reactor Regulation ALLEGATION (RI-89-A-0072)
ADJUSTMENT OF MOLDED CASE CIRCUIT BREAKERS (MCCB) AT SUSQUEHANNA We have reviewed our memorandum of July 3, 1990, regarding the adjustments of molded-case circu breakers (MCCB) at Susquehanna.
We agree that this activity is not,pro ibited by any NRC requirement.
- However, we also conclude that the reuse of a ircuit breaker which has been unsealed and adjusted without the manufactu r's approval and outside NEMA guidelines, and which has lost its UL approval in the process, constitutes a modification to the facility subject to the provision of 10 CFR 50.59.
The unsealing and adjustment of a molded-case circuit break q cannot be treated as a normal maintenance activity by licensees.
Additional d'scussion on the basis for concluding that such activities constitute modifi ations is included in Enclosure 1.
Since the unreviewed safety que tion tests included in 10 CFR 50.59 appear to be adequate and appropriate for ontrol of this type of activity, we do not intend to issue any additional guidance suggesting that such adjustments are either endorsed or prohibited.
We~could, of course, be available to assist the Region in dealing with any specs ic technical issues where you chose to inspect a licensee's 10 CFR 50.59 eva uation.
Based on my staff's discussions with yo and your staff on August 9, 1990, I understand that you are in agreement wit this approach.
In addition, I understand that your staff will review th circumstances surrounding the molded-case circuit breaker adjustments at usquehanna to assure that they were, or will be, handled as facility modif cations subject to 10 CFR 50.59.
I believe that this approach and the factual formation included in your memorandum will form the basis for our resolut on of the related allegation (RI-89-A0072).
Enclosure:
As Stated William T. Russel, Associate Director for Inspection a
d Technical Assessment cc:
B. Grimes, NRR U. Potapovs, NRR D. Letts, NRR R. Brady, NRR SEE PREVIOUS CONCURRENCE W. Brach, NRR S. Varga, NRR J.
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T. T. Martin NRC Bulle n 88-10 addressed this issue and it states "Since molded case CBs have factor >calibrated and sealed
- elements, any unauthorized modifications or refurbishing f these CBs could jeopardize their design capability and reliability." ~It was the intent of Bulletin 88-10 to prohibit the unauthorized opening of MCCB ~in the field.
During the development of the Bulletin 88-10, this issue was di 'ssed and it was concluded that such unauthorized opening and adjustments ren r MCCBs as having been modified and no longer provide the assurance of reliabi 'ty, capability and qualification of the original product as purchased from the nufacturer.
Also, in our view, in accordance with 10 CFR 50.59, the use in safety systems of MCCBs which have been opened and adjusted in the field wou constitute an unreviewed safety question.
It is unlikely, based on the abov discussions, that an analysis performed per 10 CFR 50.59 would find use such MCCBs acceptable.
Based on the above, we conclude hat there are sufficient technical and regulatory bases for not condonin the unsealing of the MCCB in the field for the purposes of refurbishment, mod ication or trip adjustment whether or 'not
't is performed under a utility qual'ty assurance program.
Therefore, I
recommend that Region I take the appr riate actions to inform the Susquehanna licensee of the NRR decision on this ma ter.
cc:
B. Grimes, NRR W. Brach, NRR U. Potapovs, NRR S. Varga D. Letts, NRR J.
ssell, Associate Director For Insp ction 5 Technical Assessment
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MEMO MARTIN
ENCLOSURE 1
The following items-indicate the significant technical considerations relating to molded-case circuit breaker adjustment whi'ch lead us to conclude that it must be viewed as a facility modification rather than as normal plant maintenance:
1.
The manufacturers of MCCBs intentionally seal the trip units to prevent any field adjustments by unauthorized personnel to ensure that the design capability and reliability of the.NCCB is not compromised.
NCCBs have very critical internal components, clearances, and adjustments, and therefore a high level of skill and detailed knowledge is required when making such adjustments to the NCCBs.
Testing to verify the functional capability of. a.breaker throughout its range of operation'equires strict adherence to manufactu'rers'etailed test procedures.'n addition, the
=test environment must be tightly controlled and the'a'c current level'and sinusoidal wave shape kept constant throughout. the test.
2.
Since the MCCBs are sealed units, any attempt. to unseal them by. using a.
soldering gun or other means may have deleterious effects on the HCCBs.
There is a potential that the commercial compounds (lock-tite) used in the field to lock the trip unit set screw in place after adjustment may migrate into the.operating mechanism and prevent proper'operation of the.
NCCB.
Also, if the MCCBs are not rea'ssembled correctly (i.e., installation
'of inter-phase barr iers and other components) after they have been
- unsealed,
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in the field, catastrophic failure may occur under normal or fault condi-tions due to lack of-insulation integrity.
We have discussed with the manufacturer and.industry standards representatives and they corroborate the above stated reasons for sealing the MCCBs.
This is-why the manu-facturers of NCCBs strongly oppose the opening of sealed NCCBs in the
- field.
3.
'Your letter and the Region' inspection report (50-387/388-90-22) indicate that the Susquehanna Steam Electric.Station's (SSES) licensee performs adjustmen'ts of sealed trip units of NCCBs without manufacturer's specific authorization or procedures.
In fact,,the reason that the SSES licensee has no such authorization and procedures is that the NCCB manufacturers (or national standards making bodies for performing this activity) do not publish any procedures for user'.,s use because of'he difficulty in perform-ing correctly: such activities outside a factory facility..
NRC Bulletin 88-10 states "Since molded 'case CBs have factory calibrated'nd sealed
- elements, any unauthorized modifications or refurbishing of these CBs could'jeopardize their design capability and reliability." It was the intent of Bulletin 88-10 to prohibit the unauthorized opening of MCCBs in the field.
During the development of the Bulletin 88-10, this
- issue was discussed and-it was concluded that such unauthorized opening and adjustments render HCCBs as having been modified and requires that the licensee reestablish the assurance of reliability, capability, and qualification of the original product as purchased from the manufacturer.
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