ML19250A797
| ML19250A797 | |
| Person / Time | |
|---|---|
| Site: | Big Rock Point File:Consumers Energy icon.png |
| Issue date: | 10/19/1979 |
| From: | Hoffman D CONSUMERS ENERGY CO. (FORMERLY CONSUMERS POWER CO.) |
| To: | Ziemann D Office of Nuclear Reactor Regulation |
| References | |
| TASK-09-01, TASK-9-1, TASK-RR NUDOCS 7910240616 | |
| Download: ML19250A797 (15) | |
Text
s Consunmers POVrer Company
.y Genee nt Offic es: 212 West Mic h' Wen Avenue, Ju an son, Michsgen 49201 e Area Code S17 7HH-05SO
, [j U
Cetober 19, 1979 Director, Nuclear Reactor Regulation Att Mr Dennis L Ziemann, Chief Operating Reactors Branch No 2 US lluelear Regulatory Co= mission
- 4ashington, DC 20555 LOCKET 50-155 - LICENSE DPR-o - BIG ROCK POI;iT PLA:iT - RESP 0:ISE TO HRC STAFF QUESTI0IIS REGARDING EXPAUSION OF SPE:iT FUEL STORAGE CAPACITY Consumers Power Company letter dated June 26, 1979 requested approval of a proposed Technical Specificat' ions change permitting increased storage capacity in the Big Rock Point spent fuel storage pool. The Description and Safety Analysis of the proposed increase had been previously submitted by Consumers Power Company letter dated April 23, 1979
- TRC letter dated August 17, 1979 transmitted a number of questions related to this request. The ansvers to those :iRC questions were transmitted October 1, 1979 iRC letter dated September h, 1979 requested additional information regarding said subj ect.
Attached is the Consumers Power Company's response to the Request for Additional Information pertaining to the proposed expansion of the storage capacity of the spent fuel pool for the Big Rock Point Plant.
David P Hoffman (Signed)
David P Hoffman Assistant liuclear Licensing Administrator CC JGKeppler, US:iRC 1206 528 7910240 9
9
ADDITIONAL INFORMATION RELATIVE TO INCREASE IN BIG ROCK POTUT SPERT FUEL STORAGE CAPACITY The additional information requested by NRC letter dated Septe=ber h, 1979 is provided below:
1.
Provide the esti=ated volume of contaminated material (e.g., spent fuel racks, seismic restraints, additional pool filters, radvaste system de-mineralizer resins) expected to be removed from the plant because of tue pool modificaton and shipped to a licensed burial site.
RESPONSE
The volume of contaminated material to be removed from the plant and shipped tc a licensed burial site as a result of the proposed spent fuel storage ex-pansion is expected to be less than that processed as a result of a typical refueling outage and is estimated to be approximately 6 ft3 During a typical refueling outage, the full core has been offloaded which has resulted in activity and crud buildup'in the spent fuel pool principally from the introduction of reactor coolant system vater to the pool through the trans-fer cask. Operating refueling experience has shown that crud buildup in the pool is the primary contributor to increased doses in the vicinity of the pool and that removal of the crud through the fuel pool " sock" filter is sufficient to reduce the dose rate. Typically, two filter socks are replaced during a refueling outage, each contributing 2 7 ft3 to the contaminated material for processing. Experience has shown that cycling fuel pool water through the radvaste demineralizer has little effect on the operating life expectancy of the demineralizer tesin beds.
Disposal of the failed fuel rack is no longer planned. This rack vill be de-conta=inated and left on site. Accordingly, no seismic restraints, racks or demineralizer resins are anticipated to be removed as a result of the proposed spent fuel storage expansion. The primary contributor to the contaminated material expected to be processed will be due to fuel pool filter sock replacement.
- 206 329 1
2.
Discuss the history of leakage of water from the opent fuel pool, the pool leak collection system and the pool leak detection system. Discuss where pool leakage would be transferred to for disposal.
RESPOIISE:
The spent fue?. pool is considered essentially leak-tight. Jo significant leakuge fror. the spent fuel pool has been encountered since initial operation of the plant in 1962. Some moist areas were identified from time to time; however, no.ollectible amounts were resultant. Since installation of a stain-less steel liner in 1974 (to resolve blistering problems with the original phenolic coating), no liquid attributable to the spent fuel pool has been observed.
A leakage detection system consisting of stainless steel channels imbedded between the concrete pool structure and the stainless steel liner was installed along with the liner. Any lea tage from the liner would flow through the channels into collection lines terminating at an open basin. Periodic inspec-tion te made at the collection lines by individually opening manual valves in the lines and observing any flow. Any such resultant flow from the collection basin would drain to the reactor building sump and thence to the liquid rad-vaste system.
Moisture observed during periodic inspection is believed to be due to conden-sation rather than pocl leakage.
Any pool leakage, should it occur, would be transferred to the liquid radvaste system via the reactor building " dirty" sump.
1206 330 2
3 Provide the number of spent fuel movements needed for the proposed pool =odi-fication. These fuel movements may disturb the crud material on the assemblies.
Discuss the addition of crud material to the pool vater because of these fuel movements during the modification of the pool, the ability of the pool filtering system to remove tne crud material from the pool vater and the effect of the crud material in the water on dose rates in the vicinity of the pool.
RESP 3 HSE:
Detailed written procedures will be prepared by the installation contractor and approved by CP Co prior to commencement of installation. These procedures vill prescribe the path of movement and sequence of installation of the new racks, the relocation of the existing racks in their final positions (including the procedures for removal and decontamination of the failed fuel rack), and the redistribution of fuel assemblies if required after all racks are in their. final positions. Specific details regarding the procedurec are not available at this time as we are currently evaluating several possible installation pathways and sequences. The number of spent fuel movements has not been determined; however, it is anticipated that no more movements than experienced during a typical re-fueling vill be required.
As a basis for the avaluation of alternate pathways and sequences of installa-tion, we have de reloped acceptance criteria that vill beco=e a functional part of the procedures. The following considerations vill be imposed as acceptance criteria on the detailed written procedures.
ALARA Considerations Occupational radiation exposures shall be maintained as lov as reasonably achievable by the following:
a.
Surveillance and monitoring by Health Physics of personnel and sreas involved in the spent fuel rack expansion.
b.
Reduction in area dose rates by the following:
(1) Filtering spent fuel water through spent fuel pool filter to minimize crud buildup; (ii) Cycle fuel pool vater through radvaste system demineralizer to reduce waterborne doses as required; (iii) Reduce disturbance of crud in pool by minimizing spent fuel movements and movement of racke near the pool floor; (iv) Vacuuming pool valls, floor, and existing racks, as necessary, and (v) Decontamination, as possible, of areas around spent fuel pool.
1206 33I 3
(Question 3 - Response - Contd)
Installation Considerations The following installation considerations provide acceptable means for ensuring that a safe plant condition is maintained and any deleterious impact on safety-related structures, systems and components or additional risk to the health and safety of the public is precluded:
a.
Installation routes shall follow routes analyzed in regard to cask-drop hazard with particular attention to precluding possible interaction between the racks (eg, direct drop or tipping) and safety-related structures, sys-tems or components. In no case shall the route chosen present a hazard to safety-related structures, syste=s or components that has not been previously review and/or analyzed.
b.
Crane speeds in both vertical and horizontal directions sha.'l be maintained so as to prevent uncontrolled motion of the racks.
c.
do rack shall be moved in the vicinity of stored spent fuel so that a direct drop or tipping of the rack vill result in damage to the spent fuel. Addi-tional administrative controls vill be developed as required to preclude the dropping or tipping of a rack on stored spent fuel, d.
All racks shall be moved only when empty.
e.
One operation vill be conducted at one time only (eg, shuffling fuel, moving racks, etc).
f.
Racks will be transferred to the spent fuel pool area during a plant shut-down unless a transfer route is available which will preclude damage to safety-related equipment as a result of any postulated direct drop or tipping of a rack.
The detailed written procedures vill, by design or through the imposition of administrative controls, preclude a hazard to safety-related structures, systems or components that has not been previously snalyzed and found acceptable.
Crud disturbed during fuel assembly or fuel raca movements will be removed through the spent fuel " sock" filter. Principal :ru/. buildup in the spent fuel pool has resulted during reloading as a result of full-core offloads which have
~
been required and the introduction of crud to the pool through the transfer cask.
Crud buildup in the pool as a result of this proposed activity is anticipated to be less serious than during reloading because no reactor coolant will be trans-ferred to the pool.
The spent fuel pool filter has proven to be effective in removing crud buildup resulting from refueling activities and consequently lowering doses in the vicinity of the pool.
1206 332 u
h.
Discuss the effect ot* the proposed pool modification on the radvaste system de=ineralizer (e.g., frequency of replacement).
RESPONSE
Spent fuel pool vater is typically cycled through the radvaste system demin-eralizer on an annual basis to reduce radiation levels in the pool and naintain water quality. No more frequent operation has been typically necessary.
The annual cycling of the pool water through the de=ineralizer has had little noticeable effect on the frequency of replacement of the resin beds. There-fore, the proposed expansion of spent fuel storage is not anticipated to impact the operation or frequency of replacement of the radvaste system desineralizer.
')2Ob 5
5 Provide the failed fuel fraction for each fuel cycle for the last 5 years at Big Rock Point.
RESPOIISE:
The failed fuel fraction for the last five years is as follows:
Cycle EOC Assemblies Failed kreentage of Core Failed 12 06/02/74 15 17.86 13 01/31/76 7
8.3 14 07/23/77 0
0 15 02/02/79 0
0 All of the above fuel asse=blies are presently stored in the spent fuel pool.
6
6.
Discuss the instrumentation to indicate spent fuel pool water level and water te=perature. Include the capability of the instrumentation to alarm and the indication of the alarms.
RESPO:ISE:
Spent fuel pool water level indication is provided by two independent means:
a.
A sight glass for the surge tank located on the south wall of the fuel pool; and b.
Direct visual observation of the fuel pool from the reactor operating deck.
Temperature indication is provided locally at the discharge of the two spent fuel pool cooling system pumps and at the outlet of the two spent fuel pool cooling system heat exchangers. Operational procedures require visual verifi-cation of surge tank level and pool water level and logging of the temperature indication at the pump discharge at least once per shift. Visual verification of spent fuel pool cooling system pump operating status can also be made during the temperature logging function.
1206 335 7
7-Identify the principal radionuclides and their respective concentrations in the spent fuel pool water found by ga==a isotopic analyses prior to and following refueling. Provide the dose rate values above and around the spent fuel pool fro = these concentrations of radionuclides.
RESPONSE
The principal radionuclide in the spent fuel pool water is iodine with the re= inder being lumped into the classifications of " crud" and " filtrate." The counts on each classification range as follows over the years 1977 and 1978:
1977 1978 Hish*
___Lov*
High*
Lo r*
~5
~9
~9 Iodine 2.4 x 10 1 x 10 3.4 x 10-1 x 10
-3
-3 Filtrate 4.6 x 10-2.7 x 10-11 7 x 10 2.31 x 10 Crud 19.8 x 10" 11 7 x 10
~
- Units: pCi/=1 The dose rate over the spent fuel pool water at vaist height is 20-30 =R/h and at other locations around the pool or below is 10 =R/h.
1246 336 8
8.
Provide an estimate of the annual man-rem from all operations in the SFP area including refueling. The estimate should be based on occupancy time and dose rates from fission and corrosion product concentrations and any contaminated equipment that may be stored in the pool.
RESPONSE
An estimated 2300 man-hours / yea.* are to be spent in the vicinity of the spent fuel pool at the time the expansion is to be made. Maintenance and Radiation Protection personnel will spend most of their time in the lgwer radiation areas around the pool while Operations and other personnel vill be working at the east end and over the spent fuel pool. The breakdown of man-hours is estimated as follows:
Onerations Maintenance Radiation Prot Other Total (Man-h/Yr)
Hormal 0
0 1/h Man-h/ Day 0
91 Man-h/ Year Ops 91 Man-h/ Year Cask 16 Man-h/
3 Men 8 Man-h/ Ship-o 576 Man-h/ Year Ship-Shipment 8 Hours ment ment 192 Man-h/Yr 288 Man-h/
96 Man-h/ Year (12/Yr)
Year R&D 3 Man-h/ Day 0
2 Man-h 2 Men 177 Man-h/ Year 5 Days / Year 2 Man-h/ Year 2 Shifts 15 Man-h/Yr 5 Days Refuel-8 Man-h/ Day 4 Man-h/ Day 1 Man-h/ Day 2 Men 1452 Man-h/ Year ing 2 Months 2 Months 2 Months 3 Shifts h80 Man-h/Yr 2h0 Man-h/
60 Man-h/ Year 2 Weeks Year 672 Man.
h/ Year Total (Man-h/
Year) 687 Man-h/Yr 528 Man-h/Yr 2h9 Man-h/Yr 832 Man-2296 Man-h/ Year
.h/ Year The averace dose rate on the reactor level which includes the fuel pool, spent fuel inspection area and the shield tank over the reactor vessel is approximately 13 mR/ hour. Therefore, the annual expected exposure for this work area is approximately 30 man-rem / year.
1206 337 9
9 In your submittal dated April 23, 1979, you stated that the failed fuel rack to be removed from the spent fuel pool vill be cut up and shipped off site for disposal. You estimated 27 man-rems will be received by personnel per-forming these operations. Based on the above actions, please provide the following information:
a.
Provide the breakdown of your evaluation of 27 can-rems as follows:
Number of workers involved in each phase of the operation including divers, if any; the duration of each phase; the exposure rate (mr/hr) to occupational workers during each phase of the operation including the dose rate expected from the rack when it is removed from the SFP vater and the man-res received by all workers involved for each phase.
Demonstrate that the removal of the rack with a cumulative dose of 27 man-rem is as lov as reasonatly achievable in contrast to other licensees that have performed the same operation removing several contaminated spent fuel racks with a lesser man-rem exposure.
b.
Demonstrate that your disposal method of cutting and shipping the failed fuel rack to be removed will provide as low as is reasonably achievable exposure as compared to crating the entire rack and then shipping it.
RESPONSE
The estimated man-dose of 27 man-Rems discussed in Subsection 3.2 3 of the April 23, 1979 Environmental Impact Evaluation represented the original esti= ate of the radiation exposure from all activities related to the proposed spent fuel storage rack expansion. It represented the "one time" exposure to individuals performing the removal of the failed fuel rock and installation of the new racks.
As a result of more definite information regarding the installation process, we have revised our original estimate of this one-time radiatic: exposure. The following information has been utilized as a basis for the occupational radia-tion exposures estimated to be received by workers as a result of the proposed fuel storage e:cpansion.
a.
The breakdown of the estimated man-dose for the spent fuel rack addition at the Big Rock Point Plant is provided in Table 9-1 attached hereto.
Table 9-1 provides a breakdown of the following: The number of workers involved in each phase of the operation; the duration of each phase; the exposure rate (mR/h) to occupational workers during each phase of the opera-tion including the dose rate expected from the failed fuel rack when it is removed from the spent fuel pool vater and the man-Rem received by all workers involved for each phase.
The estimated total exposure of 27 man-Re=s, as presented in Subsection 3.2.3 of the Environmental Impact Evaluation, has been revised to 23.3 man-Rems as shown in Table 9-1.
This revision has resulted from the de-cision to decontaminate but not dispose of the failed fuel rack as dis-cussed in response to Question 1 of this second round of requests for additional information. The cumulative total exposure of 23.3 man-Rems is considered to be as lov as reasonably achievable at the Big Rock Point Plant.Oh 3)b 10
(Question 9 - Response - Contd) b. As discussed above and in response to Question 1, the failed fuel rack will not be disposed of or shipped off site for disposal. This rack vill be decontaminated and will remain on the plant site.for use during refueling to temporarily store miscellaneous small equipment. Subsection 3.2.3 of the Environmental Impact Evaluation vill be revised to indicate a total exposure of 18.2 man-Rems for all phases of the opera-tion and clarify the final disposition of the failed fuel rack. 1206 339 11
1 TABLE 9-1 ESTIMATED MAH-DOSE FOR SPENT FUNL RACK ADDITION AT BIG ROCK POINT PLANT Number of Work Time Average Dose Man-Dose Function Personnel (Hours / Worker) Rate (mR/h) (Man-Rem) Phase I a. Failed fuel rack removal and decon-tamination. 2 16 300 9.6 b. Crating failed fuel rack and removing from containment to on-site storage locations. 2 24 40 19 c. Shuffling FAs and old rack relocation. 5 20 20 2.0 Phaue II a. Install new racks. 5 72 20 T.2 b. Shuffling FAs to final locations. 5 20 20 2.0 DJ a Phase III CT' a. Ger.eral decontamina-tion and cleaning in Lea 4?- pool area. 2 16 20 0.6 CD TOTAL MAN-DOSE FOR SPENT FUEL RACK ADDITION 23.3
10. Provide a list of all objects that are required to be moved over or near the spent fuel storage pool. For each object listed, provide its approxi-cate weight and size, a diagram or description of the transfer path utilized, and the frequency of movement.
RESPONSE
A list of the larger and heavier moveable objects currently in or around the spent fuel pool is as follows: Approx Size Weight a. Fuel Fool Filter Sock Cask 5' x 2' 2,000 Lb b. Exxon Profilometer 27' x 6" Pipe 500 Lb c. Exxon Periscope 27' x 2-3/4" 300 Lb d. Exxon Fuel Rod y-Scan T' x h" 1,500 Lb This is not intended to be exhaustive, but is representative of typical objects handled a-- the sient fuel storage pool 1206 341 13
11. Identify any heavy load or cask drop analyses performed to date for your facility. Provide a copy of all such analyses not previously submitted to the NRC staff.
RESPONSE
On February 4, 1974, USAEC requested that CP Co provide additional " analyses and other relevant information," to that previously supplied in the FHSR relating to possible damage in the event of a cask drop event. On July 1, 1974, CP Co submitted the results of a study of postulated cask drop incidents and proposed modifications intended to increase the existing margins of safety in cask handling operations. On February 6,1976, the USNRC staff issued the Safety Evaluation Report supporting the evidence provided by CP Co in the July 1,1974 submittal and subsequent re-sponses to requests for additional information. One supplemental analysis has been performed and is attached. This analysis was intended to support handling of the 15-ton and 7 5-ton cask during operation. The review, however, was terminated and the casks are not handled during oper-ation. Therefore, this analysis has not been used as a basis for plant operation. ?n.6 342 e 14}}