ML20038C442

Discusses Proposed Changes to Tech Specs Per 810428 Application.Reduction in Visual Insp of Snubbers unacceptable.Marked-up Tech Specs Encl

ML20038C442
Person / Time
Site:	Browns Ferry
Issue date:	11/18/1981
From:	Ippolito T Office of Nuclear Reactor Regulation
To:	Parris H TENNESSEE VALLEY AUTHORITY
References
NUDOCS 8112110039
Download: ML20038C442 (9)

Text

cc{cd

$t/c e

=

'f-L a s -o,p

%GX l~ W N@A y

7 Docket Hos. 50-259, 50-260 s

and 50-296 i

o 198 W '-

g

• N [ v'5 NOV I 8198 ffr. Hugh G. Parris

'/,/

Manager of Power N,

f 4

Tennessee Valley Authority 500A Chestnut Street Tower II

~li N Chattanooga, Tennessee 37401

Dear !!r. Parris:

Reference is made to your application of April 28,1981 (TVA BFNP TS 153) for changes to the Browns Ferry Technical Specifications ^o include additional requirements on snubbers. Your application was in response to our generic letter to you of November 20, 1980. He have completed our review and find your submittal acceptable except for the few minor items discussed below.

In Section 4.6.H.2, you proposed that for snubber groups in which there was no visible indication of inoperability for two successive 18 month periods, that the visual inspection lot be reduced to.50%. We agree with your philosophy of periodically reexamining inspection requirements.to detemine if they are still necessary and concentrating available resources on those areas nost important to safe operation. At this time, we cannot accept the l proposed reduction in visual inspections for several reasons. Our generic letter was prompted by numerous discoveries of inoperative snubbers in operating reactor plants. While it appears that newer snubber designs (e.g.,

using seal materials in hydraulic snubbers that are more resistant to tempera-ture and irradiation environments, etc.) and improved quality assurance and testing are likely to significantly increase the expected service life of snubbers, there is not, as yet, sufficient operating history to document the expected inprovenent. At this time, we feel it is premature to reduce the visual inspection lot. Snubbers are basically mechanical items and for mech-anical equipment (such as cars) trouble-free operation during the initial period of service is no assurance that a component will not weer out during the expected service life.

Finally, this requirement relates only to visual inspection, not functional testing. The proposed maximum inspection period of 18 months + 25% was based primarily on the failure data available to us; there was ver7 little industry input on the manpower and costs associated with visual inspections, but what we received indicated that the visual exanination was not a major burden.

If you have such data you would like to provide, we would appreciate hearing from you.

In summary, we feel that, at this tine, that 18 nonths + 25% is the longest interval between visual inspection of snubbers absenci additional justification.

In Section 4.6.H.5a and b, we suggest that a qualifying phrase "within the specified range" be added to the activation and bleed requirements..The require-nonts in 4.615.c are only innnrtant for mehanical snnhhnrs; wo sunmt 8112110039 8111 OFFICE )

- o pa o ocx 03000,1 e,..

3 PDR.

DATE OFFICIAL RECORD COPY usa--mmo Nac ronu ais om uncu o a

Ifr. Hugh G. Parris

--2--

that a qualifying phrase "for mechanical. snubbers.only" be added to this paragraph.

i The nodel Technical Specifications fomarded by our generic letter of flovember 20, 1980 included an action requirenent if a snubber failed to,

lockup or nove during testing (first paragraph,.page 3/4 7-25)_ and the cause wa.; detemined to be dua to,a manufacturing or design deficiency.

Uhile the likelihood of such an, occurrence is probably very small, we con-clude that such a mquirenent should be included in Section 4.6.11.5.

In the model Technical Specifications referenced above.we had included two paragraphs on snubber service life monitoring (Iten f, page 3/4 7-26).

We believe the intent of these paragraphs may have been nisinterpreted.

The paragraphs were included primarily for the benefit of licensees to avoid unwarranted maintenance or mplacenent.

Fma information available to us, it appears that the material manufacturers, generally reconnend a conserva-tive service life (e.g., 5 years on seals).

If the functional tetts indi-cate satisfactory perfomance, the _" service life" can be increased (e.g.,

fron 5 years to 7 years). tiarmal naintenance records are probably sufficient for the perfomance evaluation; an elaborate bookkeeping systen is not necessary. The infornation to be recorded was discussed in the bases for the model Technical Specification (page B 3/4_7-6)._ Maintenance history, environmntal conditions and results of the functional tests on a repre-sentative sanple of a particular snubber group are used in the suggested evaluation to judge whether the snubber service life can reasonably.be.

i expected to extend to the next refueling. outage. You nqy wish to reconsider adding a paragraph to Section 4.6.11.9 to insure you have the records _neces-sary for the proposed reevaluations of service life.

In Section 4.6.H.9, the reference to exenptions fron visual inspections is not approximate. As discussed _in the nodel. Technical Specifications, we will grant exemptions fmn functional testing when justified. _ Snubbers are pemitted to be classified into " accessible" and " inaccessible" groups for your convente. ice to establish inspection intervals., However, as we dis-cussed initially in this letter, visual inspection of 100% of the snubbers is required. He believe the group. classification plus the + 25% tolerance in the inspection interval will pmvide the flexibility you'~need for plant operation.

We have mrked up the proposed Technical Specifications you submitted for Umwns Ferry Unit tio.1 to incorporate the above coments, a copy of which is enclosed. He would appreciate your connents on these proposed changes within 45 dqys of receipt of this letter.

[

Sincerely, p

\\

Eginar si eo

(

f L

E. A. I no

,g

.OR..B..#. 2

.O.R. A..B..V.... s. l.... h.

O.RA

. h........

m nas A. Ippolito, W1cf C-0RB#2

..ggpgt(Hg..peaG% ors.$FaGCh E2J OFFICE)

~

ps,f,1,gl.d...Di.vi.S.iQn. 0.f.LiGCDS.iD9..

..T I p p,o,,1,M,1 o,,

h i

SURNAME)

..b.h. d h...

. 5..

.h.hI.

IT/d./

.....dgclosures..lj/1fj/.81...saa nug.ago...

11 y 81 11 81 om>

NAC FORM 318 (10-80) NRCM 0240 OFFICIAL RECORD COPY use ---u.seo

~. -...

~

Mr. Hugh G. Parris

Enclosure:

Parked Up Proposed Technical Specifications for Browns Ferry Unit flo.1 cc w/ enclosure:

See next page DISTRIBUTION:

Docket File NRC PDR Local PDP ORB #2 Rdng D. Eisenhut J. Heltemes S. Norris OELD T. Ippolito P. Polk H. Shaw R. Clark D. Crutchfield I&E (3)

NSIC TERA ACRS(10)

Gray ornce>

SURNAMEh o.we >

Nac roau ats tio-ac) sacu o24a OFFiClAL RECORD COPY usa m im _an

• Mr. Hugh G. Parris cc:

H. S. Sanger, Jr., Esquire General Counsel Tennessee Valley Authority 400 Commerce Avenue E llB 33 C

^

Knoxville,.annessee 37902 Mr. Ron Rogers Tennessee Valley Authority 400 Chestnut Street Tower II Chattanooga, Tennessee 37401 Mr. H. N. Culver 249A HBD 400 Commerce Avenue Tennessee Valley Authority Knoxville, Tennessee 37902 Robert F. Sullivan U. S. Nuclear Regulatory Commission Route 2, Box 311 Athens, Alabama 35611 Athens Public Library South and Forrest Athens, Alabama 35611 Mr. John F. Cox Tennessee Valley Authority W9-D 207C 400 Conrerce Avenue Knoxville, Tennessee 37902 Mr. Herbert Abercrombie Tennessee Valley Authority P. O. Box 2000 Decatur, Alabama 35602

LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS H. Seismic Restraints, Supports, and H. Seismic Restraints, Supports, and Snubbers (cont'd)

Snubbers (cont'd)

3. (cont'd)

2. Visuel Inspection, Schedule, and is attached to a system Lot Size (cont'd) that is required OPERABLE during the shutdown or No. Inoperable

' Subs equent refuel mode, the appropriate Snubbers per Visual Inspection LIMITING CONDITIONS statement Inspection ?eriod Period for that system shall be followed.

0 18 months + 255 1

12 months ! 255 2

6 months 5255 3,4 124 days 1 255 5,6,7 62 days t 255' 8 or more 31 days 1 255

'The inspection interval shall not be lengthened more than one step at a time.

> Visual Inspection Performance and Evaluation Visual inspections shall verify (1) that there are no visible indications of damage or impaired OPERABILITY, (2) bolts attaching the snubber to the foundation or sup-porting structure are secure, and (3) snubbers attached to sections of safety-related systems that have experienced unexpected potentially damagir.g transients since the last inspection period rFall be evaluated for the possibility of concealed damage and functionally tested, if applicable, to confirm operability.

Snubbers which a,ppear inoperable as a result of visual inspections may be determined OPERABLE for the purpose of establishing the next visual inspection interval, providing that (1) the cause of the rejection is clearly established and remedied for that particular snubber and for other-snubbers that may be generically susceptible; and (2) the affected snubber is functionally tested, if applicable, in the as-found condition and determined OPERABLE per Specification 4.6.H.5.

186

LIMITING CONDITIONS TCR OPERATION SURVEILLANCE REQUIREMENTS H. Seisnie Restraints, Supports, and H. Seismic Restraints, Supports, and Snubbers (cont'd)

Snubbers (cont'd) 3.

Visual Inspection Performance and Evaluation (cont'd)

Also, snubbers which have been made inoperable as the result of unexpected transients, iselated, damage or other such random events, when the pro-visi~ons of 4.6.H.7 and 4.6.H.8 have been met and any other appropriate corrective action implemented, shall not be counted in determining the next visual inspection interval.

4, Functien41 Test Schedule. Lot Size, and Composition At least once per 18 months during shutdown, a representative sample of 10% of the total of each group of snubbers in use in the plant shall be functionally tested either in place or in a berich test.

The representative sample selected for functional testing shall include the various configurations, operating environments, and the range of size and capacity of snubbers within the groups. The representative sample should be weighted to include more snubbers from severe service areas such as near heavy equipment.

The security of fasteners for attach-ment of the snubbers to the component and to the snubber anchorage shall be verified on snubbers selected for functional tests.

.5, Functional Test Acceptance Criteria The snubber functional test shall verify that:

a. Activation (restraining action) is achieved in both tension and compression within the specified range.

b. Snubber bleed, or release where required, is present in both compression and tension within the specified range.

187 f

• LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS H. Seismic Restraints, Supports, and H. Seismic Restraints, Supports, and Snubbers (cont'd)

Snubbers (cont'd) i 5.

Functional Test Acceptance Criteria (con t ' d)

c. For mechanical snubbers, the force required to initiate or maintain motion of the snubber is not great enough to overstress the attached piping or component during thermal movement, or to indicate impending failure of the

onubber, d.

For snubbers specifically required not to displace under continuous load, the ability of the snubber to withstand load without displacement shall be verified.

e. If any snubber selected for functional testing either fails to lockup or fails to move, i.e.,

frozen in place, the cause will be evaluated and if caused by manufacturer or design deficiency, all snubbers of the same design subject to the same defect shall be functionally tested.

This testing requirement shall be independent of the requirements stated above for snubbers not meeting the functional test acceptance criteria.

l 6.

Functional Test Failure Analysis I

and Additional Test Lots An engineering evaluation shall be made of each failure to meet the functional test acceptance criteria to determine the cause of the failure. The result of this analysis shall be used, if applicable, in selectit-g snubbers to be tested in the subsequent lot in an effort to, deter-mine the operability of other st:ubbers which may be subject to the same l

failure mode. Selection of snubbers for future testing may also be based on the. failure analysis. For each snubber that does not meet the functional test l

acceptance criteria, an additional iot 188 l

l l

LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS H. Seismic Restraints, Supports, and H. Seismic Restraints, Supports, and Snubbers (cont'd)

Snubbers (cont'd) 6, Functional Test Failure Analysis and Additional Test Lots (cont'd) equal to 10% of the remainder of that group of snubbers shall be functionally test ed.

Testing shall continue until no additional inoperable snubbers are found within subsequent lots or all snubbers of the original inspection group have been tested or all suspect snubbers identified by the failure analysis have been tested, as applicable.

The discovery of loose or missing attachment fasteners will be evaluated to determine whether the cause may be localized or generic.

The result of the evaluation will be used to select other suspect snubbers for verifying the attachment fasteners, as applicable.

7. Functional Test Failure - Attached Component Analysis For the snubber (s) found inoperable, an engineering evaluation shall be performed on the components which are restrained by the snubber (s).

The purpose of this engineering evaluation shall be to determine if the components restrained by the snubber (s) were adversely Effected by the inoperability of the snubber (s),

and in order to ensure that the re-l strained component remains capable of l

meeting the designed service.

i

8. Functional Testing of Repaired l

and Spare Snubbers l

l Snubbers which fail the visual i

inspection or the functional test l

acceptance criteria shall be repaired or replaced. Replacement snubbers and snubbers which have repairs which might i

affect the functional test results

(

shall meet the functional test criteria before installation in the unit. These i

snubbers shall have met the acceptance criteria subsequent to their most l

recent service, and the functional test j

189 i

l l

LIMITING CONDITIONS FOR OPERATION SURVEILLANCE REQUIREMENTS H. Seismic Restraints Supports, and H. Seismic Restraints Supports, and Snubeers (cont'd)

Snubbers (cont'd) 1

8. Functional Testing of Repaired and Spare Snubbers (cont'd) sust have been performed within 12 months before being installed in the unit.

9,

xemption From Visual Inspection or Functional Tests Permanent or other exemptions from functional testing for individual snubbers may be granted by the Commission if a justifiable basis for exemption is presented and if applicable snubber life destructive testing was performed to qualify snubber operability for the applicable design conditions at either the completion of their fabrication or at a subsequent date.

Snubbers so exempted shall continue to be listed in the plant instruc-tions with footnotes indicating the extent of the exemptions.

The service life of snubbers may be extended based on an evaluation of the records of functional tests, maintenance history and environmental conditions to which the snubbers have been exposed.

190