ML19290A230
| ML19290A230 | |
| Person / Time | |
|---|---|
| Site: | Crane  |
| Issue date: | 08/27/1979 |
| From: | Lanning W NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| To: | NRC OFFICE OF NUCLEAR REGULATORY RESEARCH (RES) |
| Shared Package | |
| ML19290A225 | List: |
| References | |
| NTFTM-790827-02, NTFTM-790827-2, NUDOCS 7910240135 | |
| Download: ML19290A230 (2) | |
Text
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/ s aeog*o, UNITED STATES
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'i NUCLE AR REGULATORY COMMISSION f.;
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% '" Cr_4j' August 27, 1979 In Reply Refer to:
NTFTM 790827-02 MEMO'ANDUM FOR:
Files FROM-Wayne Lanning, Separate Effects Research Branch Division of Reactor Jafety Research
SUBJECT:
RECORD OF ACTIONS, THREE MILE ISLAND ACCIDENT My major a.ctivities concerning the Three Mile Island accident were as follows:
3/30: Requested by Ron Scroggins to join himself, Stan Fabic, and Pete AntNrson to go to MNBB concerning accident at TMI-2.
Briefed by R. Budnit: concerning existence of bubble in reactor vessel. Presented data of pressure versus change in pressuriser level and changes in incore temperature measurements. Bubble size was approximately 1000 cubic feet and increasing. Concerned that core would uncover due to growth.
Participated in performing heat-up and boil off calculations for core.
Initiated Semiscale test to explore venting of bubble through pres-suriser relief valve. Obtained system volumes and sizes from Ed Kane at B&W/Lynchburg. Obtcined current IMf-2 conditions from Tad Marsh at IRC. Noted that pressuri er surge line had potential for water seal due to geometry layout. Reviewed system description and piping diagra=s concerning ways to vent bubble. Reviewed make-up and purification system in attempt to resolve blockage of letdown heat exchanger.
3/31: Monitored progress of Semiscale Test. Transmitted preliminary results of first test to B&W and IRC. B&W requested second test, doubling the size of the bubble and including RPI flow.
At request of W. Minners and in coordination with S. Lavine, 3. Budnitz, and T. Murley supplied informacion to INEL, Bretelle Columbus and Iandia Laboratories to calculate hydrogen burning and explosion poten-tial.
S. Levine transmitted results to IRC. Assisted in evaluating various methods for scavenging hydrogen from primary coolant system.
4/1:
Requested and provided information to INEL -
erform second test in Semiscale.
Obtained plan from B&W on propose; dPI flows versus time.
2226 169 791024013 5
Files Coordinated information to Labs concerning Hydrogen explosion, degassing, radiolysis and recombination of hydrogen and oxygen.
4/2:
Coordinated results of second semiscale tests to S&W and IRC.
B&W indi-cated that they were going to review HPI flow rates in contingency emergency plan to vent the bubble as the results of tests. Discussed analytical predictions of time period to vent bubble in comparison to Semiscale results.
Relocated from MNBB to East-West Towers.
Performed calculations of time period to degas using pressurizer spray. A lot of uncertainty axisted concerning flow rates in pressuriser surge and spray lines and makeup and purification system.
4/3 - Liaison between Research staff and IRC for calculations of hydrogen reduc-4/12 tion methods, core damage assessment, natural circulation, transient calculation, core blockage, containment hydrogen concentration and con-tainment temperature.
4/13 - Assigned to Industry Advisory Group (IAG) at IMI-2 site.
Coordinated 4/20 flow of iaformation between site, NRC contractors and NRC staff. Worked on assigned IAG tasks (RER, natural circulation, Reflux boiler, sump level measurement).
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Wa e Lanning Separate Effects a search Branch Division af React Safety Research cc:
I. Murley L. S. Tong S. Levine R. Sudnit:
2226 170
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MEMORANDUM FOR:
The Files FROM:
Thomas E. Murley, Director Division of Reactor Safety Research
SUBJECT:
RECORD OF ACTIONS, THREE MILE ISLAND ACCIDENT MARCH 28 - April 6 This memo records my major activities and lists the individuals with whom I had substantive contact during the Three Mile Island Accident and its immediate aftermath, March 28 - April 6,1979.
On Wednesday, March 28, I learned about 9:30 a.m. that there had been an accident at TMI.
Not much was known of the details except that there were high radiation levels in the plant and a general emergent:y had been declared by the utility.
On Thursday morning I attended a briefing of the Comission by NRR staff where I gained the impression that the situation was generally under control, although the high radioactivity levels in the plant clearly indicated extensive fuel damage.
On Friday, March 30, while on annual leave, I received a call fr:m Saul Levine at 4:00 p.m. asking me to come to Tony Buhl's office to get some tests started to help resolve some problems at TMI.
On the way to the office I heard a bulletin on the car radio that NRC had announced there was a danger of core melting at the Three Mile Island Nuclear Plant.
The following activities are listed by topic and are generally in enronological orcer.
Removal of the Hvdrocen Subble Ucon arrival in Tony Buhl's office I was informed that reasurements at the site indicated there was a noncondensible hydrogen gas bubble in
- ne reactor vessel having a volume of 1000-1500 cu. ft. at 1000 ::si anc 230*F.
The n was some concern that the bubble was growing and nignt lead to uncovering the core and potentially to fuel reiting.
One option being considered was to open the relief valve on the pressuri:er and try to vent the hydrogen bubble out the valve to me containment building.
It was recognized this would be a tricky maneuver since it would mean that the one pump operating at the time would have to be shut off and there was no assurance tnat it or any of the other tnree pumps could be rescarted if the were subsecuently needed g g j J }
DUPLICATE DOCUMENT
-QG Entire document previously y;OIy*I entered int s stem und Il ANO No. of pages:
The Files At about 5:30 p.m., we called INEL (Larry Ybarrondo, Nick Kaufman, Hank Ziele and others), described the problem to tnem and asked if there were meaningful tests that could be done in :ne Semiscale facility to help decide whether and how to vent the hydrogen bubble.
We described the TMI primary system layout and gave them the imcortant plant dimen-sions and elevations.
Later in the evening on Friday, they called back with the following information and suggestions:
A test could be run in Semiscale using nitrogen gas to simulate the hydrogen venting maneuver in TMI.
They recomended against such a maneuver in TMI, suggesting it was better to keep the plant in its then stable operating ande (this suggestion was relayed to the NRR oersonnel in the Incident Response Center).
After workN all night to set up the Semiscale facility, the INEL staff ran a test on early Saturday morning (Enclosure 1).
The results showed that the Semiscale system could be depressurized by opening the pressurizer relief valve and turning all pumps off but about half of the nitrogen gas in the bubble remained in the primary system -- princi-pally in the steam generators.
The electrically heated rods remained cooled during this maneuver.
This information was passed on to the IRC and to B&W.
During the remainder of Saturday and Sunday, Wayne Lanning of the RES staff worked with B&W engineers and INEL,te establish conditions for a second test using a larger helium gas bubole and injecting coolant from the High Pressure Injection System.
This second test was run early Monday morning, April 2 (see Enclosure 2).
The Semiscale tests provided the following general information:
They showed that the noncondensible gas in the bubble would not all vent out the relief valve -- in fact about half of the gas would remain in the primary coolant system.
They showed that.it would be difficult if not impossible te remove the gas from the primary system by subsequently restarting the primary pumps. Since the presence of gas in the high points of the steam generators could prevent natural circulation cooling, this information was a strong argument for leaving the gas bubble in the ap of the vessel.
They provided useful data for B&W in establisning tne appr oriate HPIS flow rate for their procosec emergency orocedure in the event all primary pumps were lost.