ML19321A704
| ML19321A704 | |
| Person / Time | |
|---|---|
| Site: | Browns Ferry  |
| Issue date: | 07/15/1980 |
| From: | NRC COMMISSION (OCM) |
| To: | |
| References | |
| REF-10CFR9.7 NUDOCS 8007240091 | |
| Download: ML19321A704 (21) | |
Text
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_o do NUCLEAR REGULATORY COMMISSION
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f C
In the Mattar of:
BRIEFING ON CURRENT STATUS OF BROWNS FERRY PROBLEM -- PUBLIC MEETING--
g July 15, 1980 pgs.
1 - 21 Washington, D. C.
g.
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AIDOL%X REPORTIXG f.
L 400 Vi_T "4 a. Ave., 5.W. Washing =n, D.
C.
20024 Telachena : (202) 554-2345 8oove4odil
1 1
UNITED STATES OF AMERICA 2
NUCLE AR REGUL ATORY COMMISSION f~
3 LRIEFING ON CURRENT STATUS OF 4
EROWNS FERRY PROBLEM 5
PUBLIC MEETING 6
7 Nuclear Regulatory Co:sission 8
Room 1130 1717 H Street, N.
'a'.
Washington, D. C.
9 10 Tuesday, July 15, 1980 11 The Commission met, pursuant to notice, at 2.05 p.m.
12 BEFORE4 13 10HN F. AHEARNE, Chairman of the Commission 14 VICTOR GILINSKI, Commissioner 15 JOSEPH M. HENDRIE, Commissioner 16 PETER A.
BRADFORD, Commmissioner 17 STAFF PRESENT:
18 C.
STOIBER, General Counsel
.19 ALSO PRESENT:
20 W.
DIRCKS 21 V.
STELLO 22 R.
O'REILLY 23 H.
DANCE 24 H.
DENTON 25 ALDERSON REPOATING COMPANY, INC.
2 1
ALSO PRESENT (Continued):
2 C.
MICHELSON 3
K. CORNELL 4
HANRAHAN 5
6 7
8 9
10 l
11 12 13 14 1
15 16 17 18 19 m
21 22 23 24 25 ALCERSON REPORTING COMPANY, INC.
c DISCLLWIR This is an unofficial transcript of a neating of the Uni:ed States Nuclear Regulatory Co=nission held on July 15, 1980 in the Commission's offices at 1717 E Street, N. W., Washington, D. C.
The =eeting was open to public attendance and observation.
This transe:1pt has not been reviewed, cor:se:ed, or edi:ed, and it may contain inaccuracies.
The transc-ipt is intended solely for general infor=ational purposes.
As provided by 10 CTE 9.103, it is not part of -la for=al or infor=al record of decision of the natters discussed.
Expressions of opd-d on 1= this ::anscript do not necessarily reflect final date:=1 nations or beliefs.
No pleading or other paper =ay be filed vi:h the Co dssion in any proceeding as the resul: of or addressed :o any statement or argumen: contained
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herein, except as -le Co==ission nay authorize.
i i
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3 i s- -
1 232EEE2IE92 2
CHAIRMAN AHEARNE:
I would like to vote to hold 3
wi th less than one week 's notice a briefing on the current 4
status of Browns Ferry.
All in favor say, aye.
5 (Chorus of ayes.)
6 CHAIRMAN AHEARNEs Since you are in front, you 7
have the lead, Vic.
8 MR. STELLO.
'Je arranged to put together a 9
presentation that will basically update you on where we are 10 at Browns Ferry, what we have done, what we left in 11 researen, as well as to provide you with where we are with 12 respect to the Bulletin, and tne general sense of direction 13 ve will be taking on the Bulletin in cas future.
We hope to 14 be able to hold our briefing to aboit 20 minutes.
15 Jim, if yet would start.
16 MR. O'REIlLY:
The first slide presents a 17 simplified versina of the SCRAM dit charge volume, and I was 18 going to leave that separate.
I t'tink you may have some 19 questions, and I will use that in.lescribing some of the 20 testing if you would like to go into some detail.
21 This briefing is designed to be a folicw-up 22 briefing to the briefing that Vic provided the Commission on 23 July 3rd, or thereabouts.
24 The first grouping of slides, No. 21, tha*. list 25 is an exact repeat up to item 17 of the briefing provided to ALCERSON REPORTING COMPANY, INC.
4 1
the Commission.
All those items were completed, and with no 2
problems de :ected other than the two I will discuss at the 3
latter part of this briefing of slides.
4 The first new items that was not included in the 5
previous briefing is item 18, and I will follow through and 6
give you some extra information on those items.
7 GE issued two service information bulletins on two 8
of the boiling water reactors, copies of which, of course, 9
have been presented to the NRC, are a vaila bl e, and are in 10 the public document rooms.
11 Item 19, GE does have a mock-up of a single rod 12 drive in San Jose.
Although they have performed tests 13 somewhat like this in the late '60s and early '70s as to 1-4 vhat happens to a drive when there is blockage, water 15 acrumulation, they reran tests during the last several weeks 16 at San Jose at temperature and pressure, and with some 17 provisions there to indicate some bloeding capability.
18 The test results confirmed the design, and the 19 earlier tests run in the late '60s and early '70s.
They
(
20 show that there if is inadequate SCRAM discharge volume, of 21 course, the rod will not be fully inserted.
The test did 22 not show too much more than that because the configuration 23 of that mock-up dif not permit the changing of volume.
It 24 is all very small, and a single mock-up.
25
'4e did have NRC people reviewing the performance ALDERSON REPORTING COMPANY. INC.
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of the tests at San Jose.
2 Item 20, a significant factor in letting 3rowns 3
Ferry go forth is the adequacy of the methods 'y which they c
4 would determine whether there was water in the SCRAF 5
discharga volumes.
So there were tests performed by TVA and 6
GE to assure that the ultrasonic testing to measure water 7
level in the SCHAM discharge volumes was adequate.
8
'4e observed these tests ar.d tre satisfied with 9
that UT system..
10 No. 24, they did perform drain tests to 11 demonstrate that the system will drain a particular amount 12 from a no rmal alignment.
13 No. 22, this is one of the items that I will talk 14 about in the abnormal section in the next page here.
Ther 15 did perform vacuum hold tests to demonstrated that a blocked 16 vent path will prevent drainage of the six-inch SCRAM 17 discharge piping.
I said, prevent drainage, it is hard to 18 say that it will prevent it for an extended period of time.
19 I think the proper word there would be, it certainly 20 inhibits drainage.
21 They did run a test to measure the rate of Z!
drainage with the vent totally cle' sed.
They got a discharge 23 in the first half-hour of a gallon a minute, the second half 24 hour2.777778e-4 days <br />0.00667 hours <br />3.968254e-5 weeks <br />9.132e-6 months <br /> of about a half gallon a minute, and steadily 3
declining.
But they did not extend this for an extendad i
ALDERSON REPCATING COMPANY, INC.
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period of time.
So it will inhibit, and we have provan 2
that.
3 They did run friction tests to demonstrate normal 4
in service withdrawal operation of the drives in the east 5
bank.
They can extensive SCRAM testing listed in item 24.
i 6
All the rods performed satisfactorily.
7 Item 25 was of particular interest. They did 8
select rods in the east bank tha t went in properly, and then 9
picked five that did not go in at all.
They ran an 10
.extansive test on those and timed them, and there was no 11 difference between the drives.
i 12 They did check the discharge valve leaka;e rate 13 every 200 pounds while increasing raactor pressure to see if 14 they had any unique leakage problems.
There were none.
The 15 saximum leakage rate that they got approached two gallons 16 per hour.
17 Items 27, 28 and 29 show that as they finished all 18 this testing, TVA did follow the recommendations of GE.
OE 19 did recommend that at restart, heating up, and so forth, 20 they perfors additional testing.
21 The TVA on-site safety review committee reviewed 22 all the tests, and they agreed t ha t the plant should sttrt.
23 They have a TVA nuclear safety review audit group, they 24
. reviewed tha findings and test results, GE's 25 recommendations, and the. review of their own design group, 7
ALDERSON REPORTING COMPANY, INC.
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and they authorired start-up.
2 NBC, of rourse, issued Sulletin 30-17, which 3
addresses this issue.
The TVA performed all the actions 4
required before they returned to power, the actions 5
prescribed in 80-17.
Of course, they did more, but 6
certainly they did include all of these.
7 NRC lifted the hold that ve had on TVA throuch an 8
action that we sent them the day of the event.
On Sunday, 9
the plant returned to power.
10 On the next page, the No.
2-u, there were two 11 ansaalles that were found as a result of the above tests and 12 inspections.
13 The first one was that when tney had the problem, 144 ther started cutting into the lines.
They actually opened 15 up the vent line on the east side, and actually they tried 16 to pull a vacuum to see whether or not that line was clogged 17 from the valve to the vent header.
18 They ran into the unexpected finding that they did 19 pull 3 inches of mercury with a 1.2 standard cube per minuta 20 vacuum pump.
When they reached 8 inches of mercury, it did 21 not drop immediately to the 2 inches, which is no rm al for 22 the device, indicating that there was some blockage or loss 23 of a water leak somewhere.
We don't know for sure.
Thar is 24 the only event that occurred to indicate that there was an?
25 blockage.
It was on the vent side before they did any ALDERSON REPORTING COMPANY, INC.
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cutting.
2 The cutting and flushing that took place in the 3
cast of the system that followed that was, I thought, 4
carefully designed to detect if there were any problems, any 5
debris, or whatevet in the entire system.
They used 6
boroscopes, and they could find nothing.
7 So the only indication of some blockage was that 8
vacuum pump indication, the first step following the SCEAM.
9 The other abnormal event was that in the 10 instrument volume, the level switches did not activate 11 during the first calibration fill af ter the SCRAM.
The 12 opacator observations and some of indirates in the printouts 13 did indicate that these two switches worked at least during 14 part of the sequence of events.
15 The third protective level, which is a 50 gallon 16 level SCRAM, composed of four separate switches, worked 17 properly.
18 The next slide, slide 3, I repeated the 19 tequirements of the Bulletin 80-17.
It is the same as Vic 20 Stello provided to you a week or so ago.
But I want to 21 iden tif y hece that in this Bulletin we did require licensees ZZ of boiling water reactors to monitor the SC3AM discharge 23 volumes daily, and that if that was successful they could 24 fall back to a weekly monito ring.
3 As time developed, and we focused more on the span ALCERSON REPORT.NG COMPANY. INC,
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of the cores, and our inability to feel certain on where 2
this water comes from, we have instructed the plants to 3
continue the daily type of sampling of the SCRAM discharge 4
volume until we come up with a longer range understanding er 5
fix of the problem.
6 This is discussed a little bit on the next slide.
7 We are right now developing another Bulletin, a supplement 8
to 80-17, that would require, in regard to the understanding 9
the design, the first three items.
We should get as-built 10 isometric drawings of the SCRAM discharge volume piping to 11 actually understand exactly how they were actually built.
12 Since we are concerned about the vent and drain 13 discharge systems, we will request a detailed description of 14 how they are connected, and what types of vents and systems 15 they are hooked into.
16 The third, we will discuss the evaluation of 17 design problems, if any, and discuss modifica tions as 18 appropriate.
19 There are others iteos that come up and will be 20 considered in the supplement to the Bulletin.
That would 21 include such things as the level switches.
We have to look 22 at these again.
We have to look at the p ccedures for how 23 they react if they find water in *.he SCRA discharce 24 volumes, how they opera te wi th the standby liquid ccatrol 25 systems.
ALDERSON REPORTtNG COMPANY, INC,
10 1
The reporting r equir em e rits, we vill lock at that 2
again.
Also, we must review whether or not any improvements 3
can be made for overrides to systems like the rod sequence 4
control systen, which made it very difficult to drive in the 5
rods manually once the rods would not gc in by SCP.Ad.
8 That Bulletin, we hope to have a draft of probably 7
tomorrow, and we will get it out this week.
8 Again, we looked at that as getting in f o rm a tio n,
9 and perhaps not the final design change that may be 10 _ necessary.
11 The slide 4 is the corrective action at Browns 12 Ferry.
What they have done here, in addition to the 13 Bulletin, tney have installed a vent in the four-inch header 14 on the east side.
They actually had one, although that was 15 not in the design, in the west header.
The vent in the west 16 header existed because of an instrument probe that had been 17 no kept.
Since there was a drain on it of filter water, it 18 just never was picked up.
The west heider had alway-been 19 vented, and now the east header is vented.
20 They have installed, as you can see, a large 21 number of UT detectors currently on both the east and west 22 neaders, 13 sensors.
They are continually monitoring the 23 low point of both baaders on unit No.
- 3. These read-outs 24 have lights and alarms.
They have an individual who reads 25 them who is stationed in the area to be aware.
They have ALDERSoN REPORTING COMPANY, INC.
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not yet ronnected them up to the con trol room.
They will 2
read out the remaining sensors manually once per shift.
3 Item 3, that is being installed during this week 4
on units 1 and 2.
Ihey will end up being the sane way this 5
week.
They are obtaining this equipment on a priority 6
basis, and they will be in the same position.
7 At the present tim e, tho sensors, manually they 8
are doing this on units 1 and 2 once per shif t.
9 They have provided instructione to operatinc 10 personnel in accordance with th e B ulletin, o f co u rs e, and 11 lastructions for what they do with the t e cta order and the 12 SCHAM discharge volumes.
13 They have their design group are already studyirg, 14 and they have several plans that have not been approved by 15 their saf ety groups for modifying uni ts 1 and 2.
j 16 This is about where we stand on the corrective 1
17 actions at Browns Ferry.
18 I did provide a summary slide.
Item 1 of slide 5, 19 I have found that all the events th'.t we have looked at, and 20 from inputs from the various engineerings groups that have 21 looked at tne problem, we believe and have high confidence 22 -
that the cause of the control rods to f ully insert following a
the SCHAM signal was due to accumulation of water in th_
24 east SCRAM discharge volume header.
25 Although we have hign confidence in thir action,
)
ALDERSCN REPORTING COMPANY, INC.
s 12 o-1 of course, we have --
2 CHAIRMAN AHEARNE:
Are there four P.eaders on that 3
sida?
4 MR. O'REILLY:
There are two headars.
Each header 5
is made up of two sections, but th ey are connected.
6 CHAIRMAN AHEARNE:
Your conclusion is that there 7
was uniformly water in all it?
8 MR. O'REILLY:
They are connected.
Their 9
conclusion is that the east h ead e r ---
10 Lat's go back to that first slide.
11 Just taking the top section, which is the east, 12 you can see that half the rods basically tie into one 13 six-inch section, and the other half tie into the other 14 six-inch section.
The other lines on the top and bottom of 15 that are also six-inch headers.
The whole grouping there is 16 the east header.
17 MR. DANCE:
You mean half of the rods on the east 18 side tie into this side.
19 MR. O'REILLY:
That is corrert.
I am sorry.
20 I am sorry.
There 'are fo ur six-inch pipes, 52 21 feet long that make up the SCRAM discharge volume.
Two of Zt these four are the recipients of the SCRAd water that comes 23 from the drives that are associated with the east headar.
24 CHAIRMAN AHEARNE:
'4 h a t is your conclusion?
j 25 MR. O'REILLY:
That headar is hooked, and it is 52 1
ALDERSoN REPORTING COMPANY. INC.
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feet long, and it is six inches on the down side.
That is 2
where it ties in with this two-inch header that g o e r.
to the
'3 instrument volume and drain valve.
4 3R. STELL0s He is asking for a judgment.
Was the 5
header completely full, or partially full?
6 ER. O'REILLY:
Exactly how much water there was in 7
it, I don't think that we will ever know.
I vas 8
substantially full But there was still space.
Whether or 9
not t..ere was space there, r r th e y forced some water out is s
10 a matter of conjecture.
It is my belief that it was almost 11 full.
12 CHAIRZAN AHEARNE:
But you don't have any idea 13 exactly how it happened.
14
- 52. O'REILLY:
I was going to hit that next.
15 We do believe th a t this was the cause of the 16 problem.
That is what the GE rest results and the design 17 show that you had that condition that would occur.
Of 18 course, we have looked at electrical considerations, air 19 considerations, and the misalignment of valves, or some 20 problems of saintenance that had been done on cabinets, and 21 we Jound no evidence of problems in that area at all.
22 That was the cause, there is the reason.
The Il reason for the water in the east header, we have not been 24 able to determine.
We believe that it could very well have 25 been caused by either or both of inadequate venting, which
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ALDERSON REPORTING COMPANY, INC.
4 14 1
hung some amount of water into the system, perhaps a lot, or 2
it is a very high probability that there was some foreien
/
3 material or blockage in th e piping, the 150 feet that goes 4
from the east SCRAM discharge volume to the intrument 5
volume.
6 CHAIRMAN AHEARNE:
'4ha t would be that kind of 7
foreign material?
8 MR. O'REILLY:
'Je have no t been able to find it.
9 The cutting of the pipe, and the flushing that was carefully 10 done did not detect or find any foreign material in the 11 drainage system.
The only abnormality detected was in'the 12 vent and the test that was run did show that the inadequate 13 venting did inhibit seriously the draining of water free the 14 SCRAM discharge.
15 CHAIRMAN AHEARNE:
Did you say that there was a 16 high probability that there was foreign material?
I'7
- 33. O'REILLY:
The cause we have a high 18 confidence level that it was due to accumulation of water in 19 the east SCRAM discharge vclume.
20 How did the water get there?
The water had to get 21 there either due to inadequate venting, and hanging up water 22 in the system supplemented by some excessive leakage from 23 the SCRAM discharge valves and seals, or some blockage in 24 the drain system but we have not been able to find that type i
25 of blockage.
l l
ALDERSON REPORTING COMPANY, INC.
15 1
The only abnormality that we observed, and TVA 2
observed in this whole review of the system wi th regard to 3
blockage was that problem in the vent system.
4 The steps taken by the licensee in the course of 5
OCR to ensure that adequate SCRAM volume is available.
6 CHAIRMAN AHEARNEi Could that be described as 7
saying that the conclusion is that there was an accunulation 8
of water, and so your steps are to make sure that you can 9
check whether or not water is accumulating?
10 ME. C'REILLY That is correct.
11 CHAIRMAN AHEARNE:
What confidence do you have of 12 the rate at which wa ter accumulates?
13 MR. O'REILLY:
We have looked at that.
We are 14 pleased with the way TVA has developed, which is continuous 15 monitoring.
We have notified the plants not to fall back 16 into tha t weekly review.
17 We are coming out w it h another supplement to the 18 Bulletin, and though it is not firm, I believe that the 19 Bulletin and the design modifications that will follow will 20 be requiring more extensive monitoring that may very well be 2;
continuous sonitoring and alarming the rentrol room, if 22 there is not some more severe, radical redesign :nat would 23 p ro hibi t th a t, and have some system like they have nov give 24 us better assurance.
25 Some of the newer plants do have level detections ALDERSON REPORTING COMPANY, INC.
16 1
systems that actually measure the water in the SCRA?
~
2 discharge volume rather than in a separate tank.
So some 3
design signt be adequate as viewad by our staff.
4 I said the supplement to IEB S0-17 is needed to 5
determine the adequacy of all SWR designs as built.
We will 6
be issuign the Bulletin in the near future.
7 The rest results of plants performing IE3 80-17 8
requirements to date indicate no unexpected information.
9 They have run SCRA! tests on six of the plants already.
A 10 couple of them are scheduled today, and there have been no 11 problems that are abnormal.
12 The TV A report of this abno rmal occurrence is 13 expected this week, and the NRC report will probably be 14 prepared next week, or during the next week.
15 This is about where we stand.
16 COMMISSIONER GILINSKY:
Is there going to be an 1'7 industry report on this, NSAC, or one of these other groups?
18 MR. O'REILLY:
NSAC was at the site obtaining 19 information.
I don't know whether they are going to issue 20 one.
I do know that they have been involved in informing 21 all the utilities of their findings.
INCO sent a psrson out Z1 there.
I do not know whether or not they will have a 23 special report.
24 MR. STELLO:
We will ask them.
25 COMMISSIONER 3RADFORD:
What is your sense, ;iven ALDERSON REPCRTING CCMPANY, INC.
17 1
this diagnosis, of how this serious this event was relative 2
to how serious it could have been?
I am not sure that is 3
the right way to say it.
Supposing the thing you thought 4
was partially full of water were, in fact, to be completely 5
full of water, how much serious does tha t make it?
6 HR. O'REILLY:
If there were no discharge volume, 7
the rods would not move.
Here you only had it in one 8
header, and there are two separate headers.
So you would 9
get three rods which would not 9 CRAM.
10 COMMISSIONR BRADFORD:
The only thing that purried 11 me abo"'. that was, if you thought it was substantially 12 filled with water, what is you are saying is that the little 13 bit of diff erence between substantially filled and a
14 completely filled is the difference between what happened 15 and the rods not moving at all.
16 MB. O'REIiLY:
The SCRAM discharge volume should 17 take at least three full SCRAMS.
So to get a condition like 18 this, it had to be more than two-thirds full.
19 COMMISSIONER BRADFORD:
I see.
20 COMMISSIONER HENDRIE:
On the east side, you have 21 got something like 12 rods.
You already had five f ully in.
22 You got 12 more on the first SCRAM cut of 90-or so.
That is 23 17 rods out of 92 or 93 that were all the way in, and the 24 rest of thes were not all the way in.
I don't know how far 25 they did move, but clearly not far enough.
i l
ALDERSCN 3EPORTING CCMPANY, INC.
18 0.-
1 Presumably if you had had tha t east side volume 2
just plugged plumb full and nothing moved, you would not f
3 have gotten the 12, or whatever.
But it would not have made 4
any substantial difference in the condition of the machine 5
itself.
That is, have the east side rods go in took the 6
power level way down, I think there could have been'a 7
critical region on the east side.
8 MR. STELLO:
I tried to answer that the last 9
time.
If I recall, the numbers were 10 MR. BRADFORDs The last time we were talking as to 11 whether there was any criticality left, given things as they 12 were.
I take it that if however many rods were invcived did 13 not insert at all, th en there certainly would have been sone.
14 MR. STELLO:
Yes.
15 COMMISSIONER HENDRIE:
The answer is more than was 16 the case.
17 MR. O'REILLY:
They SCR AMmed f ros 35 percent 18 power, as you know, and they went down to below 1 percent 19 power.
The issue of whether or not the plant was critical 20 is computed in the physics calculations.
l 21 MR. DENTON:
As you know, we have an AT*45 proposal 22 coming down in a couple c: days, so we have been lockino 23 back, that trying to extrapolate what this means.
These 24 numbers are preliminary, but as a bounding we started by 25 assuming th a t none of the rods in the east bank went in.
We ALDERSON REPORTING COMPANY, INC.
L9 1
assumed that the reactor coolant pumps worked, and our first 2
run through indirates that the reactor level, if this had 3
occurred at full power, would end up with 20 percent power.
4 If it really were there within about 30 minutes you could 5
expect core damage or containment over-pressurination if 6
there were no operator actions taken with the liquid poison 7
system, or any other means.
8 If you let the reactor run at 20 percent power, it 9
would blow down through the safety and relief valves.
That 10 is sort of the bounding approach we have done, assuming that 11 none of the rods in the other bank went in from full pcwer, 12 and no liquid. poison system.
13 CHAIRMAN AHEABNE:
One of the questions that was 14 asked the last time was whether that was a high power level 15 to SCRAX from?
16 NR. STELLO:
I did get the answer to that.
The 17 reason they did it is because we have them put them a rod 18 sequence control system that when you come down to a certain 19 powe r level, you are no t allowed by this device to put in 20 rods except by some prescribed maneuvering.
It is a.very 21 laborious process.
22 So when they g?t there, for the ronvenience of 23 redu cing the amount of time it takes because of the red 24 sequence control system, they SCRAM th e reactor at that 25 power level.
That is the reason that it is higher than it i
ALDERSON REPORTING COMPANY. INC.
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20-1 had been done before the run sequence control syste: was 2
on.
3 It is one of the things we also want to talk 4
about, whether there is a need to have it, and if the valvec 5
are such that it is a good idea a bypass systen built into 6
the rod sequence control system so that they can continue to 7
bring the power down lower before they SCRAM.
That is 8
another thing that we are going to look at.
9 CHAIRMAN AHEARNE:
Did you have a comment that'you 10 wanted to sake?
11 MR. MICHELSON:
I don't have any particular 12 comments I want to make.
I agree in principle wi th what has 13 been said.
14 CHAIRMAN AHEARNE:
Do you intend to work some sort 15 of a summary?
16 NR. MICHElSON:
We are writing a first draft of a j
l 17 summary now, and it should be available before the end of l
0 18 this week.
19 CHAIRMAN AHEARNEs Thank you.
20 MR. STELLO:
I wanted to leave again the one 21 thought, as I said the last time.
Harold is continuing to 22 look at where we do go after we get through with the 23 Bulletin, and what we are doing.
He is continuing to 1cok i
24 at that time.
There will be no loss of continuity.
He is 25 picking up now, and is continuing to work with us.
At some
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ALDERSON REPORTING CCMPANY. NC.
21 1
point there will be a transition, and Harold will icok at 2
where we go from here, and that will be part of the 3
atmosphere for discussion.
4 CHAIRMAN AHEARNE:
Thank you very much.
4 5
('4heceupon, at 3.05 p.m.,
the meeting w as closst.d. )
6-7 8
9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
' A..DERSON REPORTING COMPANY, INC.
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NUCLEAR REGULATORY COMMISSION This is to certify that the attached ;;roceedings before the
[
Commission Meeting in the =atter ef: Briefing on Current Status of Browns Ferry Problem
-- Public Meeting --
Date of Proce6 ding:
July 15, 1980 Docket !!u=b e r :
Place of Proceeding:
Washington, D. C.
were held as herein appears, and that this is the original transcript thereof for the file of the Cec =ission.,
Patricia A. Minson Official Reporter (Typed)
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. m O nc,.. -
Official Reporter (Signature) w-
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FOLLOW-UP BRIEFING 4
BROWNS FERRY UNIT 3 FAILURE 0F 76 of 185 CONTROL RODS TO FULLY INSERT DURING A SCRAM i
JULY 15, 1980 I
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BROWNS FERRY INVESTIGATION S AND TESTS COMPLETED 1.
CORRECT HYDRAULIC CONTR0L UNIT ALIGNMENT VERIFIED 2.
EAST DANK VENT VALVE VERIFIED OPERABLE 3.
FRICTION TESTED 35 RODS - PERFORMED NORMAL 4.
VERIFIED CALIBRATION OF 3-GALLON, 25-GALLON, AND 50-GALLON LEVEL SWITCHES ON INSTRUMENT VOLUME 5.
COMPLETED RADIATION SURVEY OF DRAIN LINES TO DETERMINL IF HOT SPOTS EXIST INDICATING OLOCKAGE 6.
COMPLETED RADIATION SURVEY OF #3 EQUIPMENT DRAIN SUMP 7.
SAMPLED #3 EQUIPMENT DRAIN SUMP 8.
SAMPLED REACTOR COOLANT SYSTEM - FOUND NORMAL 9.
VERIFIED THAT OFF GAS RADIATION LEVELS WERE NORMAL 10.
COMPLETED VISUAL AND MECHANICAL INSPECTIONS OF VENTS AND DRAINS IN SCRAM DISCHARGE VOLUME 11.
VERIFIED THAT NO MAINTENANCE OR MODIFICATIONS IN PROGRESS OR RECENTLY PERFORMED THAT W0llLD' AFFECT CONTROL ROAD DRIVES 12.
R E 'II E WE D SCRAM HISTORY FOR PREVIOUS FAILURES 13.
PERFORMED PRESSURE, FLOW AND DRAIN TIME TESTING ON EAST AND WEST HEADERS 2-1
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- 14. -
PERFORMED EVA,LUATION AND INSPECTION TO ASSURE ELECTRICAL SEPARATION AND DIVERSITY 15.
GE ENGINEERS PERFORMED EXTENSIVE EVALUATIONS AND INSPECTIONS 16.
SCRAM ACTUATORS TESTED' T0- ENSURE ZERO VOLTAGE TO EACH GROUP PILOT SOLEN 0ID VALVE 17.
CUT AND INSPECTED 2-INCH LINE VENT HEADER PIPING WITH BUR 0 SCOPE INSPECTION OF 6-INCH HEADERS AND SCRAM DISCHARGE INSTRUMENT VOLUME 18.
GE ISSUED TWO SERVICE INFORMATION BULLETINS 19.
GE PERFORMED TEST ON CONTROL ROD DRIVE AND PRESSURE VESSEL MOCKUP IN SAN JOSE 20.
PERFORMED TESTS TO CONFIRM ADEQUACY OF ULTRASONIC TESTING TO MEASURE WATER LEVEL IN SCRAM DISCHARGE VOL'UME 6-INCH HEADERS 21.
PERFORMED DRAIN TEST TO DEMONSTRATE THAT THE SYSTEM WILL DRAIN IN A PREDICTABLE MANNER FROM A NORMAL ALIGNMENT 1
22.
PERFORMED VACUUM HOLD TEST TO DEMONSTRATE THAT A BLOCKED VENT PATH WILL PREVENT DRAINAGE OF THE SIX-INCH SCRAM DISCHARGE PIPING 23.
FRICTION TEST - DEMONSTRATE NORMAL INSERT - WITHDRAWAL OPERATION OF THE DRIVES IN THE EAST DANK 24.
SCRAM TESTING a.
FULL SchAM TEST AT RATED CONDITIONS FROM ZERO POSITION TO VERIFY PROPER OPERATION OF ELECTRIC COMPONENTS AND HYDRAULIC CONTROL UNITS 2-2
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INDIVIDUAL ROD SCRAMS AT VARIOUS CONDITIONS FROM POSITION 48 TO VERIFY SCRAM CAPABILITY WITHIN TECH SPECS TIMES (EAST BANK RODS).
25.
PERFORMED SCRAM TIME TEST OF FIVE RODS THAT FULLY INSERTED AND FIVE THAT DIDN'T ON THE EAST BANK - NO DIFFERENCE.
26.
CHECKED FOR SCRAM DISCHARGE VALVE LEAKAGE EVERY 200 POUNDS WHILE INCREASING REACTOR PRESSURE 27.
GE RECOMPJ5NDED RESTART OF REACTOR TO PERFORM SCRAM TESTS 28.
TVA ON-SITE SAFETY REVIEW COMMITTEE RECOMMENDED RESTART 29.
TVA NUCLEAR SAFETY REVIEW COMMITTEE RECOMMENDED RESTART 30.
NRC ISSUED IE BULLETIN 80-17 31.
LICENSEE PERFORMED ACTIONS OF IE BULLETIN 80-17 32.
NRC ISSUED CONFIRMATION OF CONCURRENCE LETTER TO ALLOW RETURN TO POWER i
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-. 3 ONLY TWO ANOMALIES WERE FOUND AS A RESULT OF THE ABOVE TESTS AND INSPECTIONS.
A.
WHEN A VACUUM PUMP WAS C0'NNECTED TO THE EAST VENT LINE ON THE DRAINAGE SIDE, A VACUUM OF 8" 0F MERCURY WAS PULLED FOR A SHORT PERIOD WHICH DROPPED SHARPLY TO 2".
THE REASON FOR THIS TEMPORARY VACUUM WAS NOT DETERMINED.
B.
THE LOW LEVEL (3-GALLONS) AND ROD BLOCK (25-GALLONS) LEVEL SWITCHES DID NOT ACTIVATE DURING THE FIRST CALIBRATION FILL AFTER THE' SCRAM.
OPERATOR OBSERVATIONS DID INDICATE THAT THE6E TWO SWITCHES WORKED AT LEAST DURING PART OF THE EVENT.,THE THIRD PROTECTIVE LEVEL, 50-GALLONS LEVEL SCRAM, COMPOSED OF FOUR SEPARATE SWITCHES WORKED PROPERLY.
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m IE BULLETIN 80-17 REQUIREMENTS 1.
WITHIN 3 DAYS OF BULLETIN, PERFORM PRESCRIBED SURVEILLANCE TESTS ON THE SCRAM DISCHARGE VOLUME SYSTEM.
2.
WITHIN 20 DAYS, UNLESS OTHERWISE DIRECTED, PERFORM ONE AUTOMATIC AND ONE MANUAL SCRAM AT NORMAL OPERATING TEMPERATURE AND PRESSURE WITH MORE THAN 50% OF THE RODS FULLY WITHDRAWN.
3.
AT THE CONCLUSION OF SCRAM TESTS, VEEIFY THE OPERABILITY OF THE SCRAM DIScilARGE VOLUME SYSTEM.
4.
REVIEW EMERGENCY OPERATING PROCEDURES.(INCLUDE THOSE PREPARED BY THE NSSS)
TO ENSURE THAT REQUIRED SPECIFIC OPERATOR ACTIONS FOR THE OCCURRENCE OF THIS TYPE OF EVENT ARE ADEQUATE.
5.
DEVELOP SURVEILLANCE PROCEDURES TO MONITOR THE SCRAM DISCHARGE VOLUME FOR WATER ACCUMULATION.
i 6.
TAKE SPECIFIED ACTIONS TO MITIGATE THE CONSEQUENCES OF AN ATWS EVENT.
7.
RESULTS OF COMPLETED TESTS TO DE SUDMITTED TO Tile NRC WITHIN 5 DAYS OF THE PERFORMANCE OF EACll TEST.
3 Til0SE DWRS TilAT ARE CURRENTLY IN A SilUT DOWN STATUS WILL PERFORM TilESE TESTS PRIOR TO POWER OPERATION.
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i PENDING BULLETIM - SUPPLEMENT TO 80-17 1.
SUBMIT CORRECT (AS-BUILT) ISOMETRIC DRAWINGS OF ALL SCRAM DISCHARGE VOLUME PIPING.
2.
DESCRIBE IN DETAIL THE CONNECTING VENT AND DRAIN DISCHARGE SYSTEMS (AS-BUILT).
l 3.
DISCUSS EVALUATION OF DESIGN PROBLEMS, IF ANY, AND PLANS
& SCHEDULES FOR MODIFICATIONS AS APPROPRIATE.
3-2
CORRECTIVE ACTIONS AT BROWNS FERRY 1.
INSTALLED VENT IN SDV VENT 4" HEADER - EAST SIDE SIMILAR VENT ALREADY EXISTS ON WEST SIDE.
- 2. -
INSTALLED ULTRASONIC DETECTORS ON UNIT #3 (EAST & WEST HEADERS) 2 ON LOW POINT OF_6" HEADERS 2 ON MID-POINT OF 6" HEADERS 1 ON 2" DRAIN LINE AT 6" x 2" REDUCER 1 ON 1" VENT LINE AT HIGH POINT 1 ON 2" INSTRUMENT VOLUME DRAIN LINE CONTIN 0US UT MONITORING OF LOW POINT OF 6" HEADERS. READOUT REMAINING SENSORS 1/ SHIFT 3.
SENSORS ARE BEING INSTALLED DURING THE WEEK OF JULY 14 ON UNITS 1 & 2.
HEADERS ARE DEING MONITORED ONCE PER DAY SHIFT.
MONITORING OF THE REMAINING SENSORS IS PLANNED AS SOON AS EQUIPMENT CAN BE PROCURRED.
4.
PROVIDED INSTRUCTIONS TO OPERATING' PERSONNEL IN ACCORDANCE WITH IED 80-17 AND FOR DETECTION OF WATER IN SDV.
5.
EXPEDITED REVIEW OF MODIFICATIONS REQUIRED TO THE SCRAM DISCHARGE VOLUME INCLUDING ADDITIONAL VENT FOR UNITS 1 & 2.
4-1 i
S UMMA R Y 1.
THE CAUSE.OF THE CONTROL RODS TO FULLY INSERT FOLLOWING THE SCRAM SIGNAL WAS DUE TO ACCUMULATION OF WATER IN THE EAST SCRAM DIScilARGE VOLUME (SDV) HEADER.
2.
Tile REASON.FOR WATER ACCUMULATION IN THE EAST SDV HEADER HAS NOT BEEN SPECIFICALLY DETERMINED; HOWEVER, IT IS BELIEVED DUE TO INADEQUATE DRAINING AND/OR VENTING OF THE SDV llEADER.
3.
STEPS TAKEN DY LICENSEES, IN ACCORDANCE WITH IED 80-17, ARE ADEQUATE TO ASSURE AN ADEQllATE SCRAM VOLUME IS AVAILABLE.
4.
A SUPPLEMENT TO IED 80-17 IS NEEDED TO DETERMINE ADEQUACY OF ALL BWR DESIGNS (AS OUILT).
5.
Tile TEST RESULTS OF PLANTS PERFORMING IED 80-17 REQUIREMENTS, TO DATE, INDICATE NO UNEXPECTED INFORMATION.
6.
Tile TVA REPORT OF TilIS EVENT IS EXPECTED THIS WEEK - THE WEEK OF JULY 14Til.
7.
Tile NRC REPORT IS CURRENTLY IN PREPARATION ON A PRIORITY BASIS.
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