ML19256D298

Summary of 710223-24 Meeting W/Met Ed & Consultants Re Amend 15 & 17.Items Discussed Included Site Reactor Design, Primary Coolant Sys,Instrumentation,Accident Analysis & Miscellaneous Issues

ML19256D298
Person / Time
Site:	Crane
Issue date:	03/11/1971
From:	Ross D US ATOMIC ENERGY COMMISSION (AEC)
To:	Deyoung R US ATOMIC ENERGY COMMISSION (AEC)
References
NUDOCS 7910170808
Download: ML19256D298 (18)

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MAR 11 M R. C. DaToung, Assistant Director PWRs THRU:

C. G. Long, Chief, PWR Branch 2 MEETING WITH HETROPOLITAN EDISON ON THREE MILE ISLAND NUCLEAR UNIT NO.1 We met with representatives of Metropolitan Edison Company and their i

vendors and consultants on February 23 and 24,1971 to discuss the Three Mile Island Nuclear Station Unit No.1.

A list of attendees is attached.

The purpose of the meeting was to discuss Amendments 15 and 17 which contained the answers to our first question list. We also discussed the items that are at issue between us, and the proposed schedule for our first ACES meeting. In many cases we informed the applicant of our final i

er near final positions, which were discussed at a recent Task Force meeting.

SITE 1.

Meteorology We informed Metropolitan Edison that the data made available so far did not substantiate the asserted diffusion values. In fact, we were vast able to eaae1=de that the two-hour accident meteorology of Fasquill-F and 1 meter-per-emeaad was justified. On the very limited data nada available so far, it may be that a wind speed of 0.5 meter per second is warranted. However, the applicant has installed a nov meteorology caser which has Delta T instruments would provide more t

information on the Fasquill conditions actually present. We agreed to have a meteorology meeting sometime during the week of March 15, I

and turther discuss the data that have been recently generated from i

the Delta T instrument. At that meeting, we expect to have l

Dr. Vanderhoven, our consultant from NOAA. Meteorology thnafore remains an unresolved issue.

2.

Floo2 i

j We reviewed the probable m=v4=== flood calculations with the applicant.

The representative from Cilbert Associates, Mr. MacImmore, and the I

DEL staff hydrologist, Dwighe taan, discussed the issues in detail at a separate sub-seeting. They returned to the main meeting and i

l summarized the additional informarion that we require, in order to complete our review. In general, we are satisfied with the procedures that Gilbert has used and the required information constitutes a

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y P00ROR8NAL written verification of our verbal understanding. The applicant agreed to furnish the required information on the basis of the understandings reached at the meeting. This item theretore can be considered as informally resolved, subject to utisfactory documentation.

REACTOR DESIGN

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1.

Fuel Design Ua requested the applicant's reactor vendor, B&W, to discuss:

the frsi design, in particular the high burcup tests that have been performed by B&W; the recently observed fuel pellet abnormalitics; j

and the procedures that B&W uses in calculating fuel swelling and consequent clad strain. Neil Hookar of B&W gave a presentation on this subject. He stated that both the pellet vendor and B&W have L

QA procedures on the cladding and the fuel pellets. The observations te data show that the fuel pellets have been remaining well witha the QA tolarances. He stated that the semil amount of chipping and flaking that our reviewers had noticed during a tour of the fuel fabrication plant were only a minor aberracion in the pellet lesign and that-the pellet din==ters wata mot becoming excessively large.

In regard to the high burnap tests B&W personnel statad that it was not their intent to prove current designe with the high burnap test; rather they were aimed at advanced daaigns. They stated that they

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could not get the same fluzes and enrichments at the B&W test reactor, therefore the commercial design and the high burnap test do not have a one-to-one correspondence. They have not completed their evaluation of the high burnap tests. They do intend to coes to DEL with a presentation on this ashjeet when they completa this work, sometime in 1971. At present, they do not plan a formal report.

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Hooker stated that B&W calculates clad strain in the same manner that he believes the other vendors do. We asked, and he agreed, and i

Metropolitan Edison agreed, that the details of how clad strain is calculated be doctamented in a forthcoming amendment.

2.

Burnable Poison End Assemblies (BPRA)

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Hooker described the design criteria for the burn 61e poison rod ass emblies. They werer (1) the zircaloy tube should be free standing; (2) there should be no clad : train due to diametral growth l

from thermal or radiation effects on the poison material and (3) there should be no clad strain due to av4=1 thermal or irradiation swelling.

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P00R'tlRGNAL They provide a twelve mil diametral gap betveen the pellet and the clad. At end-of-life this gap will not be filled. For the axial strain they provide a design margin of 13 inches using corrugated e

spacers. They predict only 7-1/2 inches of axial growth. The helium j

pressure from the B reaction will be approximately 600 lbs. at end H

j of life. The clad thickness of the zircaloy tube is 32-1/2 mille.

I' We agree that MV had properly assessed the safety aspects of the BFRA's and consider this item resolved.

3.

Pressurized Fuel The Metropolitan Edison Unit 1 will use pressurized fuel assemblies.

This will be documsated in the next anacdment.

PRIMARY CDOfJLNT SYSTEM f

1.

Flywheel Inspection We asked EW to suusarise the flywheel inspection criteria for i.he primary coolant puerps. MW told us thnt, at the time that increased '

flywheel inspection uns becoming a regulatory requirement, the TMI-1 primary pusy motors had already i a fabricated, with the flywheela shrunk on. The motors are manafactured by Allis Chalmers. In order to provide inspectism to the extent possible, AC performed an

~ inspection on the upper face and outer rim of the upper flywheel en each pump, and took the flywheels completely off one pup. By b

drilling calibratism holes, they determined that they could measure

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a flaw size apprwimately 3/4 of a S/16 fach hole,1/2 inch deep.

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Or, they==*4==*= that a flaw in the general size of a 1/4 inch diameter by a half inch deep is detectable. They have computed the l

critical flav size for the large flywheel (72-inch diameter);

approximately an 8.4-inch radial crack from the bore out is requirwd before critical stresses are reached. We asked that this information be documented and Metropolitan Edison agreed to furnish it.

Based on l

our informal understandi. we believe this item to be closed.

5 In a related discussion Metropolitan Edison informed us that due to problems that had develop:4 with the Eingham pump, which they intended to use on unit 1, they have decided to switch to Westinghouse pumps.

The changeover is not as severe as it was on 0 cones primary system which was assembled; TMI-l welding has not started. We told Metropolitan Edison that they should document the change and verify the stress calculations that might be affected by the switch in pump design.

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2.

Fracture Toughness of Primary System i

We discussed with Metropolitan Edison tho recent changes that have takan place regarding the determination of fracture toughness in the primarv coolant systen, including the vessel. We told them that our position on Oconee was, since certain brittle fracture data were not available, that we would use a conservative pressurization temperature.

l This temperature limit was 275*.

Below that temperature the primary I

system pressure could not exceed 550 psi. Above that temperature the l

pressure could go to full system design pressure of 2200 pai.

I When more information is realized through operation of tha plant and I

from testing of the surveillance specimens, this temperature limit may be lowered. Metropolitaa Edison understands our position. We I

expect Metropolitan' Edison to adt.pt the same general temperature pressura limit in technical specifications.

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Vibration Monitoring Metropolita amisen proposes a ceafirmatory vibration monitoring system. Heil Booker of B&W discussed some preliminary vibration monitoring tests that had been performed at the 36W shop in Barberton, Chio. The Three Mile T=1==d internals, weighing some 300,000 lbs.,

were instrumsated with accelerators and subjected to shaking action by a vibrator and impact action by a rubber malist. In general, the measurements confirmed some pralfainary design calculations and also confirmed the ability cf the instrumentation to provide data during

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hot functional tests. We stated that it was our opinion that they should do either ceafirmatory vibration monitoring or that they l

should remove the internals for inspectise for undue wear, galling, etc. af ter the hot functional tests.

i "ote: At a subsequent neeting, I

we decided that confirmatory vibration monitoring would be sufficient and that the applicant is not required to remove the internals.

However, we do intend to urge him and will so state at our technical specification meeting to visually inspect to the extent possible the cara internals after the hot functional tests.

l 4.

Feedvater Ring Header We told Metropolitan Edison that-during our ocor.ee review we required i

additional inspection of the welds of the primary system in the f

vicinity of the feedwater ring header on the stes= generator, since it could not be established on Oconee that a failure of the primary system would not cause a subsequent failure of the secondary systen.

However, the Cilbert representative showed us detailed drawings and I

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. '00R ORGINAL referred to the explicit design basis in the FSAR whereby restraints are provided on Three Mile Island that were not provided on 0conee.

Ibey have designed a primary system such that the piping cannot prop-agate a failure at the feedsater ring header area. This appears to i

be sufficient justification for not requiring increased primary system l

inspection.

5.

In Service Inspection We asked the applicant to describe the extent to which the ASME Section 11 code for inservice inspection could be utilized on the primary systaa. The applicant noted that there would be some areas that he could not inspect to Section 11 standards, due to access. We

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asked them to== mad the FSAR and ta be prepared to incorporate in the taehnfeal specification bases the extent they do not comply with Section 11 and why.

'6.

Decay Meat System Isolation valve The R&W design provides two isolation valves between the low pressure decay heat system and the high pressure primary system. Between the two isolation velves there is a small tall-tale relief valve which is

7. sized on the basis of only a minate leakage from the high pressure side. One of the high pressure isolation valves is provided wiln an e

. interlock to procInde inadvertent operat*- -

Although this deoign is met strictly in accordance with our pro;

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' valves we shall' accept it, due to the as-ouilt nature of the design.

7.

Once Through Steen Generator

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i We asked B&W if they had completed the vibratory neasurements that they were taking on the as-built steam generator. They have completed the test; a supplemental report is in preparation.

STRUCTURES WERE COFERED AT THE SECOND DAY. WEDNESDAY, FEBRUARY 24th AND I

THEREFORE IS INCLUDED AT THE END OF THIS ME!ORANDUM.

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ENGINmun SAFETY FEATURES 1.

Thioe,alfate We told Metropolitan Edison in November 1970 we had listed four conditions relevant to the use of thiosulfate and we asked them to l -.

what extent they had been considered. Upon request, we reiterated the four items; they were:

(a) that a pH monitor should be provided, i

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(b) that the ability to replenish the sodium hydroxide tank should be provided, (c) that the use of copper and alminum should be kept at a minimum and (d) that the thiosulfate storage tanks should be monitored frequently. Metropolitan Edison agreed to doctament in the next amend-ment items (a) and (b). We said that from their design it appeared they had already complied with ites (c), with the coment that they should not subsequently add copper or aluminun objects inside con-tainment. As for item (d), we said that that item would be covered with the technical specifications.

In regard to the removal credit for thiosulfate, we said that our position had not changed. B&W and Metropolitan Edison arn aware of how we calculate dose reductions. Cordon Burley described briefly ser currest model which shows doses slightly above Part 100 for j

the less of coolant accident. Bill Nischan pointed out that the exact j

value was 328 rem at this site bondary. The potential for reduction in the meteorology to half-a-meter-per-second wind speed could double j

the dose. Burley said that he was censidering, and it was under

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internal review, minor chasses in the DE evaluation model which could j

bring their dose from slightly over to slightly ader Part 100. We notifiod Metropolitan Edison that we would communicate our final j

posities with regard to the licensing of this plant at our meeting j

to be held daring the week of March 15th.

t This item remains unresolved.

2.

Emergency Cote Cooling System Report l

B&W said that they expected to file this report on schedule next week.

i We said that we would try to have an initial evaluation in approxi-j nately six weeks. However, this evaluation would not be timely with respect to the ACRS meeting in May, and therefore a subsequent ACRS meeting on this and perhaps other subjects is foreseen. Since the report is not in hand and since we are presently committed to evalua-ting the ECCS report before final TMI-1 resolution with the ACRS, this item remains unresolved.

3.

Engineered Safety Features Instrinnentation We inquired into the design of the level indicators for the borated i

water storage tank and core flooding tanks. Centrary to what the FSAR shows, two (not one) level instruments are provided on the borated j

water storage tank and the two core flooding tanks. Thus redtmdancy i

does exist, although it is not clear what independence exists.

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that it was not. We said that we wanted Metropolitan Edison to document this information in the next amendment. We reserved decisions on the adequacy of the redimdancy that is provided and the degree to which they don' t meet IEEE-279. This item remains unresolved at this time.

4.

Spray System Actuation Set Point I

We asked why they set the spray system actuation pressure at 30 lbs.

They responded that they saw no reason for turning on the sper.j rrstem for pressures lower than that, and that inadvertent action of the spray would create a housekeeping problem inside containment, to say the least. They notad that some facilities even provide a time delay to preciade inadvertent actuation. We said that this is properly a technical specification discussion, but we thought that advance notice should be given so that B&W would have time for preparation. We suggestad 10 psi as a lower value although we admitted that there is very little time difference between 10 and 30 psi for large breaks.

. This item remains unresolved in that is is a technical specification item and we do expect-to resolve it at that time.

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He discassed our presamt plans for facilities such as Three Mile Ir. Land Dait 1.

Under certain conditions we expect to approve purging cf the containment, when the purge dose should be less than 10% of Part 100 guidelines. We told Metropolitan Edison that we had not completed our dose calculations although it appeared that the thyroid purge dose would be within the 30 rem value. We expect to complete, we said, our calculations by next week using an estir.ated annual-average meteorology. We told Metropolitan Edison that we would comuni-este our calculations to them about March 15. If we can agree with the applicant that the whole body and thyroid doses at the site boundary

.due to purging are less than 10% of Part 100 guidelines then we do expect to accept the purging concept.

We have additional requests regarding the purge equipment for which Metropolitan Edison most provide additional information. We told Metropolitan Edison that we wanted them to document:

(a) the purge

' procedure; (b) the meteorology inatruments that would be available; (c) the long time utilization of the reactor building fan coolers; (d) the details on the hydrogen monitor qualification tests; (e) the ability to extract a grab sample; and (f) the effects of moisture on the hydrogen monitor. B&W maderstood the items and agreed that the next amendment would provide these decmfia.

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Lone Term Cooling i

We discussed the phenonena that might occur in the vessel following a cold leg break whereby buillag would occur as the principal ciode of heat removal. Should this happen, the possibility exists for a long-term buildup of solids in the vessel, and subsequent inter-forence with core eeoling. We agreed to discuss by telephone the ground rules for this calculation. It was agreed that B&W would instigate the phone call and that Ifatt Taylor and D. Ross would be

' parties to the DRL end of the conversation.

7.

ESF Pump Performance We asked if Metropolitan Edison or Gilbert Associates had received the first four safety guides that had been published. They had. We asked if the engineered safety featuree pumps conform to the net positive suction head requirements of Safety Guide No. 1.

Gilbert's answer was that they assumed a containment pressure to be in equilib-

. rinse with the sump water temperature. On inspection of the sump water temperature time relationship, it appeared that for some time af ter "the accident, the sump was up to 220*F. They referred to figure

'14-57 of the FSAR showing 220'F sump water at 15 minutes af ter the j

accident.- Sines.the use of an equilibrium pressure equal to saturation

. pressure at this temperature implicitly assumes that the containment

.pressura is_ above atseephere, then we can state that tha design of -

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'the ESP pumps is not in comformance with the safety guide regarding MFSI. The Gilbert representative stated that should the containment pressure for some reason drop to a lower value than that. assumed, then the operator would have to throttle back on the low prcssure

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injection flow or would have to stop one pump. They noted that the low pressure system, nominally rated at 3.000 gpm, cot id well be

_ delivuring in excess of this value due to conservativism in the hydraulic design. We told the applicant that we had not made a final decision on this matter and therefore this is unresolved at this time.

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8.

Fan Cooler Design We told Metropolitan Edison that the material submitted as Appendix 6A was generally satisfactory and that we had no further questions on the fan cooler,, design. -

9. ' Core Flooding Task Isolation 1raiva

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f BW said that the isolation valve system for Three Mile Istant wee-essentially the same as that provided on Oconee. We asked Metropolitan Edison to provide in the next -andmant the following three items:

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(a) that there are two independent acana of determining valve position:

(b) that the condition of not-full-open be alarmed in the control roon; and (c) that the power to the motor-operateo valve be locked out during normal operation without interrupting power to the valve position indicators or alarm.

It appears that this design information can be supplied and this should not be an unresolved ites.

10.

Zine When asked, the applicant said that there was no exposed zine inside the containment.

INSTREMENTATION 1.

Post-Accident Ranges We asked how the range of the ra=== instruments compared to the doses that might be expected after sa accident. A Cilbert representative 7

had some informal information. "It appeared that this information is eatisfactory, and we mai=J Hatropolitan Edison to document it in the meat amendmaat. -

~2..

Divarse ICCS Signal for Reactor Trip

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' We told Metropolitan Edison that on Oconee we required a diverse reactor trip following the less of coolant accident phenomenom and stated that on the Oconee reactor a high building pressure of 4 psig aus added as a reactor trip input. The applicant understood the problem and it appears that the sama reactor scram method will be provided for Three Mile Talmed.

l 3.

Failed Fuel Detector l

As on other plants a gamma monitor on the letdovn line will be used.

i the sensitivity of the instrument was discussed. The upper li: nit of sensitivity corresponds to about 10% failed fuel. We asked and Metropolitan Edison had agreed to document the informal inferr:ation i

presented at the meeting.

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i 4.

Use of Dusew Bistables i

We discussed at some length how'dammiy bistablem were used as a bypass apparatus on the TMI design. The specific designers were not present at the meeting, and information was not readily available. Our con-cern was that use of dummay bistables should be indicated in a manner t

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1 readily visible to the control room operator. The B&W people and the Metropolitan Edison people were not sure whether that in f act was the i

case. We agreed that this information could be furnished by telephone I

and based on the telephone call, we would decide what additional infor-I mation needed to be filed. B&W will instigate this telephone call and will call Don Sullivan directly.

5.

Qualification of Equipment. Topical Esport BAW-10003 B&W intends to file this topical report around April lat. We stated that the report was essential to our review sad it appeared that it might he part of a supplemental ACRS report. Sullivan asked the Cilbert people te what extant had tests been rm on cables. His

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r questhe concerned temperature, radiation, humidity. The Gilbert people

-f.id not have a ready answer and they will discuss this issue with Sullivan over the phone. At that time we will decide what additional information needs to be filed. In aesver to Sullivan's question, the Gilbert people stated that now each diesel has a separate annunciator to indicate the est-of-service condition.

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~ 0er seoe-to-be-issued Safety Ceide states that the fuel pool' atwa shoeld be exhausted threagh ducts and filters to the mit vent. The

,. Metropolitan Edison design provides for isolating the exhaust system med the supply system and essentially bottling up the fuel pool aus-iliary building. Metropolitaa Edison feels that due to the airplane impact desige that they have desiseed or provided a fairly leak-tight building. Therefore, they think that the dose to the public would be

'less if they simply turned off the fans than if they kept the fan running and have a high radiation signal. We had felt that filtration and ventilation should continue even if a high radiation signal existed downstream of the filters. As a result of discussions with the appli-caat, we are new not so sure. This item remains aresolved on our part.

2.

Isetopic Analyses I

f We discussed our proposed Safety Guide which would require isotopic i

analysee en the general order of quarterly, and after startup or unusual changes in activity. We noted that this was a suitable subject for our technical specification meeting. Bill Nischan also had some detailed questions en the Radvaste System. Es asked how the OFFEE >

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P00R ORIGINAL applicant would detect and control iodine released through the condensar ejector. They stated that they planned to use Krypton 85 an an indicator.

Their plan is to establish a set-point on the meter on the basis 6

that all of the activity (which should be Krypton 85) is hypo-I thetically Iodine 131. If this set-point is reached daring normal operation they will extract a sample and analyze ic isotopically to determine the proportion of the activity that is Iodine 131. For example, if the ratio of Kryptoa 85 to Iodine 131 is 50, then they

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would readjust the set-point higher by a factor of 50. We asked if they intended to use an iodine monitor on their wasta gas tank, in addition to isotopic analyses; they did not. Nischan had e addi-

' tf==m1 questien in response to the amaver to our question 11.2 con-estning concentrations devastream after a liquid rule.asa. He noted that there were four errors in a table 11-14 of the FSAR concerning MFC values. Es also asked why no Cesium 134 was listed. Metropolitan Edisoa said that in a subsequent amendment they would correct table t

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.ao 2 arer r=adily available. In regard to our question and their

' answer to.11.3 we asked about the use of the Radrasta Treatment equipment. Gilbert Associate representative pointed out that there

was as way.for high activity release to get to the affluent line

_without going through both as evaporator and a domineralizer. They provide f r redundasey in equipment. Eagarding our question 11.5 9

we acted that Yankee Bowe and Connecticut Tankee had experienced

- differmat valass of r=1===e in that corrosion products constituted the principal items, in centrast to the tabla in the Metropolitan Edison FSAR where the corrosion products are only a miniaurs. The Metropolitas Edison people pointed oct that the Tankee core is stain-less staal and that the Three Mile Island unit postulates a certain failed fuel activity.

l 3.

Fuel Cask We asked if the fuel pool could withatmd the effects of a dropped fuel cask,, They said that for the portions of the fuel pool over which a cask might be moved (and there are interlocks on the crane to prevent any other movement) the fuel pool concrete is extended all the way to bedrock. Therefore the pool and its liner could with-stand the effects of a dropped cask.

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f' ACCIDENT ANALYSIS 1.

LOCA Domes We noted that in discussing the meteorology and thiosulfate we had i

already reasonably well defined our position on accident doses. As l

a review, the two hour thyroid dose following the loss of coolant accident is still above Part 100 Guidelines. If the meteorology gets j

down to 1/2 meter per second wind speed, then it is not impossible i

that the fuel pool handling accident would also approach Part 100 i

Guidelines.

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2.

ATWS We motified Metropolitan Edison that the subject of anticipated trans-innta without scram would not be a review item for their operating "licasse.

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' ' ' Metropol'itan ' Edison stated that'they vers in essential compliance with

. AMS-3 standard on training and staffing and that they would so document in the technical specifications.

.2.

Industrial SecurityJ We notified Metropolitan Edison that we required a small amount of additional information on the record concerning industrial security.

.We referred them to our Oconee Safety Evaluation, page 75, and to the Duke Power AmenAmant No.11 for on a guide as to the quantity and type of additional information. They agreed to furnish this information.

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3.

Technical Specifications Metro'politen Edison plans to make the first draft available about the first day of May. We told them sight copies would be sufficient and to make them available informally.

4.

Restricted Area J

We asked Metropolitan Edison to define on a large scale map where the

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femen would be and what they considered a restricted area to be.

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vould follow the dika around the island. No one can get on to the north end of the island without authorization, as there is a guard at the mainland side of the permanent bridge. The south end of the island which is accessible via a " temporary bridgo" will be continuously available to the general public. However, the road access to the plant I

from the south will be barred to casual travelers. There will be I

double fencing from that side separated by open land area which will f

be useful for spotting interlopers.

5.

Startup Temes, We motified Metropolitan Edison that we required additional information to be submitted with the PSAlt concerning startup tests. As a beginning we referred them to what had been made available on Oconee We thought that the depth of the material could be increased in comparison to Oconas. %e Oconee acceptance criteria were very short almost to the point of being meaningless. Metropolitan Edison agreed to file sone additional information. We concluded the first day meeting and recon-vened the following morning to discuss the structural design items.

~

l 6.

Structures Structures was category 4 en the agenda; agenda item I was the contain-ment design in general. We had asked a number of questions in our september 1970 list. The answers which were made available in January 1971 were met fully acceptable. Most of our questions that we asked on structures ronived around the generally deficient area of their January 1971 response. Don Croneburger of Gilbert discussed their contentions that esmerate strength under a biarial stress condition has a higher alH=ata strength value than in safarial compression. He referred to a November 1970 article in the journal of the American Concrete Institute proceeding V-67, Page 908. ne article of the paper was " Strength of Plain Concrete Under Biarfal Strest". It appeared from that article that for the case where concrete was loaded biaxially in conpression j

that the ultimate strength could be increased by approximately a factor of 2.

If true, then the resistence of the structure to an air-craft impact would be considerably increased. Our consultant on air-craft impact deeign, Jim Proctor of Naval Ordinance Laboratory, was very interested in the utilization of that reference. It was sufficiently recent that it had not been noted by Metropolitan Edison in the January t

1971 Amendment, t

i Mr. Proctor acted a number of deficiencies in the recent response to our question area regarding the calculation of the dynamic load factors, in particular, the utilization of a coarse approximation to the load time curve which does not preserve the momentum of the airplane. He also

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pointed out that, at the time of maximtsa strain, the strain rate is sero, therefore there would be no attendant increase in concrete pro-i perties. He aise noted some errors in some of the tables in Appendix 5A.

In each case the Cilbert personnel agreed that mistakes have been made i

and they agreed to correct these values in the next amendment.

Ia discussion of the November 1970 paper in the ACI Journal, Doctor Glackman said that what really exists in the done of the contain-ment is a triaxial fiald where there are two compression forces and one tensile. He thought that this might reduce the properties of ultimate strergth, rather than increase. Mr. Chen Chang, a Gilbert employee, said that there would always be radical compression in the done and d

f there would not exist a tension field before impact. However, Doctor Gluckman pointed out that in the vicinity of the tendons there would be a teosten fiald and that cracks would have grown. He said that

_ if Gilbert could justify that due to impact there is radial compression, them perhaps we could agree that the ultimate strength properties of

. eenerate could be increased ebeve their meninal value in a multi-exial

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fiald. Doeter Clucknen reviewed the difficulties that have been emeoamtared La a Turkey Feint done and said that these la part are

, reopensible for our coneers abeet the response of the Three Mile Island '

. dame to an aircraft impact. We agreed with Metropolitan Edison and

' Gilbert to have an additiemal meeting during the week of March 15th on the subject of aircraft impact design. At that time, Gilbert expects

'te have corrected their tables and have drafts of the additional infor-nation which.hm.u be avellable for filing.

Our next question area concerned the calculations of thernal gradients sud stresses in the vicinity of variable thickness zones, such as the transition from the base to the wall and in the vicinity of the ring girder. They use the finite element method for the calculation of stresses in the transition region. They had additional information on momenta and shears that were not included in Figure 53-18 of the application. They had calculated the temperature profiles for one-half day, one day, two days, six days,- and twenty days af ter startup. They j

did not de stress analyses for all conditions. It appeared that we were aatisfied with their informal response. We asked if they had considered slightly higher temperatures which would give slightly higher stresses should an event such as happened on Dresden 2 also occur at Three Mile 3

Island.

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liftoff test was that the results would not be impeded by friction of the tendon wires in a curved conduit.

We noted that they had not provided the allowable bearing values for the structures adjasent to the bedrock. We asked what did they actually use.

l and to give the same information for dyn==fe conditions. We said that we had looked at their unterial on surveillance of the structure during the proof test. We wated that although they were taking three meridional measurements, we might prefer as many as six, with a smaller number of points per measurene.at. They said that this seemed to be excessive in comparisos with what had been done recently on other prestressed contain-ments.

We brought up the subjeat et the seismic instrument to be provided and said that we would lika information in the FSAR concerning: tow the instrument will be asistained; what will be done when the instrument has reaorded a signel; and how the signals arill be processed and interpreted.

~ They said that the sensitivity of the instrument was.01C, and that they would laspect periodiem11y. A leeal indicator would signify that a record had been made. At that time, the record would be played back.

If than mecaleraties was greater than 1/2 of the design basis earthquake,

.that is, if the acceleration was greater than.03C then they would digitise the time history from the r2 cord to get a response spectra.

This in turn would be compared to the design.

We brought up the face that recent construction at their facility had used concrete which was peered is montanformance with the specifications.

They said that they were going to cL*ck the 284ay corpression specimens e the concrete that was poured that dsy. There were nome 200 yards involved whers the pour was interfaced at a surface below 32*F.

Based on the 28-day specimens, they will decide what to do next.

We next discussed the dynamic analysis of piping. We said thst the AEC l

has not agreed with the Biggs and Roesset method for dynamic analyses.

l Chen of Gilbert said that it depends on how the Biggs and Roesset method is used. He said that Biggs did not use a single degree of freedom f

system and referred to tL, 1965 paper entitled " Earthquake Response of Appendage on a Multi-story Building", bf J. Penzien and A. Chopra, given at the third world conference on earthquake engineering in 1965 at New Zaaland, Volume 2.

Chen discussed what had been calculated by Stone ad Webster on their Beaver Valley calculation. Dave Lange of DRS asked hsw is reeenance handled in the Biggs Method. The answer was that a h

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possibly not be conservative. Lange said that the only way to demon-strate conservatism was to do a multimass time history analysis. Chen said that he does not think that the time history method is fully j us tified. Lange's respons( vas that the time history envelopee the response spectra for this site. We notad that what DRL has come to refer to as the " Robinson Fix" could be employed at Three Mile Island g

ales. This involves the application of pipe supports at a much more frequent interval. The unresolved itass en structural design include

• the aircraft impact design, soma elements of the static design involving the presones of teamile stresses, the dynamic analysis of piping, and certain aspects of the tendon and structure surv=411=e= program.

The last structurd subject discussed was the cavity design. Gilbert summarized the final calculations. They said that they had provided

,in their final design a vest area of 141.6 square feet. This corresponds to blowing eet of the insulation around the primary pipe from the cavity

' to the sesans generator area. Per a 14.1 square foot pipe break the cavity pressure goes to 186 psi. At that pof at, they have as estimated 45,000 psi in their robar of the enter fibere of the cavity. They had specified in procuremsat that the rebar should be at yield at 40,000 pai, however, the as-bought materials were souewhat higher. They de

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est expect therefore any sianificant deformation of the cavity. They de expect treeking, but ne propagation of camerata missiles. The pipe tummel for the primary piping is lined with a steel liner which nerved as a form for esmatraction. We stated that that information was satisfactory and that no addf tional information on the cavity would be seguired.

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..'ZZTL.C WITH E7 TAG 20LII c. ELI3Sa C.. Tr'.d2.CL2 25IED NUCLZAR L~ NIT NO.1 We ca;. wich repre4er.tatives of Metropolitan Edison Company and their vence s and consultanta on February 23 anc 2i.,1971 to discuss the Tnree Mile Island.u. clear Station U21: So. 1.

A liat of attendees is attached.

Tr.e purme of the ::a:ecing waa o act.ss A= enc =ents 15 and 17 which centuned the acswers to our firr:,: question list. We also discussed the itema enat are at is s ue b e tweer. us, ana :ha proposed schedule for our

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ing.

In ma.y cases e infor:ned the applicant of our final or near final positions, wnich were discussed at a recent Task Force me e ting.

SITE 4.

&teoroiczv We informac Ntropolitan Edison ch4.: the data made available so far did not substantists the asserted diffusion values.

In fact, we vere not able to conclude that the two-hour accident meteorology of Pasquill-/ and 1 meter-oer-second was justified. On the very lira.ted data =ade available so far, it nay be that a wind speed of 0.5 r..eter par second i: warranted. However, the applicant has ins talled a new u toc rology :wer which has Delta T instruments would provide rore information on the Pasquill conditions a::cally present. We agreed

o have a x:eorology :tecting scwa:ine during the week of March 15, saa further discuss :ne data cha:..ava been recently generated from

he Lelta T instrument. At tha

reeting, we expect to have Or. Vanderhovsn, our c:r.sultant from SOAA. &teorology therefore rs: mains an unresolved issue.

2.

Flo : c.

We ravleved the prcLQ1 ~ *-

1. 1ood calculations with the applicant.

Tae ::nres;r.:ative frc.: Cilbert Associa:es, Mr. MacLa: ore, and the DF'. ::af f hyd: lop:, Dwg.:

r.n, discussed the lasues in detail at

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Tc.'cy r :urt.c.:2 :o the main meeting and

.,marized :~aa addi:10c.ei nf s:-

ion that we require, in order to conolate our reviev. In E 'n' nl, we nra satisfied with the procedures that Gilb ert has t.s o.nd c.c raqc:. rec inforn.a:1on constitutes a 1450 281

P00ROR8Na written verifier.cion of our verbal understanding. The applicant

t. greed to furnish the required information on the basis of the understandings re uned at the meeting. This item therefore can be considered as informally resolved, subject to satisfactory documentation.

REACIOR DESIGN 1.

Fuel Design We requested the applicant's reactor vendor, B&W, to discuss:

the fuel design, in particular the high burnup tests that have been performed by B&W; the recently observed fuel pellet abnormalities; and the procedures that B&W uses in calculating fuel swelling and consequent clad strain. Neil Hooker of B&W gave a presentation on this subject. He stated that both the pellet vendor and B&W have QA procedures on the cladding and the fuel pellets. The observations to date show chat the fuel pellets have been remaining well within the QA tolerances. He stated that the small amount of chipping and flaking that sur reviewers had noticed during a tour of the fuel f abrication plant were only a minor aberration in the pellet design and that the pellet diameters were not becoming excessively large.

In regard to the high burnup tests, B&W personnel stated that it was not their intent to prove current designs with the high burnup test; rather they were aimed at advanced designs. They stated that they could not get the same fluxes and enrichments at the B&W test reactor, therefore the commercial design and the high burnup test do not have a one-to-one correspondence. They have not completed their evaluation of the high burnup tests. They do intend to come to DRL with a presentation on this subject when they complete this work, sometime in 1971. At present, they do not plan a formal report.

Hooker stated that B&W calculates clad strain in the same manner that he believes the other vendors do.

We asked, and he agreed, and Metropolitan Edison agreed, that the details of how clad strain is calculated be doctmented in a forthcoming amendment.

2.

Burnable Poison Rod Asse:blies (BPRA)

Hooker described the design criteria for the burnable poison rod ass emblies. They were:

(1) the zircaloy tube should be free standing; (2) there should be no clad strain due to diametral growth from thermal or radiation effects on the poison material and (3) there should be no clad strain due to axial thermal or irradiation swelling.

1450 282

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P00RORMAL They provide a twelve :sil diametral gap between the pellet and the clad. At end-of-life this gap will not be filled. For *:he axial atrain they provice a design =argin of 13 inches, using corrugated spacers. They predict only 7-1/2 inchea of axial growth. The helium IO pressure from the B reaction will be approximately 600 lbs. at end of life. The clad thi::kness of the zircaloy tube is 32-1/2 mills.

We agree that B&W had properly assessed the safety aspects of the BPRA's and consider this item resolved.

3.

Pressurized Fuel The Metropolitan Edison Unit 1 will use pressurized fuel assemblies.

This will be documented in the next amendment.

PRIMARY COOLANT SY.3 TEM 1.

Flywheel Inspection We asked B&W to sumrarize the flywheel inspect: ion criteria for the primary coolant pumps. B&W told us that, at the time tint increased flywheel inspection uns becasing a regulatory requireme t.

the TMI-l primary pump motors had already been fabricated, with the flywheels shrunk on.

The motors are manufactured by Allis Chalmers.

In order to provide inspection to the extent possible, AC performed an inspection on the upper face and outer rim of tLa upper flywheel on each pu=p, and took the flywheels completely off one pump.

By drilling calibration holes, they determined that they could measure a flaw size approximately 3/4 of a 5/16 inch hole,1/2 inch deep.

Or, they estimate that a flaw in the general size of a 1/4 inch diameter by a half inch deep is detectable. They have computed the critical flaw size for the large flywheel (72-inch df ameter);

approximately an 8.4-inch radial crack frem the bore out is required before critical stresses are reached. We asked that this information be documented and Metropolitan Edison agreed to furnish it.

Based on our informal understanding we believe this item to be closed.

In a related discussion Metropolitan Edison informed us that due to proble=s that had developed with the Bingham pump, which they intended to use on unit 1, they have decided to switch to Westinghouse pumps.

The cha geover is not as severe as it was on Oconee primary system which was assembled; DiI-l welding has not started.

Ws. told Metropolitan Edison that they should document the change and verify the stress calculations that might be affected by the switch in pump design.

1450 20

100R OR GINAL 2.

Fracture Touahness of Primrv System We discussed with Metropoliten Edison the recent changes that have taken place regarding the determination of f racture toughness in the pri=ary coolant system, including the vessel. We told them that our position on Oconee was, since certain brittle fracture data were not available, that we would use a conservative pressurization temperature.

This tenperature limit was 275*.

Below that temperature the primary system pressure could not exceed 550 pai.

Above that tet:perature the pressure could go to full system design pressure of 2200 psi.

When tore information is realized through operation of the plant and from testing of the surveillance specimens, this temperature limit may be lowered. Metropolitan Edison understands our position. We expect Metropolitan Edison to adopt the same general temperature pressure limit in technical specifications.

3.

Vibration Monitoring Metropolitan Edison proposes a confirmatory vibration monitoring system. Neil Hooker of B&W discussed some preliminary vibration monitoring tests that had been performed at the B&W shop in Barberton, Ohio. The Three Mile Island internals, weighing some 300,000 lbs.,

were instrumented with accelerators and subjected to shaking action by a vibrator and impact action by a rubber mallet.

In general, d e measurements confirmed some preliminary design calculations and also confirmed the ability of the instrumentation to provide data during hot functional tests. We stated that it was our opinion that they should do either confirmatory vibration monitoring or that they should remove the internals for inspection for undue wear, galling, etc. af ter the hot functional tests. Note: At a subsequent meeting, we decided that confirmatory vibration monitoring would be sufficient and that the applicant is not required to remove the internals.

However, we do intend to urge him and will so state at our technical specification meeting to visually inspect to the extent possible the core internals af ter the hot functional tests.

4.

Feedwater Ring Header We told Metropolitan Edison that during our Oconee review we required additional inspection of the welds of the primary system in the vicinity of the feedwater ring header on the steam generator, since it could not be established on Oconee that a failure of the primary system would not cause a subsequent failure of the secondary system.

However, the Gilaert representative showed us detailed drawings and 1450 284

. referred to the exnlicit design basis in.ne FSAR whereby restraints are provided on Three Mile Island that were not provided on Oconee.

They have designed a primary system such that the piping cannot prop-agate a tailure at the feedwater ring header area.

This appears to be sufficient justification for not requiring increased primary system inspection.

5.

In Service Inspection We asked the applicant to describe the extent to which the ASME Section il code for inservice inspection could be utilized on the primary system. The applicant noted that there would be some areas that he could not inspect to Section 11 standards, due to access. We asked them to amend the FSAR and to be prepared to incorporate in the technical specification bases the extent they do not comply with Section 11 and why.

6.

Decay Heat System Isolation Valve The B&W design provides two isolation valves between the low pressure decay heat system and the high pressure primary system. Between the two isolation valves there is a small tell-tale relief valve which is sized on the basis of only a minute leakage from the high pressure side. One of the high pressure isolation valves is provided with an interlock to preclude inadvertent operation. Although this design is not strictly in accordance with our proposed new standard on isolation valves we shall accept it, due to the as-built nature of the design.

7.

Once Through Steam Generator We asked B&W if they had completed the vibratory measurements t. hat they were taking on the as-built steam generator. They have completed the test; a supplemental report is in preparation.

STRUCTURES WERE COVERED AT T'!E SECOND DAY, WEDNESDAY. FEBRUARY 24th AND THEREFORE IS INCLUDED AT THE END OF THIS ME}ORANDUM.

ENGINEERED SAFEIY FEATURES 1.

Thiosulfate We told Metropolitan Edison in November 1970 we had listed four conditions relevant to the use of thiosulfate and we asked them to what extent they had been considered. Upon request, we reiterated the four items; they were:

(a) that a pH monitor should be provided, 1450 285 s

. (b) that the ability to replenish the sodiu:n hydroxide tank should be provided, (c) that the use of copper and altaninum should be kept at a

mininum and (d) that the thicaulfate storage tanks should be monitored frequently. Metropolitan Edison agreed to document in the next amend-ment items (t) and (b). We said that from their design it appeared they had already complied with item (c), with the ~ cot:inent that they should not subsequently add copper or alumintam objects inside con-tainment. As for item (d), we said that that item would be covered with the technical specifications.

In regard to the removal credit for thiosulfate, we said that our position had not changed. B&W and Metropolitan Edison are aware of how we calculate dose reductions. Gordon Burley described briefly our current model which shows doses slightly above Part 100 for the loss of coolant accident. Bill Nischan pointed out that the exact value was 328 res at this site boundary. The potential for reduction in the meteorology to half-a-seter-per-second wind speed could double the dose. Burley said that he was considering, and it was under internal review, minor changes in the DRL evaluation model which could bring their dose frcza slightly over to slightly under Part 100. We notified Metropolitan Edison that we would consrunicate our final positica with regard to the licensing of this plant at our meeting to be held during the week of March 15th.

This item remains unresolved.

2.

Emergency Core Cooling Systen Report B&W said that they expected to file this report on schedule next week.

We said that we would try to have an initial evaluation in approxi-mately six weeks. However, this evaluation would not be timely with respect to the ACES meeting in May, and therefore a subsequent ACRS meeting on this and perhaps other subjects is foreseen. Sinca the report is not in hand and since we are presently committed to evalua-ting the ECCS report before final TMI-l resolution with the ACRS, this ites remains unresolved.

3.

Engineered Safetv Features Instrumentation we inquired into the design of the level indicators for the borated water storage tank and core flooding tanks. Contrary to what the FSAR shows, two (not one) level instrunents are provided on the borated water storage tank and the two core flooding tanks. Thus redtsidancy does exist, although it is not clear what independence exists.

Don Sullivan asked if IEEE-279 was used as a design basis and B&W said 1450 286

9

_7-that it was not. We said that we wanted Metropolitan Edison to document this infernation in the next amendnent. We reserved decisions on the adequacy of the redundancy that is provided and the degree to which thev don't meet IEEE-279. This item remains unresolved at this tine.

4.

Spray System Actuation Set Point We asked why they set the spray system actuation pressure at 30 lbs.

They responded that they saw no reason for turning on the spray system for pressures lower than that, ar.d that inadvertent action of the spray would create a housekeeping problem inside containment, to say the least. They noted that some f acilities even provide a tien delay to preclude inadvertent actuation. We said that this is properly a technical specification discussion, but we thought that advance notice should be given so that B&W would have time for preparation. We suggested 10 psi as a lower value although we admitted that there is very little time dif ference between 10 and 30 psi for large breaks.

This item remains unresolved in that is is a technical specification item and we do expect to resolve it at that time.

5.

Hydrogen Purge We discussed our present plans for facilities such aa Three Mile Island Unit 1.

Under certain conditions we expect to approve purgiag of the containment, when the purge dose should be less than 10% of Part 100 guidelines. We told Metropolitan Edison that te had not completed our dose calculations although it appeared that the thyroid purge dose would be within the 30 rem value. We expect to complete, we said, our calculations by next week using an estimated annual-average satsorology. We told Metropolitan Edison that we would co 2 uni-cate our calculations to them about March 15.

If we can agree with the applicant that the whole body and thyroid doses at the site boundary due to purging are less than 10% of Part 100 guidelines then we do expect to accept the purging concept.

We have additional requests regarding the purge equipment for which Metropolitan Edison must provide additional information. We told Metropolitan Edison that we wanted them to document:

(a) the purge procedure; (b) the meteorology instruments that would be available; (c) che long time utilization of the reactor building fan coolers; (d) the details on the hydrogen monitor qualification tests; (e) the ability to extract a grab sample; and (f) the effects of moisture on the hydrogen monitor. B&W understood the items and agreed that the next amendment would provide these details.

1450 287 e

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Lon2 Term Cooline We discussed the phenomena that micht occur in the vessel following a cold lez break whereby boiling would occur as the principal mode of heat removal. Should this happen, the possibility exists for a long-term buildup of solids in ene vessel, and subsequent inter-ference with core cooling. We agreed to discuss by telephone the ground rules for this calculation.

It was agreed that B&W would instigat.e the phone call and that Matt Taylor and D. Ross would be parties to the DRL end of the conversation.

7.

ESF Pumo Performance We asked if Metropolitan Edison or Gilbert Associates had received the first four safety guides that had been published. They had. We asked if the engineered safety features pumps conform to the net Gilbert's positive suction head requirements of Safety Guide No.1.

answer was that they assumed a containment pressure to be in equilib-rium with the sump water temperature. On inspection of the sump water for some time after temperature time relationship, it appeared that the accident, the sump was up to 220*F.

They referred to figure 14-57 of the FSAR showing 220*F sump water at 15 minutes af ter the Since the use of an equilibrium pressure equal to saturation accident.

pressure at this temperature implicitly assumes that the containmect pressure is above atmosphere, then we can state that the design of the ESF pumps is not in conformance with the safety guide regarding NPSH. The Gilbert representative stated that should the containment pressure for some reason drop to a lower value than that assumed, then the operator would have to throttle back on the low pressure injection flow or would have to stop one pump. They noted that the low pressure svetani, nominally rated at 3,000 epm, could well be delivering ar excess of this value due to conservativism in the hydraulic desien. We told the applicant that we had not made a final decision on this matter and therefore this is unresolved at this time.

8.

Fan Cooler Desien We told Metropolitan Edison that the material submitted as Appendix 6A was generally satisfactory and that we had no further questions on the fan cooler design.

9.

Core Floodine Tank Isolation Valve 35W said that the isolation valve system for Three Mile Island was essentially the sa=e as that provided on Oconee. We asked Metropolitan Edison to provide in the next amendment the following three items:

1450 288 (a) that there are two independent means of det<.rminirig valve position; (b) that the condition of not-full-open be alarmed in the control room; and (c) that the power to the tutor-operated valve be locked out during normal operatien without interrupting power to the valve position indicators or alarm.

It appears that this design information can be supplied and this should not be an unresolved item.

10.

Zine When asked, the applicant said that there was no exposed zine inside the containment.

INSTRUMENTATION 1.

Post-Accident Ranges We asked how the range of the gama instruments compared to the doses that might be expected after an accident. A Gilbert representative had some informal information.

I*. appeared that this information is satisfactory, and we asked Metropolitan Ediscs to document it in the next amendment.

2.

Diverse ECCS Signal for Reactor Trip We told Metropolitan Edison that on Oconee we required a diverse reactor trip following the loss of coolant accident phenomenon and stated that on the Oconee reactor a high building pressure of 4 psig was added as a reactor trip input. The applicant understood the problem and it appears that the same reactor scram method will be provided for Three Mile Island.

3.

Failed Fuel Detector As on other plants a gama monitor on the letdown line will be used.

the sensitivity of the instrument was discussed. The upper limit of sensitivity corresponds to about 10% failed fuel. We asked and Metropolitan Edison had agreed to document the informal information presented at the meeting.

4.

Use of Dumnry Bistables We discussed at some length how dt=ny bistables were used as a bypass apparatus on the TMI design. The specific designers were not present at the meeting, and information was not readily available. Our con-cern was that use of dumy bistables should be indicated in a manner 1450 289

, readily visible to tha control room operator. The B&W people and the Metropolitsa Edison people were not sure whether that in f act was the We agreed that this information could be furnished by telephone cas e.

and based on the telephone call, we would decide what additional infor-mation needed to be filed. B&W will instigate this telephone call and will call Don Sullivan directly.

5.

Qualification of Equipment, Topical Report BAW-10003 B&W intends to file this topical report around April 1st. We stated that the report was essential to our review and it appeared that it might be part of a supplemental ACRS report. Sullivan asked the Gilbert people to what extent had tests been run on cables. His question concerned temperature, radiation, hunidity. The Gilbert people did not have a ready answer and they will discuss this issue with Sullivan over the phone. At that time we will decide what additional information needs to be filed. In answer to Sullivan's question, the Gilbert people stated that now each diesel has a separate annunciator to indicate the out-of-service condition.

AUXILIARY 1.

Fuel Pool Filters our soon-to-be-issued Safety Guide states that the fuel pool area should be exhausted through ducts and filters to the unit vent. The Metropolitan Edison design provides for isolating the exhatist system and the supply system and essentially bottling up the fuel pool aux-iliary building. Metropolitan Edison feels thst due to the airplane impact design that they have designed or provided a fairly leak-tight building. Therefore, they think that the dose to the public would be less if usey simply turned off the fans than if they kept the fan running and have a high radiation signal. We had felt that filtration and ventilation should continue even if a high radiation signal existed dowr. stream of the filters. As a result of discussions with the appli-cant, we are now not so sure. This item remains unresolved on our p art.

2.

Isotopic Analvses We discussed our proposed Safety Guide which would require isotopic analyses on the general order of quarterly, and after startup or unusual changes in activity. We noted that this was a suitable subj ect for our technical specification meeting. Bill Nischan also had some detailed questions on the Radwaste System. He asked how the 1450 290

.~ applicant would detect and control iodine released through the condenser ejector. They stated that they planned to use Krvpton 85 as an indicator.

Their plan is to establish a set-point on the meter on the basis that all of the activity (which should be Krypton 85) is hypo-thetically Iodine 131. If this set-point is reached during normal operation they will extract a sas::ple and analyze it isotopically to determine the proportion of the activity that is Iodine 131. For example, if the ratio of Krypton 85 to Iodine 131 is 50, then they would readjust the set-point higher by a factor of 50.

We asked if they intended to use an iodine monitor on their waste gas tank, in addition to isotopic analyses; they did not.

Nischan had an addi-tional question in response to the answer to our question 11.2 con-cerning concentratiou downstream after a liquid release. He noted that there were fovi errors in a table 11-14 of the FSAR concerning MPC values. He also asked why ao Cesium 134 was listed. Metropolitan Edison said that in a subsequent amendment they would correct table 11-14. Nischan noted that Molybdenum 99 was the primary isotope and wondered is there any procedure for further reducing liquid releases by concentrating on the most prolific emitter. There was no answer readily available. In regard to our question and their answer to 11.3 we asked about the use of the Radwaste Treatment equipment. Gilbert Associate representative pointed out that there was no way for high activity release to get to the effluent line without going through both an evaporator and a demineralizer. They provide for redt:ndancy in equipment. Regarding our question 11.5 we noted that Yankee Rowe and Connecticut Yankee had experienced different values of release in that corrosion products constituted the principal items, in contrast to the table in the Metropolitan Edison FSAR where the corrosion products are only a minimum. The Metropolitan Edison people pointed out that the Yankee core is stain-less steel and that the Three Mile Island unit postulates a certain failed fuel activity.

3.

Fuel Cask We asked if the fuel pool could withstand the effects of a dropped fuel cask. They said that for the portions of the fuel pool over which a cask might be moved (and there are interlocks on the crane to prevent any other movement) the fuel pool concrete is extended all the way to bedrock. Therefore the pool and its liner could with-stand the effects of a dropped cask.

1A50 20 ACCIDENT ANALYSIS 1.

LOCA Doses We noted that in discussing the meteorology and thiosulfate we had already reasonably well defined our position on accident doses. As a review, the two hour thyroid dose following the loss of coolant accident is still above Part 100 Guidelines. If the meteorology gets down to 1/2 meter per second wind speed, then it is not impossible that the fuel pool handling accident would also approach Part 100 Guidelines.

2.

ATWS We notified Metropolitan Edison that the subject of anticipated trans-ients without scram would not be a review item for their operating license.

MISCELLANEOUS 1.

Staffing Metropolitan Edison stated that they were in essential compliance with AMS-3 standard on training and staffing and that they would so document in the technical specifications.

2.

Industrial Security We notified Metropolitan Edison that we required a small amount of additional information on the record concerning industrial security.

We referred them to our Oconee Safety Evaluation, page 75, and to the Duke Power Amendment No.11 for on a guide as to the quantity and type of additional information. They agreed to furnish this information.

3.

Technical Soecifications Metropolitan Edison plans to make the first draft available about the first day of May. We told them eight copias would be sufficient and to make them available informally.

4 Restricted Area We asked Metropolitan Edison to define on a large scale map where the fence would be and what they considered a restricted area to be.

They showed that essentially a 8-foot chain link fence topped b r barbed wire 1450 292

, would fellow the dika around the island. No one can get on to the north end of the island without authorization, as there is a guard at the mainland side of the permanent bridge. The south end of the island which is accessible via a " temporary bridge" will be con *inuously available to the general public. However, the road access to the plant from the south will be barred to casual travelers. There will be double fencing from that side separated by open land area which will be useful for spotting interlopers.

5.

Startup Tests We notified Metropolitan Edison that we required additional information to be submitted with the FSAR concerning startup tests. As a beginning we referred them to what had been made available on Oconee We thought that the depth of the material could be increased in comparison to Oconee. The Oconee acceptance criteria were very short almost to the point of being meaningless. Met opolitan Edison agreed to file some additional information. We cor Loded the first day meeting and recon-vened the following morning to discuss the structural design items.

6.

Structures Structures was category 4 on the agenda; agenda item 1 was the contain-ment design in general. We had asked a number of questions in our September 1970 list. The answers which were made available in January 1974 were not fully acceptable. Most of our questions that we asked on structures revolved around the generally deficient area of their January 1971 response. Don Cro 1 burger of Gilbert discussed their contentions thac concrete strength us. der a biaxial stress condition has a higher ultimate strength value than in uniaxial compression. He referred to a November 1970 article in the journal of the American Concrete Institute proceeding V-67, Page 908. The article of the paper was " Strength of Plain Concrete Under Biaxial Stress".

It appeared from that article that for the case where concrete was loaded biaxially in compression that the ultimate strength could be increased by approximately a factor of 2.

If true, then the resistence of the structure to an air-craft i= pact would be considerably increased. Our consultant on air-craf t impact design, Jim Proctor of Naval Ordinance Laboratory, was very interested in the utilization of that reference. It was sufficiently recent that it had not been noted by Metropolitan Edison in the January 1971 Amendment.

Mr. Proctor noted a number of deficiencies in the recent response to our question area regarding the calculation of the dynamic load factors, in partienlar, the utilization of a coarse approximation to the load time curve which does not preserve the momentum of the airplane. He also said that a factor of 20% increase that Gilbert assumed on the ultimate 1450 293

- strength of concrete in compression would be difficult to approve, in that it asserted that the strain rate of the concrete was relavant in aasessing the proper value of ultimate strength.

Mr. Proctor pointed out that, at the time of maxi =un strain, the strain rate is zero, therefore there would be no attendant increase in concrete pro-perties. He also noted some errors in some of the tables in Appendix 5A.

In each case the Gilbert personnel agreed that mistakes have been made and they agreed to correct these values in the next amendment.

In discussion of the November 1970 paper in the ACI Journal, Doctor Gluckman said that what really exists in the dome of the contain-ment is a triaxial field where there are two compression forces and one tensile. He thought that this might reduce the properties of ultimate

.,trength, rather than increase.

Mr. Chen Chang, a Gilbert employee, said that there would always be radical compression in the dome and there would not exist a tension field before impact. However, Doctor Gluckman pointed out that in the vicin Aty of the tendons there would be a tension field and that cracks wosld have grown. He said that if Gilbert could justify that due to impar c Gere is radial compression, then perhaps we could agree that the ulti ute strength properties of concrete could be increased above their n<minal value in a multi-axial field. Doctor Gluckman reviewed the difficulties that have been encountered in a Turkey Point done and said that these in part are responsible for our concern about the response of the Three Mile Island dome to an aircraf t impact. We agreed with Metropolitan Edison and Gilbert to have an additional meeting during the week of March 15th on the subject of aircraft impact design. At that time, Gilbert expects to have corrected their tables and have draf ta of the additional infor-mation which should be available for filing.

Our next question area concerned the calculations of thermal gradients and stresses in the vicinity of variable thickness zones, such as the transition from the base to the wall and in the vicinity of the ring girder. They use the finite element method for the calculation of stresses in the transition region. They had additional information on moments and shears that were not included in Figure 5B-18 of the application. They had calculated the temperature profiles for one-half day, one day, two days, six days, and twenty days af ter startup. They did not do stress analyses for all conditions.

It appeared that we were satisfied with their infomal response. We asked if they had considered slightly higher temperatures which would give slightly higher stresses should an event such as happened on Dresden 2 also occur at Three Mile Island.

Our next question area was on the use of.85f' as a design basis. They stated that they use ultimate strength value 5f.85' to design to 1450 294

dimensions, and to siza the

,inforcing. They did not use it in the final design however. We s. id that we would like to know the maximum compression in the structure cad its relation to f'. On the next subject of bond and anchorage stresses, Doctor GluEkman said that the recent Los Angeles earthquake showed that rebars had been pulled out of the concrete rather than destroyed. He wanted to know therefore what are the critical bond and anchorage stresses and the relationship to the code. They stated that size 18 bars are provided in the base zone and at the ring girder zone. They are anchored in the wall on the inside face where compression exists.

We asked about the existence of shear stress and, had they been cal-culated? Their response was that the shear stress was about 24 psi near the ring girder. We asked if the shear stress influenced the allowable ultimate compression stress for the structure. That is, could there be everywhere enough prestressing to handle the slight tensile forces?

We noted that they used load factors equal to 1.0 and asked if this was designing for rupture, in other words, would the stresses always be below.85f' for the concrete, or.9 of the yield strength for the steel?

We asked teen to answer this by giving an example of the margin of safety.

They agreed to provide the figure.

For the same type of information in the anchorage zone we asked what the safety factors would be.

That is, wotid f' be reduced in the presence of tensile stresses? We said that they co0ld answer this by giving an example of the high stress under the bearing plate and the relationship of tensile stresses at that value.

On the subject of reinforcing on the inside the concrete near the liner, we asked what the actual compression forces would be on the concrete.

They said that the compression would be approximately 900 psi. Up near the ring girder they do get some tensile forces and they have provided steet there. They also get tensile forces on an aircraft impact.

We brought up the subject of surveillance of the structure and noted that when we discussed this item in the technical specification meetings, we would be discussing such items as the number of tendons, the location, frequency of the test, and how to pull out a sample wire. We si.id that we did not intend to accept an unstressed wire for curveillance. However, Croneburger of Gilbert said that strees corrosion has been proven not to be a problem. We asked if they had considered the number of tendone that should be inspected. They had used as a beginning the recommendations of the ACI 349 Committee for surveillance of the tendon anchorage zone. The Com=ittee recommendations are 2*. of the tendons which for Three Mile would be 13. Metropolitan Edison plans to inspect 15.

For lift off tests the iA50 295

. Committee suggests 1/4% which for Metropolitan Edison would be 3.

They intend to lif toff 6; they also intend that all 6 of these to be vertical tendons. Their justification for using all vertical tendons in the lif toff test was that the results would not be impeded by friction of the tendon wires in a curved conduit.

We noted that they had not provided the allouable bearing values for the structures adjacent to the bedrock. We asked what did they actuai;y use, and to give the same information for dynamic conditions. We said tnat we had looked at their riaterial on surveillance of the structure during the proof test. We noted that although they were taking three meridional measurements, we might prefer as many as six, with a smaller number of points per measurement. They said that this seemed to be 6. cessive in comparison with what had been done recently on other prestressed contain-ments.

We brought up the subject of the seismic instrument to be provided and said that we would like information in the FSAR concerning: how the instrument will be maintained; what will be done when the instrument has recorded a signal; and how the signals will be processed and interpreted.

They said that the sensit.vity of the instrument was

.ui"., and that they would inspect periodically. A local indicator would signify that a record had been made. At that time, the record would be played back.

If the acceleration was greater than 1/2 of the design basis earthquake, that is, if the acceleration was greater than.03G then they would digitize the time history from the record to get a response spectra.

This in turn would be compared to the design.

We brought up the fact that recent construction at their facility had used concrete which was poured in nonconformance with the specifications.

They said that they were going to check the 28-day compression specimens on the concrete that was poured that day. There were some 200 yards involved where the pour was interfaced at a surface below 32*F.

Based on the 28-day specimens, they will decide what to do next.

We next discussed the dynamic analysis of piping. We said that the AEC has not agreed with the Biggs and Roesset method for dynamic analyses.

Chen of Gilbert said that it depends on how the Biggs and Roesset method is used. He said that Biggs did not use a single degree of freedom system and referred to the 1965 paper entitled " Earthquake Response of Appendsge on a Multi-story Building", by J. Penzien and A. Chopra, given at the third world conference ou earthquake engineering in 1965 at New Zealand, Volume 2.

Chen discussed what had been calculated by Stone and Webster on their Beaver Valley calculation. Dave Lange of DRS asked how is resonance handled in the Biggs Method. The answer was that a 1450 296 n

~

2-degree of freedom model was used to calculate the response in the resonance region. Lange felt that the time history can be conservative but the superposition of modes which is used in the Biggs method can possibly not be conservative. Lange said that the only way to demon-strate conservatism was to do a multimass time history analysis. Chen said that he does not think that the time history method is fully j us tified. Lange's response was that the time history envelopes the response spectra fcr this site. We noted that what DRL has come to refer to as the "Rooinson Fix" could be employed at Three Mile Island also. This involves the application of pipe supports at a arch more frequent interval. The 'eresolved items on structural design include the aircraft impact design, some elements of the static design involving the presence of tensile stresses, the dynamic analysis of piping, and certain aspects of the tendon and structure surveillance program.

The last structural subject discussed was the cavity design. Gilb ert sumanarized the final calculations. They said that they had provided in their final design a vent area of 141.6 square feet. This corresponds to blowing out of the insulation arotaid the primary pipe from the cavity to the steam generator area. For a 14.1 square foot pipe break the cavity pressure goes to 186 pai. At that point, they have an estimated 45,000 psi in their rebar of the outer fibers of the cavity. They had specified in procurement that the rebar should be at yield at 40,000 psi, however, cna as-bought materials were somewhat higher. They do not expect therefore any significant deformation of the cavity. They do expect cracking, but no propagation of concrete missiles. The pipe tunnel for the primary piping is lined with a steel liner which served as a form for construction. We stated that that information was satisfactory and that no additional information on the cavity would be required.

y,C /,f, c,- p, o

D. F. Ross Reactor Projects Branch 2 Division of Reactor Licensing 1450 297

-s DISTRIBUTION:

Docket File PWR-2 Reading DRL Reading P. A. Morris F. Schroeder T. R. Wilson R. S. Boyd D. Skovholt E. G. Case, DRS R. R. Maccary Compliance (2)

DRL & DRS Branch Chiefs n

F. Ross

..W.

Karas R. W. Klecker W. Nischan G. Burley D. Nunn L. Hulman J. Knight D. Lange D. Sullivan 1450 298

~

LIST OF ATTENDEES Division of Reactor Standards Division of Reactor Licensing W. Nischan J. Knight D. Lange D. Ross D. Sullivan G. Burley D. Nunn L. Hulman Metropolitan Edison Company C. Long Consultants (Picker & Lowe Associates)

J. He rbein G. Bierman J. Miller F. Schwoerer J. Larizza J. Pickard Gilbert Associates General Public Utilities F. Symons D. Reppert A. Larson J. Thorpe S. Reid J. McConnell C. Bitting R. MacLemore Babcock & Wilcox W. Meek J. Cutchin Chen Chang E. Nodland G. Ward W. Delicate G. Glei W. Smith E. Hooker F. Thomasson 1450 299